866  
FXUS02 KWBC 012219 AAA  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION...UPDATED  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
619 PM EDT WED OCT 1 2025  
 
VALID 12Z SAT OCT 4 2025 - 12Z WED OCT 8 2025  
 
   
..GENERAL OVERVIEW
 
 
THE OVERALL WEATHER PATTERN ACROSS THE CONTINENTAL U.S. WILL BE  
FEATURED WITH A GENERAL UPPER RIDGE SITUATED OVER THE INTERMOUNTAIN  
WEST, AND A BUILDING UPPER RIDGE OVER THE EASTERN HALF OF THE  
NATION. THERE WILL LIKELY BE A SPLIT FLOW PATTERN ALOFT, WITH THE  
SOUTHERN STREAM SHOWING INCREASED POTENTIAL FOR A CLOSED UPPER LOW  
TO DEVELOP OVER CALIFORNIA/NEVADA BY EARLY NEXT WEEK. MEANWHILE,  
THE NORTHERN STREAM WILL SUPPORT AN AMPLIFYING SHORTWAVE WITH AN  
ATTENDANT COLD FRONT, USHERING IN MUCH COLDER TEMPERATURES ACROSS  
THE NORTHERN ROCKIES AND NORTHWESTERN PLAINS, AND HEAVY SNOW FOR  
THE HIGHER MOUNTAIN RANGES OF WYOMING AND MONTANA. FARTHER SOUTH,  
TROPICAL MOISTURE INTERACTING WITH A LINGERING STATIONARY FRONT  
WILL LIKELY PRODUCE PERIODS OF HEAVY RAIN AND THUNDERSTORMS ALONG  
THE EAST COAST OF FLORIDA, AND ALSO PORTIONS OF THE CENTRAL GULF  
COAST FOR THE UPCOMING WEEKEND.  
 
   
..GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
THE 12Z MODEL GUIDANCE SUITE FEATURES GOOD OVERALL SYNOPTIC SCALE  
AGREEMENT THROUGH THE UPCOMING WEEKEND, WITH A GENERAL  
DETERMINISTIC MODEL COMPROMISE USED FOR FRONTS/PRESSURES. THE UKMET  
IS SLIGHTLY FASTER WITH THE LARGE SHORTWAVE TROUGH OVER THE FOUR  
CORNERS REGION, AND RECENT RUNS OF THE GFS HAVE BEEN FASTER WITH  
THE PASSAGE OF THE COLD FRONT ACROSS EASTERN CANADA AND THE GREAT  
LAKES REGION EARLY NEXT WEEK. BY MONDAY AND BEYOND,  
THE GREATEST MODEL DIFFERENCES ARE MAINLY ACROSS SOUTH-CENTRAL  
CANADA REGARDING TIMING OF INDIVIDUAL SHORTWAVES. THE AIFS  
GUIDANCE GENERALLY HAS A BROADER UPPER TROUGH SITUATED OVER THE  
GREAT LAKES AND SOUTHERN CANADA BY WEDNESDAY, WHEREAS THE  
OPERATIONAL GUIDANCE FAVORS MORE OF A SHARPER TROUGH. THE ENSEMBLE  
MEANS WERE GRADUALLY INCREASED TO ABOUT 40% BY NEXT WEDNESDAY AS  
MESOSCALE DIFFERENCES INCREASED.  
 
   
..WEATHER/HAZARDS HIGHLIGHTS
 
 
COASTAL PORTIONS OF THE CENTRAL GULF COAST AND SOUTHEAST GEORGIA  
INTO FLORIDA WILL REMAIN IN AN ACTIVE, WET PATTERN AS TROPICAL  
MOISTURE INTERACTS WITH A STATIONARY FRONTAL BOUNDARY, AND A  
COUPLE OF WEAK LOW PRESSURE CENTERS MAY FORM ON THE FRONT AND  
ENHANCE THE RAINFALL. A MARGINAL RISK OF EXCESSIVE RAINFALL WAS  
MAINTAINED FOR BOTH DAY 4 AND DAY 5 ALONG THE EASTERN COAST OF  
FLORIDA, WITH URBAN LOCATIONS MOST PRONE TO FLOODING, AND AN  
EVENTUAL SLIGHT RISK AREA COULD BE NEEDED AS THE EVENT GETS CLOSER  
IN TIME. THE DAY 4 MARGINAL REMAINS FOR SOUTHEAST LOUISIANA WHERE  
HEAVY SHOWERS AND THUNDERSTORMS ARE EXPECTED ALONG THE COASTLINE  
AND POINTS INLAND FOR THE SOUTHEAST PARISHES. LOCALLY, 3 TO 4  
INCHES OF RAIN WILL BE POSSIBLE AND MAY LEAD TO ISOLATED AREAS OF  
FLOODING. A NEW DAY 5 MARGINAL RISK WAS ALSO ADDED FOR THE CENTRAL  
GULF COAST TO ACCOUNT FOR THIS.  
 
MULTIPLE ROUNDS OF PRECIPITATION ARE FORECAST FOR THE WESTERN U.S.  
AS SHORTWAVES WITHIN THE UPPER TROUGH AND ASSOCIATED SURFACE  
FRONTS TRACK EASTWARD, ESPECIALLY FOR THE ROCKIES AND INTERMOUNTAIN  
WEST. THE HIGHER ELEVATIONS CAN EXPECT MODERATE TO LOCALLY HEAVY SNOW  
WITH THE PASSAGE OF THE UPPER TROUGH, ESPECIALLY FOR THE HIGHER  
TERRAIN OF WESTERN WYOMING AND SOUTHWESTERN MONTANA. FARTHER EAST,  
MOISTURE LEVELS WILL BE ABOVE NORMAL, AND EVEN THOUGH INSTABILITY  
WILL NOT BE ALL THAT HIGH, AREAL QPF OF 1-2 INCHES ON SATURDAY  
COULD BE ENOUGH TO LEAD TO SOME INSTANCES OF MINOR FLOODING IN POOR  
DRAINAGE AREAS, AND THEREFORE A MARGINAL RISK AREA HAS BEEN  
INTRODUCED FOR THE DAY 4 PERIOD FROM THE LOWER ELEVATIONS OF  
NORTHERN WYOMING AND SOUTHERN MONTANA, EASTWARD TO THE CENTRAL  
DAKOTAS.  
 
SUMMER-LIKE TEMPERATURES WILL HOLD ON ACROSS MUCH OF THE CENTRAL  
U.S. UNDER THE DEEP-LAYER RIDGE. EACH DAY THE MAXIMUM TEMPERATURES  
WILL AVERAGE 10-20+ DEGREES ABOVE NORMAL GOING INTO SATURDAY, WELL  
INTO THE 80S EVEN TO THE CANADIAN BORDER WHERE DAILY RECORD HIGH  
TEMPERATURES WILL MOST LIKELY BE CHALLENGED OR BROKEN SATURDAY  
AFTERNOON. FOR THE DESERT SOUTHWEST AND PORTIONS OF TEXAS, 90S ARE  
LIKELY TO CONTINUE FOR EARLY OCTOBER. BY SUNDAY, WARMER THAN  
AVERAGE TEMPERATURES AFFECT AREAS TO THE EAST AND COVER THE GREAT  
LAKES REGION AND NORTHEAST, WHILE THE NORTHERN PLAINS GETS MUCH  
COLDER BEHIND THE STRONG COLD FRONT. MEANWHILE, BELOW NORMAL  
TEMPERATURES ESPECIALLY FOR HIGHS ARE LIKELY ACROSS THE WEST DUE TO  
UPPER TROUGHING AND RAINY/CLOUDY CONDITIONS.  
 
HAMRICK/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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