424  
FXUS02 KWBC 221851  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
250 PM EDT SUN MAY 22 2022  
 
VALID 12Z WED MAY 25 2022 - 12Z SUN MAY 29 2022  
 
...HEAVY/EXCESSIVE RAINFALL AND STRONG/SEVERE WEATHER THREAT TO  
SPREAD FROM EASTERN TEXAS TO THE LOWER MISSISSIPPI/TENNESSEE/OHIO  
VALLEYS THEN APPALACHIANS WEDNESDAY INTO THURSDAY...  
 
   
..WEATHER PATTERN OVERVIEW
 
 
A LARGE SCALE UPPER TROUGH WILL BE EXITING THE ROCKIES AND  
EMERGING OVER THE PLAINS BY WEDNESDAY, AND THIS WILL SUSTAIN A  
SURFACE COLD FRONT WITH MULTIPLE WAVES OF LOW PRESSURE THAT WILL  
SLOWLY TRACK EASTWARD AND SHOULD REACH THE EAST COAST BY EARLY  
FRIDAY. MULTIPLE ROUNDS OF HEAVY TO EXCESSIVE RAINFALL AND STRONG  
TO SEVERE THUNDERSTORMS ARE LIKELY ACROSS THE SOUTH-CENTRAL U.S.  
AHEAD OF THE COLD FRONTAL PASSAGE. ANOTHER TROUGH ENTERS THE  
NORTHWESTERN U.S. BY THE END OF THE WEEK WITH AN UPPER RIDGE  
BUILDING IN AHEAD OF IT ACROSS THE INTERMOUNTAIN WEST, AND THIS  
TROUGH WILL LIKELY SPUR SURFACE CYCLOGENESIS ACROSS THE HIGH  
PLAINS BY NEXT WEEKEND.  
   
..MODEL GUIDANCE AND PREFERENCES
 
 
THE 00/06/12 UTC GUIDANCE BUNDLE CONTINUES TO OFFER GOOD SYNOPTIC  
SCALE AGREEMENT ACROSS THE CONTINENTAL U.S. FOR THE MAJORITY OF  
THE FORECAST PERIOD, WITH THE NORMAL LEVELS OF DIFFERENCES IN  
MESOSCALE FEATURES. THE GFS/ECMWF/CANADIAN ARE CLOSE TO THEIR  
RESPECTIVE ENSEMBLE MEANS FOR A MAJOR LEAD TROUGH OVER THE  
EAST-CENTRAL U.S. MID-LATER THIS WEEK AND MODEL DIFFERENCES HAVE  
IMPROVED FOR A SECOND SYSTEM REACHING THE WESTERN U.S. LATE WEEK.  
THE BASIS FOR THE WPC FORECAST WAS DERIVED FROM A BLEND OF THE  
GFS/ECMWF/UKMET/CANADIAN ALONG WITH WPC CONTINUITY AND THE  
NATIONAL BLEND OF MODELS (NBM) WEDNESDAY-FRIDAY. THE NBM AND THE  
GEFS/ECMWF ENSEMBLE MEANS ALONG WITH BEST CLUSTERED MODEL GUIDANCE  
FROM THE ECMWF AND THE GFS/CANADIAN WAS HIGHLIGHTED FOR NEXT  
WEEKEND.  
   
..SENSIBLE WEATHER/THREAT HIGHLIGHTS
 
 
PERIODS OF HEAVY RAINFALL WILL CONTINUE TO MAKE WEATHER HEADLINES  
GOING INTO WEDNESDAY ACROSS THE SOUTH-CENTRAL U.S., PARTICULARLY  
AROUND THE ARKLATEX REGION AND EXTENDING EASTWARD TO MISSISSIPPI,  
WHERE LOCAL 2 TO 4+ INCHES OF ADDITIONAL RAINFALL IS EXPECTED.  
PORTIONS OF THIS REGION ARE FORECAST TO GET HEAVY RAINFALL EARLY  
IN THE WEEK AS WELL, THUS THE GROUND WILL LIKELY BE SATURATED AND  
INCREASES THE POTENTIAL FOR FLOODING. MULTIPLE CLUSTERS OF  
CONVECTION ARE LIKELY AND THESE MAY ALSO PRODUCE EPISODES OF  
SEVERE WEATHER AS PER SPC. THE EXPERIMENTAL MEDIUM RANGE EXCESSIVE  
RAINFALL OUTLOOK (ERO) ALSO DEPICTS A "SLIGHT" RISK AREA FOR  
WEDNESDAY INTO EARLY THURSDAY FROM EASTERN TEXAS TO WESTERN  
TENNESSEE, WITH ADDITIONAL POTENTIAL DOWNSTREAM ACROSS THE SOUTH  
AND UP THROUGH THE GREAT LAKES/OHIO VALLEY. BEYOND THIS TIME, THE  
MAGNITUDE OF THE HEAVY RAINFALL THREAT ABATES SOME AS THE FRONT  
BECOMES MORE PROGRESSIVE ACROSS THE APPALACHIANS AND THEN THE EAST  
COAST REGION, ALTHOUGH SOME INSTANCES OF REPEATING CONVECTION MAY  
ALSO LEAD TO SOME FLOODING CONCERNS ON A MORE LOCALIZED LEVEL.  
LATE WEEK INTO NEXT WEEKEND, THE FRONT MOVING INLAND ACROSS THE  
NORTHWESTERN U.S. AND EVENTUALLY THE CENTRAL/NORTHERN PLAINS IS  
EXPECTED TO BRING SOME SHOWERS AND THUNDERSTORMS (AND SOME LATE  
MAY MOUNTAIN SNOWS) FROM THE PACIFIC NORTHWEST TO THE NORTHERN  
ROCKIES. STORMS SHOULD EMERGE OVER THE PLAINS/UPPER MIDWEST NEXT  
WEEKEND WITH SYSTEM PROGRESSION.  
 
IN TERMS OF TEMPERATURES, PLEASANTLY COOL CONDITIONS CAN BE  
EXPECTED ACROSS MUCH OF THE PLAINS AND MIDWEST IN THE WAKE OF THE  
COLD FRONT FOR THE MIDDLE OF THE WEEK, FOLLOWED BY A WARM-UP TO  
CLOSE OUT THE WEEK WITH ABOVE NORMAL HIGHS RETURNING BY THE  
WEEKEND WITH 90S LIKELY AS FAR NORTH AS SOUTHERN NEBRASKA, AND  
EVEN SOME LOW 100S FOR PORTIONS OF WESTERN TEXAS. HOT WEATHER IS  
ALSO EXPECTED FOR THE INTERIOR VALLEYS OF CALIFORNIA AND THE LOWER  
ELEVATIONS OF THE DESERT SOUTHWEST FOR WEDNESDAY THROUGH FRIDAY AS  
AN UPPER LEVEL RIDGE IS EXPECTED TO BE IN PLACE, AND THEN  
RETURNING CLOSER NORMAL FOR NEXT WEEKEND. ELSEWHERE, EXPECT HIGHS  
TO GENERALLY BE WITHIN 5 DEGREES OF CLIMATOLOGICAL AVERAGES ACROSS  
MOST OF THE EASTERN U.S., ALTHOUGH OVERNIGHT LOWS COULD END UP  
BEING MILDER THAN USUAL OWING TO MORE CLOUD COVER AND HUMIDITY.  
 
SCHICHTEL/HAMRICK  
 
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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