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
…SUMMARY…
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.
…SYNOPSIS…
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.
…SRN/CENTRAL TX…
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
TODAY.
Severe Threat Saturday
…SUMMARY…
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
COLORADO.
…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
…SUMMARY…
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
SUNDAY.
…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
REGION.
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
