917  
FXUS02 KWBC 220656  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
256 AM EDT SUN MAY 22 2022  
 
VALID 12Z WED MAY 25 2022 - 12Z SUN MAY 29 2022  
 
...HEAVY RAINFALL AND STRONG THUNDERSTORMS FOR THE SOUTH-CENTRAL  
U.S. FOR THE MIDDLE OF THE WEEK WITH THE POTENTIAL FOR SOME  
FLOODING ISSUES FROM EASTERN TEXAS TO TENNESSEE...  
 
   
..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 RAINFALL AND STRONG  
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 WESTERN HIGH PLAINS BY NEXT  
WEEKEND.  
   
..MODEL GUIDANCE AND PREFERENCES
 
 
THE 00Z MODEL GUIDANCE SUITE CONTINUES TO INDICATE DECENT OVERALL  
SYNOPTIC SCALE AGREEMENT ACROSS THE CONTINENTAL U.S. FOR THE  
MAJORITY OF THE FORECAST PERIOD, WITH THE NORMAL LEVELS OF  
DIFFERENCES IN MESOSCALE FEATURES. MODEL DIFFERENCES HAVE  
IMPROVED FOR THE SECOND SYSTEM REACHING THE WESTERN U.S., AND THE  
GFS AND ECMWF ARE CLOSE TO THEIR RESPECTIVE ENSEMBLE MEANS FOR THE  
MAJOR TROUGH ACROSS THE EAST-CENTRAL U.S., WITH THE 00Z CMC  
SLIGHTLY MORE AMPLIFIED WITH THE TROUGH AS IT CROSSES THE  
MISSISSIPPI RIVER VALLEY. THE WPC FORECAST INITIALLY STARTED WITH  
A MULTI-DETERMINISTIC MODEL BLEND THROUGH FRIDAY, AND THEN MORE OF  
THE ENSEMBLE MEANS WHILE STILL MAINTAINING SOME OF THE OPERATIONAL  
GFS AND ECMWF WITH A LITTLE LESS OF THE CMC.  
   
..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 2 TO 3+ 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 MCS CLUSTERS ARE  
LIKELY AND THESE MAY ALSO PRODUCE EPISODES OF SEVERE WEATHER.  
THEREFORE, A SLIGHT RISK AREA OF EXCESSIVE RAINFALL REMAINS FOR  
WEDNESDAY INTO EARLY THURSDAY FROM NORTHEAST TEXAS TO WESTERN  
TENNESSEE. 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. BY NEXT WEEKEND, THE FRONT  
MOVING INLAND ACROSS THE NORTHWESTERN U.S. AND EVENTUALLY THE  
CENTRAL/NORTHERN PLAINS IS EXPECTED TO BRING SOME SHOWERS AND A  
FEW STORMS FROM THE PACIFIC NORTHWEST TO THE NORTHERN ROCKIES AND  
THEN DAKOTAS.  
 
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.  
 
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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