537  
FXUS02 KWBC 120649  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
248 AM EDT TUE APR 12 2022  
 
VALID 12Z FRI APR 15 2022 - 12Z TUE APR 19 2022  
 
   
..OVERVIEW
 
 
LOWER AMPLITUDE FLOW SHOULD DOMINATE THE LOWER 48, AT LEAST THE  
FIRST HALF OF THE PERIOD, BEHIND A DEPARTING DEEP UPPER LOW WHICH  
MAY LINGER ACROSS EASTERN CANADA INTO NEXT WEEK. GUIDANCE  
GENERALLY SHOWS A SHORTWAVE PROGRESSING INTO/THROUGH THE WEST  
DURING THE WEEKEND AND INTO THE PLAINS/MISSISSIPPI VALLEY BY EARLY  
NEXT WEEK. THIS FEATURE MAY PRODUCE ANOTHER ROUND OF PRECIPITATION  
OVER THE NORTHERN AND EASTERN PART OF THE COUNTRY. ALTHOUGH THERE  
IS SOME AGREEMENT WITH THE LARGE SCALE PATTERN, THERE IS STILL  
PLENTY OF UNCERTAINTY WITH RESPECT TO SPECIFIC  
SYSTEM/PRECIPITATION DETAILS ALL THE WAY FROM THE WEST COAST INTO  
THE EAST. WEST COAST MAY GET A BREAK FOR A DAY OR TWO BEFORE THE  
NEXT SYSTEM APPROACHES NEXT TUESDAY.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
THE GFS CONTINUES TO BE A LITTLE BIT ON THE FASTER SIDE WITH THE  
DEEP UPPER LOW COMING OUT OF THE UPPER MIDWEST ON FRIDAY, AS WELL  
AS A WEAK LOW THAT MAY TRACK OFFSHORE NEW ENGLAND. DESPITE THIS, A  
GENERAL BLEND OF THE DETERMINISTIC GUIDANCE GAVE A GOOD STARTING  
POINT. THE NEXT SYSTEM ENTERS THE WEST BY SATURDAY, WITH THE  
GFS/ECMWF A BIT FASTER THAN THE CMC/UKMET. BY SUNDAY-MONDAY  
HOWEVER, UNCERTAINTIES IN THE DETAILS OF THIS SYSTEM REALLY RAMP  
UP. THE GFS HAS CONSISTENTLY THE PAST FEW RUNS BEEN A BIT QUICKER  
AND MUCH FLATTER/WEAKER, BUT ALSO DOESN'T HAVE GREAT RUN TO RUN  
CONTINUITY. THE ECMWF HAS PRESENTED THE BEST RUN TO RUN CONTINUITY  
WITH THIS SYSTEM BUT IS ALSO BY FAR THE STRONGEST AND QUICKEST TO  
DEVELOP A RATHER DEEP/WOUND UP SYSTEM OVER THE MIDWEST STATES BY  
NEXT TUESDAY. THE CMC IS WEAKER AND FLATTEST WITH THE ENERGY AS IT  
COMES THROUGH THE PLAINS NEXT WEEKEND BUT IT DOES EVENTUALLY SHOW  
A DEEP CLOSED LOW ACROSS THE MIDWEST LIKE THE ECMWF. CONFIDENCE IS  
LOW ON ANY ONE SOLUTION, BUT REGARDLESS IT SEEMS LIKELY SOME SORT  
OF LOW PRESSURE SYSTEM WILL MOVE ACROSS THE CENTRAL/EASTERN STATES  
LATE PERIOD. YET ANOTHER SYSTEM LOOKS TO MOVE INTO THE WEST NEXT  
TUESDAY, AND AT THIS POINT, MODELS SHOW DECENT AGREEMENT ON TIMING  
BUT OF COURSE DIFFER IN INTENSITY AND DETAILS. THE WPC BLEND  
TRENDED TOWARDS THE ENSEMBLE MEANS LATE PERIOD TO HELP MITIGATE  
DIFFERENCES.  
 
   
..WEATHER HIGHLIGHTS/THREATS
 
 
THE DEPARTING LOW PRESSURE SYSTEM WILL LIKELY CONTINUE TO BRING  
GUSTY WINDS INTO FRIDAY ACROSS THE NORTHERN TIER, RESULTING IN  
BLOWING A DRIFTING OF SNOW AND POSSIBLE HAZARDOUS TRAVEL  
CONDITIONS IN REGIONS THAT RECEIVED HEAVY SNOWFALL IN PRIOR DAYS.  
SOME GENERALLY LIGHT PRECIPITATION SHOULD ALSO LINGER ACROSS THE  
GREAT LAKES/NORTHEAST AS WELL ASSOCIATED WITH THIS SYSTEM.  
MOISTURE AND INSTABILITY INTERACTING WITH A WARM FRONT LIFTING  
THROUGH THE SOUTHEAST NEXT WEEKEND SHOULD BRING MODERATE TO  
LOCALLY HEAVY RAINFALL TO PARTS OF THE SOUTHEAST/LOWER MISSISSIPPI  
VALLEY. OUT WEST, A COUPLE SYSTEMS MAY BRING RAIN/MOUNTAIN SNOW TO  
PARTS OF THE PACIFIC NORTHWEST AND CALIFORNIA INTO THE NORTHERN  
ROCKIES LATE THIS WEEK INTO THE WEEKEND. SOME OF THE ACTIVITY FROM  
THE WEST COAST INTO THE CASCADES COULD BE MODERATE TO HEAVY BUT  
THERE IS CONSIDERABLE UNCERTAINTY OVER SPECIFICS OF EACH SYSTEM,  
SO CONFIDENCE IS LOWER THAN AVERAGE FOR DETERMINING  
COVERAGE/TIMING OF THE MOST SIGNIFICANT PRECIPITATION. MOISTURE  
SHOULD SPREAD EAST BEYOND THE ROCKIES BY NEXT SUNDAY-MONDAY AS LOW  
PRESSURE/FRONTS REACH THE CENTRAL/EASTERN U.S. AT LEAST SOME  
PRECIPITATION ACROSS THE NORTHERN TIER MAY BE IN THE FORM OF SNOW  
WHILE RAINFALL COVERAGE/INTENSITY OVER THE EAST WILL DEPEND ON  
CURRENTLY UNCERTAIN SYSTEM DETAILS. THE CENTRAL ROCKIES/HIGH  
PLAINS COULD SEE A BRIEF PERIOD OF STRONG WINDS AROUND SUNDAY WITH  
SYSTEM PASSAGE.  
 
EXPECT THE CORE OF BELOW NORMAL TEMPERATURES TO PERSIST ACROSS THE  
NORTHERN HIGH PLAINS INTO EARLY NEXT WEEK, WITH DAYTIME HIGHS  
GENERALLY 20-30F BELOW NORMAL. LOCALLY COLDER READINGS (ESPECIALLY  
FOR DAYTIME HIGHS) ARE POSSIBLE LATE THIS WEEK WHEN SOME LINGERING  
DAILY RECORDS FOR LOWS/COLD HIGHS ARE POSSIBLE. OVER THE WEST,  
TEMPERATURES SHOULD MODERATE IN BETWEEN SYSTEMS AS A PERIOD OF  
UPPER RIDGING MOVES THROUGH. THURSDAY-SATURDAY WILL FEATURE CHILLY  
READINGS OVER THE NORTHERN HALF OF THE REGION (MINUS 10-15F  
ANOMALIES FOR HIGHS) AND CLOSER TO NORMAL TEMPERATURES FARTHER  
SOUTH. AN UPPER RIDGE BUILDING OVER THE REGION BY THE START OF  
NEXT WEEK SHOULD BRING NORTHERN LOCATIONS TOWARD NORMAL AND  
SOUTHERN AREAS MODERATELY ABOVE NORMAL. THE EAST SHOULD STAY NEAR  
NORMAL THIS WEEKEND, BUT THE SYSTEM POTENTIALLY REACHING THE  
MIDWEST/EAST EARLY NEXT WEEK COULD DRAW SOME OF THE CHILLY  
NORTHERN PLAINS AIR SOUTHWARD AND EASTWARD BEHIND IT, WITH  
EXPANDING COVERAGE OF MINUS 10-20F ANOMALIES. MODERATELY ABOVE  
NORMAL TEMPS SHOULD ALSO SHIFT FROM THE SOUTHERN PLAINS INTO THE  
SOUTHWEST/CENTRAL GREAT BASIN EARLY NEXT WEEK.  
 
SANTORELLI/RAUSCH  
 
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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