680
FXUS02 KWBC 301959
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
359 PM EDT TUE SEP 30 2025
VALID 12Z FRI OCT 03 2025 - 12Z TUE OCT 07 2025
..OVERVIEW
DEEP UPPER TROUGHING IS FORECAST TO PROGRESS THROUGH THE WEST TO
ERODE A STRONG RIDGE INITIALLY DOMINATING THE EASTERN TWO-THIRDS OF
THE COUNTRY. THIS SHIFT IN THE SYNOPTIC PATTERN WILL BRING THE
FIRST FROST/FREEZE OF THE SEASON INTO THE LOWER ELEVATIONS FROM
THE NORTHERN ROCKIES TO THE NORTHERN PLAINS AFTER RECORD WARMTH IN
THE UPPER MIDWEST. TROPICAL MOISTURE INTERACTING WITH A STATIONARY
FRONT COULD DELIVER HEAVY RAIN AND THUNDERSTORMS ALONG THE EAST
COAST OF FLORIDA AND ALONG PORTIONS OF THE CENTRAL GULF COAST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
OVERALL, THERE IS DECENT MODEL AGREEMENT ON THE AFOREMENTIONED
EVOLUTION OF THE LARGE SCALE PATTERN ACROSS THE U.S. STRONG UPPER
RIDGING INITIALLY EXTENDING FROM THE SOUTHWEST TO NORTHEAST WILL
BE GRADUALLY ERODED BY DEEP UPPER TROUGHING FORECAST TO ADVANCE
THROUGH THE WESTERN U.S. BY EARLY NEXT WEEK, MODELS SHOW GOOD
AGREEMENT FOR AN UPPER LOW TO DETACH FROM THE MAIN POSITIVELY-
TILTED UPPER TROUGH OVER THE SOUTHWEST. ACROSS THE NORTHERN TIER
STATES, MODEL CONSENSUS SHOWS A SIGHTLY FASTER EASTWARD PROGRESSION
OF THE COLD FRONT AND THE POSITIVELY-TILTED UPPER TROUGH BY EARLY
NEXT WEEK.
THE WPC MEDIUM-RANGE FORECASTS BEGAN WITH A GENERAL CONSENSUS OF
40% FROM THE 06Z GFS/GEFS, 40% FROM THE 00Z ECMWF/EC MEAN, AND 20%
FROM THE 00Z CMC/CMC MEAN, WITH HIGHER PROPORTIONS FROM 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 U.S. UPPER-
TROUGH AND ASSOCIATED SURFACE FRONTS TRACK EASTWARD, ESPECIALLY
FOR THE ROCKIES AND INTERMOUNTAIN WEST. THE HIGHER ELEVATIONS CAN
EXPECT SNOW WITH THE PASSAGE OF 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.
TROPICAL MOISTURE INTERACTING WITH A STATIONARY FRONT WILL LEAD TO
HEAVY SHOWERS AND THUNDERSTORMS LURKING NEAR OR JUST OFF THE GULF
COAST AND OFF THE SOUTHEAST U.S. A MARGINAL RISK OF EXCESSIVE
RAINFALL IS MAINTAINED FOR DAY 4 AND DAY 5 ALONG THE EASTERN COAST
OF FLORIDA AS URBAN AREAS TEND TO BE MORE SENSITIVE. A COUPLE OF WEAK
LOW PRESSURE CENTERS MAY FORM ON THE FRONT AND COULD LIFT NORTH TO
ENHANCE RAINFALL NEAR THE CENTRAL GULF COAST, AND FROM THE EAST
COAST OF FLORIDA UP INTO THE GEORGIA COAST OVER THE WEEKEND.
MEANWHILE, MOST AREAS UNDER AN EXPANSIVE DEEP-LAYER RIDGE 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. UNDER THE DEEP-LAYER RIDGE, DAILY HIGH
TEMPERATURES WILL AVERAGE 15 TO 25 DEGREES ABOVE NORMAL THROUGH
LATE WEEK, WELL INTO THE 80S EVEN TO THE CANADIAN BORDER WHERE
DAILY RECORD HIGH TEMPERATURES WILL MOST LIKELY BE CHALLENGED OR
BROKEN SATURDAY AFTERNOON. MEANWHILE, 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.
KONG/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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