139  
FXUS02 KWBC 161900  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 PM EDT FRI MAY 16 2025  
 
VALID 12Z MON MAY 19 2025 - 12Z FRI MAY 23 2025  
 
...SEVERE WEATHER AND FLASH FLOODING FORECAST FOR PARTS OF THE  
CENTRAL U.S. MONDAY-TUESDAY...  
 
...HAZARDOUS AND RECORD HEAT COULD CONTINUE ESPECIALLY ACROSS TEXAS  
AND FLORIDA INTO MID-NEXT WEEK...  
 
   
..OVERVIEW
 
 
THE PRIMARY WEATHER FEATURE NEXT WEEK WILL BE AN UPPER TROUGH/LOW  
OVER THE ROCKIES MONDAY THAT TRACKS EAST AS THE WEEK PROGRESSES  
ALONG WITH ITS ASSOCIATED SURFACE LOW PRESSURE/FRONTAL SYSTEM. THIS  
PATTERN WILL PROVIDE AMPLE LIFT AND INSTABILITY FOR RAIN AND  
THUNDERSTORMS IN THE PLAINS, MISSISSIPPI VALLEY, AND OHIO VALLEY  
EARLY WEEK AND SPREADING INTO THE EAST FOR MIDWEEK AND BEYOND.  
MEANWHILE A SUBTROPICAL UPPER RIDGE WILL CONTINUE TO CAUSE HOT  
CONDITIONS TO AREAS OF THE SOUTHEAST, PARTICULARLY INTO SOUTHERN  
TEXAS AND FLORIDA, WHERE THE HEAT COULD BE HAZARDOUS AND/OR RECORD  
SETTING.  
 
   
..GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
MODEL GUIDANCE BEGINS THE MEDIUM RANGE PERIOD MONDAY IN REASONABLY  
GOOD AGREEMENT WITH THE PRIMARY UPPER TROUGH AND EMBEDDED UPPER  
LOW(S) IN THE INTERIOR WEST AND SPINNING UP A SURFACE LOW IN THE  
CENTRAL PLAINS. MODELS DIVERGE RATHER QUICKLY WITH THE EVOLUTION OF  
THE EJECTION OF EMBEDDED UPPER-LEVEL ENERGIES AND SUBSEQUENT  
DETAILS AT THE SURFACE. A SECOND UPPER-LEVEL SHORTWAVE LOOKS TO  
LEAD TO SECONDARY LOW DEVELOPMENT OVER THE CENTRAL/SOUTHERN PLAINS  
TUESDAY SOUTH OF THE INITIAL SURFACE LOW DEVELOPMENT. THE 00Z  
ECMWF/UKMET AND 00/06Z GFS MAINTAIN THE MORE NORTHERN LOW BEFORE A  
COMPLEX EVOLUTION THAT GENERALLY TENDS TO FAVOR THE SOUTHERLY LOW  
BECOMING THE MAIN LOW AS THE SYSTEM PROGRESSES NORTHEASTWARD INTO  
THE MIDWEST/OHIO VALLEY BY MID-NEXT WEEK. THE EVOLUTION OF THE  
SURFACE LOW PATTERN IN THE 06Z GFS IS A BIT MORE SIMILAR TO THE 00Z  
ECMWF COMPARED TO THE 00Z RUN INITIALLY IN FEATURE  
LOCATION/PROGRESSION. THE 06Z THEN SHOWS A MUCH FASTER PROGRESSION  
OF LEADING ENERGY EASTWARD OUT OF THE OHIO VALLEY AND INTO THE MID-  
ATLANTIC/NORTHEAST WHILE THE 00Z GFS REMAINS MORE SIMILAR TO THE  
00Z ECMWF WITH A SLOWER PROGRESSION. THE PROGRESSION OF THE LOW(S)  
IS ALSO FASTER IN THE DETERMINISTIC GUIDANCE COMPARED TO THE  
ECENS/GEFS MEANS, WHICH IS ALSO FASTER COMPARED TO THE PRIOR  
GUIDANCE AS WELL AS WPC FORECAST. THE 00Z CMC IS MORE AGGRESSIVE IN  
HAVING THE SOUTHERLY LOW BECOME THE SOLO, PRIMARY LOW QUICKLY IN  
THE SUBSEQUENT EVOLUTION OF THE PATTERN WITH A MUCH SLOWER AND  
SOUTHERLY TRACK. ANOTHER COMPLEX EVOLUTION LOOKS TO OCCUR HEADING  
INTO LATER NEXT WEEK AS THE UPPER-TROUGH MERGES WITH NORTHERN  
STREAM ENERGY, AND A COASTAL LOW DEVELOPS OFF THE COAST OF THE MID-  
ATLANTIC, LIFTING NORTHEASTWARD IN PARALLEL WITH THE COAST. BOTH  
THE 00Z GFS/ECMWF AND THE RESPECTIVE MEANS ARE IN GENERALLY GOOD  
AGREEMENT DESPITE TYPICAL LOCATION/TIMING DIFFERENCES WITH  
INCREASING LEAD TIME. THE 06Z GFS REMAINS MUCH FASTER, BRINGING THE  
COASTAL LOW WELL OFFSHORE COMPARED TO THE OTHER GUIDANCE,  
SUGGESTING A HIGHER LEVEL OF UNCERTAINTY DESPITE THE GOOD  
AGREEMENT. THE UPDATED WPC FORECAST BEGINS WITH A BLEND OF THE 00Z  
ECMWF/UKMET AND 00/06Z GFS GIVEN THE TRANSITION BETWEEN THE 06Z TO  
00Z WITH RESPECT TO BETTER AGREEMENT WITH THE OTHER GUIDANCE. THE  
00Z CMC WAS NOT INCLUDED BECAUSE OF THE OUTLIER NATURE OF THE  
SOUTHERLY SYSTEM TRACK. A CONTRIBUTION FROM THE ENSEMBLE MEANS IS  
ADDED FOR THE MID- TO LATE PERIOD GIVEN THE LOSS OF THE TIME-  
LIMITED UKMET, REMOVAL OF THE 06Z GFS GIVEN A DIVERGING SOLUTION,  
AND GENERAL INCREASE IN UNCERTAINTY. THE BLEND RESULTS IN A  
FORECAST THAT MAINTAINS GENERALLY GOOD CONTINUITY WITH THE PRIOR  
WPC FORECAST, WITH THE GREATEST DIFFERENCES BEING A FASTER  
PROGRESSION OF THE SYSTEM EASTWARD THROUGH THE OHIO VALLEY AND A  
STRONGER COASTAL LOW TOWARDS THE END OF THE PERIOD.  
   
..WEATHER/HAZARDS HIGHLIGHTS
 
 
THE NOTABLE SURFACE LOW PRESSURE SYSTEM CONSOLIDATED OVER THE  
CENTRAL PLAINS BY MONDAY WILL DRAW IN ABOVE AVERAGE MOISTURE (WITH  
PRECIPITABLE WATER VALUES AROUND THE 90TH PERCENTILE FOR THIS TIME  
OF YEAR) AND AMPLE INSTABILITY AHEAD OF ITS ASSOCIATED COLD FRONT.  
THE UPPER LOW SPINNING ALOFT WILL PROVIDE GOOD DYNAMICAL LIFT, AND  
THIS COMBINATION OF INGREDIENTS WILL LEAD TO WIDESPREAD RAIN AND  
THUNDERSTORMS AND MESOSCALE CONVECTIVE SYSTEMS, WITH BEST CHANCES  
SLOWLY PROGRESSING EAST FROM THE CENTRAL TO EAST-CENTRAL TO EASTERN  
U.S. AS NEXT WEEK PROGRESSES. THE GREATEST CHANCES FOR HEAVY RAIN  
CAUSING FLASH FLOODING LOOK TO BE ACROSS THE MID-MISSISSIPPI AND  
WESTERN OHIO VALLEYS MONDAY, AND A MORE EXPANSIVE AREA FROM THE  
MID- MISSISSIPPI EAST THROUGH THE OHIO VALLEY AND INTO THE CENTRAL  
APPALACHIANS TUESDAY, AS MOISTURE AND INSTABILITY POOL NEAR A WARM  
FRONT STRETCHING WEST-EAST THAT COULD PROMOTE TRAINING STORMS. THUS  
SLIGHT RISKS ARE IN PLACE FOR THE DAY 4/MONDAY AND DAY 5/TUESDAY  
ERO OVER PRETTY SIMILAR AREAS BEFORE THE UPPER/SURFACE LOWS EJECT  
EASTWARD. BROAD MARGINAL RISKS SURROUND THE SLIGHTS TO THE SOUTH  
AND EAST WHERE CONVECTION MAY BE MORE SCATTERED, AND ON MONDAY A  
MARGINAL CURLS BACK WEST CLOSER TO THE LOW TRACK. SEVERE WEATHER IS  
ALSO POSSIBLE PER THE STORM PREDICTION CENTER, AS THEY DELINEATE A  
SEVERE AREA ON MONDAY FOR THE SOUTH-CENTRAL PLAINS TO MISSOURI  
VALLEY MONDAY, WITH THE GREATEST THREAT OVER EASTERN OKLAHOMA, AND  
ANOTHER AREA FOR THE LOWER/MIDDLE MISSISSIPPI VALLEY ON TUESDAY.  
RAIN AND THUNDERSTORM POTENTIAL SHOULD PRESS TOWARD THE EASTERN  
SEABOARD BY MID TO LATE WEEK WITH MODERATE TO LOCALLY HEAVY  
RAINFALL POSSIBLE FOR THE MID-ATLANTIC WEDNESDAY INTO COASTAL NEW  
ENGLAND THURSDAY.  
 
SOME PRECIPITATION IS FORECAST IN THE INTERMOUNTAIN WEST UNDER THE  
UPPER TROUGH/LOW FOR THE FIRST HALF OF NEXT WEEK. THE COOL  
TEMPERATURES ALOFT COULD LEAD TO MAY SNOW IN HIGHER ELEVATIONS OF  
THE ROCKIES PARTICULARLY MONDAY. CONVECTIVE SHOWERS ARE POSSIBLE  
NEAR THE FOUR CORNERS REGION. MEANWHILE ROUNDS OF MODEST  
PRECIPITATION MAY BE POSSIBLE IN THE NORTHWEST. LIGHT RAIN MAY  
LINGER IN THE NORTHEAST EARLY NEXT WEEK UNDER THE INFLUENCE OF A  
NORTHERN TROUGH.  
 
WARM TO HOT TEMPERATURES ARE LIKELY ACROSS THE SOUTHEASTERN U.S.  
AS THE SUBTROPICAL UPPER RIDGE REACHES THE REGION. SOUTHERN TEXAS  
IN PARTICULAR WILL REMAIN HOT, WITH TEMPERATURES WELL INTO THE 100S  
LEADING TO MAJOR TO EXTREME HEATRISK THROUGH TUESDAY. THE FLORIDA  
PENINSULA SHOULD SEE WARM TEMPERATURES IN THE MID TO UPPER 90S.  
BOTH AREAS COULD SEE RECORD OR NEAR RECORD WARM LOWS AND HIGHS.  
MEANWHILE THE TROUGH ALOFT WILL PROMOTE BELOW NORMAL TEMPERATURES,  
ESPECIALLY FOR HIGHS, ACROSS THE INTERIOR WEST MONDAY AND INTO THE  
NORTHERN PLAINS TUESDAY. BELOW AVERAGE HIGHS BY AROUND 10 DEGREES  
ARE ALSO POSSIBLE IN THE NORTHERN TIER. AS THE TROUGH TRACKS EAST,  
COOLER THAN AVERAGE TEMPERATURES SHOULD SHIFT INTO THE EASTERN  
THIRD OF THE COUNTRY UNDER IT. THIS MAY ALSO MODERATE THE  
TEMPERATURES SOMEWHAT IN THE SOUTH. BUT UPPER RIDGING POKING INTO  
THE WEST WILL RAISE TEMPERATURES TO ABOVE NORMAL THERE BY LATER  
WEEK, BRINGING HIGHS WELL INTO THE 100S FOR THE DESERT SOUTHWEST.  
 
PUTNAM/TATE  
 
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 FORECAST (QPF), EXCESSIVE RAINFALL  
OUTLOOK (ERO), WINTER WEATHER OUTLOOK (WWO) PROBABILITIES, HEAT  
INDICES, AND KEY MESSAGES CAN BE ACCESSED FROM:  
 
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  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW  
 

 
 
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