918  
FXUS02 KWBC 230655  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
255 AM EDT MON MAY 23 2022  
 
VALID 12Z THU MAY 26 2022 - 12Z MON MAY 30 2022  
   
..WEATHER PATTERN OVERVIEW
 
 
A LARGE SCALE UPPER TROUGH WILL BE CROSSING THE EAST-CENTRAL U.S.  
THROUGH THE END OF THE WORK WEEK, AND THIS WILL SUSTAIN A SURFACE  
COLD FRONT THAT WILL TRACK EASTWARD AND SHOULD EXIT THE EAST COAST  
BY FRIDAY AFTERNOON, WITH A WEAK SURFACE HIGH FOLLOWING FOR THE  
WEEKEND. ANOTHER TROUGH ENTERS THE NORTHWESTERN U.S. BY THE END  
OF THE WEEK WITH AN UPPER RIDGE BRIEFLY BUILDING IN AHEAD OF IT  
ACROSS THE INTERMOUNTAIN WEST AND ROCKIES, AND THIS TROUGH WILL  
SPUR SURFACE CYCLOGENESIS ACROSS THE HIGH PLAINS BY NEXT WEEKEND,  
ALTHOUGH PROBABLY WEAKER THAN THE ONE THAT WILL BE IN PLACE FOR  
THE BEGINNING TO MIDDLE OF THIS WEEK. BY NEXT MONDAY, AN UPPER  
RIDGE BUILDS BACK IN ACROSS THE EASTERN U.S. ALONG WITH WARMER  
TEMPERATURES.  
   
..MODEL GUIDANCE AND PREFERENCES
 
 
THE 00Z MODEL GUIDANCE SUITE IS INITIALLY IN GOOD SYNOPTIC SCALE  
AGREEMENT ON THURSDAY ACROSS THE MAJORITY OF THE NATION. HOWEVER,  
NOTEWORTHY DIFFERENCES IN THE GUIDANCE APPEAR AS EARLY AS THURSDAY  
NIGHT AND INTO FRIDAY WITH THE EVENTUAL EVOLUTION OF THE TROUGH  
REACHING THE EAST COAST. THE 18Z GFS DIFFERED CONSIDERABLY FROM  
ITS EARLIER 12Z RUN WITH A MUCH SLOWER SOLUTION WITH A CLOSED LOW  
DEVELOPING, WHEREAS THE 12Z MODEL CONSENSUS WAS MORE PROGRESSIVE  
AND GENERALLY DID NOT CLOSE OFF THE LOW. AT THE TIME OF THE  
FRONTS/PRESSURES PREPARATION, THE 12Z GFS WAS SUBSTITUTED FOR THE  
18Z SINCE THE EARLIER RUN HAD MORE ENSEMBLE SUPPORT. GOING  
FORWARD TO THE 00Z CYCLE, THE UKMET AND CMC TRENDED MORE AMPLIFIED  
AND SLOWER ACROSS THE OHIO VALLEY, AND THE LARGE MODEL CHANGES  
FROM EARLIER CYCLES LOWERS FORECAST CONFIDENCE FRIDAY AND INTO THE  
WEEKEND FOR THE EASTERN STATES. THE 00Z ECMWF TRENDED ONLY  
SLIGHTLY STRONGER, BUT OVERALL MORE OF AN OPEN WAVE AND CLOSE TO  
ITS ENSEMBLE MEAN. 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 THURSDAY ACROSS PORTIONS OF THE SOUTHEAST, WITH A  
COUPLE INCHES OF RAIN LIKELY FOR PARTS OF THE SOUTHERN  
APPALACHIANS. THIS REGION IS FORECAST TO GET HEAVY RAINFALL  
THROUGH THE MIDDLE OF THIS WEEK AS WELL, THUS THE GROUND WILL  
LIKELY BE SATURATED AND INCREASES THE POTENTIAL FOR FLOODING. A  
SLIGHT RISK AREA IN THE DAY 4 EXPERIMENTAL EXCESSIVE RAINFALL  
OUTLOOK IS NOW IN EFFECT FROM FAR NORTHERN GEORGIA TO SOUTHWESTERN  
NORTH CAROLINA WHERE THE BEST OROGRAPHIC FORCING WILL BE PRESENT  
IN A MOIST ENVIRONMENT. 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 PERHAPS SOME LATE MAY MOUNTAIN SNOWS) FROM THE  
PACIFIC NORTHWEST TO THE NORTHERN ROCKIES. STORMS SHOULD EMERGE  
OVER THE CENTRAL/NORTHERN PLAINS TO THE UPPER MIDWEST NEXT WEEKEND  
AS THE LOW PROGRESSES EASTWARD.  
 
IN TERMS OF TEMPERATURES, PLEASANTLY COOL CONDITIONS CAN BE  
EXPECTED ACROSS MUCH OF THE MIDWEST AND GREAT LAKES REGION IN THE  
WAKE OF THE COLD FRONT FOR THE END OF THE WEEK, FOLLOWED BY A  
WARM-UP WITH ABOVE NORMAL HIGHS RETURNING BY THE WEEKEND ACROSS  
MUCH OF THE PLAINS, WITH 90S LIKELY AS FAR NORTH AS CENTRAL  
NEBRASKA, AND EVEN SOME LOW 100S FOR PORTIONS OF WESTERN TEXAS.  
HOT WEATHER IS ALSO EXPECTED FOR THE LOWER ELEVATIONS OF THE  
DESERT SOUTHWEST FOR THURSDAY THROUGH THE WEEKEND AS AN UPPER  
LEVEL RIDGE IS EXPECTED TO BE IN PLACE, ALTHOUGH A COOLING TREND  
WILL COMMENCE FOR THE INLAND VALLEYS OF CENTRAL CALIFORNIA.  
ELSEWHERE, EXPECT HIGHS TO GENERALLY BE WITHIN 5 DEGREES OF  
CLIMATOLOGICAL AVERAGES ACROSS MOST OF THE EASTERN U.S. THROUGH  
SATURDAY, ALTHOUGH OVERNIGHT LOWS COULD END UP BEING MILDER THAN  
USUAL OWING TO MORE CLOUD COVER AND HUMIDITY. HEAT RETURNS TO  
MUCH OF THE NORTHEAST U.S. AND OHIO VALLEY BY EARLY NEXT WEEK AS  
THE UPPER RIDGE BUILDS BACK IN.  
 
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  
 

 
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page