308  
FXUS02 KWBC 120658  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
258 AM EDT MON MAY 12 2025  
 
VALID 12Z THU MAY 15 2025 - 12Z MON MAY 19 2025  
   
..HEAVY RAIN FOR THE NORTHERN PLAINS AND HEAT BUILDS ACROSS TEXAS  
 
 
   
..GENERAL OVERVIEW  
 
THE SLOW MOVING UPPER LOW ACROSS THE SOUTHEAST U.S. THROUGH THE  
MIDDLE OF THIS WEEK WILL BE WEAKENING AND EVOLVING INTO AN OPEN  
TROUGH BY THURSDAY AS IT EXITS THE EAST COAST. ANOTHER UPPER TROUGH  
AND CLOSED LOW ACROSS THE NORTHERN ROCKIES MID-WEEK WILL SUSTAIN A  
SURFACE LOW CROSSING THE NORTHERN PLAINS AND THEN INTO SOUTH-  
CENTRAL CANADA BY THE END OF THE WEEK, WITH HEAVY RAIN FOR THE  
DAKOTAS/MINNESOTA AND LATE SEASON MOUNTAIN SNOW FOR THE NORTHERN  
ROCKIES. A SECOND TROUGH WILL LIKELY DEVELOP ACROSS THE INTERIOR  
WEST BY NEXT WEEKEND WITH AN UPPER RIDGE REDEVELOPING ACROSS THE  
PLAINS. WIDESPREAD ABOVE NORMAL TEMPERATURES ARE LIKELY EAST OF THE  
ROCKIES THROUGH MUCH OF THE FORECAST PERIOD.  
   
..GUIDANCE/PREDICTABILITY ASSESSMENT  
 
THE 00Z MODEL GUIDANCE SUITE FEATURES VERY GOOD SYNOPTIC SCALE  
AGREEMENT FOR THE MIDDLE TO END OF THE WEEK, WITH A MULTI-  
DETERMINISTIC MODEL BLEND SUFFICING AS A STARTING POINT IN THE  
FORECAST PROCESS. THE GFS IS A LITTLE TO THE NORTH OF THE MODEL  
CONSENSUS BY EARLY SATURDAY WITH THE LOW PRESSURE SYSTEM NEAR THE  
NORTHERN GREAT LAKES, WHEREAS THE ECMWF IS A LITTLE TO THE SOUTH  
AND THE AIFS FALLING NEAR THE MIDDLE OF THE GUIDANCE. FOR THE NEXT  
TROUGH BUILDING OUT WEST, THE GUIDANCE HAS TRENDED A LITTLE MORE  
AMPLIFIED WITH THE CMC/GFS DEPICTING A CLOSED LOW DEVELOPING OVER  
THE GREAT BASIN BY NEXT MONDAY. THE ENSEMBLE MEANS WERE INCREASED  
TO ABOUT HALF BY THAT TIME.  
   
..WEATHER/HAZARDS HIGHLIGHTS  
 
THE REGION WITH HEAVIEST RAINFALL GOING INTO THE SECOND HALF OF THE  
WORK WEEK WILL BE ACROSS NORTH DAKOTA AND INTO MINNESOTA. ALTHOUGH  
RAINFALL RATES ARE NOT EXPECTED TO BE ALL THAT HIGH, MULTIPLE  
HOURS OF MODERATE RAINFALL WITH RATES OF HALF AN INCH PER HOUR IN  
SOME CASES MAY JUST BE ENOUGH TO CAUSE SOME MINOR FLOODING ISSUES  
IN VULNERABLE AREAS, AND THEREFORE THE MARGINAL RISK AREA HAS BEEN  
MAINTAINED FOR THURSDAY (DAY 4) FROM EASTERN NORTH DAKOTA INTO  
CENTRAL/NORTHERN MINNESOTA. GOING INTO FRIDAY (DAY 5), SHOWERS AND  
THUNDERSTORMS INCREASE IN COVERAGE AND INTENSITY ACROSS THE MID-  
SOUTH IN THE GENERAL VICINITY OF A QUASI-STATIONARY FRONT THAT WILL  
BE INTERCEPTING ADVECTION OF DEEP MOISTURE FROM THE SOUTH. A  
MARGINAL RISK AREA IS NOW VALID FROM ARKANSAS TO EASTERN KENTUCKY  
WHERE THE MODEL QPF IS STRONGEST FOR ORGANIZED CONVECTION.  
 
ELSEWHERE ACROSS THE NATION, THE STORM PREDICTION CENTER IS  
MONITORING THE POTENTIAL FOR SOME SEVERE STORMS ON THURSDAY ACROSS  
PORTIONS OF THE MIDWEST. OUT WEST, IT WILL SEEM MORE LIKE MARCH ACROSS  
THE NORTHERN ROCKIES WITH HEAVY SNOW FOR THE HIGHEST RANGES OF  
SOUTHWESTERN MONTANA AND NORTHERN WYOMING, WITH THE POTENTIAL FOR  
6-12 INCHES OF ACCUMULATION IN SOME CASES THROUGH MID-WEEK, AND A  
SECOND ROUND OF SNOW FOR THE CENTRAL AND NORTHERN ROCKIES SUNDAY  
INTO MONDAY AS THE NEXT UPPER TROUGH AND SHORTWAVE MOVES INTO THE  
REGION. LIGHTER SNOWS ARE LIKELY ELSEWHERE ACROSS THE HIGHER  
TERRAIN OF THE NORTHERN ROCKIES AND INTERMOUNTAIN WEST.  
 
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 LOWER 90S FROM THE OHIO VALLEY AND MID-ATLANTIC  
SOUTHWARD TO THE GULF COAST. VERY HOT CONDITIONS ARE EXPECTED  
ACROSS SOUTHERN TEXAS FOR THE ENTIRE FORECAST PERIOD WITH HIGHS  
EXCEEDING 100 DEGREES NEAR THE RIO GRANDE, 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 WITH HIGHS RUNNING 5-15 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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