740  
FXUS02 KWBC 192012  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
412 PM EDT THU MAY 19 2022  
 
VALID 12Z SUN MAY 22 2022 - 12Z THU MAY 26 2022  
 
...EXCESSIVE HEAT LINGERING SUNDAY FOR SOUTH TEXAS AND  
MID-ATLANTIC/NORTHEAST TO REFOCUS OVER INTERIOR CALIFORNIA/DESERT  
SOUTHWEST EARLY-MID NEXT WEEK...  
 
...HEAVY RAIN/CONVECTION THREAT FROM THE CENTRAL GULF COAST TO  
SOUTHERN MID-ATLANTIC SUNDAY/MONDAY THEN SOUTHERN PLAINS/LOWER  
MISSISSIPPI VALLEY EARLY-MID NEXT WEEK...  
 
   
..OVERVIEW
 
 
THE UPPER FLOW PATTERN DURING THE MEDIUM RANGE PERIOD SHOULD STAY  
AMPLIFIED AND ACTIVE INTO EARLY-MID NEXT WEEK. SHORTWAVES PUSHING  
A STRONG COLD FRONT THROUGH THE EASTERN U.S. SUNDAY SHOULD BRING  
AN END TO RECORD WEEKEND HEAT. SPC ALSO SHOWS A THREAT FOR SEVERE  
WEATHER SUNDAY OVER THE NORTHERN TIER OF A WARMED NORTHEAST. A  
DIGGING TROUGH ACROSS THE WESTERN U.S. WILL SHIFT EAST WITH TIME,  
WITH AN INCREASING SIGNAL FOR A POTENTIAL MULTI-DAY HEAVY RAINFALL  
EVENT FOR THE SOUTH-CENTRAL U.S. EARLY NEXT WEEK DESPITE  
INCREASING VARIED MODEL TIMING ISSUES. MEANWHILE, LEADING SOUTHERN  
STREAM ENERGY WILL INTERACT WITH INCREASING TROPICAL MOISTURE TO  
FUEL HEAVY RAIN AND STORMS FROM THE CENTRAL GULF COAST TO THE  
SOUTHERN APPALACHIANS/MID-ATLANTIC SUNDAY INTO MONDAY.  
 
   
..GUIDANCE EVALUATION/PREFERENCES
 
 
GUIDANCE SHOWS ENOUGH MASS FIELD AGREEMENT TO SUPPORT A  
DETERMINISTIC MODEL BLEND OF THE LATEST GFS/ECMWF/CMC FOR DAYS 3/4  
(SUNDAY/MONDAY), BUT IN PARTICULAR LEANED TOWARD SOLUTIONS WITH  
HEAVIER RAINFALL FROM THE CENTRAL GULF COAST STATES TO THE  
APPALACHIANS GIVEN OVERALL DEEPER MOISTURE FEED AND SOUTHERN  
STREAM IMPULSE/FRONTAL WAVE SUPPORT. THE 00 UTC UKMET WAS LESS  
AMPLIFIED WITH UPPER TROUGHING ACROSS THE WEST INTO EARLY NEXT  
WEEK, BUT THE NEWER 12 UTC RUN HAS TRENDED STRONGER/LESS  
PROGRESSIVE. HOWEVER, FORECAST PREDICTABILITY QUICKLY LOWERS TO  
BELOW NORMAL FOR THE REST OF THE PERIOD AMID GROWING FORECAST  
SPREAD. BY NEXT TUESDAY-THURSDAY, SIGNIFICANT TIMING DIFFERENCES  
ARISE WITH THE ECMWF/CMC BECOMING UNCHARACTERISCALLY FASTER/LESS  
AMPLIFIED THAN THE GFS WHICH HOLDS BACK THE AMPLIFIED TROUGH OVER  
THE SOUTHERN PLAINS MUCH LONGER. THE WPC FORECAST TRENDED TOWARDS  
THE COMPATIBLE GEFS/ECMWF ENSEMBLE MEANS NEXT TUESDAY-THURSDAY  
WHICH ACTUALLY SHOWS A MORE MODERATE AND MIDDLE GROUND SOLUTION.  
 
   
..WEATHER/THREAT HIGHLIGHTS
 
 
THE RELENTLESS HEAT THAT HAS PLAGUED THE SOUTHERN U.S. FOR THE  
PAST WEEK SHOULD FINALLY BREAK THIS WEEKEND AS THE UPPER RIDGE  
PUSHES INTO THE EAST. AHEAD OF THE COLD FRONT ON SUNDAY THOUGH,  
EXCESSIVE HEAT WITH SOME LINGERING RECORD TEMPS (ESPECIALLY FOR  
WARM LOWS) WILL STILL BE POSSIBLE. MEANWHILE, EXPECT LOCALLY HEAVY  
RAIN AND POSSIBLY STRONG STORMS TO ACCOMPANY THE COLD FRONT AS IT  
PUSHES THROUGH THE OHIO VALLEY/EAST ON SUNDAY. TEMPERATURES BEHIND  
THE FRONT NEXT WEEK SHOULD HOVER NEAR SEASONABLE NORMAL VALUES.  
LOW PRESSURE FORMING ALONG THE TRAILING FRONT AS IT BEGINS TO LIFT  
BACK NORTH AS A WARM FRONT MAY CONTINUE A RAINFALL THREAT INTO  
MONDAY AS WELL FOR PARTS OF THE SOUTHERN MID-ATLANTIC.  
 
LEADING SOUTHERN STREAM IMPULSE ENERGY MAY ALSO FOCUS HEAVY  
RAINFALL ACROSS PARTS OF THE SOUTH, ESPECIALLY THE GULF COAST,  
WITH TROPICAL MOISTURE SURGING NORTHWARD FROM THE GULF OF MEXICO  
ON SUNDAY. AT LEAST A LOCALIZED FLOOD AND FLASH FLOOD THREAT  
SHOULD EXIST AS THE ENVIRONMENT COULD BE FAVORABLE FOR HIGH  
RAINFALL RATES. THE NEXT SYSTEM DIGGING INTO THE SOUTH-CENTRAL  
U.S. INTO NEXT WEEK HAS BECOME INCREASINGLY LIKELY TO RE-KINDLE  
WIDESPREAD CONVECTION/RAINFALL ACROSS THE SOUTH-CENTRAL U.S. WITH  
RETURN FLOW INTO ANOTHER WAVY FRONTAL SYSTEM, ALBEIT DEPENDENT ON  
FLOW DETAILS AND CONVECTIVE INTERACTIONS. AGAIN, FLASH FLOODING IS  
EXPECTED TO BE A CONCERN WITHIN A VERY MOIST AND UNSTABLE  
ATMOSPHERE. THE WPC EXPERIMENTAL EXCESSIVE RAINFALL OUTLOOK (ERO)  
SHOWS A "SLIGHT" RISK AREA MONDAY INTO TUESDAY. DEPENDING ON FLOW  
PROGRESSION, SOME GUIDANCE SUGGESTS THE THREAT COULD LINGER FOR A  
COUPLE OF DAYS.  
 
THE WESTERN-CENTRAL U.S. TROUGH SHOULD KEEP TEMPERATURES BELOW  
NORMAL ACROSS ROCKIES AND PLAINS THROUGH AT LEAST TUESDAY. WITH  
THE EXCEPTION OF LIGHT PRECIP ACROSS THE ROCKIES ON SUNDAY, 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. THIS MAY LEAD TO AN  
EXCESSIVE HEAT FOCUS OVER INTERIOR CALIFORNIA AND THE DESERT  
SOUTHWEST.  
 
SCHICHTEL/SANTORELLI  
 
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 CENTRAL/SOUTHERN PLAINS, AND  
THE MIDDLE/LOWER MISSISSIPPI  
VALLEY, MON-WED, MAY 23-MAY 25.  
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHEAST, THE LOWER  
MISSISSIPPI VALLEY, THE SOUTHERN  
APPALACHIANS, AND THE TENNESSEE VALLEY, SUN, MAY 22.  
- SEVERE WEATHER ACROSS PORTIONS OF THE LOWER GREAT LAKES, AND THE  
NORTHEAST, SUN, MAY 22.  
- FLOODING POSSIBLE ACROSS PORTIONS OF THE MIDDLE MISSISSIPPI  
VALLEY, THE UPPER MISSISSIPPI VALLEY, AND THE NORTHERN PLAINS.  
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE UPPER  
MISSISSIPPI VALLEY, AND THE NORTHERN PLAINS.  
- FLOODING LIKELY ACROSS PORTIONS OF THE NORTHERN PLAINS.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE CENTRAL GREAT BASIN,  
CALIFORNIA, AND THE SOUTHWEST,  
MON-THU, MAY 23-MAY 26.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE NORTHEAST, THE CENTRAL  
APPALACHIANS, THE SOUTHERN PLAINS,  
THE MID-ATLANTIC, THE SOUTHERN APPALACHIANS, AND THE LOWER GREAT  
LAKES, SUN, MAY 22.  
 
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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