474  
FXUS02 KWBC 021955  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
355 PM EDT THU OCT 2 2025  
 
VALID 12Z SUN OCT 05 2025 - 12Z THU OCT 09 2025  
 
***HEAVY RAIN LIKELY FOR PORTIONS OF THE COASTAL SOUTHEAST U.S.  
THROUGH THE WEEKEND INTO EARLY NEXT WEEK***  
   
..GENERAL OVERVIEW  
 
A GENERAL UPPER RIDGE WILL BE SITUATED OVER THE INTERMOUNTAIN WEST  
ALONG WITH 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 AND INTO MONDAY, WITH A  
GENERAL DETERMINISTIC MODEL COMPROMISE USED FOR FRONTS/PRESSURES AS  
A STARTING POINT. NOTEWORTHY MODEL DIFFERENCES BECOME APPARENT BY  
TUESDAY MORNING OFF THE PACIFIC NORTHWEST COAST WITH A STORM SYSTEM  
ORIGINATING FROM THE GULF OF ALASKA, AND BY WEDNESDAY THIS RESULTS  
IN BIG DIFFERENCES ACROSS THE NORTHWESTERN QUADRANT OF THE NATION.  
THE ECMWF AND TO A LESSER EXTENT THE CMC BRING IN THE UPPER TROUGH  
FASTER THAN THE GFS AND THE GEFS MEAN. THEREFORE, THE GFS GROUP OF  
SOLUTIONS HAS MORE OF AN UPPER RIDGE ACROSS THE NORTHERN ROCKIES IN  
CONTRAST TO THE CMC/ECMWF WHICH ARE WELL TO THE EAST WITH THAT SAME  
RIDGE AXIS. THE LATEST AIFS GUIDANCE SUGGESTS A SOLUTION THAT IS  
CLOSER TO THE GFS/GEFS AND DELAYS THE ARRIVAL OF THE NORTHWESTERN  
TROUGH, AND HAS THE RIDGE AXIS GENERALLY BETWEEN THE GFS AND ECMWF  
SOLUTIONS. THE ENSEMBLE MEANS WERE INCREASED TO ABOUT 2/3RDS BY  
NEXT THURSDAY GIVEN THE HIGHER MODEL SPREAD AND BELOW AVERAGE  
FORECAST CONFIDENCE BY THIS TIME.  
 
   
..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. THE DAY 4  
MARGINAL REMAINS FOR SOUTHEAST LOUISIANA WHERE HEAVY SHOWERS AND  
THUNDERSTORMS ARE EXPECTED ALONG THE COASTLINE FOR DAY 3 AND  
CONTINUING INTO DAY 4 FOR THE SOUTHEAST PARISHES. LOCALLY, A TWO  
DAY ACCUMULATION MAY EXCEED 3 TO 4 INCHES OF RAIN AND WITH  
ADDITIONAL RAIN EXPECTED, A MARGINAL RISK OF EXCESSIVE RAINFALL  
WILL REMAIN IN PLACE.  
 
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. SCATTERED TO  
WIDESPREAD SHOWERS AND THUNDERSTORMS TRACKING THROUGH THE PLAINS  
MAY HAVE LOCALLY HEAVY AMOUNTS FROM KANSAS/NEBRASKA NORTHEAST TO  
THE WISCONSIN/ILLINOIS BORDER. A MARGINAL RISK AREA REMAINS VALID  
ON DAY 5 FOR THE POTENTIAL FOR LOCALLY EXCESSIVE RAINFALL AND  
ISOLATED INSTANCES OF FLASH FLOODING.  
 
IN THE TEMPERATURE DEPARTMENT, IT WILL BE RATHER WARM BY EARLY  
OCTOBER STANDARDS ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION  
SUNDAY, AND THIS ANOMALOUS WARMTH REACHES THE OHIO VALLEY AND  
NORTHEAST STATES FOR THE BEGINNING OF NEXT WEEK WITH BOTH HIGHS AND  
OVERNIGHT LOWS RUNNING 10-20 DEGREES ABOVE AVERAGE IN MANY CASES.  
THERE MAY BE A FEW DAILY RECORDS ON SUNDAY ACROSS THE UPPER MIDWEST  
AHEAD OF THE COLD FRONT. READINGS WILL TURN SHARPLY COLDER BEHIND  
THAT SAME FRONT FOR THE NORTHERN PLAINS WITH HIGHS RETURNING TO  
SLIGHTLY BELOW AVERAGE WITH BREEZY CONDITIONS. THIS BOUNDARY IS  
EXPECTED TO REACH THE EAST COAST BY THIS TIME NEXT WEEK WITH A  
RETURN TO MORE SEASONABLE CONDITIONS THEN.  
 
CAMPBELL/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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