854  
FXUS02 KWBC 132040  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
439 PM EDT WED APR 13 2022  
 
VALID 12Z SAT APR 16 2022 - 12Z WED APR 20 2022  
 
...OVERVIEW AND GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT..  
 
RELATIVELY LOW AMPLITUDE MEAN FLOW ALOFT SHOULD PREVAIL OVER THE  
LOWER 48 THROUGH THE WEEKEND, IN THE WAKE OF A DEPARTING DEEP  
UPPER LOW WORKING FROM THE GREAT LAKES/NORTHEAST TO THE CANADIAN  
MARITIMES. GUIDANCE SHOWS A GRADUALLY AMPLIFYING SHORTWAVE TROUGH  
AND ASSOCIATED RAIN/SNOW FOCUSING SYSTEM PROGRESSING INTO AND  
THROUGH THE WEST DURING THE WEEKEND ONWARD TO THE NORTH-CENTRAL  
U.S. BY EARLY NEXT WEEK.  
 
HOWEVER, THE PATTERN OVER THE LOWER 48 IS THEN EXPECTED TO  
TRANSITION TO MORE AMPLIFIED FLOW, LIKELY IN PART DUE TO EFFECT  
FROM THE UPSTREAM PROGRESSION AS A DEEP EXTRATROPICAL LOW TO THE  
ALEUTIANS OF CURRENT WEST PACIFIC TYPHOON MALAKAS. AS SUCH, AN  
AMPLIFIED UPPER TROUGH REACHING THE WEST COAST BY TUESDAY WOULD  
BUILD DOWNSTREAM UPPER RIDGING TO ALSO ALLOW POTENTIAL TO  
DIG/CARVE OUT A CLOSED LOW OVER THE GREAT LAKES/MIDWEST THAT IS  
EXPECTED TO WORK IN EARNEST INTO THE NORTHEAST BY MIDWEEK.  
 
ACCORDINGLY, THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY  
DERIVED FROM A COMPOSITE BLEND OF THE 00 UTC ECMWF/CANADIAN AND  
ECMWF ENSEMBLE MEAN THAT OFFER A DECENTLY CLUSTERED OVERALL  
SOLUTION THAT IS ON THE MORE AMPLIFIED SIDE OF THE FULL ENVELOPE  
OF GUIDANCE SOLTUIONS. LATEST 12 UTC GUIDANCE IS TRENDING TOWARD A  
MORE COMMON PATTERN AMPLITUDE EVOLUTION. THIS RAISES FORECAST  
CONFIDENCE TO A DEGREE, ALBEIT WITH OVERALL FLOW NOT QUITE AS  
AMPLIFIED AS THE EARLIER DERIVED WPC GUIDANCE BLEND, BUT MORE  
AMPLIFIED THAN THE 00/06 UTC GFS/GEFS MEAN.  
 
   
..WEATHER HIGHLIGHTS/THREATS
 
 
THE DEPARTING LOW PRESSURE SYSTEM NORTH OF THE GREAT LAKES SHOULD  
CONTINUE TO PRODUCE SOME GENERALLY LIGHT TO MODERATE PRECIPITATION  
ACROSS THE GREAT LAKES/NORTHEAST AS A SECONDARY SURFACE LOW LIFTS  
OFF THE COAST. MOISTURE AND INSTABILITY INTERACTING WITH A WARM  
FRONT LIFTING THROUGH THE SOUTH/SOUTHEAST THIS WEEKEND AND  
APPROACH OF A COLD FRONT FROM THE NORTH SHOULD BRING AREAS OF  
MODERATE TO LOCALLY HEAVY RAINFALL TO PARTS OF THOSE AREAS, BUT  
FOR NOW WITH LOW CONFIDENCE IN EXACT PLACEMENT OF HEAVIEST TOTALS.  
FARTHER WEST, A SYSTEM FORECAST TO REACH THE WEST BY SATURDAY  
SHOULD CONTINUE TO FOCUS RAIN/MOUNTAIN SNOW OVER THE CENTRAL AND  
NORTHERN WEST COAST INTO THE NORTHERN ROCKIES LATE THIS WEEK INTO  
THE WEEKEND. MOISTURE SHOULD SPREAD EAST BEYOND THE ROCKIES SUNDAY  
ONWARD 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, AGAIN. GUIDANCE IS TRENDING SIGNIFCANTLY UPWARD THE  
PRECIPITATION POTENTIAL/INTENSITY OVER THE EAST. THIS SEEMS  
ESPECIALLY EVIDENT OVER NEW ENGLAND AS THE EXPECTED APPROACH OF  
THE AFOREMENTIONED UPPER LOW MAY SPAWN DEEP SURFACE CYCLOGENESIS.  
THIS WILL OFFER THE POTENTIAL FOR RUNOFF ISSUES OUTSIDE OF  
NORTHERN AREAS IN AN EMERGING THREAT AREA FOR WRAPPING/WINDY  
SPRING SNOWS.  
 
MEANWHILE, THE CENTRAL ROCKIES/HIGH PLAINS COULD SEE A BRIEF  
PERIOD OF STRONG WINDS AROUND SUNDAY WITH SYSTEM PASSAGE.  
UPSTREAM, EXPECT ANOTHER EPISODE OF PRECIPITATION FROM THE PACIFIC  
NORTHWEST/NORTHERN CALIFORNIA INTO THE NORTHERN ROCKIES THROUGH  
EARLY NEXT WEEK, WITH SOME ENHANCED TOTALS POSSIBLE OVER FAVORED  
COASTAL/TERRAIN AREAS. PRECIPITATION POTENTIAL MAY INCREASE INTO  
NEXT MIDWEEK WITH APPROACH OF ANOTHER AMPLIFIED UPPER TROUGH AND  
FRONTAL PROGRESSION.  
 
THE CORE OF BELOW NORMAL TEMPERATURES ACROSS THE NORTHERN PLAINS  
AND VICINITY WILL LIKELY PERSIST INTO EARLY NEXT WEEK, WITH  
DAYTIME HIGHS GENERALLY 20-30F BELOW NORMAL, AND MODERATING SLOWLY  
WITH TIME. OVER THE WEST, TEMPERATURES SHOULD MODERATE IN BETWEEN  
SYSTEMS AS A PERIOD OF UPPER RIDGING MOVES THROUGH. 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. AS THE UPPER RIDGE BUILDS OVER THE  
REGION BY THE START OF NEXT WEEK, NORTHERN LOCATIONS SHOULD TREND  
TOWARD NORMAL AND SOUTHERN AREAS ABOVE NORMAL. THE GREAT BASIN AND  
SOUTHWEST COULD SEE HIGHS AS WARM AS 10-15F ABOVE NORMAL. THE EAST  
SHOULD STAY NEAR NORMAL ON SATURDAY, 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. THE SOUTHERN PLAINS  
WILL SEE HIGHS 10-15F ABOVE NORMAL NEXT WEEKEND FOLLOWED BY A  
COOLING TREND.  
 
SCHICHTEL/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  
 
HAZARDS:  
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE NORTHEAST, TUE, APR  
19.  
- HEAVY RAIN ACROSS PORTIONS OF CALIFORNIA AND THE PACIFIC  
NORTHWEST, WED, APR 20.  
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHEAST, THE LOWER  
MISSISSIPPI VALLEY, THE SOUTHERN APPALACHIANS, AND THE TENNESSEE  
VALLEY, SUN, APR 17.  
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHEAST AND THE  
MID-ATLANTIC, MON, APR 18.  
- HEAVY SNOW ACROSS PORTIONS OF THE UPPER MISSISSIPPI VALLEY AND  
THE NORTHERN PLAINS, SUN, APR 17.  
- FLOODING POSSIBLE ACROSS PORTIONS OF THE NORTHERN PLAINS, THE  
UPPER/MIDDLE MISSISSIPPI VALLEY, THE SOUTHEAST, THE GREAT LAKES,  
AND THE OHIO VALLEY.  
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE SOUTHEAST,  
THE MIDDLE MISSISSIPPI VALLEY, THE UPPER MISSISSIPPI VALLEY, AND  
THE NORTHERN PLAINS.  
- FLOODING LIKELY ACROSS PORTIONS OF THE UPPER MISSISSIPPI VALLEY  
AND THE NORTHERN PLAINS.  
- HIGH WINDS ACROSS PORTIONS OF THE CENTRAL ROCKIES, THE CENTRAL  
PLAINS, AND THE CENTRAL GREAT BASIN, SUN, APR 17.  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE CENTRAL  
ROCKIES, THE CENTRAL PLAINS, THE NORTHERN PLAINS, AND THE NORTHERN  
ROCKIES, SAT-SUN, APR 16-APR 17.  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE UPPER  
MISSISSIPPI VALLEY AND THE NORTHERN PLAINS, SAT-TUE, APR 16-APR 19.  
 
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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