478
FXUS02 KWBC 220752
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
352 AM EDT WED OCT 22 2025
VALID 12Z SAT OCT 25 2025 - 12Z WED OCT 29 2025
***HEAVY RAIN FOR BOTH THE GULF COAST AND THE WEST COAST THIS
WEEKEND, AND SNOW INCREASES FOR THE ROCKIES***
..GENERAL OVERVIEW
A SPLIT UPPER LEVEL FLOW PATTERN WILL BE IN PLACE ACROSS THE
CONTINENTAL U.S. FOR THIS UPCOMING WEEK, WITH A SOUTHERN STREAM
SHORTWAVE/CLOSED LOW CROSSING THE SOUTHERN PLAINS TO THE MID-SOUTH,
WITH HEAVY RAIN AND STRONG/SEVERE THUNDERSTORMS FROM THE ARKLATEX
TO THE DEEP SOUTH THROUGH SUNDAY. MEANWHILE, AN AMPLIFYING UPPER
TROUGH OVER THE WESTERN U.S. THIS WEEKEND WILL HERALD A PATTERN
CHANGE TO THE REGION, WITH COLDER CONDITIONS AND WIDESPREAD SNOW
FOR THE HIGHER TERRAIN, AND MODERATE TO HEAVY RAIN FOR THE PACIFIC
NORTHWEST COAST. THIS TROUGH WILL LIKELY SPUR SURFACE CYCLOGENESIS
OVER THE PLAINS THAT WILL RESULT IN ANOTHER ROUND OF SHOWERS AND
STORMS EARLY NEXT WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE 00Z MODEL GUIDANCE SUITE IS IN GOOD OVERALL AGREEMENT ACROSS
THE CONTINENTAL U.S. FOR THE WEEKEND, WITH MAINLY MINOR MESOSCALE
DIFFERENCES, SO A MULTI-DETERMINISTIC MODEL BLEND WAS USED THROUGH
THIS TIME PERIOD. THERE IS STILL CONSIDERABLE MODEL SPREAD
REGARDING HOW SURFACE CYCLOGENESIS TAKES PLACE ACROSS THE PLAINS
AS SHORTWAVE ENERGY EJECTS EASTWARD FROM THE SYNOPTIC SCALE TROUGH
OVER THE ROCKIES, WITH CONFIDENCE IN THE EVENTUAL EVOLUTION LOWER
THAN IT WAS YESTERDAY. IT LOOKS LIKELY THAT TWO SEPARATE LOWS COULD
DEVELOP, WITH ONE NEAR THE CANADIAN BORDER, AND ANOTHER OVER THE
MIDWEST AND OHIO VALLEY BY THE MIDDLE OF NEXT WEEK. THE ENSEMBLE
MEANS WERE INCREASED TO ABOUT HALF BY NEXT WEDNESDAY AMID THE
INCREASED UNCERTAINTY IN MODEL SPECIFICS.
..WEATHER/HAZARDS HIGHLIGHTS
THE SURFACE LOW PRESSURE SYSTEM THAT IS FORECAST TO EVOLVE OVER
THE SOUTHERN PLAINS LATER THIS WEEK, ALONG WITH STRONG WARM AIR
ADVECTION AND INCREASING INSTABILITY, WILL FUEL THE DEVELOPMENT OF
WIDESPREAD SHOWERS AND THUNDERSTORMS FROM EASTERN OKLAHOMA TO THE
LOUISIANA COAST ON SATURDAY. THERE IS STILL A STRONG SIGNAL FOR 2
TO 4 INCHES OF RAINFALL WITH LOCALLY HIGHER TOTALS ACROSS SOUTHEAST
TEXAS INTO CENTRAL LOUISIANA, SO A SLIGHT RISK OF EXCESSIVE
RAINFALL REMAINS VALID FOR THIS REGION ON THE DAY 4/SATURDAY ERO.
THE STORM PREDICTION CENTER WILL CONTINUE TO MONITOR THE POSSIBLE
SEVERE THREAT WITH THIS SYSTEM. THE AXIS OF HEAVIER RAINFALL THEN
REACHES THE CENTRAL GULF COAST BY SUNDAY, AND A MARGINAL RISK OF
EXCESSIVE RAINFALL IS VALID HERE FOR THE DAY 5 PERIOD WITH 1 TO 2
INCHES GENERALLY EXPECTED.
OUT WEST, AN AMPLIFYING UPPER TROUGH WILL DIRECT AN ATMOSPHERIC
RIVER AT COASTAL AREAS AND INLAND GOING INTO SATURDAY FROM NORTHERN
CALIFORNIA TO COASTAL OREGON. STEADY MODERATE TO OCCASIONAL HEAVY RAIN
ALONG THE COAST AND IN LOWER ELEVATIONS COULD LEAD TO SOME MINOR
INSTANCES OF FLOODING IN THE PACIFIC NORTHWEST AND EXTENDING SOUTH
INTO NORTHERN CALIFORNIA ON SATURDAY, SO A MARGINAL RISK REMAINS IN
EFFECT THEN BEFORE AN ABATEMENT IN THE RAINFALL ON SUNDAY, WHEN NO
RISK AREAS ARE CURRENTLY NECESSARY FOR THIS REGION. ANOTHER THING
THAT WILL MAKE WEATHER HEADLINES IS THE INCREASE OF HEAVY MOUNTAIN
SNOW FROM THE CASCADES TO THE NORTHERN ROCKIES, WHERE 1 TO 2 FEET
OF SNOW IS BECOMING MORE LIKELY FOR THE HIGHER RANGES. A NEW
SURFACE LOW IS LIKELY TO DEVELOP BY MONDAY ACROSS THE
CENTRAL/NORTHERN PLAINS AS A POTENT SHORTWAVE EJECTS EASTWARD FROM
THE ROCKIES, SUPPORTING AN INCREASE IN SHOWERS/STORMS AND GUSTY
WINDS FROM THE DAKOTAS TO THE MIDWEST STATES.
THE PATTERN CHANGE COMING OUT WEST WILL RESULT IN COLDER WEATHER
FROM NORTHERN CALIFORNIA AND OREGON EASTWARD TO THE GREAT BASIN AND
NORTHERN ROCKIES THROUGH MONDAY. HIGHS ARE EXPECTED TO BE 5 TO 15
DEGREES BELOW AVERAGE, PERHAPS LOCALLY MORE, BUT OVERNIGHT LOWS
SHOULD BE CLOSER TO AVERAGE OWING TO INCREASED CLOUD COVER AND
PRECIPITATION. LATE SEASON WARMTH SHOULD BE THE CASE FROM THE
DAKOTAS TO THE MIDWEST THROUGH MONDAY BEFORE THESE AREAS ALSO GET A
COOL DOWN TOWARDS NEXT WEDNESDAY AS THE UPPER LOW DEVELOPS BEHIND
THE COLD FRONT. MUCH OF THE EAST COAST REGION SHOULD GENERALLY BE
SLIGHTLY BELOW AVERAGE FOR BOTH HIGHS AND LOWS THROUGH MOST OF THE
FORECAST PERIOD.
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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