393
FXUS02 KWBC 300750
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
350 AM EDT TUE SEP 30 2025
VALID 12Z FRI OCT 03 2025 - 12Z TUE OCT 07 2025
..OVERVIEW
A PLODDING, BLOCKY PATTERN WILL BE IN STORE FOR THROUGH THE
WEEKEND AND INTO MIDWEEK. ROUNDS OF RENEWING UPPER TROUGHING ARE
LIKELY IN THE WEST, WITH MULTIPLE FRONTAL PASSAGES BRINGING COOLER
TEMPERATURES AND ROUNDS OF PRECIPITATION. IN CONTRAST, WARMER
TEMPERATURES AND GENERALLY DRIER CONDITIONS WILL PERSIST UNDER AN
UPPER RIDGE SPANNING FROM THE DESERT SOUTHWEST TO THE MIDWEST.
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
OVERALL, THERE IS DECENT CLUSTERING WITH THE LARGE SCALE 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. A PRIMARY UPPER LOW NEAR
BRITISH COLUMBIA IS EXPECTED TO USHER IN TROUGHING TO THE
NORTHWEST/INTERMOUNTAIN WEST; HOWEVER THERE REMAINS MODEL VARIANCE
ON THE TIMING OF ITS TRACK DUE TO UPSTREAM SHORTWAVE ENERGY
DROPPING SOUTH FROM THE NORTHEAST PACIFIC. IT WAS PREVIOUSLY NOTED
THAT IN PRIOR RUNS THE CMC DEPICTED A STRONGER SHORTWAVE BUT THE
MOST RECENT VERSION HAD TRENDED CLOSER TO CONSENSUS. IN COMPARISON
TO THE LATEST RUN OF THE EC AND GFS, THIS REMAINS TRUE. CONSENSUS
STILL FAVORS A SLOWER PROGRESSION OF THE TROUGH/CLOSED LOW OVER THE
WEST THIS WEEKEND BEFORE PIVOTING WITH THE THE SECOND SHORTWAVE
EARLY IN THE COMING WEEK. THESE TIMING DIFFERENCES WILL HAVE DIRECT
IMPACT TO SENSIBLE WEATHER.
THE WPC FORECAST BEGAN WITH A BLEND OF THE 12Z GFS, 12Z ECMWF, AND
LESSER AMOUNTS OF THE 12Z CMC EARLY IN THE FORECAST PERIOD, WITH
INCREASING PROPORTIONS OF THE ENSEMBLE MEANS FOR DAYS 5-7.
..WEATHER/HAZARDS HIGHLIGHTS
MULTIPLE ROUNDS OF PRECIPITATION IS FORECAST FOR THE WEST AND
INTERMOUNTAIN WEST AS SHORTWAVES WITHIN THE WESTERN TROUGH AND
ASSOCIATED SURFACE FRONTS TRACK EASTWARD; 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. 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. A MARGINAL RISK FOR EXCESSIVE RAINFALL WAS
HOISTED FOR DAY 4 AND DAY 5 ALONG THE EASTERN COAST OF FLORIDA AS
URBAN AREAS 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.
CAMPBELL/TATE
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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