499  
FXUS02 KWBC 100701  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 AM EDT SUN APR 10 2022  
 
VALID 12Z WED APR 13 2022 - 12Z SUN APR 17 2022  
 
...POTENT STORM SYSTEM TO BRING HEAVY SNOW/BLIZZARD CONDITIONS  
ACROSS THE NORTHERN PLAINS WITH HEAVY RAINFALL AND SEVERE WEATHER  
FROM THE GULF COAST TO THE MID-MISSISSIPPI VALLEY...  
   
..OVERVIEW
 
 
THE LATEST GUIDANCE CONTINUES TO SUPPORT AN ACTIVE WEATHER PATTERN  
ACROSS THE LOWER 48 INTO NEXT WEEKEND. THE MAIN SYSTEM OF INTEREST  
IS AN AMPLIFIED TROUGH/DEVELOPING CLOSED LOW OVER THE NORTHERN  
U.S./UPPER MIDWEST WHICH SHOULD SPIN UP A RATHER IMPRESSIVE  
LOOKING SPRING STORM SYSTEM. THIS SYSTEM BRINGS A FULL ARRAY OF  
WEATHER HAZARDS MID TO LATER NEXT WEEK... INCLUDING HEAVY SNOW AND  
POSSIBLE BLIZZARD CONDITIONS TO THE NORTH AND WEST OF THE LOW  
TRACK ACROSS THE NORTHERN PLAINS AND SEVERE WEATHER AND HEAVY TO  
EXCESSIVE RAINFALL IN THE WARM SECTOR. UPSTREAM, UNCERTAINTY IS  
HIGH REGARDING FLOW INTO THE WESTERN U.S. BUT CHANGES ARE THAT  
ANOTHER TROUGH MAY KICK OUT INTO THE WEST NEXT WEEKEND.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
MODELS CONTINUE TO SHOW HIGHER THAN AVEARGE UNCERTAINTY  
SURROUNDING AN AMPLIFIED TROUGH IN THE CENTRAL U.S. WHICH  
EVENTUALLY DEVELOPS INTO A DEEP CLOSED UPPER LOW TRACKING ACROSS  
THE NORTHERN PLAINS AND UPPER MIDWEST. WHILE ALL MODELS NOW  
SUGGEST A RATHER SIGNIFICANT STORM SYSTEM, THERE REMAINS A LOT OF  
QUESTIONS ON TRACK AND TIMING OF THE SURFACE LOW AND ATTENDENT  
COLD FRONT ACROSS THE SOUTH AND MIDWEST. THE 18Z/APR 9 GFS IS THE  
FASTEST WITH CLOSED LOW DEVELOPMENT, BUT IS ACTUALLY NOT TOO FAR  
OUT OF LINE WITH LOCATION OF SURFACE LOW PRESSURE AT DAY 3-4 IN  
THE UPPER MIDWEST. AFTER THIS, LIKELY A RESULT OF A MUCH BLOCKIER  
WESTERN ATLANTIC RIDGE, THE GFS GETS MUCH FASTER WITH STEERING  
THIS LOW QUICKLY NORTHWARD, WHILE THE ECMWF AND CMC SUGGEST THE  
UPPER SYSTEM IS SHEARED/REDEVELOPS OVER THE GREAT LAKES/EASTERN  
CANADA NEXT WEEKEND. ENSEMBLE MEANS DO NOT REALLY GIVE A CLEAR  
ANSWER HERE AS THEY GENERALLY CONTINUE TO FOLLOW THEIR  
DETERMINISTIC COUNTERPARTS. IN THE INTEREST OF CONTINUITY,  
CONTINUED TO FAVOR THE ECMWF OVER THE GFS, WITH INCREASING  
WEIGHTING TOWARDS THE ECENS/GEFS MEANS LATE PERIOD.  
 
BEYOND WEDNESDAY/THURSDAY, FLOW UPSTREAM ACROSS THE WEST BECOMES  
VERY UNCERTAIN WITH SOME SIGNIFICANT MODEL VARIABILITY ESPECIALLY  
BY THE DAY 6-7 TIME FRAME. THERE IS INCREASED CONSENSUS ON SOME  
KIND OF OPEN SHORTWAVE (OR CLOSED LOW) INTO THE PACIFIC NORTHWEST  
ON FRIDAY. MODELS SUGGEST ANOTHER TROUGH INTO THE WEST NEXT  
WEEKEND, BUT THE DETAILS ON EMBEDDED ENERGY WITHIN THAT TROUGH AND  
AMPLIFCATION BECOME VERY MURKY NEXT WEEKEND WITH VERY POOR MODEL  
RUN TO RUN CONTINUITY. A BLEND HEAVILY WEIGHTED TOWARDS THE  
ENSEMBLE MEANS GETS SOME WEAK TROUGHING ACROSS THE WEST WITH A  
HINT AT LOW PRESSURE ONCE AGAIN MOVING INTO THE PLAINS NEXT SUNDAY.  
 
   
..WEATHER HIGHLIGHTS/THREATS
 
 
SOME LINGERING SNOWFALL IS LIKELY AS THE PERIOD BEGINS WEDNESDAY  
ACROSS THE WEST, BUT BY THEN A WELL DEVELOPED STORM SHOULD BE  
TRACKING ACROSS THE NORTHERN PLAINS/UPPER MIDWEST WITH A  
SIGNIFICANT SNOW STORM LIKELY TO THE NORTH AND WEST OF THE SURFACE  
LOW ACROSS THE DAKOTAS AND NORTHWEST MINNESOTA. HEAVY SNOWFALL,  
POSSIBLY EXCEEDING A FOOT IN SOME LOCATIONS, WITH GUSTY WINDS  
COULD CREATE BLIZZARD CONDITIONS LEADING TO HAZARDOUS TRAVEL AND  
POWER OUTAGES IN MANY AREAS. MEANWHILE IN THE WARM SECTOR, THERE  
WILL BE INCREASING COVERAGE AND INTENSITY OF RAIN AND  
THUNDERSTORMS AHEAD OF THE ATTENDANT COLD FRONT GIVEN PERSISTENT  
GULF MOISTURE AND INSTABILITY. THE STORM PREDICTION CENTER'S  
EXTENDED OUTLOOK INDICATES SEVERE POTENTIAL ACROSS THE LOWER AND  
MIDDLE MISSISSIPPI VALLEY ON WEDNESDAY, WITH MORE UNCERTAIN  
POTENTIAL FARTHER EAST INTO THE SOUTHEAST ON THURSDAY. HEAVY TO  
EXCESSIVE RAINFALL CONCERNS MAY FOCUS ON THE SOUTHERN SIDE ACROSS  
THE LOWER MISSISSIPPI AND TENNESSEE VALLEY, BUT FARTHER NORTH,  
DYNAMICS WRAPPING AROUND THE LOW MAY SUPPORT AN ADDITIONAL AREA OF  
MODEST RAINFALL ACROSS THE UPPER MISSISSIPPI VALLEY. THIS MAY  
CAUSE LOCALIZED FLOODING AND FLASH FLOODING ISSUES THERE AS WELL  
PARTICULARLY IF RAIN FALLS OVER FROZEN OR SNOW COVERED GROUND.  
RAINFALL MAY LINGER THROUGH FRIDAY ACROSS THE SOUTHEAST AS THE  
WESTERN PART OF THE BOUNDARY STALLS ACROSS THE REGION.  
 
OUT WEST, MODERATE TO HEAVY RAIN/MOUNTAIN SNOWS ARE POSSIBLE  
ACROSS PARTS OF CALIFORNIA/OREGON WITH THE NEXT LOW PRESSURE  
SYSTEM MOVING IN LATE THIS WEEK. MOISTURE LOOKS TO SPREAD EAST  
INTO THE INTERMOUNTAIN WEST, WITH MORE UNCERTAINTY BY NEXT SUNDAY  
REGARDING PRECIPITATION INTO THE PLAINS.  
 
MUCH BELOW NORMAL TEMPERATURES (WITH ANOMALIES 20+ DEGREES BELOW  
AVERAGE) WILL SHIFT EASTWARD WITH TIME INTO THE NORTHERN PLAINS  
INTO NEXT WEEKEND. SOME MODERATION IS LIKELY BY LATER IN THE WEEK  
ACROSS THE WEST, THOUGH STILL BELOW NORMAL WITH ADDITIONAL  
TROUGHING MOVING IN. MEANWHILE, AHEAD OF THE BIG STORM, EXPECT  
TEMPERATURES FROM THE SOUTH-CENTRAL U.S. TO THE EAST TO BE ABOVE  
NORMAL, BUT TRENDING BACK TOWARDS NORMAL FOLLOWING PASSAGE OF THE  
COLD FRONT.  
 
SANTORELLI  
 
ADDITIONAL 3-7 DAY HAZARD INFORMATION CAN BE FOUND ON THE WPC  
MEDIUM RANGE HAZARDS OUTLOOK CHART AT:  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP  
 
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION, EXPERIMENTAL EXCESSIVE RAINFALL  
OUTLOOK, WINTER WEATHER OUTLOOK PROBABILITIES AND HEAT INDICES ARE  
AT:  
 
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=ERO  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML  
 

 
 

 
 
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