600
FXUS02 KWBC 311918
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
318 PM EDT FRI OCT 31 2025
VALID 12Z MON NOV 03 2025 - 12Z FRI NOV 07 2025
..OVERVIEW
INTO EARLY NEXT WEEK, A DEEP UPPER TROUGH WILL SWING ACROSS THE
GREAT LAKES REGION WHILE A CLOSED LOW SEEMS MOST LIKELY TO MOVE
EAST ACROSS THE SOUTHEAST. IT IS APPEARING INCREASINGLY LIKELY THAT
THE BULK OF THE ENERGY ASSOCIATED WITH THE SOUTHERN LOW WILL BE
INFLUENCED BY THE TROUGH AND MOVE FAIRLY QUICKLY OFFSHORE, BUT
THERE IS STILL A CHANCE THAT SOME ENERGY WITH THE LOW MAY LINGER
NEAR BACK NEAR THE GULF. ANOTHER TROUGH IS EXPECTED TO SWEEP ACROSS
THE GREAT LAKES AND NORTHEAST RIGHT AFTER THE FIRST ONE, WHICH
WILL RESULT IN PERSISTENT PRECIPITATION CHANCES FOR THESE REGIONS
THROUGH LATER NEXT WEEK. THIS MAY INCLUDE SOME WRAP-BACK PLOWABLE
SNOW POTENTIAL OVER NORTHERN NEW ENGLAND. MEANWHILE, A STORMY
PATTERN WILL DEVELOP IN THE WEST AS A SERIES OF PACIFIC FRONTAL
SYSTEMS BRING WIDESPREAD PRECIPITATION CHANCES TO THE REGION, WITH
HEAVY PRECIPITATION POTENTIAL OVER THE NORTHWEST/WEST COAST. MEAN
RIDGING WILL DOMINATE THE WEATHER PATTERN FOR MUCH OF THE CENTRAL
U.S. AND SOUTHWEST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE HAS BEEN QUITE UNCERTAIN ABOUT THE EVOLUTION OF THE
NORTHEASTERN TROUGH AND UPPER LOW OVER THE SOUTHEAST EARLY NEXT
WEEK, WHICH IS THE MOST UNCERTAIN PART OF TODAY'S FORECAST. SOME
SOLUTIONS HAVE SHOWN LITTLE INTERACTION BETWEEN THE TWO FEATURES,
RESULTING IN THE CLOSED LOW LINGERING LONGER AND DRIFTING FURTHER
SOUTH OVER THE SOUTHEAST, BUT SOME HAVE SHOWN THE LOW BEING SWEPT
QUICKLY OFFSHORE BY THE TROUGH. THE MAJORITY OF THE AVAILABLE
DETERMINISTIC MODEL SOLUTIONS, INCLUDING THE EC-AIFS, OVERALL FAVOR
THE QUICKER SOLUTION. THE GFS SEEMS TO BE A BIT OF AN OUTLIER WITH
A SLOWER SOLUTION. GIVEN THIS, WPC'S FORECAST CONTINUES TO REFLECT
A REASONABLY PROGRESSIVE SOLUTION WITH 12 UTC CYCLE GUIDANCE STILL
MORE MIXED THAN USUAL, BUT IMPROVING INTO SHORT RANGE TIME FRAMES.
MODEL AGREEMENT SEEMS BETTER FOR THE SECOND HALF OF NEXT WEEK AS A
SERIES OF STRONGER PACIFIC TROUGHS/FRONTAL SYSTEMS MOVE INTO THE
WEST, ALBEIT WITH SOME LINGERING VARIANCES.
ACCORDINGLY, THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY
DERIVED FROM COMPOSITE OF MODELS AND ENSEMBLES THAT OVERALL SEEMS
IN LINE WITH THE NATIONAL BLEND OF MODELS AND WPC CONTINUITY.
..WEATHER/HAZARDS HIGHLIGHTS
PRECIPITATION CHANCES WILL FOCUS IN THE EAST AND WEST WHILE THE
CENTRAL U.S. REMAINS FAIRLY DRY NEXT WEEK. UPPER LEVEL TROUGHING
WILL SUPPORT PERSISTENT PERIODS OF PRECIPITATION THROUGHOUT THE
WEEK FOR THE GREAT LAKES AND NORTHEAST AS A FEW FRONTAL SYSTEMS
MOVE ACROSS THESE REGIONS. THESE SYSTEMS SHOULD BE PROGRESSIVE,
WHICH WILL LIMIT THE CHANCE OF ANY HEAVY PRECIPITATION, BUT EXPECT
SOME EARLY SEASON WRAPBACK SNOW POTENTIAL OVER NORTHERN NEW
ENGLAND INTO LATER NEXT WEEK MAY BE ENHANCED OVER FAVORED TERRAIN
GIVEN ORGANIZED LOW DEVELOPMENT AND ROUGHLY ALONG THE CANADIAN
BORDER TRACK. AN AT LEAST INITIALLY CLOSED LOW OVER THE SOUTHEAST
WILL ALSO SUPPORT LIGHT TO MODERATE RAIN SHOWERS EARLY NEXT WEEK.
RAINFALL TOTALS WILL ULTIMATELY DEPEND ON THE SPEED AND DURATION OF
THIS SYSTEM, BUT IT LOOKS INCREASINGLY LIKELY THAT THE LOW WILL NOW
MOVE FAIRLY QUICKLY TO THE ATLANTIC, LIMITING RAINFALL POTENTIAL.
AN UNSETTLED WEATHER PATTERN WILL DEVELOP IN THE WEST NEXT WEEK AS
SEVERAL RELATIVELY STRONGER SYSTEMS MOVE ONSHORE FROM THE PACIFIC.
WIDESPREAD PRECIPITATION CHANCES ARE EXPECTED ACROSS THE PACIFIC
NORTHWEST AND NORTHERN CALIFORNIA THROUGH THE WEEK. THE HEAVIEST
PRECIPITATION IS EXPECTED TO FOCUS OVER NORTHERN CALIFORNIA AND
SOUTHWESTERN OREGON AS AN ATMOSPHERIC RIVER EVENT UNFOLDS TUESDAY
INTO WEDNESDAY. MOST PRECIPITATION SHOULD FALL AS RAIN WITH THIS
EVENT, BUT HEAVY SNOW WILL BE POSSIBLE IN THE HIGHER ELEVATIONS OF
THE CASCADES AND SIERRA NEVADA. A MARGINAL RISK OF EXCESSIVE
RAINFALL REMAINS IN THE DAY 5/TUESDAY EXCESSIVE RAINFALL OUTLOOK,
REPRESENTING A RISK FOR ISOLATED FLASH FLOODING WITH HEAVY RAIN
ALONG THE COAST AS ADJUSTED FOR LATEST GUIDANCE TRENDS THAT ARE
SLIGHTLY SLOWER TO WORK ACTIVITY INLAND. THE SYSTEM RESPONSIBLE
FOR THIS MOVES STEADILY INLAND TO LIMIT PRECIPITATION TOTALS.
ANOTHER SYSTEM WILL APPROACH THE PACIFIC NORTHWEST THURSDAY INTO
FRIDAY, WHICH SHOULD BRING ANOTHER SHOT OF POTENTIALLY HEAVY
PRECIPITATION, WITH LOW ELEVATION RAIN AND MOUNTAIN SNOW INLAND
FROM WESTERN WASHINGTON AND OREGON TO THE NORTHERN ROCKIES.
ABOVE AVERAGE TEMPERATURES ARE FORECAST FROM THE SOUTHWEST TO THE
PLAINS THROUGH MUCH OF NEXT WEEK UNDER THE INFLUENCE OF UPPER
LEVEL RIDGING. HIGH TEMPERATURES ARE FORECAST TO RUN 10-20 DEGREES
ABOVE AVERAGE. ELSEWHERE, TEMPERATURES SHOULD BE NEAR TO SLIGHTLY
BELOW AVERAGE.
DOLAN/SCHICHTEL
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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