139  
FXUS02 KWBC 130658  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
258 AM EDT TUE MAY 13 2025  
 
VALID 12Z FRI MAY 16 2025 - 12Z TUE MAY 20 2025  
 
***HEAT BUILDS ACROSS THE SOUTHERN PLAINS WHILE LATE SEASON SNOW IS  
EXPECTED FOR THE ROCKIES***  
 
   
..GENERAL OVERVIEW
 
 
THE STRONG LOW PRESSURE SYSTEM OVER THE NORTHERN PLAINS ON THURSDAY  
IS FORECAST TO LIFT NORTHEAST ACROSS ONTARIO GOING INTO FRIDAY,  
WITH A STRONG TRAILING COLD FRONT THAT WILL BRING A REFRESHING  
CHANGE TO COOLER TEMPERATURES. NUMEROUS SHOWERS AND STORMS ARE  
LIKELY AHEAD OF THE FRONT FROM THE MID-SOUTH TO THE OHIO VALLEY AND  
GREAT LAKES. ATTENTION THEN TURNS TO THE INTERMOUNTAIN WEST BY THE  
WEEKEND AS ANOTHER AMPLIFIED UPPER TROUGH AND CLOSED LOW DEVELOPS  
AND BRINGS ADDITIONAL ROUNDS OF VALLEY RAIN AND MOUNTAIN SNOW  
ALONG WITH COLD CONDITIONS FOR THIS TIME OF YEAR. HEAT WILL  
CONTINUE TO MAKE WEATHER HEADLINES FOR THE SOUTH-CENTRAL U.S. WITH  
LOTS OF SUNSHINE AND AN UPPER RIDGE AXIS GOVERNING THE OVERALL  
WEATHER PATTERN.  
   
..GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
THE 00Z MODEL GUIDANCE SUITE FEATURES VERY GOOD SYNOPTIC SCALE  
AGREEMENT FOR THE END OF THE WEEK, WITH A MULTI-DETERMINISTIC  
MODEL BLEND SUFFICING AS A STARTING POINT IN THE FORECAST PROCESS  
AND SLIGHTLY MORE WEIGHTING APPLIED TO THE ECMWF/GFS SOLUTIONS.  
THE UKMET IS A BIT TO THE NORTHWEST OF THE MODEL CONSENSUS WITH  
THE STORM SYSTEM OVER THE NORTHERN GREAT LAKES, AND THE CMC IS  
STRONGER WITH THE UPPER RIDGE AXIS NEAR THE SOUTHEAST U.S. COAST  
OVER THE WEEKEND. THE GUIDANCE AGREES WELL WITH THE NEXT AMPLIFYING  
TROUGH ACROSS THE INTERIOR WEST BY SUNDAY, BUT THERE ARE SOME  
DIFFERENCES IN THE EVOLUTION OF THE DOWNSTREAM SURFACE LOW OVER THE  
CENTRAL PLAINS BY NEXT TUESDAY. THE ENSEMBLE MEANS WERE INCREASED  
TO ABOUT 40% THAT TIME.  
   
..WEATHER/HAZARDS HIGHLIGHTS
 
 
SHOWERS AND THUNDERSTORMS INCREASE IN COVERAGE AND INTENSITY  
ACROSS THE MID-SOUTH AND OHIO VALLEY AHEAD OF A COLD FRONT THAT  
WILL BE INTERCEPTING DEEPER RETURN MOISTURE. AN ERO MARGINAL RISK  
AREA REMAINS VALID FOR FRIDAY (DAY 4) FROM ARKANSAS TO THE CENTRAL  
APPALACHIANS, WITH AN EXPANSION NORTHWARD TO INCLUDE SOUTHERN  
PORTIONS OF ILLINOIS, INDIANA, AND OHIO WHERE THE 00Z GUIDANCE HAS  
TRENDED HEAVIER WITH EXPECTED RAINFALL. GOING INTO SATURDAY (DAY 5)  
ATTENTION THEN TURNS TO PORTIONS OF THE SOUTHERN PLAINS AND  
EXTENDING TO THE MID-SOUTH WITH ENHANCED MOISTURE CONVERGENCE NEAR  
THE SAME FRONTAL BOUNDARY AND AHEAD OF A DEVELOPING WAVE OF LOW  
PRESSURE NEAR THE TEXAS PANHANDLE.  
 
ELSEWHERE ACROSS THE NATION, THE STORM PREDICTION CENTER IS  
MONITORING THE POTENTIAL FOR SEVERE WEATHER FROM THE MIDWEST TO THE  
MID-SOUTH TO CLOSE OUT THE WORK WEEK WITH FAVORABLE INSTABILITY AND  
KINEMATICS. ACROSS THE ROCKIES, EXPECT ADDITIONAL CHANCES FOR LATE  
SEASON SNOW FOR THE CENTRAL AND NORTHERN ROCKIES BY SUNDAY INTO MONDAY  
AS THE NEXT UPPER TROUGH AND SHORTWAVE MOVES IN, WITH THE POTENTIAL  
FOR OVER A FOOT OF ACCUMULATION FOR SOME OF THE HIGHEST MOUNTAIN  
RANGES. NUMEROUS SHOWERS ARE ALSO LIKELY TO DEVELOP ACROSS THE  
GREAT BASIN OVER THE WEEKEND IN RESPONSE TO THE DEVELOPING UPPER  
LOW, AND THIS MAY BECOME LOCALLY HEAVY ENOUGH TO EVENTUALLY NEED A  
MARGINAL RISK AREA FOR EXCESSIVE RAINFALL AS THE EVENT GETS CLOSER.  
 
VERY WARM WEATHER WILL BE COMMONPLACE ACROSS THE EASTERN HALF OF  
THE COUNTRY TO CLOSE OUT THE WORK WEEK, WITH HIGHS WELL INTO THE  
80S AND EVEN SOME LOWER-MIDDLE 90S FROM THE OHIO VALLEY AND MID-  
ATLANTIC SOUTHWARD TO THE GULF COAST. VERY HOT CONDITIONS ARE  
EXPECTED ACROSS SOUTHERN TEXAS THROUGH THE UPCOMING WEEKEND WITH  
HIGHS EXCEEDING 100 DEGREES NEAR THE RIO GRANDE AND INTO MUCH OF  
CENTRAL TEXAS, AND HEATRISK REACHING THE MAJOR TO EXTREME CATEGORY  
FOR SOME OF THESE AREAS. IN CONTRAST, CHILLY CONDITIONS ARE LIKELY  
FOR THE INTERMOUNTAIN WEST AND NORTHERN ROCKIES/PLAINS WITH HIGHS  
RUNNING 10 TO PERHAPS 20 DEGREES BELOW AVERAGE WITH THE UPPER LEVEL  
TROUGH AND INCREASED CLOUD COVER.  
 
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 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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