165  
FXUS02 KWBC 200651  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
251 AM EDT FRI MAY 20 2022  
 
VALID 12Z MON MAY 23 2022 - 12Z FRI MAY 27 2022  
 
...HEAVY RAIN AND STRONG STORMS FROM TEXAS TO THE OHIO VALLEY AND  
GREAT LAKES EARLY-MID NEXT WEEK...  
 
   
..WEATHER PATTERN OVERVIEW
 
 
A COLD FRONT IS FORECAST TO EXIT THE EAST COAST BY EARLY MONDAY  
AFTER A HOT WEEKEND FOR MUCH OF THE EASTERN U.S., WITH A COOLER  
AND MORE COMFORTABLE AIRMASS SETTLING IN BEHIND IT FOR EARLY IN  
THE WEEK. MEANWHILE, A RATHER ACTIVE WEATHER PATTERN IS EXPECTED  
TO DEVELOP ACROSS THE CONTINENTAL U.S. GOING INTO NEXT WEEK, AS  
MULTIPLE WAVES OF LOW PRESSURE DEVELOP ALONG A FRONTAL BOUNDARY  
SITUATED OVER THE PLAINS AND EXTENDING TO THE GREAT LAKES. THIS  
WILL BE IN RESPONSE TO A BUILDING UPPER LEVEL TROUGH OVER THE  
WESTERN HIGH PLAINS THAT WILL SLOWLY MOVE EASTWARD THROUGH THE  
WEEK.  
 
   
..GUIDANCE EVALUATION/PREFERENCES
 
 
THE 00Z MODEL GUIDANCE SUITE IS IN DECENT SYNOPTIC SCALE AGREEMENT  
FOR THE BEGINNING OF NEXT WEEK, WITH DIFFERENCES BECOMING MORE  
APPARENT BY WEDNESDAY AS THE TROUGH AMPLIFIES OVER THE PLAINS.  
THE PAST FEW RUNS OF THE GFS HAVE BEEN SLOWER AND STRONGER WITH  
THE TROUGH OVER THE SOUTH-CENTRAL U.S. AND DEVELOPING A CLOSED  
UPPER LOW, WHEREAS THE CMC/ECMWF AND MANY OF THE ENSEMBLE MEMBERS  
WERE MORE PROGRESSIVE AND HAD THE TROUGH AXIS REACHING THE EAST  
COAST BY THE END OF THE WEEK. IT IS INTERESTING TO NOTE THAT THE  
00Z CMC TRENDED MORE TOWARDS THE GFS FOR THIS TROUGH, WITH OVERALL  
FORECAST CONFIDENCE FOR THE THURSDAY-FRIDAY TIME PERIOD LIMITED  
AND THUS SUBJECT TO POTENTIAL NOTEWORTHY CHANGES IN FUTURE  
FORECASTS. THERE IS ALSO A GOOD MODEL SIGNAL FOR AN AMPLIFYING  
TROUGH IN THE GENERAL VICINITY OF THE PACIFIC NORTHWEST BY NEXT  
FRIDAY.  
 
THE WPC FRONTS/PRESSURES FORECAST WAS PRIMARILY DERIVED FROM A  
MULTI-DETERMINISTIC MODEL CONSENSUS THROUGH TUESDAY, AND THEN  
INCORPORATED MORE OF THE 12Z CMC/ECMWF AND INCREASED USE OF THE  
ENSEMBLE MEANS FOR THE WEDNESDAY-FRIDAY TIME PERIOD.  
 
   
..SENSIBLE WEATHER/THREAT HIGHLIGHTS
 
 
TEMPERATURES BEHIND THE COLD FRONT EXITING THE EAST COAST NEXT  
WEEK SHOULD RETURN TO NEAR SEASONAL LEVELS AFTER A POTENTIALLY  
RECORD SETTING EARLY SEASON HEATWAVE. LOW PRESSURE FORMING ALONG  
THE TRAILING FRONT AS IT MEANDERS NEAR THE SOUTHEAST COAST MAY  
CONTINUE A MODERATE TO HEAVY RAINFALL THREAT INTO MONDAY AS WELL  
FOR PARTS OF THE CAROLINAS AND THE SOUTHERN APPALACHIANS.  
 
THE NEXT SYSTEM DEVELOPING OVER THE SOUTH-CENTRAL U.S. INTO  
EARLY-MID NEXT WEEK IS EXPECTED TO BECOME THE MAIN WEATHER  
HEADLINE OF THIS FORECAST PERIOD. THERE WILL LIKELY BE WIDESPREAD  
CONVECTION AND HEAVY RAINFALL FROM TEXAS TO THE OHIO VALLEY WITH  
MOIST RETURN FLOW INTO ANOTHER SLOW MOVING AND WAVY FRONTAL  
SYSTEM. THERE IS THE POTENTIAL FOR SOME FLASH FLOODING WITH THE  
SLOWER MOVING STORMS WITHIN A VERY MOIST AND UNSTABLE ATMOSPHERE.  
THE LATEST WPC EXPERIMENTAL EXCESSIVE RAINFALL OUTLOOK INDICATES A  
SLIGHT RISK AREA FOR MONDAY INTO TUESDAY MORNING ACROSS PORTIONS  
OF CENTRAL TEXAS, AND THIS COULD BE EXPANDED IN LATER FORECASTS,  
AND THE POTENTIAL EXISTS FOR ADDITIONAL HEAVY RAIN GOING INTO  
TUESDAY AND WEDNESDAY ACROSS THE MISSISSIPPI RIVER VALLEY, ALBEIT  
WITH GREATER UNCERTAINTY IN PLACEMENT OF MCS ACTIVITY. SOME  
SEVERE STORMS ARE CERTAINLY WITHIN THE REALM OF POSSIBILITY FOR  
THESE SAME GENERAL AREAS.  
 
THE WESTERN-CENTRAL U.S. TROUGH SHOULD KEEP TEMPERATURES BELOW  
NORMAL ACROSS ROCKIES AND PLAINS THROUGH AT LEAST TUESDAY. MUCH  
OF THE WESTERN U.S. SHOULD REMAIN MAINLY DRY THROUGH THE MIDDLE OF  
NEXT WEEK AS UPPER RIDGING BUILDS OVER THE REGION AND WARMER  
TEMPERATURES EXPAND ACROSS THE REGION, WITH THE EXCEPTION OF SOME  
SHOWERS ENTERING THE PACIFIC NORTHWEST BY FRIDAY. THIS MAY LEAD  
TO AN EXCESSIVE HEAT EPISODE OVER INTERIOR CALIFORNIA AND THE  
DESERT SOUTHWEST FOR THE END OF THE WEEK.  
 
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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