586  
FXUS02 KWNH 240637  
PREEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
236 AM EDT THU JUL 24 2025  
 
VALID 12Z SUN JUL 27 2025 - 12Z THU JUL 31 2025  
 
***MAJOR AND PERSISTENT HEAT WAVE CONTINUES FROM THE SOUTHEAST TO  
THE CENTRAL U.S. THIS WEEKEND INTO NEXT WEEK***  
   
..GENERAL OVERVIEW
 
 
A MAJOR HEATWAVE WILL CONTINUE TO MAKE WEATHER HEADLINES ACROSS A  
LARGE EXPANSE OF THE CENTRAL AND EASTERN U.S. GOING INTO NEXT  
WEEK. THIS IS IN RESPONSE TO A SPRAWLING UPPER RIDGE THAT WILL  
INITIALLY BE CENTERED OVER THE SOUTHEAST STATES, AND THEN BUILDS  
BACK TO THE WEST ACROSS THE CENTRAL AND SOUTHERN PLAINS BY THE  
MIDDLE OF THE WEEK. COMPLEXES OF SHOWERS AND STORMS ARE LIKELY FROM  
THE NORTHERN PLAINS TO THE MIDWEST, AND MONSOONAL MOISTURE MAKES A  
RETURN TO THE SOUTHWEST STATES. A PATTERN CHANGE IS LIKELY TO  
EVOLVE BY THE END OF THE FORECAST PERIOD AS THE UPPER LEVEL FLOW  
BECOMES MORE AMPLIFIED, WITH THE RIDGE BUILDING NORTH ACROSS THE  
ROCKIES AND A TROUGH FROM CANADA BUILDING SOUTHWARD ACROSS THE  
GREAT LAKES AND THE NORTHEAST, BRINGING A RETURN TO MUCH MORE  
PLEASANT CONDITIONS BEHIND A COLD FRONT BY THURSDAY.  
 
   
..GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
EXCELLENT OVERALL MODEL AGREEMENT EXISTS AMONG THE 00Z GUIDANCE  
SUITE REGARDING THE MAIN UPPER LEVEL AND SURFACE PRESSURE PATTERN  
ACROSS THE NATION FOR SUNDAY AND MONDAY. LOOKING AHEAD TO THE  
MIDDLE OF NEXT WEEK, THE EXPANSIVE UPPER RIDGE/HIGH IS THE MOST  
CONFIDENT ASPECT OF THE FORECAST WITH THE BEST MODEL AGREEMENT.  
THERE ARE SOME MESOSCALE DIFFERENCES WITH THE SHORTWAVES THAT CROSS  
THE NORTH-CENTRAL U.S., BUT NOTHING MAJOR. THERE HAS BEEN A TREND  
IN THE GUIDANCE FOR A MORE AMPLIFIED UPPER TROUGH DEVELOPING OVER  
ONTARIO AND QUEBEC THAT WILL BEGIN TO EXERT ITS INFLUENCE ACROSS  
THE NORTHEAST STATES STARTING MID-WEEK, IN RESPONSE TO THE UPPER  
RIDGE RETROGRADING TO THE WESTERN HIGH PLAINS. A GENERAL MODEL  
BLEND WORKED FOR SUNDAY INTO TUESDAY, WITH A TRANSITION TO ABOUT  
40% ENSEMBLE MEANS BY NEXT THURSDAY.  
 
   
..WEATHER/HAZARDS HIGHLIGHTS
 
 
THE OVERALL WEATHER PATTERN IS EXPECTED TO REMAIN RATHER ACTIVE  
ACROSS THE NORTHERN TIER STATES AS STORM SYSTEMS TRAVERSE THE  
NORTHERN PERIPHERY OF THE UPPER HIGH. THE MAIN AREA OF CONCERN IN  
TERMS OF HEAVY RAINFALL POTENTIAL EARLY THIS PERIOD WILL BE ACROSS  
THE UPPER MIDWEST, WITH THE HEAVIEST RAINFALL LIKELY ON SUNDAY AS  
A SURFACE LOW DEVELOPS ALONG A COLD FRONT AND INTERCEPTS AN  
ANOMALOUSLY HUMID AIRMASS ACROSS MUCH OF MINNESOTA. GIVEN GOOD  
MODEL QPF AGREEMENT FOR THIS TIME RANGE AND THE RECENT HEAVY  
RAINFALL, A SLIGHT RISK AREA WILL REMAIN VALID FOR THE DAY  
4/SUNDAY PERIOD FROM EXTREME EASTERN NORTH DAKOTA, ACROSS NORTHERN  
MINNESOTA, AND INTO FAR NORTHWEST WISCONSIN.  
 
ELSEWHERE ACROSS THE NATION, THE POSITION OF THE UPPER HIGH/RIDGE  
OVER THE WESTERN HIGH PLAINS BY EARLY NEXT WEEK WILL RESULT IN  
DEEPER MONSOONAL MOISTURE BEING ADVECTED NORTHWARD ACROSS THE  
DESERT SOUTHWEST. THIS FIRST BECOMES NOTICEABLE ACROSS SOUTHERN NEW  
MEXICO ON SUNDAY, BUT BECOMES MORE WIDESPREAD AND ENCOMPASSES MORE  
OF NEW MEXICO AND INTO MUCH OF CENTRAL/EASTERN ARIZONA AND  
COLORADO BY MONDAY AND TUESDAY. THEREFORE, THE DAY 4/SUNDAY ERO  
FEATURES A MARGINAL RISK AREA CENTERED OVER CENTRAL AND SOUTHERN  
NEW MEXICO, AND THE DAY 5/MONDAY OUTLOOK HAS THE MARGINAL RISK AREA  
EXTENDING INTO EASTERN ARIZONA AND SOUTHERN COLORADO. EVEN GREATER  
COVERAGE OF SHOWERS AND STORMS IS LIKELY BY THE MIDDLE OF NEXT WEEK  
AS DEEPER LOW-MID LEVEL MOISTURE ENTERS THE REGION. SCATTERED  
STORMS WILL ALSO BE POSSIBLE ACROSS PORTIONS OF THE NORTHERN  
ROCKIES AND THE CASCADES. SOME LOCALLY HEAVY RAINFALL WILL ALSO BE  
POSSIBLE ACROSS THE NORTHEAST ON SUNDAY, AND A MARGINAL RISK AREA  
IS VALID HERE AS WELL.  
 
IN THE TEMPERATURE DEPARTMENT, HEAT WILL CONTINUE TO BE A MAJOR  
PROBLEM FROM THE CENTRAL PLAINS TO THE SOUTHEAST STATES GIVEN THE  
SIZE OF THE UPPER RIDGE AND THE JET STREAM WELL TO THE NORTH.  
DANGEROUS HEAT INDICES ON THE ORDER OF 105 TO 115 DEGREES WILL  
LIKELY BE COMMON FOR THE PIEDMONT AND COASTAL PLAIN OF THE  
SOUTHEAST U.S. AND INCLUDING NORTHERN FLORIDA, WITH HEAT RISK IN  
THE MAJOR TO EXTREME CATEGORY FOR MUCH OF NEXT WEEK. THE HEAT THEN  
BUILDS ACROSS THE MIDWEST AND EXTENDING SOUTH TO THE GULF COAST AS  
THE UPPER RIDGE RETROGRADES TO THE WEST FOR THE FIRST HALF OF THE  
WORK WEEK, WITH HEAT INDICES ALSO REACHING 110 DEGREES AT TIMES FOR  
SOME OF THESE AREAS, WITH HEAT ADVISORIES AND EXTREME HEAT  
WARNINGS LIKELY TO CONTINUE. WARM AND HUMID OVERNIGHT LOWS WON'T  
PROVIDE MUCH RELIEF EITHER. SOME GOOD NEWS TO REPORT IS THAT A COLD  
FRONT IS EXPECTED TO DROP SOUTH FROM THE GREAT LAKES TO THE OHIO  
VALLEY AND EVENTUALLY THE MID-ATLANTIC AND NORTHEAST TOWARDS THE  
END OF THE WEEK, PROVIDING SOME BADLY NEEDED RELIEF AS A HIGHER  
QUALITY AIRMASS BUILDS IN BEHIND THE FRONT.  
 
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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