450  
FXUS02 KWBC 291956  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
356 PM EDT MON SEP 29 2025  
 
VALID 12Z THU OCT 02 2025 - 12Z MON OCT 06 2025  
 
   
..OVERVIEW  
 
THROUGH LATE WEEK INTO EARLY NEXT WEEK, MUCH OF THE LOWER 48 WILL  
BE IN A RELATIVELY SLOW-MOVING AND BLOCKY PATTERN. ROUNDS OF  
RENEWING UPPER TROUGHING ARE LIKELY IN THE WEST, WITH MULTIPLE  
FRONTAL PASSAGES BRINGING COOLER TEMPERATURES AND ROUNDS OF  
PRECIPITATION. MEANWHILE, AN UPPER RIDGE WILL STRETCH FROM THE  
DESERT SOUTHWEST INTO THE MIDWEST PROMOTING WARM TEMPERATURES AND  
MAINLY DRY CONDITIONS. SOUTHERN STREAM ENERGY AND A POSSIBLE  
FRONTAL BOUNDARY ATOP THE GULF COAST/FLORIDA COULD ALLOW FOR ROUNDS  
OF RAIN AND STORMS THERE.  
 
   
..GUIDANCE/PREDICTABILITY ASSESSMENT  
 
THE EXTENDED PERIOD BEGINS WITH A REASONABLY WELL CLUSTERED  
PATTERN. POSITIVELY TILTED UPPER RIDGING WILL BE IN PLACE FROM THE  
SOUTHWEST TO NORTHEAST; HOWEVER THERE WILL BE LINGERING ENERGY FOR  
THE GULF REGION TO THE SOUTH OF THE RIDGE AXIS. FARTHER WEST, A  
PRIMARY UPPER LOW NEAR BRITISH COLUMBIA IS EXPECTED TO USHER IN  
TROUGHING TO THE NORTHWEST/INTERMOUNTAIN WEST. THE TIMING OF THIS  
TROUGH MOVING IN LATE WEEK REMAINS SOMEWHAT QUESTIONABLE. THE  
TROUGH TRACK IS GENERALLY SLOWER THAN A DAY AGO, BUT WILL DEPEND ON  
AN UPSTREAM SHORTWAVE DROPPING SOUTH FROM THE NORTHEAST PACIFIC.  
THE 00Z CMC WAS AN OUTLIER IN HAVING A STRONGER UPSTREAM SHORTWAVE  
FARTHER SOUTH BY FRIDAY, BUT THE 12Z CMC HAS TRENDED CLOSER TO  
CONSENSUS. THE 00Z UKMET WAS FARTHER WEST AND STRONGER WITH THIS  
UPSTREAM SHORTWAVE, BUT KICKS OUT THE INITIAL TROUGHING MORE LIKE  
MOST MODELS FROM A DAY AGO, AND WAS NOT FAVORED. NEW 12Z MODEL RUNS  
ARE GENERALLY EVEN SLOWER ACROSS THE WEST AROUND SATURDAY,  
ESPECIALLY THE ECMWF. THIS SHOULD GENERALLY PIVOT EAST WHILE THE  
SECOND SHORTWAVE CONTINUES TO DEVELOP TROUGHING IN THE NORTHWEST,  
BUT THERE ARE TIMING DIFFERENCES IN THE SHORTWAVES AFFECTING  
SENSIBLE WEATHER. BY NEXT MONDAY MOST GUIDANCE INDICATES ENERGY  
PULLING AWAY TO CREATE POSSIBLY CLOSED UPPER LOW DEVELOPMENT ATOP  
CALIFORNIA AND VICINITY. THIS APPEARS TO BE IN GOOD AGREEMENT DAY 7  
BUT THE VARIATIONS IN THE DAYS 4-6 FORECAST LIMIT CONFIDENCE.  
 
GIVEN INITIAL REASONABLE AGREEMENT, THE WPC FORECAST BEGAN WITH A  
BLEND OF THE 06Z GFS, 00Z ECMWF, AND LESSER AMOUNTS OF THE 00Z CMC  
EARLY IN THE FORECAST PERIOD, WITH INCREASING PROPORTIONS OF THE  
ENSEMBLE MEANS TO 60 PERCENT DAYS 6-7.  
 
   
..WEATHER/HAZARDS HIGHLIGHTS  
 
SHORTWAVES WITHIN THE WESTERN TROUGH AND ASSOCIATED SURFACE FRONTS  
WILL PROMOTE ROUNDS OF PRECIPITATION ESPECIALLY FOR THE ROCKIES  
AND INTERMOUNTAIN WEST. THE HIGHER ELEVATIONS CAN EXPECT SNOW UNDER  
THE UPPER TROUGH. MOISTURE LEVELS WILL BE ABOVE NORMAL, BUT THE  
RAIN SEEMS UNLIKELY TO CAUSE FLOODING CONCERNS WITH NOT MUCH  
INSTABILITY IN PLACE, LIMITING RAIN RATES. THE PACIFIC NORTHWEST  
COULD SEE PRECIPITATION ESPECIALLY THURSDAY. RAIN CHANCES ARE  
FORECAST TO EXPAND INTO THE NORTH-CENTRAL U.S. LATE WEEK INTO THE  
WEEKEND AS A COUPLE OF FRONTAL SYSTEMS EMERGE INTO THE PLAINS.  
 
SOME WEAK ENERGY ALOFT IN THE SOUTHERN STREAM COULD STALL SOUTH OF  
THE SOUTHWEST TO NORTHEAST ORIENTED TROUGH, WHICH ALONG WITH A  
FRONTAL BOUNDARY AND SUFFICIENT MOISTURE COULD LEAD TO SCATTERED  
SHOWERS AND STORMS ACROSS FLORIDA AND FOR THE SOUTHEAST, ESPECIALLY  
ALONG THE GULF COAST. RAIN ACCUMULATIONS AND HOURLY RATES SEEM TO  
BE BELOW THE THRESHOLD FOR EXCESSIVE RAINFALL AT THIS TIME, BUT  
WILL CONTINUE TO MONITOR FOR FLOODING CONCERNS ESPECIALLY IN URBAN  
AREAS THAT TEND TO BE MORE SENSITIVE. MOISTURE AND INSTABILITY  
COULD LIFT NORTH INTO GEORGIA AND THE CAROLINAS OVER THE WEEKEND.  
MEANWHILE MOST AREAS UNDER THE UPPER TROUGH STAY DRY THROUGH THE  
LATTER HALF OF THE WEEK INTO THE WEEKEND, INCLUDING THE  
SOUTHWEST/SOUTHERN PLAINS EXTENDING INTO THE OHIO VALLEY AND THE  
NORTHEAST/MID-ATLANTIC.  
 
WARMER THAN SEASONAL AVERAGE TEMPERATURES ARE EXPECTED FOR A VAST  
MAJORITY OF THE CENTRAL U.S., MOST ANOMALOUS FOR THE NORTHERN  
PLAINS TO UPPER MIDWEST. WITH THE BUILDING RIDGE, DAILY HIGH  
TEMPERATURES WILL AVERAGE 15 TO 25 DEGREES ABOVE NORMAL THROUGH  
LATE WEEK, WELL INTO THE 80S EVEN TO THE CANADIAN BORDER. 90S ARE  
LIKELY TO CONTINUE FOR EARLY OCTOBER INTO THE DESERT SOUTHWEST AND  
TEXAS. BY THE WEEKEND, WARMER THAN AVERAGE TEMPERATURES COULD SHIFT  
A BIT EAST AND COVER THE GREAT LAKES REGION AND NORTHEAST, WHILE  
THE NORTHERN PLAINS COOLS. MEANWHILE, BELOW NORMAL TEMPERATURES  
ESPECIALLY FOR HIGHS ARE LIKELY ACROSS THE WEST DUE TO UPPER  
TROUGHING AND RAINY/CLOUDY CONDITIONS.  
 
TATE/CAMPBELL  
 
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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