487  
FXUS02 KWBC 061943  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
341 PM EDT WED APR 06 2022  
 
VALID 12Z SAT APR 09 2022 - 12Z WED APR 13 2022  
   
..OVERVIEW
 
 
AN AMPLIFIED PATTERN IN THE MEDIUM RANGE WILL BEGIN WITH A TROUGH  
MOVING OUT OF THE EAST WHILE ANOTHER TROUGH DEEPENS/GETS  
REINFORCED AND SLOWLY MOVES EASTWARD IN THE WEST DURING THE FIRST  
PART OF NEXT WEEK. THE LATTER WILL SPREAD RAIN/HIGHER ELEVATION  
SNOW AND WELL BELOW NORMAL TEMPERATURES ACROSS THE WEST, WITH THE  
COLDER AIR AND RAIN/SNOW REACHING INTO PARTS OF THE NORTHERN AND  
CENTRAL PLAINS BY EARLY-MID WEEK. AHEAD OF THE UPPER TROUGH AND  
ASSOCIATED WAVY SURFACE FRONT, MOISTURE FLOWING NORTHWARD FROM THE  
GULF OF MEXICO SHOULD PROMOTE RAINFALL OF VARYING INTENSITY OVER  
THE EASTERN PLAINS/MISSISSIPPI VALLEY NEXT WEEK. THE EAST SHOULD  
SEE COOL WEATHER WITH SHOWERS OVER SOME AREAS OVER THE WEEKEND,  
BUT AN UPPER RIDGE MOVING FROM THE CENTRAL TO EASTERN U.S. WILL  
BRING WARMER TEMPERATURES TO THE EASTERN HALF OF THE COUNTRY FOR  
THE WORKWEEK.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
WHILE MODEL AGREEMENT AND CONFIDENCE REMAIN GOOD REGARDING THE  
EASTERN TROUGH'S TRACK EASTWARD THIS WEEKEND AS IT DEPARTS, AND  
MODELS GENERALLY SHOW TROUGHING AMPLIFYING AND RELOADING OVER THE  
WEST, THERE REMAIN AMPLE DIFFERENCES AMONG GUIDANCE FOR THE  
EVOLUTION OF DETAILS REGARDING THE WESTERN TROUGH. SHORTWAVES THAT  
SHOULD BE EMBEDDED WITHIN THE TROUGH STEM FROM LOW PREDICTABILITY  
AREAS OF THE NORTHERN PACIFIC AND NEAR ALASKA, TEMPERING FORECAST  
CONFIDENCE IN ANY PARTICULAR SOLUTION. EXAMPLES OF MODEL  
DIFFERENCES AMONG THE 00/06Z MODELS INCLUDE A NARROWER TROUGH AXIS  
BY SUNDAY IN THE CMC AND UKMET WITH A HINT OF RIDGING ON THE  
WESTERN SIDE IN THE PACIFIC NORTHWEST COMPARED TO GFS/ECMWF  
GUIDANCE, AS WELL AS THE STRENGTH AND POSITION OF SHORTWAVES IN  
THE NORTH-CENTRAL U.S. AND DIGGING INTO THE WESTERN SIDE OF THE  
TROUGH BY MONDAY. WITH THE LATTER SHORTWAVE, MODELS HAVE TENDED TO  
SHOW A STRONGER SURFACE REFLECTION JUST OFFSHORE THE PACIFIC  
NORTHWEST BUT WITH VARYING POSITIONS. INTO TUESDAY AND WEDNESDAY,  
GFS AND ECMWF RUNS CONTINUE TO SHOW A DEEPER AND SLOWER TROUGH  
THAN CMC RUNS. BUT GFS RUNS ARE MORE PHASED THAN THE ECMWF, AS THE  
EC HAS BEEN INDICATING ADDITIONAL STRONG ENERGY DROPPING INTO THE  
PACIFIC NORTHWEST BY THE END OF THE PERIOD. THE WPC FORECAST  
GENERALLY FAVORED THE ECMWF OVERALL IN TERMS OF THE DETERMINISTIC  
GUIDANCE, CONSIDERING ITS PERSISTENCE AND CONTINUITY FROM RUN TO  
RUN. THE NEWER 12Z ECMWF HAS GENERALLY KEPT A SIMILAR PATTERN.  
OVERALL THE WPC FORECAST BEGAN WITH A MULTI-MODEL DETERMINISTIC  
BLEND LED BY THE ECMWF AND GFS, BUT AS THE PERIOD PROGRESSED  
REDUCED THE WEIGHTING OF OPERATIONAL MODELS OTHER THAN THE ECMWF  
IN FAVOR OF THE REASONABLY WELL CLUSTERED (ALBEIT LESS DETAILED)  
EC AND GEFS ENSEMBLE MEANS TO ACCOUNT FOR THE INCREASING MODEL  
DIFFERENCES.  
   
..WEATHER HIGHLIGHTS/THREATS
 
 
THE UPPER TROUGH CURRENTLY EXPECTED TO AMPLIFY INTO THE WEST AND  
APPROACH OR REACH THE PLAINS BY NEXT WEDNESDAY WILL FIRST BRING  
RAIN AND HIGHER ELEVATION SNOW INTO THE PACIFIC NORTHWEST AND  
NORTHERN ROCKIES DURING THE WEEKEND. MOST TOTALS SHOULD BE IN THE  
LIGHT TO MODERATE RANGE THOUGH SOME LOCALIZED ENHANCEMENT IS  
POSSIBLE OVER FAVORED TERRAIN. A MORE FAVORABLE COMBINATION OF  
UPPER TROUGH DYNAMICS AND LOW LEVEL UPSLOPE FLOW SHOULD INCREASE  
PRECIPITATION OVER THE NORTHERN-CENTRAL ROCKIES AND HIGH PLAINS  
DURING THE FIRST PART OF NEXT WEEK, WITH THE HIGH PLAINS POSSIBLY  
SEEING SOME SPRINGTIME SNOW IN ADDITION TO THE ROCKIES. THERE ARE  
STILL IMPORTANT UNCERTAINTIES OVER THE DETAILS OF THE UPPER TROUGH  
SO CONFIDENCE IS NOT GREAT IN SOUTHWARD EXTENT AND AMOUNTS OF  
PRECIPITATION ACROSS CENTRAL/SOUTHERN PARTS OF THE WEST--AND TO  
SOME DEGREE OVER THE ROCKIES/PLAINS--AT THIS TIME. MEANWHILE IN  
THE WARM SECTOR, THERE WILL BE INCREASING COVERAGE AND INTENSITY  
OF RAINFALL OVER THE EASTERN PLAINS/MISSISSIPPI VALLEY WITH THE  
ESTABLISHMENT OF MOIST LOW LEVEL FLOW FROM THE GULF OF MEXICO.  
FARTHER EAST, COLD AIR ALOFT ASSOCIATED WITH THE UPPER TROUGH  
CROSSING THE EAST DURING THE WEEKEND WILL PROMOTE AREAS OF  
DIURNALLY ENHANCED SHOWERS FROM THE OHIO VALLEY/APPALACHIANS INTO  
THE NORTHEAST ESPECIALLY ON SATURDAY BEFORE A DRIER TREND OVER THE  
EASTERN SEABOARD EARLY NEXT WEEK. SOME PRECIPITATION COULD BE IN  
THE FORM OF SNOW, WITH THE BEST CHANCES ACROSS THE PEAKS OF THE  
CENTRAL APPALACHIANS IN WEST VIRGINIA.  
 
COLDER AIR MOVING INTO THE WEST WILL INITIALLY BRING HIGHS DOWN TO  
AS MUCH AS 10-15F BELOW NORMAL OVER THE NORTHWEST/NORTHERN ROCKIES  
DURING THE WEEKEND. AN AREA OF MINUS 10-25F ANOMALIES FOR HIGHS  
SHOULD THEN REACH INTO THE INTERMOUNTAIN WEST, ROCKIES, AND  
NORTHERN-CENTRAL PLAINS BY NEXT TUESDAY-WEDNESDAY. SUNDAY MAY  
PROVIDE THE BEST POTENTIAL FOR SOME LOCATIONS IN THE NORTHWEST TO  
SEE MAX TEMPERATURES NEAR OR BELOW CURRENT RECORD COLD HIGHS.  
MEANWHILE THE EASTERN HALF OF THE COUNTRY WILL TREND FROM MOSTLY  
BELOW NORMAL TEMPERATURES (UP TO MINUS 10-20F ANOMALIES SATURDAY),  
AND POTENTIAL FOR A LATE FROST ACROSS PARTS OF THE SOUTHEASTERN  
QUADRANT OF THE COUNTRY, TO MOSTLY ABOVE NORMAL READINGS (PLUS  
5-15F ANOMALIES) SPREADING FROM WEST TO EAST AFTER THE WEEKEND.  
 
TATE/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  
 
HAZARDS:  
- HEAVY RAIN ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY, THE  
TENNESSEE VALLEY, THE MIDDLE  
MISSISSIPPI VALLEY, THE SOUTHEAST, THE SOUTHERN PLAINS, AND THE  
OHIO VALLEY, MON-WED, APR 11-APR 13.  
- HEAVY SNOW ACROSS PORTIONS OF THE PACIFIC NORTHWEST AND THE  
NORTHERN GREAT BASIN, SAT-SUN, APR  
9-APR 10.  
- HEAVY SNOW ACROSS PORTIONS OF THE CENTRAL ROCKIES, THE CENTRAL  
PLAINS, THE CENTRAL GREAT BASIN,  
THE NORTHERN PLAINS, AND THE NORTHERN ROCKIES, SUN-WED, APR 10-APR  
13.  
- SEVERE WEATHER ACROSS PORTIONS OF THE CENTRAL PLAINS, THE MIDDLE  
MISSISSIPPI VALLEY, THE LOWER  
MISSISSIPPI VALLEY, AND THE SOUTHERN PLAINS, MON-TUE, APR 11-APR  
12.  
- FLOODING POSSIBLE ACROSS PORTIONS OF THE MIDDLE MISSISSIPPI  
VALLEY, THE GREAT LAKES, THE UPPER  
MISSISSIPPI VALLEY, AND THE NORTHERN PLAINS.  
- FLOODING LIKELY ACROSS PORTIONS OF THE MIDDLE MISSISSIPPI VALLEY.  
- HIGH WINDS ACROSS PORTIONS OF THE CENTRAL PLAINS, THE CENTRAL  
ROCKIES, THE CENTRAL GREAT BASIN,  
THE SOUTHERN ROCKIES, THE SOUTHERN PLAINS, AND THE SOUTHWEST,  
SUN-WED, APR 10-APR 13.  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE LOWER  
MISSISSIPPI VALLEY, THE CENTRAL  
APPALACHIANS, THE TENNESSEE VALLEY, THE MIDDLE MISSISSIPPI VALLEY,  
THE MID-ATLANTIC, THE SOUTHERN  
APPALACHIANS, THE SOUTHEAST, THE SOUTHERN PLAINS, AND THE OHIO  
VALLEY, SAT-SUN, APR 9-APR 10.  
- ENHANCED WILDFIRE RISK ACROSS PORTIONS OF THE SOUTHERN ROCKIES,  
THE SOUTHERN PLAINS, AND THE  
SOUTHWEST, SUN-TUE, APR 10-APR 12.  
 
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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