Heavy Snow in April
Take a look at the image below from the Wyoming Highway Patrol Facebook page… Heavy snow and high speeds led to this near 50-car pile up along highway I-80 on Thursday.
*Update for I 80 multi-vehicle crash between Cheyenne and Laramie*
33 commercial vehicles and 12 passenger vehicles is the latest estimate that were involved in one of the three crash sequences along with multiple other vehicles that were not part of an actual crash, but became stranded in the event due to road blockage. 16 motorists were transported by ambulance and 11 motorists were transported by a Laramie County School District bus to Cheyenne Regional Medical Center in Cheyenne, Wyoming. Six of those injured were critical to serious leg or spine injuries. No fatalities were reported from this event.
Speeds too fast for the blizzard conditions and loss of control are being investigated as contributing factors in the crashes that caused a “domino” style chain reaction after the first couple of vehicles lost control.
Agencies that responded were the Wyoming Highway Patrol, Laramie County Sheriff’s Office, Albany County Sheriff’s Office, Wyoming Office of Homeland Security, Laramie County Fire Districts 1, 2, and 10, AMR Ambulance, F.E. Warren First Responders, Wyoming National Guard First Responders, City of Laramie Fire Department, WYDOT and multiple tow companies from Cheyenne and Laramie. Joint training between all of these agencies and their dispatchers was credited for the rapid response, extrication, treatment and transport of those injured in the event.
Interstate 80 between Cheyenne and Laramie is expected to remain closed into tonight and possibly through the early morning hours of tomorrow (April 17th) as the investigation and cleanup continues through the evening. Weather will hold a strong determining factor for the investigators and cleanup crews as to when I 80 will be ready to reopen. Again, we ask motorists at the road closed gates in Cheyenne and Laramie to please be patient and check for updates at www.wyoroad.info or by calling 1-888-WYO-ROAD (1-888-996-7623)
Heavy Snow Reports…
Here are some of the heaviest snowfall reports I could find from earlier this week. These reports came in from the National Weather Service out of Salt Lake City, UT – note the 45″ amount from Snowbird in the Wasatch Mountains!!
Active Thursday Weather
From heavy snow in the Mountains to severe weather and tornadoes in the Central U.S.; it was a very active Thursday. In all, there were nearly 150 reports of severe weather (hail, damaging winds and tornadoes), 10 of which were tornado reports.
2015 Tornado Reports
According to NOAA’s SPC (thru April 15th), the PRELIMINARY tornado count was 107. Until recently, 2015 was off to an incredibly slow start to the severe weather season. We are currently on pace with 2014, which was a pretty quiet year. The 2005-2014 tornado average through April 15th is 348.
National Weather Outlook
Our slow moving storm system will continue to pump out snow across the Intermountain-west with heavy rain and strong to severe thunderstorms across the Plains into the weekend. Snow will begin to taper by late weekend, while heavy rain and strong to severe storms begin to shift a little farther east on Sunday.
Severe Threat Friday
SEVERE THUNDERSTORMS ARE POSSIBLE…MAINLY THIS AFTERNOON AND
EVENING…FROM THE EASTERN PLAINS OF COLORADO TO WESTERN AND CENTRAL
OKLAHOMA AND SOUTHWARD TO SOUTH TEXAS. THE THREATS WILL INCLUDE
LARGE HAIL…DAMAGING WINDS AND A FEW TORNADOES.
IN MID-UPPER LEVELS…SPLIT-FLOW PATTERN IS EVIDENT OVER CONUS WITH
NEARLY ZONAL NRN BRANCH NEAR CANADIAN BORDER…AND BIG/WELL-DEFINED
CYCLONE INITIALLY CENTERED OVER WRN PORTIONS CO/NM BORDER. THAT
CYCLONE IS EXPECTED TO MOVE SLOWLY ENEWD-NEWD ACROSS CO THROUGH
PERIOD…AS SEVERAL VORTICITY LOBES ORBIT ITS 300-400-NM-WIDE
CIRCULATION CORE. REGIME OF DIFLUENT FLOW AND SPORADIC SHOTS OF
LOBE-PRECEDING DCVA ARE EXPECTED TO PIVOT NEWD FROM BASE REGION OF
ASSOCIATED SHORTWAVE TROUGH OVER NM…AND ACROSS CENTRAL/SRN PLAINS.
MEANWHILE…BY 00Z…SWLY SRN-BRANCH JET…ENHANCED BY GRADIENT
EFFECTS OF CYCLONE…WILL ATTAIN SPEEDS OF 100-110 KT AT 250 MB FROM
NRN COAHUILA TO CENTRAL/N-CENTRAL TX.
AT SFC…11Z ANALYSIS SHOWED LOWS OVER SWRN KS AND MAF AREA…WITH
DRYLINE EXTENDING SSWWD FROM MAF LOW INTO BIG BEND REGION. DRYLINE
WAS ILL-DEFINED AND ERRATIC BETWEEN THOSE TWO LOWS…BECAUSE OF
INFLUENCES OF PRIOR CONVECTIVE PROCESSES. DRYLINE SHOULD BECOME
BETTER DEFINED AGAIN THIS AFTN AS DEEP MIXING OCCURS ABOVE HIGH
PLAINS FROM SERN CO ACROSS ERN NM AND W TX. NET RESULT SHOULD BE
POSITIONING OF DRYLINE NEAR 100W FROM SWRN KS SWD BY LATE
AFTN…ARCHING DIFFUSELY NWWD ACROSS ERN CO. MULTIPLE SUCCESSIVE
CONVECTIVE EPISODES HAVE LEFT STG COLD POOL OVER PORTIONS
KS/OK…WITH OUTFLOW BOUNDARY EVIDENT OVER PARTS OF NERN…S-CENTRAL
AND SWRN OK ATTM.
SCATTERED TO LOCALLY NUMEROUS TSTMS ARE FCST TO DEVELOP THIS AFTN
INTO AT LEAST EARLY EVENING AND MOVE ACROSS THIS AREA. A FEW
SUPERCELLS WITH LARGE HAIL…DAMAGING GUSTS AND A TORNADO OR TWO ARE
POSSIBLE INITIALLY…TRANSITIONING TO ONE OR MORE UPSCALE-EVOLVING
MCS WITH DAMAGING WIND AS PRIMARY CONCERN.
EXTENSIVE PRIOR-DAY CONVECTION HAS LEFT BEHIND RESERVOIR OF
RELATIVELY STABLE/LOW-THETAE AIR ACROSS PORTIONS SE TX AND LA.
NONETHELESS…RICH LOW-LEVEL MOISTURE IS EVIDENT IN SFC
ANALYSES…CRP/DRT RAOBS AND REMOTELY SENSED PW DATA S AND W OF THAT
REGIME ACROSS NWRN GULF AND S-CENTRAL/DEEP SOUTH TX. NWD ADVECTION
OF THIS MOISTURE IS EXPECTED TODAY AROUND WRN RIM OF OLD OUTFLOW
AREA…WHILE LATTER AIR MASS SLOWLY MODIFIES IN FAVORABLE FASHION
FROM W-E AS DIABATIC SFC HEATING PROCEEDS THROUGH AFTN. NET EFFECT
WILL BE TO SUPPLY VERY FAVORABLE BUOYANCY…WITH MLCAPES RISING INTO
2500-3000 J/KG RANGE IN SOME AREAS. ALTHOUGH LOW-LEVEL WINDS AND
SHEAR EACH WILL BE MODEST…DEEP-LAYER AND CLOUD-LAYER SHEAR SHOULD
VENTILATE CONVECTION WELL BENEATH SUBTROPICAL JET BRANCH.
…CENTRAL HIGH PLAINS TO OK…
EXTENSIVE COOLING/STABILIZATION OF BOUNDARY LAYER BY MULTIPLE
OVERNIGHT CONVECTIVE COMPLEXES HAS OCCURRED AND CONTINUES ATTM OVER
MUCH OF WRN/CENTRAL OK…FOR A FEW HUNDRED MILES UPSTREAM IN PROGGED
LOW-LEVEL TRAJECTORIES FEEDING INTO CENTRAL HIGH PLAINS. THIS HAS
RENDERED AIR-MASS RECOVERY AND POTENTIAL FOR ANY SUBSTANTIAL SVR
EVENT MORE CONDITIONAL AND MORE UNLIKELY ACROSS AREAS PREVIOUSLY IN
ENHANCED RISK. SVR PROBABILITIES ARE DOWNGRADED…BUT STILL PRESENT
AS SLGT RISK FOR NOW.
ISOLATED TO WIDELY SCATTERED STG-SVR TSTMS ARE POSSIBLE THIS
AFTN…AS DIABATIC SFC HEATING BEHIND MORNING ACTIVITY COMBINES WITH
RESIDUAL MOISTURE AND COOLING ALOFT TO GENERATE SFC-BASED BUOYANCY
AND REMOVE CINH. LARGE HAIL AND STG/ISOLATED SVR GUSTS ARE
POSSIBLE…AND A TORNADO OR TWO CANNOT BE RULED OUT. ALTHOUGH
OUTFLOW BOUNDARY ACROSS SRN OK SEEMS TO BE IDEAL FOR FOCUSING
CONVECTION LATER TODAY…AND MAY INDEED DO SO…RELATIVE WEAKNESS IN
MIDDLE-UPPER-LEVEL FLOW AND DEEP SHEAR COMPARED TO FARTHER NW AND S
CASTS SOME DOUBT ON POTENTIAL STORM ORGANIZATION. STILL…MESOSCALE
TRENDS MAY COMPEL GREATER SVR PROBABILITIES NEAR THAT BOUNDARY LATER
Severe Threat Saturday
SEVERE THUNDERSTORMS WITH WIND DAMAGE AND HAIL ARE POSSIBLE SATURDAY
ACROSS MUCH OF CENTRAL AND EASTERN TEXAS EASTWARD INTO LOUISIANA.
THUNDERSTORMS WITH HAIL AND A FEW STRONG WIND GUSTS ARE ALSO
POSSIBLE FROM OKLAHOMA NORTHWESTWARD ACROSS KANSAS INTO NORTHEASTERN
…SOUTH AND CNTRL TX/SW LA…
AN UPPER-LEVEL TROUGH IS FORECAST TO MOVE INTO THE SRN HIGH PLAINS
ON SATURDAY AS A SFC TROUGH DEVELOPS ACROSS WCNTRL TX EXTENDING SWD
INTO THE RIO GRANDE VALLEY. A LOW-LEVEL JET IS FORECAST AT THE START
OF THE PERIOD OVER LA WHERE WIDESPREAD THUNDERSTORM DEVELOPMENT MAY
BE ONGOING. THIS ACTIVITY COULD HAVE A MARGINAL SEVERE THREAT DURING
THE DAY. FURTHER TO THE WEST…THE MODELS SUGGEST A CORRIDOR OF
MODERATE INSTABILITY WILL BE IN PLACE BY AFTERNOON ACROSS SRN AND
CNTRL TX. ALTHOUGH CONVECTIVE COVERAGE IS UNCERTAIN…THE GFS AND
ECWMF SOLUTIONS DEVELOP CONVECTION FROM THE TX HILL COUNTRY SEWD TO
THE TX COAST SATURDAY AFTERNOON.
GFS FORECAST SOUNDINGS AT 21Z/SATURDAY AT CORPUS CHRISTI SHOW MLCAPE
AROUND 1500 J/KG WITH SFC DEWPOINTS IN THE LOWER 60S F AND STEEP LOW
TO MID-LEVEL LAPSE RATES. IN ADDITION…0-6 KM SHEAR IS 45 TO 50 KT
WITH SOME DIRECTIONAL SHEAR BELOW 850 MB. THIS SHOULD SUPPORT
SUPERCELL DEVELOPMENT WITH LARGE HAIL AND WIND DAMAGE POSSIBLE. IF
THE MORE AGGRESSIVE GFS SOLUTION IS CLOSER TO VERIFYING…THEN AN
ENHANCED SEVERE THREAT MAY DEVELOP ACROSS PARTS OF SRN AND CNTRL TX
SATURDAY AFTERNOON. FURTHER TO THE NORTH ACROSS NCNTRL TX…ENOUGH
INSTABILITY IS FORECAST FOR A SEVERE THREAT. HOWEVER…DEEP-LAYER
SHEAR SHOULD BE WEAKER HELPING TO KEEP THE POTENTIAL FOR HAIL AND
WIND GUSTS MORE ISOLATED.
…SRN AND CNTRL PLAINS…
AN UPPER-LEVEL LOW IS FORECAST TO MOVE EWD INTO THE CNTRL HIGH
PLAINS ON SATURDAY AS A SFC LOW DEEPENS ACROSS THE TX PANHANDLE. A
NARROW CORRIDOR OF INSTABILITY IS FORECAST FROM WRN OK NWWD INTO
WCNTRL KS AND INTO NERN CO. THE AIRMASS SHOULD BECOME UNCAPPED BY
AFTERNOON WITH SCATTERED THUNDERSTORMS DEVELOPING ALONG THIS
CORRIDOR. A FEW CLUSTERS OF THUNDERSTORMS MAY ORGANIZE AND PERSIST
FROM LATE AFTERNOON INTO THE EVENING.
GFS FORECAST SOUNDINGS AT 00Z/SUNDAY IN NW OK AND SRN KS SHOW SFC
DEWPOINTS NEAR 60 F WITH MLCAPE OF 1000 TO 1500 J/KG. IN
ADDITION…0-6 KM SHEAR IS FORECAST TO BE NEAR 40 KT WITH STEEP
MID-LEVEL LAPSE RATES. THIS SHOULD SUPPORT SEVERE STORMS WITH HAIL
AND STRONG WIND GUSTS POSSIBLE. CELLS THAT CAN DEVELOP IN AREAS
WHERE INSTABILITY IS MAXIMIZED…MAY BE ABLE TO ROTATE AND PRODUCE
LARGER HAILSTONES. FURTHER TO THE NORTHWEST INTO NW KS…SRN NEB AND
NE CO…INSTABILITY IS FORECAST TO BE WEAKER THAN IN THE SRN PLAINS.
HOWEVER…COLD AIR ALOFT AND STEEP LAPSE RATES BENEATH THE
UPPER-LEVEL LOW MAY BE ENOUGH FOR STORMS THAT PRODUCE HAIL.
Severe Threat Sunday
THUNDERSTORMS WITH WIND DAMAGE AND SEVERE HAIL WILL BE POSSIBLE FROM
EASTERN PARTS OF THE SOUTHERN PLAINS EASTWARD TO THE CENTRAL GULF
COAST STATES ON SUNDAY AFTERNOON. THUNDERSTORMS WITH WIND DAMAGE
POTENTIAL WILL ALSO BE POSSIBLE ACROSS THE MID MISSISSIPPI VALLEY
…ARKLATEX/LOWER TO MID MS VALLEY…
A BROAD UPPER-LEVEL TROUGH IS FORECAST TO MOVE EWD ACROSS THE SRN
AND CNTRL PLAINS ON SUNDAY AS A COLD FRONT ADVANCES QUICKLY EWD INTO
THE ARKLATEX AND OZARK MOUNTAINS. AHEAD OF THE FRONT…A BROAD WARM
SECTOR IS FORECAST FROM EAST TX EWD INTO THE CNTRL GULF COAST STATES
WHERE MODERATE INSTABILITY SHOULD BE IN PLACE BY AFTERNOON. MODEL
FORECASTS ARE IN FAIRLY GOOD AGREEMENT…DEVELOPING CONVECTION ALONG
A PRE-FRONTAL TROUGH JUST AHEAD THE FRONT AND MOVING THE CONVECTION
EWD ACROSS THE ARKLATEX AND MID MS VALLEY SUNDAY AFTERNOON. NAM
FORECAST SOUNDINGS ALONG THE INSTABILITY AXIS AT 21Z ON SUNDAY FOR
LITTLE ROCK AR AND SHREVEPORT LA SHOW AN IMPRESSIVE THERMODYNAMIC
ENVIRONMENT WITH MLCAPE FORECAST TO BE IN THE 3000 TO 4000 J/KG
RANGE. THIS COMBINED WITH 0-6 KM SHEAR OF 30 TO 40 KT WITH STEEP
LAPSE RATES SHOULD BE FAVORABLE FOR STRONG UPDRAFTS. SUPERCELLS
SHOULD BE CAPABLE OF PRODUCING LARGE HAIL AND WIND DAMAGE. AS STORM
COVERAGE INCREASES DURING THE AFTERNOON…LINEAR DEVELOPMENT MAY
ALSO OCCUR. VEERED WINDS JUST AHEAD OF THE FRONT WITH UNIDIRECTIONAL
WIND PROFILES ABOVE 850 MB COULD BE FAVORABLE FOR AN ENHANCED
WIND-DAMAGE THREAT ESPECIALLY IF A COLD POOL CAN ORGANIZE ACROSS THE
FURTHER SOUTH ACROSS THE CNTRL GULF COAST AND LOWER MS
VALLEY…THUNDERSTORM DEVELOPMENT WILL ALSO BE POSSIBLE SUNDAY
AFTERNOON. HOWEVER…LARGE-SCALE ASCENT SHOULD BE LIMITED KEEPING
ANY CONVECTIVE DEVELOPMENT ISOLATED IN NATURE AND CONCENTRATED ALONG
OUTFLOW BOUNDARIES OR ZONES OF LOW-LEVEL CONVERGENCE.
STILL…DEEP-LAYER SHEAR MAY BE STRONG ENOUGH WHICH COMBINED WITH
MODERATE INSTABILITY COULD SUPPORT MARGINALLY SEVERE WIND GUSTS
ACROSS THE REGION.
Heavy Rainfall/Flooding Potential
According to NOAA’s HPC, the 3 day precipitation forecast suggests pockets of heavy rainfall across parts of the Plains and the Gulf Coast States. Through AM Monday, some spots could see 1″ to 3″ with isolated higher amounts in heavier thunderstorms, especially across the Gulf Coast States.
Cooler Weather Ahead…
It’s not too bad now; in fact, it’s quite mild across much of the nation. Here’s a look at the temperature profile a few thousand feet off the ground PM Friday – note that much of the nation looks fairly mild.
Highs Friday/Highs From Average
High temperatures on Friday look mild/above average for much of the nation with the only exception being the Rockies/4 Corners Region thanks to that stubborn, slow moving upper level low.
Cooler Next Week
As that slow moving low pressure system slides east, it will draw cooler temperatures south of the border into next week. By Wednesday, temperatures in the eastern half of the U.S. will be cooler than average, while folks in the western half of the country look to once again be above average!
Highs Wednesday/Highs From Average
Temperatures will fall back to near March levels in a few spots across the Upper Midwest, dropping -10F to -15F below average! A little lingering precipitation across these areas could actually mix in with a little wet snow next week!
Extended Temperature Outlook
According to NOAA’s CPC, the 8 to 14 day temperature outlook (April 24th-30th) suggests cooler than average conditions continuing across the Eastern U.S. through the end of the month. Meanwhile, folks across far southern Florida, the Pacific Northwest and Alaska look to be warmer than average.
Thanks for checking in and have a great weekend ahead! Don’t forget to follow me on Twitter @TNelsonWX
We’re watching a upper level low over the Four Corners that is helping to drive much of the weather over the next few days, with heavy snow in the mountains, severe storms in the Central Plains, and even more flooding threats as it helps drive moisture from the Gulf of Mexico northward to interact with a warm front.
Numerous Severe Threats
Let’s jump right into the severe threat today. An Enhanced Risk of severe storms is present over parts of Kansas, Oklahoma and Texas (in the orange shaded area), surrounded by a Slight Risk (in yellow). A Marginal Risk of severe storms then extends itself all the way to the Florida Panhandle. While large hail and damaging winds will be possible across the entire severe threat area, the best chance of large hail or even seeing a tornado is in that enhanced risk area.
On Friday, another pulse of storms are expected in a lot of the same areas as today. An Enhanced Risk of severe storms is located over southern Texas, with a Slight Risk from Texas into southern Louisiana. A second Slight Risk area is over parts of western and central Kansas into northwestern Oklahoma. Over the south, the main threats will be large hail and damaging winds. Over Kansas, large hail and an isolated tornado are possible
On Saturday, our upper level low will slowly start to creep out into the Central Plains, and slowly the storms will follow it. A Slight Risk of severe weather has been placed from Kansas into Texas, and over toward the Mobile, AL area. Large hail will be possible from Kansas into Oklahoma. From Texas along the Gulf Coast, damaging winds will possible along with large hail.
On Sunday, we’ll watch the severe chance continue to move east across parts of the Mid-Mississippi Valley. Again, we will be looking at large hail and damaging winds.
Not only are we watching a severe threat the next few days along the northern Gulf Coast, but a flooding threat as well. Gulf moisture continues to surge northward, interacting with a warm front across the region. The result is days upon days of rain, and with totals of over a half a foot in numerous locations. And it’s just going to continue. I’m just going to post today’s area that could see flooding rains, as much of the same is expected through Saturday.
A Flash Flood Watch is in effect for the next few days across portions of the northern Gulf Coast due to the continuing heavy rain.
New Orleans, LA, has seen seven straight days of rain through Wednesday, totaling 6.59″ during that time period. There’s a good chance that the rainy streak will continue over the next four days as they continued to get hit with rain.
Mobile, AL, has seen five straight days of rain through Wednesday, with a whopping 10.41″ of rain – about 70% of that liquid falling on Sunday alone. The 7.28″ that fell Sunday counted as the fourth wettest April day on record for Mobile. It’s looking like they’ll see the rain continue for about another four days as well before a break hopefully works in!
Heavy snow has been falling in parts of the Rockies over the past 24 hours. Here are some of the snow totals so far – some locations picking up more than a foot of snow!
This was the view from Denver, CO, earlier this morning where some snow was making it to the ground! (Webcam image: CO Department of Public Health & Environment).
And we’re watching the potential of more heavy snow in parts of the Rockies over the next few days as that upper level low slowly meanders its way eastward. Some of the higher elevations could pick up over two feet of snow by the time it is done falling.
Meteorologist D.J. Kayser
On Tuesday, April 14th, a fairly rare tornado was reported near Eugene, OR! Here was the report:
“At 405 pm a small tornado of unknown intensity briefly touched down on the campus of lane county community college. a lane county community college official witnessed a rain and hail wrapped tornado that damaged three vehicles significantly.”
Rare OR Tornado…
There have only been 102 documented tornadoes in the state of Oregon between 1950-2011. Interestingly, the state averages only 3 tornadoes per year, 0 of which typically occur in April.
National Weather Outlook
The same storm system that produced a tornado in Oregon on Tuesday, will also be the same storm system responsible for snow across the Intermountain West and a few strong/severe storms across the Plains through the end of the week. Interestingly, Denver, CO saw a high temperature of 75° on Tuesday and will likely see a few inches of sloppy snow by the end of the week! We’re also tracking a weak area of low pressure along the Gulf Coast States that will slowly churn up a few strong/severe storms with heavy rain today/tomorrow.
Here’s a look at the snowfall potential through PM Friday. Note that there could be some fairly significant amounts across parts of the Rockies! The forecast calls for up to 12″ to 24″ across parts of the Colorado Rockies through PM Friday!
(Image Courtesy: WeatherBell)
According to NOAA’s HPC, the 3 day precipitation outlook suggests a few pockets of heavy rainfall through AM Saturday. Upwards of 1″ to 3″+ may be possible across parts of the Plains, Gulf Coast States and South Carolina; mainly driven by convective precipitation
Severe Threat Wednesday
…SYNOPSIS… THE PRIMARY UPPER-AIR FEATURE OF INTEREST THIS PERIOD IS AN
AMPLIFIED SHORT-WAVE TROUGH WHICH WILL CONTINUE GENERALLY
SWD…FORMING A CLOSED LOW OVER THE CNTRL INTO SRN ROCKIES.
ELSEWHERE A SHORT-WAVE TROUGH OVER THE CNTRL/SRN PLAINS WILL
PROGRESS NEWD INTO THE OH AND TN VALLEYS BY TONIGHT.
AT THE SURFACE…MORNING MESOANALYSIS REVEALS A COUPLE OF LEE
CYCLONES…ONE OVER SRN SASKATCHEWAN AND THE OTHER IN NERN CO. THE
FORMER WILL WEAKEN WHILE DEVELOPING NEWD ALONG A COLD FRONT MOVING
THROUGH THE CANADIAN PRAIRIE PROVINCES. IN CONTRAST…DOWNSLOPE
DIABATIC WARMING COUPLED WITH THE APPROACH OF THE CNTRL ROCKIES
TROUGH WILL CONTRIBUTE TO DEEPENING OF THE CO CYCLONE AND ATTENDANT
LEE TROUGH THROUGH AFTERNOON. THIS LOW PRESSURE WILL BEGIN TO FILL
TONIGHT AS IT IS OVERTAKEN BY A COLD FRONT ADVANCING SEWD INTO THE
CNTRL HIGH PLAINS. ELSEWHERE A WEAK AREA OF LOW PRESSURE OVER THE
ARKLATEX WILL DRIFT NEWD INTO THE LOWER OH VALLEY WHILE A BACKDOOR
COLD FRONT ADVANCES SWD ALONG THE SERN ATLANTIC COAST.
…CNTRL/SRN HIGH PLAINS THIS AFTERNOON AND EVENING…
THE WEAKENING FRONTAL SYSTEM OVER SRN TX DENOTES THE NRN EXTENT OF
ROBUST BOUNDARY-LAYER MOISTURE CONTENT WITH CURRENT OBSERVATIONS
INDICATING DEWPOINTS MAINLY IN THE 40S AHEAD OF THE HIGH PLAINS LEE
TROUGH. AND WHILE SOME MOISTENING MAY OCCUR TODAY VIA HORIZONTAL
ADVECTION…STEEPENING LOW TO MID-LEVEL LAPSE RATES WILL LARGELY
CONTRIBUTE TO AFTERNOON MLCAPE APPROACHING 500-1000 J/KG FROM THE
TX/OK PNHDLS INTO SWRN NEB/NERN CO.
MORE SUBSTANTIAL MID-LEVEL HEIGHT FALLS/FORCING FOR ASCENT WILL BE
RELEGATED TO THE SRN PLATEAU REGION WITH MODEL GUIDANCE HINTING AT
THE POSSIBILITY OF A WEAK VORTICITY LOBE EJECTING FROM THE TROUGH
BASE INTO THE CNTRL HIGH PLAINS BY EVENING. BUT IT APPEARS THAT
BOUNDARY-LAYER HEATING AND SUSTAINED CONVERGENCE/UPLIFT INVOF THE
CYCLONE AND LEE TROUGH WILL BE THE PRIMARY MECHANISMS FORCING
ISOLATED TO WIDELY SCATTERED LATE-DAY STORMS. FORECAST HODOGRAPHS
EXHIBIT VERTICALLY VEERING AND STRENGTHENING WINDS WITH HEIGHT WITH
SUFFICIENT VERTICAL SHEAR FOR HIGH-BASED SUPERCELLS CAPABLE OF
MAINLY LARGE HAIL AND LOCALLY DAMAGING WIND GUSTS INTO THIS
…LOWER MS/TN VALLEYS THIS AFTERNOON INTO TONIGHT…
THE SRN EXTENSION OF THE CNTRL/SRN PLAINS SHORT-WAVE TROUGH
MENTIONED ABOVE WILL OVERSPREAD THE REGION LATER TODAY INTO THIS
EVENING ENHANCING FORCING FOR ASCENT AND VERTICAL SHEAR WITHIN A
MOIST AND MODERATELY UNSTABLE AIR MASS. THOUGH SPECIFIC DETAILS
REGARDING TSTM EVOLUTION REMAIN UNCLEAR DUE TO VARYING MODEL
SOLUTIONS…IT SEEMS PLAUSIBLE THAT A FEW STRONG TO SEVERE STORMS
MAY DEVELOP LATER TODAY INTO TONIGHT WITH A RISK FOR HAIL AND
LOCALLY DAMAGING WIND GUSTS.
…SAVANNAH VALLEY THIS AFTERNOON…
THE GRADUAL INCREASE IN SHOWERS AND TSTMS EARLY THIS MORNING OVER
ERN AL INTO WRN/NRN GA APPEARS TO BE RELATED TO A WEAK MID-LEVEL
PERTURBATION TRAVERSING THE REGION. THE CONTINUED ENEWD MOVEMENT OF
THIS FEATURE IN CONJUNCTION WITH LOW-LEVEL UPLIFT ALONG THE COLD
FRONT SHOULD GIVE RISE TO WIDESPREAD AFTERNOON TSTMS AMIDST A MOIST
AND MODERATELY UNSTABLE ENVIRONMENT. VERTICAL SHEAR WILL REMAIN
WEAK…BUT THE HIGH MOISTURE CONTENT COULD ENHANCE WATER LOADING OF
CONVECTIVE DOWNDRAFTS AND A RESULTANT RISK OF DAMAGING SURFACE WIND
Severe Threat Thursday
SCATTERED SEVERE THUNDERSTORMS ARE LIKELY ACROSS MUCH OF TEXAS WITH
OTHER SEVERE STORMS POSSIBLE INTO CENTRAL KANSAS AND WESTERN
OKLAHOMA. DAMAGING WINDS AND AN ISOLATED TORNADO WILL BE POSSIBLE
OVER SOUTHERN TEXAS…WITH LARGE HAIL AND AN ISOLATED TORNADO
POSSIBLE ACROSS THE TEXAS PANHANDLE INTO WESTERN OKLAHOMA.
AN UPPER LOW WILL SINK SLOWLY SWD ACROSS THE FOUR CORNERS AREA WITH
GRADUAL HEIGHT FALLS INTO THE SRN HIGH PLAINS. AT THE SURFACE…LOW
PRESSURE WILL DEVELOP OVER ERN NM/W TX…WITH WITH A DRYLINE
DEVELOPING AND FOCUSING AFTERNOON SUPERCELL DEVELOPMENT.
MEANWHILE…A SRN STREAM JET WILL EXTEND EWD FROM MEXICO INTO SRN TX
WHERE BACKED SURFACE WINDS WILL BRING SUBSTANTIAL LOW-LEVEL MOISTURE
NWWD DURING THE DAY. IN BOTH AREAS…COLD TEMPERATURES ALOFT AND
FAVORABLE DEEP-LAYER SHEAR PROFILES WILL FAVOR SEVERE THUNDERSTORMS.
ELSEWHERE…DAYTIME STORMS WILL OCCUR ALONG THE CNTRL GULF COAST
INTO THE SERN STATES AS WELL…BUT SHEAR WILL BE LACKING.
…CNTRL INTO SERN TX…
STRONG INSTABILITY IS FORECAST TO QUICKLY DEVELOP BY LATE
MORNING/EARLY AFTERNOON AS A RESULT OF UPPER 60S F DEWPOINTS BENEATH
COOL PROFILES ABOVE 700 MB. DESPITE THE LACK OF MUCH SURFACE FOCUS
FOR LIFT…THE GFS AND ECMWF MODELS ARE IN STRONG AGREEMENT WITH A
LARGE CONVECTIVE SIGNATURE BY 18Z…POSSIBLY AIDED BY A WEAK
DISTURBANCE ALOFT ASSOCIATED WITH THE SRN STREAM JET. WHILE THIS
MIGHT INDICATE RAPID OVERTURNING OF THE AIR MASS AND AN
MCS…VEERING WINDS WITH HEIGHT SUGGEST SUPERCELLS MAY BE PRESENT AS
WELL. THUS…DAMAGING WINDS AND HAIL ARE BOTH POSSIBLE WITH A
CONDITIONAL RISK OF A CLUSTERING OF SEVERE REPORTS. IF STORM MODE
WITH THIS ACTIVITY REMAINS MORE CELLULAR…A TORNADO OR TWO MAY
OCCUR AS WELL. STRONGER HEATING INTO THE RIO GRANDE VALLEY MAY ALSO
SUPPORT ANY STORMS THAT FORM ACROSS THE BORDER DURING THE AFTERNOON
AND EVEN OVERNIGHT AS CAPPING WILL NOT BE PARTICULARLY STRONG.
…NWRN TX…TX PANHANDLE…FAR WRN OK…SRN KS…
DEEPENING LOW PRESSURE WILL CAUSE SURFACE WINDS TO BACK ACROSS THE
CNTRL AND SRN HIGH PLAINS…BRINGING LOW-LEVEL MOISTURE WWD BENEATH
VERY COOL PROFILES ALOFT. WITH VEERING WINDS WITH HEIGHT…THIS WILL
FAVOR SUPERCELL DEVELOPMENT DURING THE LATE AFTERNOON FROM WRN TX
INTO SWRN KS. WHILE MODEL DIFFERENCES STILL EXIST WITH THIS
SYSTEM…THE GREATEST THREAT AREA FOR VERY LARGE HAIL AND A TORNADO
OR TWO WILL BE OVER THE ERN TX PANHANDLE INTO FAR NWRN TX AND WRN
OK. MODELS VARY AS TO HOW STRONG THE LOW LEVEL SHEAR WILL BE…BUT
REGARDLESS…SEVERE STORMS ARE LIKELY. SUPERCELLS WITH HAIL WILL
ALSO OCCUR INTO SWRN/CNTRL KS…BUT MOISTURE WILL BE LESSER.
…SWRN TX INTO THE MID RIO GRANDE VALLEY LATE…
SOME HEIGHT FALLS/FORCING FOR ASCENT ARE FORECAST TO PERSIST
OVERNIGHT ACROSS WRN TX. THE DRYLINE WILL LIKELY BACK WWD…WITH
SUBSTANTIAL MOISTURE HELPING TO MINIMIZE CAPPING DESPITE BEING
NIGHTTIME. MODELS DO AGREE THAT ISOLATED TO SCATTERED SUPERCELLS MAY
OCCUR BETWEEN FT. STOCKTON AND DEL RIO…AND IF THIS HAPPENS…VERY
LARGE HAIL WOULD BE LIKELY.
Severe Threat Friday
…SYNOPSIS AND DISCUSSION…
SIGNIFICANT FORECAST UNCERTAINTY EXISTS ACROSS THE CNTRL AND SRN
PLAINS ON FRIDAY WITH THE POSITION OF THE UPPER LOW ACROSS CO/AZ/NM
AS WELL AS THE DRYLINE POSITION INTO THE PLAINS. AS A RESULT…ONLY
LOW SEVERE PROBABILITIES ARE BEING INTRODUCED FOR HAIL AND WIND.
THE EXCEPTION WILL BE ACROSS SRN TX…WHERE THE SEVERE THREAT WILL
NOT DEPEND SO MUCH ON THE UPPER LOW POSITION. HERE…SUBSTANTIAL
MOISTURE AND INSTABILITY WILL REMAIN FOR SEVERE STORMS AND BENEATH
FAVORABLY STRONG FLOW ALOFT WHICH WILL ENHANCE DEEP-LAYER SHEAR
PROFILES. WIND AND HAIL WILL BE POSSIBLE. SEVERAL MODELS INDICATE A
NEWD PROPAGATING CLUSTER OF STORMS FORMING BY EARLY AFTERNOON ACROSS
S CNTRL TX…THEN CONTINUING E/NEWD ACROSS SERN AND ERN TX. WITH
RELATIVELY WEAK FLOW IN THE LOWEST 3KM…THE IDEA OF A
FORWARD-PROPAGATING MCS SEEMS REASONABLE.
High Fire Danger
MULTIPLE ELEVATED/CRITICAL FIRE WEATHER AREAS ARE FORECAST ACROSS
THE CONUS TODAY. HIGH-END CRITICAL CONDITIONS MAY OCCUR THIS
AFTERNOON/EARLY EVENING ACROSS A PORTION OF THE SRN HIGH PLAINS.
A SHORTWAVE TROUGH OVER THE NRN ROCKIES/GREAT BASIN EARLY THIS
MORNING WILL CLOSE OFF AND SLOWLY MOVE SWD TO THE VICINITY OF THE
FOUR CORNERS REGION BY LATE THIS EVENING. AT THE SFC…A PACIFIC
COLD FRONT SHOULD CONTINUE MOVING EWD ACROSS THE NRN/CNTRL
PLAINS…WHILE FURTHER S CYCLOGENESIS OVER ERN CO WILL ENCOURAGE LEE
TROUGHING OVER THE SRN HIGH PLAINS TO BECOME ESTABLISHED BEHIND A
DRYLINE. THE COLD FRONT WILL ALSO MOVE SWD OVER THE GREAT
BASIN/DESERT SW THROUGH THE PERIOD. ACROSS THE NERN CONUS…A WEAK
DRY COLD FRONT SHOULD MOVE SWD ACROSS THIS REGION WITH HIGH PRESSURE
REMAINING OVER ONTARIO/QUEBEC CANADA.
…PORTIONS OF THE CNTRL/SRN HIGH PLAINS…
WIDESPREAD STRONG/GUSTY WLY/SWLY DOWNSLOPE WINDS OF 20-35 MPH WITH
GUSTS OF 40-50 MPH WILL OCCUR ACROSS NERN NM…ERN CO…FAR SWRN
KS…AND PART OF THE TX/OK PANHANDLES THIS MORNING AND AFTERNOON
AHEAD OF THE APPROACHING COLD FRONT. WARMING/DRYING OF THE LOW-LEVEL
AIRMASS ASSOCIATED WITH THE DOWNSLOPE WINDS WILL LIKELY SUPPORT
TEMPERATURES RANGING FROM THE UPPER 60S TO UPPER 70S…WITH
RESULTANT RH VALUES OF 10-15 PERCENT LIKELY. THE CRITICAL AREA HAS
BEEN EXPANDED NWD INTO ERN CO AS LATEST GUIDANCE SUGGESTS THE COLD
FRONT NOW IN CNTRL WY WILL BE DELAYED LONG ENOUGH THIS AFTERNOON TO
ALLOW CRITICAL FIRE WEATHER CONDITIONS TO DEVELOP FURTHER N. THE
CRITICAL FIRE WEATHER THREAT SHOULD END WITH THE ARRIVAL OF THE COLD
FRONT LATE THIS EVENING INTO EARLY THU MORNING…ALTHOUGH ANY
ONGOING FIRES WILL SEE AN ABRUPT SHIFT IN WINDS FROM SWLY/WLY TO
IT IS NOT OUT OF THE REALM OF POSSIBILITY THAT SOME ISOLATED DRY
THUNDERSTORMS MAY OCCUR ACROSS ERN NM THIS AFTERNOON WITH LIFT FROM
THE UPPER TROUGH APPROACHING THIS REGION. HOWEVER…GIVEN A VERY DRY
ATMOSPHERIC COLUMN IN ERN NM AND UNCERTAINTY IN THE OCCURRENCE AND
POTENTIAL COVERAGE OF ANY THUNDERSTORMS IN THIS AREA…NO ISOLATED
DRY THUNDERSTORM AREA HAS BEEN INTRODUCED AT THIS TIME.
…PORTIONS OF THE SOUTHWEST…
BEHIND A COLD FRONT…STRONG NLY WINDS WITH CRITICALLY LOWERED RH
VALUES ARE FORECAST ACROSS THE LOWER CO RIVER VALLEY AND ADJACENT
AREAS OF THE DESERT SOUTHWEST. THE CRITICAL AREA HAS BEEN EXPANDED
INTO SERN AZ WHERE SUSTAINED WLY WINDS AHEAD OF THE COLD FRONT
SHOULD GENERALLY RANGE FROM 20-25 MPH…WITH HIGHER GUSTS. THESE
STRONG/GUSTY WINDS WILL COINCIDE WITH RH VALUES BELOW 15 PERCENT.
LATEST FUEL GUIDANCE FROM THE SW GACC FOR THIS REGION SUGGESTS FINE
FUELS HAVE RECENTLY BECOME DRY TO VERY DRY AND ARE READY TO BURN.
…PORTIONS OF SRN CA…
MODERATE TO LOCALLY STRONG OFFSHORE WINDS ARE EXPECTED TO INCREASE
THIS MORNING ACROSS PORTIONS OF SRN CA AS HIGH PRESSURE BUILDS OVER
THE GREAT BASIN. THERE SHOULD BE A RELATIVE MINIMUM IN WINDS LATER
MORNING AND AFTERNOON AS THE SFC PRESSURE GRADIENT RELAXES SOMEWHAT.
THE CRITICAL AREA HAS BEEN EXPANDED INTO THE SANTA ANA/SAN DIEGO
MTNS AND ADJACENT FOOTHILLS AS OFFSHORE WINDS SHOULD BEGIN TO
INCREASE LATE TONIGHT INTO EARLY THU MORNING ACROSS THIS AREA. AS
TEMPERATURES WARM INTO THE 70S/LOWER 80S…RH VALUES WILL RANGE FROM
THE UPPER SINGLE DIGITS TO LOW TEENS WITH POOR OVERNIGHT RECOVERY.
NELY WINDS OF 20-30 MPH WITH GUSTS TO 40 WILL BE LIKELY IN THE
FOOTHILLS WITH GUSTS NEAR 60 MPH IN HIGHER-TERRAIN FAVORED PASSES
…PORTIONS OF THE NRN PLAINS/UPPER MIDWEST…
ELEVATED TO CRITICAL FIRE WEATHER CONDITIONS WILL OCCUR ACROSS
PORTIONS OF THE NRN PLAINS/UPPER MIDWEST THIS AFTERNOON AHEAD OF A
COLD FRONT MOVING EWD OVER THE NRN HIGH PLAINS. SIMILAR TO
YESTERDAY…STRONG/GUSTY SLY WINDS SHOULD COMBINE WITH REDUCED RH
VALUES GIVEN A DRY LOW-LEVEL AIRMASS THAT REMAINS IN PLACE OVER THE
REGION. LOW-LEVEL WINDS OF 20-30 MPH WILL BE ENHANCED THIS AFTERNOON
ACROSS PORTIONS OF THE ERN DAKOTAS AND MUCH OF MN AS DIURNAL MIXING
OF THE BOUNDARY LAYER PROMOTES STRONGER WINDS ALOFT TO THE SFC. A
CRITICAL AREA HAS BEEN INTRODUCED AS CONFIDENCE IN STRONG WINDS
COMBINED WITH CRITICALLY LOWERED RH HAS INCREASED.
…PORTIONS OF THE NERN STATES…
BEHIND A WEAK COLD FRONT MOVING SWD FROM CANADA…NLY WINDS OF 10-15
MPH MAY COMBINE WITH RH VALES GENERALLY FALLING INTO THE 20-25
PERCENT RANGE THIS AFTERNOON FOR A PORTION OF ERN NY…SRN
VT/NH…FAR SRN ME…AND PORTIONS OF MA/RI. THE LACK OF STRONGER
FORECAST WINDS ALONG WITH MARGINAL FUEL DRYNESS PRECLUDES THE NEED
FOR A CRITICAL AREA.
Thanks for checking in and have a great rest of your week! Don’t forget to follow me on Twitter @TNelsonWX
We’re watching a busy weather map over the next few days. First, the threat of flooding rains continue along the Gulf Coast in places that have already seen over a half a foot of rain in the past few days. Second, a severe threat exists each day through Thursday across portions of the south. Third, something that isn’t exactly visible on the forecast loop above, but extreme fire danger exists over portion of the Northern Plains today. And fourth, we’re watching a storm system in the west that could bring feet of snow to some of the mountains. We’ll break down each of these below.
[TRACK STORMS: Interactive Radar]
Flooding Rains Continue
We’re looking at a potentially wide swath of 3″+ of rain from Texas into the Mid-Atlantic over the next five days, over the same areas that have seen heavy rain in the past few days and weeks. Parts of the northern Gulf Coast have already seen over 7″ of rain in the past few days.
We’ll continue to watch moisture from the Gulf of Mexico stream north and combine with a few disturbances that move across the area. Flooding rains are possible today over parts of the Gulf Coast from New Orleans to Mobile, and up in the Ohio Valley and Mid-Atlantic from Nashville to Charleston, WV.
On Thursday, we’ll be watching the potential of flooding along the Carolina coastline. Meanwhile, another system starts moving in and the threat of flooding rains will return again in southern Louisiana.
We’ll also be watching the severe threat over the next few days. Today a marginal threat of severe weather exists from southern Texas along the northern Gulf Coast, and in parts of North Carolina. The main severe threats today will be large hail and damaging winds.
Wednesday we’ll watch the next disturbance move off the Rockies, and a marginal risk of severe weather will exist from Colorado and Kansas into western Texas. Hail will be the main threat from any storms that turn severe.
The severe threat Thursday shifts east over much of central and eastern Texas. Damaging winds and large hail would be the main threats, but the potential of an isolated tornado will exist depending on how the severe situation develops.
We have an extreme fire threat over parts of South Dakota today in the pink shaded area, with a critical fire threat shaded in red from Arizona all the way into the Northern Plains. Today is the day to not start a fire, as any that are started will quickly spread with strong winds and dry conditions.
While it is mid-April, we are watching the potential of a snow storm forming out west over the next couple days with some areas under Winter Storm and Blizzard advisories. We are even watching the potential of snow in the Denver area heading into Thursday. Some upper higher elevation areas could see a foot or two of snow over the next couple days. What is also concerning is the potential the upper level low will hang out and slowly move east, prolonging the snow chance across the area.
Meteorologist D.J. Kayser
Soggy Sunday in Mobile, AL
It was a VERY wet day along the Gulf Coast on Sunday. Get this, Mobile, AL saw 7.28″ of rain; shattering the previous record of 3.61″ set in 1980. Not only was it a daily rainfall record for Mobile, AL, but it was also the 4th wettest April day in recorded history!
Flash Flood Watch
* THROUGH TUESDAY EVENING
* SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS ARE EXPECTED THROUGH
TUESDAY EVENING…AND AREAS OF HEAVY RAINFALL ARE EXPECTED.
ADDITIONAL RAINFALL AMOUNTS OF 3 TO 5 INCHES WILL BE POSSIBLE.
MANY AREAS OF SOUTHEAST LOUISIANA AND ACROSS THE MISSISSIPPI
COAST ALONG AND SOUTH OF THE INTERSTATE 10 12 CORRIDOR HAVE
SATURATED SOILS FROM RECENT HEAVY RAINFALL…AND ADDITIONAL
HEAVY RAINFALL MAY QUICKLY RUNOFF RESULTING IN FLASH FLOODING OF
POORLY DRAINED…LOW LYING AREAS.
* AREAS THAT SEE CONTINUOUS TRAINING OF HEAVY RAINFALL WITHIN A
SHORT TIME COULD RECEIVE FLOOD WATER TO DEPTHS THAT WOULD
IMPACT PROPERTY AND PEOPLE IN THOSE AREAS. AREA CREEKS…
STREAMS AND RIVERS ARE ALSO LIKELY TO EXPERIENCE RISES…AND
SOME MAY RISE TO BANKFULL OR FLOOD LEVELS OVER THE NEXT
National Weather Outlook
A fairly weak upper level disturbance will keep the rain/thunder threat ongoing across the Gulf Coast States through midweek. Heavy rainfall and a few strong storms can’t be ruled out. Another disturbance will begin to feed into the Rockies through the first half of the week with snow accumulations across the high elevations.
Severe Threat Monday
…TX THIS AFTERNOON/EVENING…
AN OVERALL WEAKENING TREND TO THE DEEP-LAYER CYCLONE IS FORECAST
TODAY AS IT DRIFTS EWD. HOWEVER…BREAKS IN THE CLOUDS WITHIN THE
MID-LEVEL DRY SLOT PRECEDING THE UPPER CIRCULATION CENTER COUPLED
WITH BOUNDARY-LAYER DEWPOINTS IN THE 60S WILL CONTRIBUTE TO
CORRIDORS OF MODERATE AFTERNOON INSTABILITY WITH MLCAPE VALUES
APPROACHING 1000-2000 J/KG. LOW-LEVEL UPLIFT ALONG ACTIVE
CONVECTIVE OUTFLOWS AND THE COLD FRONT MAY BE AUGMENTED BY A
VORTICITY LOBE ROTATING AROUND THE PARENT UPPER-AIR CIRCULATION TO
FOSTER AN UPTICK IN STORM COVERAGE AND INTENSITY BY AFTERNOON FROM
PORTIONS OF THE PERMIAN BASIN AND BIG COUNTRY INTO NRN AND CNTRL TX.
DESPITE RELATIVELY WEAK LOW-LEVEL FLOW…FORECAST HODOGRAPHS EXHIBIT
VEERING AND STRENGTHENING WINDS WITH HEIGHT WITH SUFFICIENT VERTICAL
SHEAR TO SUPPORT SUPERCELL STORM MODES WITH A RISK FOR LARGE HAIL
AND LOCALLY DAMAGING WIND GUSTS. A BRIEF TORNADO IS
POSSIBLE…ESPECIALLY WITH ANY SUSTAINED STORMS NEAR AND EAST OF THE
SURFACE TRIPLE POINT WHERE LOW-LEVEL SHEAR IS ENHANCED.
…CNTRL GULF COAST TODAY…
A LONG-LIVED QLCS AND ASSOCIATED MCV ARE PRESENT AS OF 12Z FROM THE
SABINE RIVER VALLEY SWD INTO THE NWRN GULF OF MEXICO WITH AN
OBSERVED SYSTEM MOTION OF 240/30-35 KT. PROXIMITY SOUNDINGS AT LCH
AND LIX SAMPLED A VERY MOIST AIR MASS WITH PW VALUES OF AROUND 1.9
INCHES AND LOWEST-100-MB MEAN-MIXING RATIOS OF 15-16 G/KG. WHILE
WIDESPREAD CLOUDS WILL LIMIT DAYTIME HEATING…THE COMBINATION OF
THE MOIST AIR MASS AND ENHANCEMENTS TO VERTICAL SHEAR AND FORCING
FOR ASCENT ON THE MESOSCALE SHOULD SUPPORT THE CONTINUATION OF THE
QLCS ACROSS THE MARGINAL RISK. WHILE ISOLATED STRONG WIND GUSTS
WILL BE THE PRIMARY HAZARD…A BRIEF TORNADO CANNOT BE RULED OUT.
…UPPER OH VALLEY/LOWER GREAT LAKES THIS AFTERNOON…
BOTH FORCING FOR ASCENT AND WSWLY DEEP-LAYER FLOW WILL INCREASE
TODAY AHEAD OF THE SHORT-WAVE TROUGH MOVING THROUGH THE REGION WITH
A BROKEN BAND OF TSTMS FORMING ALONG THE COLD FRONT BY AFTERNOON.
GENERALLY WEAK MID-LEVEL LAPSE RATES AND MARGINAL BOUNDARY-LAYER
MOISTURE CONTENT SHOULD LIMIT THE DEGREE OF AIR MASS DESTABILIZATION
AND RELATED POTENTIAL FOR HIGHER-ORDER STORM MODES.
NONETHELESS…LOCALLY STRONG WIND GUSTS MAY OCCUR WITH THE PASSAGE
OF THIS LINE OF STORMS.
Severe Threat Wednesday
…CNTRL AND SRN HIGH PLAINS…
STRONG HEATING WILL OCCUR DURING THE DAY WITH SURFACE CONVERGENCE
INCREASING DUE TO THE DEEPENING LOW. WEAK INSTABILITY WILL DEVELOP
LATE IN THE DAY COINCIDENT WITH THE ARRIVAL OF AN INCREASINGLY MOIST
AIR MASS AS SURFACE WINDS BACK. LAPSE RATES ALOFT WILL BE
STEEP…AND ISOLATED STORMS CAPABLE OF LARGE HAIL APPEAR LIKELY FROM
ERN CO INTO FAR WRN KS…ERN NM AND WRN TX. THE STRONGLY BACKED
LOW-LEVEL WINDS MAY SUPPORT A BRIEF/ISOLATED TORNADO INTO ERN CO. TO
THE S…STORMS OVER SWRN TX MAY PERSIST INTO THE OVERNIGHT PERIOD
WITH MARGINAL HAIL/WIND WITH ACCESS TO BETTER MOISTURE.
Heavy Rainfall Forecast
According to NOAA’s HPC, the 5 day rainfall forecast shows nearly 3″ to 5″+ possible through AM Saturday. Keep in mind that these are areas that have have seen quite a bit of precipitation over the past 30 days already!
Precipitation Past 30 Days
The graphic below shows how much precipitation we’ve seen over the past 30 days. Note the near 10″ to 20″ from parts of the Lower Mississippi Valley to the Ohio Valley!
(Image courtesy: WeatherBell)
Precipitation Percent of Normal
Interestingly, the swath of heavy precipitation above is any were from 110% to nearly 200%+ above average precipitation over the last 30 days. Also note that the Southwest over the last 30 days has been quite dry!
Thanks for checking in and have a great rest of your week. Don’t forget to follow me on Twitter @TNelsonWX
I hope you’re having a great weekend! Things look generally quiet across the country today with the exception of the central and southern U.S.. As a cold front works its way across the country, showers and thunderstorms will be possible. Some storms that develop later this afternoon and into this evening in eastern Kansas and northwestern Missouri could turn on the strong to severe side. Southern Texas also has a chance at seeing some severe weather tonight. Strong winds and heavy downpours are the main concerns. A Flash Flood Watch continues through tomorrow morning from Hebbronville to McAllen. Here’s the severe storm threat today from the Storm Prediction Center:
The biggest threats with any of the storms that develop in the Central Plains this evening will be strong, damaging winds and large hail.
Soggy Pattern Developing for the Southern U.S.
A stalled frontal boundary across the Gulf Coast states will continue to slowly meander northward through this week. Because the front is moving at such a slow pace, parts of the South and Southeast could pick up some impressive rainfall amounts. New Orleans to Mobile, AL have the potential of seeing some isolated 5″+ pockets of rain over the next five days. We’ll have to keep an eye on the risk for flash flooding. Here’s a look at the rainfall forecast across the Southeast for this upcoming work week:
Fire Danger in the High Plains
After a cold front works its way across the Northern Plains today, a much drier air mass will settle into the area. Pairing this with downslope westerly winds, increasing temperatures, and decreasing relative humidity leads to a critical fire risk across the High Plains. Winds will be sustained between 20-25mph today with gusts up to 30mph. Mild temperatures will cause RH values to drop between 10-15% in some locations.
Masters Golf Tournament
The weather looks beautiful for the final day of the Masters tournament in Augusta, GA. Great golfing conditions are on the way with plenty of sunshine, temperatures in the upper 70s, and light easterly winds.
Today’s National Forecast
Temperatures will continue to stay above average across much of the Upper Midwest today. The Twin Cities will warm into the low 70s this afternoon with a chance of thunderstorms developing by the evening hours. A beautiful day for viewing the cherry blossoms in Washington, D.C. with plenty of sunshine and temperatures in the upper 60s. Showers and storms are likely from Texas to Louisiana, where daytime highs will only reach the mid to upper 70s. Miami looks beautiful with temperatures in the low 80s and a slight chance of a few afternoon rain showers. Phoenix will be in the mid 80s today, but more 90s are expected later this week as a ridge of high pressure continues to build over the Southwest.
Have a great rest of your weekend!
-Meteorologist Ashley O’Connor
Follow me on Twitter!
Tornadoes in Northern Illinois
It was a busy severe weather day yesterday across the middle part of the country. Nearly 350 reports of hail, high wind and tornadoes came in; 16 of which were PRELIMINARY tornado reports. Take a look at this large tornado from near Rochelle, IL!
(Image Courtesy: NWS Chicago via Scott Prader)
Based on reports from trained storm spotters and chasers as well as radar and environmental evidence, there were at the very least two tornadoes, but likely more across North Central Illinois on April 9th.
At least two long-lived supercell thunderstorms produced these tornadoes, or family of tornadoes, across North Central Illinois.
Communities impacted based on reports include Cherry Valley, Flagg Center, Fairdale, and Kirkland.
Three damage survey teams are in the field today surveying. This process may need to go into Saturday.
Another brief tornado occurred earlier in the afternoon north of Peoria.
The atmosphere was ripe for severe weather due to highly anomalous moisture and instability for early April across the region. A strong low pressure system advanced into this favorable air mass helping to trigger these potent storms.
The potential for severe weather was mentioned in NWS forecast graphics and products as early as Saturday, April 4th.
Tornado on Radar
The loop below is from the National Weather Service out of Chicago, IL – note the fairly robust line of storms that moves into the northern part of IL by the end of the loop; at one point, you can see a classic “Hook Echo” just south of Rockford… this was one of the tornadoes that passed just NW of Rochelle, IL (pictured above).
Thursday Severe Recap
According to NOAA’s SPC, there were nearly 350 severe weather reports across the nation yesterday; 16 of those were PRELIMINARY tornado reports!
National Weather Outlook
Our severe weather threat has ended across the mid-section of the nation today. However, the same front will kick out more strong/severe thunderstorms across the eastern/southern part of the country today. Another impulse of energy may ignite a few strong/severe storms this weekend.
Severe Threat Friday
…MID-ATLANTIC INTO CAROLINAS THIS AFTERNOON INTO EVENING…
THE EWD PROGRESSION OF THE PRE-FRONTAL CONVECTIVE BAND PRESENT FROM
THE UPPER-OH VALLEY INTO CUMBERLAND PLATEAU AS OF 12Z IS FASTER THAN
MOST MODEL GUIDANCE WITH EXTRAPOLATION PLACING THE REMNANTS OF THESE
STORMS EAST OF THE BLUE RIDGE BY LATE MORNING. AHEAD OF THIS
ACTIVITY…THE SRN EXTENSION OF A SWLY LLJ WILL MAINTAIN THE
POLEWARD FLUX OF HEAT AND MOISTURE E OF THE APPALACHIANS WITH
AFTERNOON MLCAPE APPROACHING 500-1000 J/JG ALONG AND TO THE SOUTH OF
THE WARM FRONT. THIS AIR MASS DESTABILIZATION COUPLED WITH
CONVERGENCE ALONG THE SYNOPTIC FRONTS AND CONVECTIVE OUTFLOW
BOUNDARIES IS EXPECTED TO FOSTER THE DEVELOPMENT AND/OR
RE-INTENSIFICATION OF STORMS BY EARLY AFTERNOON OVER THE PIEDMONT.
A LARGELY UNIDIRECTIONAL WIND FIELD WITH DEEP-LAYER SHEAR RANGING
FROM 40-50 KT OVER THE DELMARVA TO 30-35 KT OVER THE CAROLINAS WILL
BE SUPPORTIVE ORGANIZED STORM MODES…INCLUDING SUPERCELLS AND
BOWING STRUCTURES AS ACTIVITY PROGRESSES EWD INTO THE COASTAL PLAIN.
DAMAGING STRAIGHT LINE WINDS AND MARGINALLY SEVERE HAIL WILL BE THE
PRIMARY HAZARDS WITH THESE STORMS. THE GREATEST RISK FOR A BRIEF
TORNADO OR TWO APPEARS TO BE IN THE VICINITY OF THE WARM FRONT OVER
VA…PERHAPS INTO PARTS OF MD WHERE LOW-LEVEL SHEAR IS ENHANCED.
…GULF COAST STATES INTO GA THIS AFTERNOON INTO EVENING…
12Z OBSERVED SOUNDINGS SAMPLED A MOIST ENVIRONMENT TO THE SOUTH OF
THE ONGOING STORMS WITH BOUNDARY-LAYER DEWPOINTS IN THE MID TO UPPER
60S AND LOWEST-100-MB MEAN-MIXING RATIOS OF 13-15 G/KG. THIS
MOISTURE WILL OFFSET THE TEMPERING OF DAYTIME HEATING BY EXISTING
CLOUDS TO SUPPORT POCKETS OF MODERATE AFTERNOON INSTABILITY
CHARACTERIZED BY MLCAPE OF 1000-2000 J/KG. ACTIVE COLD POOLS
ASSOCIATED WITH MORNING STORMS WILL COMBINE WITH THE ARRIVAL OF THE
SURFACE COLD FRONT TO SUPPORT AN INCREASE IN STORMS BY AFTERNOON
AMIDST A KINEMATIC ENVIRONMENT FEATURING A LARGELY UNIDIRECTIONAL
WIND FIELD AND AROUND 30 KT OF DEEP-LAYER SHEAR. THIS SETUP SHOULD
FAVOR MULTICELL CLUSTERS AND LINE SEGMENTS CAPABLE OF LOCALLY
DAMAGING WINDS AND PERHAPS MARGINALLY SEVERE HAIL INTO THIS
…SOUTH TX THIS AFTERNOON AND EVENING…
CLUSTERS OF TSTMS ARE ONGOING AS OF 12Z OVER THE EDWARDS PLATEAU
INTO BRUSH COUNTRY INVOF THE SWD-MOVING COLD FRONT…PERHAPS IN
ASSOCIATION WITH A WEAK PERTURBATION APPROACHING THE LOWER RIO
GRANDE VALLEY FROM THE W. WHILE MID-LEVEL LAPSE RATES WERE NOT
PARTICULARLY STEEP ON THE 12Z RAOBS…MOIST BOUNDARY-LAYER
CONDITIONS AND DAYTIME HEATING TO THE SOUTH OF THIS EARLY-DAY
ACTIVITY SHOULD SUPPORT MODERATE AFTERNOON INSTABILITY…AND THE
POTENTIAL FOR A FEW STRONG TO SEVERE STORMS LATER TODAY.
…SOUTHWEST TX THIS AFTERNOON AND EVENING…
POST-FRONTAL WINDS WILL BECOME ELY TODAY…ALLOWING FOR THE
ADVECTION OF AN INCREASINGLY MOIST BOUNDARY LAYER FROM THE EDWARDS
PLATEAU. HEATING ALONG THE HIGH TERRAIN WILL COMBINE WITH WEAK
DISTURBANCES EMBEDDED WITH THE SUB-TROPICAL AIR STREAM TO FOSTER
ISOLATED AFTERNOON TSTMS. STEEPENING MID-LEVEL LAPSE RATES AND
VERTICALLY VEERING WIND PROFILE WITH 40-45 KT OF DEEP-LAYER SHEAR
WILL BE SUPPORTIVE OF ROTATING STORMS WITH A RISK FOR MAINLY HAIL.
Severe Threat Saturday
…ERN CO INTO WRN KS…
DEWPOINTS INTO THE 40S F WILL RETURN NWD INTO THE LEE-TROUGHING ZONE
FROM EXTREME ERN CO INTO WRN KS BY 00Z. GIVEN 500 MB TEMPERATURES ON
THE ORDER OF -16 TO -18 C…THIS WILL BE SUFFICIENT IN COMBINATION
WITH DAYTIME HEATING TO YIELD AROUND 1000 J/KG MUCAPE. HEATING WILL
ERODE CAPPING BY LATE AFTERNOON AND CONVERGENCE WITHIN THE TROUGH
SHOULD BE ENOUGH TO INITIATE AT LEAST ISOLATED STRONG THUNDERSTORMS.
WHILE MOISTURE WILL BE LIMITED…VEERING WINDS WITH HEIGHT WILL
FAVOR CELLULAR STORM MODE…PERHAPS A HIGH-BASED SUPERCELL OR
TWO…CAPABLE OF LARGE HAIL. STORMS MAY EVENTUALLY MERGE INTO A
SMALL MCS…CONTINUING EWD ACROSS KS AND SUPPORTED BY A STRONG SLY
LOW-LEVEL JET. HOWEVER…SEVERE WEATHER IS NOT EXPECTED WITH THIS
Severe Threat Sunday
…SERN KS…MO…NRN OK…
STORMS ARE EXPECTED TO BE ONGOING EARLY SUNDAY FROM ERN KS INTO MO
IN ASSOCIATION WITH AFOREMENTIONED LEADING DISTURBANCE AND A 40 KT
SWLY LOW-LEVEL JET. WITH COOL PROFILES ALOFT AND FAVORABLE WIND
PROFILES…SOME OF THESE STORMS COULD PRODUCE HAIL.
LATER IN THE DAY IN THE WAKE OF THE EARLY ACTIVITY…HEATING AHEAD
OF THE WEAK/TRAILING FRONT WILL BE A FOCUS FOR DEVELOPMENT NEAR AND
SHORTLY AFTER 00Z DESPITE SOME CAPPING INVERSION NEAR 700 MB. AMPLE
DEEP-LAYER SHEAR AND STEEP LAPSE RATES ALOFT WILL PROMOTE VIGOROUS
UPDRAFTS AND HAIL PRODUCTION. HOWEVER…THE EVENTUAL UNDERCUTTING
FRONT MAY CONSOLIDATE THE STORMS INTO A SWD-MOVING MCS WITH SPORADIC
WIND DAMAGE POTENTIAL. PORTIONS OF THIS AREA MAY BE UPGRADED TO A
SLIGHT RISK IN LATER OUTLOOKS WHEN CONFIDENCE INCREASES.
INSTABILITY WILL BUILD DURING THE DAY PRECEDING THE ARRIVAL OF THE
UPPER TROUGH. STORMS ARE EXPECTED TO FORM OVER NRN MX INTO SWRN
TX…AND DEVELOP EWD ACROSS THE RIO GRANDE. INCREASING MEAN WIND
FIELDS ALOFT AS WELL AS SOME LOW-LEVEL TURNING WITH HEIGHT SUGGEST
PERHAPS AN MCS AND MARGINAL WIND THREAT SUNDAY NIGHT ACROSS SRN TX.
According to NOAA’s HPC, the 5 day rainfall forecast suggests another round of heavy rainfall across the south-central part of the country. The forecasts suggests an additional 1″ to 3″ through early next week.
Thanks for checking in and have a great rest of your week/weekend ahead! Don’t forget to follow me on Twitter @TNelsonWX
Numerous severe storms popped across the country yesterday from the South into the Central Plains and further east into the Mid-Atlantic. We’re taking a look back at the severe weather yesterday, as well as the severe weather threat to end the week and the ongoing flooding threat.
Recap Of Wednesday Severe Weather
Between 8 AM ET Wednesday to 2 AM ET Thursday, National Weather Service offices across the country issued 220 severe thunderstorm warnings across thirteen states and 18 tornado warnings across parts of Oklahoma, Kansas, Missouri and Indiana.
There were ~300 storm reports yesterday across the central and eastern portions of the country, with almost 200 hail reports alone. The largest hail stones were reported in Sullivan, MO (4″ hail) and Moon, KY (3″ hail).
A total of ten tornadoes were reported Wednesday, mainly across south central Kansas.
More Severe To End The Week
A multi-day severe weather event will continue today from the Ohio Valley into parts of the South, with storms spreading into the Mid-Atlantic and Southeast Friday. Meanwhile, the northern side of the storm could put out some snow in parts of Michigan and Wisconsin.
[TRACK THE STORMS: Interactive Radar]
Here is the severe threat for today – a widespread threat from Texas all the way into the lower Great Lakes. In the orange is an enhanced area of severe weather, surrounded by a slight risk in yellow. In the afternoon hours, there will be the potential for some supercell storms that could produce a few tornadoes, however large hail and damaging winds will also be possible. As we head into the evening and overnight, a line of storms ahead of the cold front will form, with damaging wind and some large hail the main threat.
As we head into Friday, the severe chances shift south and east along with the cold front, and a slight risk of severe weather is in place from Philadelphia down through Charlotte, Mobile and into Texas. Damaging winds and large hail would be the main threat with any severe storms we see on Friday.
Flooding Concerns Continue As Well
Check out the precipitation from the South into Ohio Valley over the past 60 days – many locations have seen 10″+ of liquid! So far this year, Louisville has seen 19.07″ of precipitation in 2015, a good 7.49″ above average for this time of year! It’s easy to see how some of these areas are seeing flooding risks with even just an inch of rain in a short period of time.
The threat of heavy rain continues a flooding threat across parts of the Ohio Valley into the South. Here is expected rainfall over the next five days – parts of Texas, Louisiana and Arkansas could pick up over 4″ of rain by next Tuesday!
This is how much rain is needed within a three hour period for flash flooding to occur, based off of current soil moisture conditions. Red areas would need about an inch or less, areas in yellow between about 1.5-2″, and green areas between 2-3″ of rain. Some of these areas, particularly in the Ohio Valley, would need much less within an hour for flash flooding to occur, and just like yesterday we could see that occur again.
Here is the area that the Weather Prediction Center has highlighted that rainfall rates could exceed the flash flood guidance. Areas as far north as Green Bay could see heavy, flooding rains through the afternoon and evening hours.
Have a great rest of your week – you’re almost to Friday!
A large storm system moving into the middle part of the country will be responsible for severe weather potential over the next few days. Hail, damaging winds, tornadoes and flooding rains will all be possible as the storm system pushes east through Friday.
Severe Threat Wednesday
…SRN/CENTRAL PLAINS TO OH VALLEY…
SCATTERED TO WIDELY SCATTERED TSTMS ARE EXPECTED TO DEVELOP IN
MULTIPLE EPISODES THROUGHOUT THIS PERIOD…MOVING EWD TO ENEWD
ACROSS OUTLOOK AREA WITH POTENTIAL FOR SEVERAL TORNADOES ALONG WITH
VERY LARGE/DAMAGING HAIL AND DAMAGING GUSTS.
INITIAL THREAT THIS MORNING WILL BE HAIL FROM ELEVATED TSTMS SUCH AS
THOSE NOW OVER PORTIONS MO AND IL/INDIANA. HAIL POTENTIAL EARLY
WILL BE MORE MRGL IN SIZE WITH EWD EXTENT AWAY FROM STRONGER CAPE
AND LAPSE RATES RELATED TO EML. REF SPC WW 31 AND RELATED MESOSCALE
DISCUSSIONS…ALONG WITH MESOSCALE DISCUSSION 226…FOR NEAR-TERM
INFO ON THESE SCENARIOS.
GREATEST TORNADO AND HAIL THREATS WILL ARISE THIS AFTN INTO EVENING
FROM ANY SUPERCELLS THAT MOVE THROUGH A BROAD SWATH OF FAVORABLE
CAPE AND SHEAR PARAMETER SPACE FROM NRN OK/SRN KS ACROSS MO TO SWRN
IL. TWO MOST PROBABLE — AMONG SEVERAL POSSIBLE — MECHANISMS FOR
THIS ARE CONVERGENCE NEAR FRONT AND DRYLINE THIS AFTN…AND
WARM-SECTOR DEVELOPMENT FROM ABOUT MIDDAY ONWARD.
ATTM…LARGEST-PROBABILITY TORNADO/HAIL RISK APPEARS TO ARISE FROM
AFTN CONVECTION MOVING ENEWD OFF DRYLINE AND FRONT OVER NRN OK/SRN
KS REGION THEN MOVING EWD ON EITHER SIDE OF KS/OK BORDER INTO MO
TONIGHT. CONVECTION OVER THIS AREA INITIALLY MAY DEVELOP IN
SOMEWHAT HIGHER-LCL SETTING NEAR DRYLINE…BUT MOVE INTO MORE
FAVORABLY BACKED SFC FLOW WITH TIME AND EWD EXTENT…AS WELL AS
DEEPER MOIST LAYERS NEAR FRONT AND LOWER LCLS FOR A FEW HOURS
STARTING AROUND 00Z…BEFORE MLCINH STARTS TO BECOME A HINDRANCE TO
MAINTENANCE OF DISCRETE STORMS THAT DO NOT HAVE WELL-DEVELOPED COLD
POOLS. SFC DEW POINTS 60S F AND MEAN MIXING RATIOS 11-13 G/KG WILL
CONTRIBUTE TO MLCAPE 2000-3000 J/KG…JUXTAPOSED WITH 40-50 KT
EFFECTIVE-SHEAR MAGNITUDES AND 0-1-KM SRH INCREASING TO OVER 300
J/KG ONCE LOW-LEVEL JET BEGINS TO STRENGTHEN. ONE FACTOR PRECLUDING
RISK UPGRADE ATTM INVOLVES COVERAGE UNCERTAINTY…ANOTHER BEING
SHALLOWNESS OF LOW-LEVEL MOIST LAYER EVIDENT IN UPSTREAM 12Z OUN/FWD
ANOTHER UNCERTAINTY ATTM INVOLVES TIMING AND LOCATION OF ANY
DEVELOPMENT AWAY FROM DRYLINE…IN WARM SECTOR. THIS SCENARIO IS
INDICATED BY MOST MODELS…BOTH OPERATIONAL AND EXPLICITLY
CONVECTION-ALLOWING…BUT WILL DEPEND ON RATHER POORLY FOCUSED
PROCESSES OCCURRING ABOVE SFC. INITIALLY ELEVATED/MIDLEVEL
CONVECTION POTENTIALLY MAY EVOLVE INTO SFC-BASED TSTMS ACROSS PARTS
OF NERN OK AND EWD OVER OZARKS. SUCH ACTIVITY CAN COOL/ERODE
INITIALLY WARM CAPPING LAYER VIA PRECIP…AND/OR MOVE EWD INTO AREAS
WHERE DIABATIC SFC HEATING HAS RENDERED EFFECTIVELY SFC-BASED INFLOW
SEPARATE BUT SIMILARLY EVOLVING CONVECTION ALSO MAY OCCUR FROM
SWRN/W-CENTRAL TX INTO RED RIVER REGION OF N TX/SRN OK WHERE
LOW-LEVEL WINDS/SHEAR AND BUOYANCY EACH SHOULD BE WEAKER THAN
FARTHER N…BUT STILL AT LEAST MRGLLY FAVORABLE FOR SVR.
Severe Threat Thursday
…GREAT LAKES/OH VALLEY SWWD INTO TX…
WIDESPREAD SHOWERS AND THUNDERSTORMS WILL BE ONGOING AT THE START OF
THE PERIOD WITHIN A BROAD AREA ENCOMPASSING THE UPPER GREAT LAKES
AND MID MS/OH VALLEYS. EXPECT THIS CONVECTION TO SHIFT EWD WITH
TIME…POSSIBLY INTENSIFYING DURING THE AFTERNOON ACROSS THE MID AND
UPPER OH VALLEY WHERE RISK FOR HAIL AND LOCALLY DAMAGING WINDS MAY
MEANWHILE FARTHER W…HEATING/DESTABILIZATION OF THE MOIST BOUNDARY
LAYER AHEAD OF THE FRONT SHOULD COMMENCE IN THE WAKE OF EARLIER
CONVECTION…RESULTING IN MODERATE /1500 TO 2500 J/KG/ MIXED-LAYER
CAPE ALONG THE ADVANCING COLD FRONT FROM THE MID MS VALLEY SWWD INTO
TX — THOUGH SOME QUESTIONS REMAIN AS TO WHETHER THE AIRMASS WILL
FULLY RECOVER ACROSS THE MO/IL AREAS DEPENDENT UPON EVOLUTION OF
IN ANY CASE…IT APPEARS THAT STORMS SHOULD REDEVELOP NEAR/AHEAD OF
THE FRONT DURING THE AFTERNOON…LIKELY FROM FAR SRN WI SWWD ACROSS
WRN IL AND INTO THE OZARKS AND EVENTUALLY ACROSS THE SERN
OK/ARKLATEX AREAS. WITH A BROAD AREA OF FAVORABLY STRONG WSWLYS AT
MID LEVELS SPREADING ACROSS THE WARM SECTOR…SHEAR WILL SUPPORT
RAPID ORGANIZATION OF CONVECTION — AND ATTENDANT RISKS FOR DAMAGING
WINDS AND LARGE HAIL /WITH RISKS SOMEWHAT DEPENDENT UPON WHETHER
LINEAR VS. CELLULAR STORM MODE PREVAILS/. TORNADO RISK IS ALSO
EVIDENT — PARTICULARLY ACROSS THE IL/SRN WI AREA AND VICINITY WHERE
STRONGEST/BACKED LOW-LEVEL FLOW IS EXPECTED NEAR AND AHEAD OF THE
LOW /AGAIN — DEPENDENT UPON AMPLE DESTABILIZATION IN THE WAKE OF
OVERNIGHT…EXPECT SEVERE RISK TO CONTINUE…AS STORMS EXPAND ALONG
MUCH OF THE LENGTH OF THE FRONT WHILE SPREADING EWD/SEWD ACROSS THE
MS AND OH VALLEYS.
Severe Threat Friday
…MID-ATLANTIC REGION SWWD ACROSS THE CAROLINAS…
SHOWERS AND STORMS SHOULD BE ONGOING NEAR AND W OF THE APPALACHIANS
AT THE START OF THE PERIOD…WITH THE CONVECTION — AND ASSOCIATED
COLD FRONT — TO CROSS THE MOUNTAINS THROUGH THE DAY. DEPENDING
UPON THE SPEED OF THE ADVANCE OF THE CLOUDS/PRECIPITATION INTO THE E
COAST STATES…SOME AFTERNOON DESTABILIZATION SHOULD
OCCUR…SUPPORTING AN INCREASE IN CONVECTIVE COVERAGE/INTENSITY.
WHILE VEERED FLOW THROUGH A DEEP LAYER SUGGESTS QUASI-UNIDIRECTIONAL
FLOW WITH HEIGHT…MID-LEVEL FLOW ON THE ORDER OF 40 TO 50 KT WILL
CONTRIBUTE TO SUFFICIENT SHEAR FOR ORGANIZED STORMS…AND ATTENDANT
RISKS FOR HAIL AND DAMAGING WINDS. CONVECTION — AND ASSOCIATED
SEVERE RISK — SHOULD GRADUALLY SHIFT OFFSHORE OVERNIGHT.
…THE SRN HALF OF TX EWD TO THE CENTRAL GULF COASTAL REGION…
ONGOING CONVECTION IS FORECAST ALONG THE SAGGING COLD FRONT AT THE
START OF THE PERIOD…WITH THE PRECIPITATION/CLOUDINESS CASTING
UNCERTAINTY UPON DEGREE OF HEATING/DESTABILIZATION THAT WILL OCCUR
THROUGH THE DAY NEAR AND S OF THE FRONT. PRESUMING AMPLE
DESTABILIZATION CAN OCCUR AT LEAST LOCALLY…AN INCREASE IN
CONVECTIVE COVERAGE/INTENSITY IS FORECAST…WITH STORM ORGANIZATION
TO BE AIDED BY LOW-LEVEL SELYS PROGGED ACROSS THIS AREA BENEATH
MODERATE WSWLY FLOW AT MID LEVELS. AS SUCH…RISK FOR HAIL AND
LOCALLY DAMAGING WINDS — AND POSSIBLY A TORNADO OR TWO — WARRANTS
INTRODUCTION OF SLIGHT RISK ACROSS THIS REGION.
Heavy Rainfall Potential
According to NOAA’s HPC, the 3 day rainfall forecast suggests another 1″ to 3″+ possible along and east of the Mississippi River Valley through AM Saturday. Keep in mind that a number of areas near the Ohio Valley have seen quite a bit of heavy rainfall already this month, so any additional heavy rain could lead to additional flooding.
Thanks for checking in and have a great rest of your week! Don’t forget to follow me on Twitter @TNelsonWX
Happy Tuesday! We’re watching the potential of another busy week across the country, with severe threats through Saturday and much needed western snow. That snow will come over the next couple days, as you can see in the forecast loop above. Meanwhile, rounds of storms (possibly severe) are likely in the Plains and Ohio Valley in areas that don’t need any more rain. You can see some of those rounds above as well.
[TRACK THE STORMS: Interactive Radar]
Today we are watching a potential of severe weather (marginal risk in dark green) over parts of northern and central California, as well as parts of the Central Plains into the Ohio Valley and Mid-Atlantic. The main threat today in California will be hail – meanwhile, further east, the main threats would be large hail and damaging winds. A chance of a tornado does exists, however, over parts of southeast Kansas.
The chances of severe weather starts to ramp up on Wednesday, with a slight risk of severe weather (yellow) from Oklahoma up into parts of Iowa and Illinois. Meanwhile, a marginal risk of severe weather exists from the Texas/Mexico border up into southern Minnesota and Wisconsin, and as far east as the Kentucky/West Virginia border as a large upper trough moves out of the Inter-Mountain West and into the High Plains. Very large hail, damaging winds, and tornadoes will be possible.
The severe threat continues to increase on Thursday, where an enhanced risk of severe weather exists over much of Illinois and into Missouri. A slight risk area surrounds that from southern Wisconsin and Michigan down through Texas. We will be watching for large hail, damaging winds and tornadoes as well on Thursday as we expect some supercell storms to exist at least early on in the storm initiation. There is the concern of left over clouds and storms from the previous night in the morning hours – that might help adjust where severe weather is possible in the afternoon.
The system continues east on Friday, and there is at least a 15% chance of severe weather (denoted by the blue circled area) from near the New York City area down into Georgia. It would appear hail and winds would be the main threat.
On Saturday, we’ll watch a chance of severe weather across parts of western and central Texas as gulf moisture surges into Texas. Storms will be possible later in the day, some of which could be severe.
Besides severe weather, heavy rains will also be front and center over the next few days in some areas that have already seen way too much over the past month or so. Last Thursday and Friday, Louisville, KY picked up 6.81″ of rain – 5.64″ of that on Friday alone. Both days set records in the Louisville area. Unfortunately, more rain is in their forecast, with thunderstorms possible each day through Friday. Heavy rain will be possible from Texas all the way into the Ohio Valley and Northeast.
Here is a map of three hour flash flood guidance. This indicates how much rain on average could fall before flash flooding would occur based on current soil moisture content. Numerous areas in the Ohio Valley fall into only needing 1-3″ in a three hour period for flash flooding to occur. Many of these areas would only need 1-2″ of rain in an hour for it to happen.
Heavy rains that exceed flash flood guidance are possible from Missouri into West Virginia on Wednesday.
Flooding rains will be possible Thursday from Indianapolis through Memphis into Shreveport.
Western Rain and Snow
Meanwhile, some much needed snow is coming to the Sierras and the western United States, where a couple feet are possible over the next few days. This is coming after the news that the Sierra Nevada snowpack is only sitting at 5% of its historical water content for the beginning of April. So while the coming snow will be helpful… they need a lot more to make up the ever increasing deficit they’ve seen over the past few years.
Have a great Tuesday – and a great rest of the week!