744
FXUS02 KWBC 301848
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
248 PM EDT THU OCT 30 2025
VALID 12Z SUN NOV 02 2025 - 12Z THU NOV 06 2025
..OVERVIEW
SHORTWAVE ENERGY DIVING THROUGH THE MIDWEST HAS BEEN EXPECTED TO
CLOSE OFF AN UPPER LOW WHICH LOOKS TO TRAVERSE THE GULF COAST
BEFORE WEAKENING AND LIFTING OFF THE SOUTHEAST COAST AROUND NEXT
TUESDAY. HOWEVER, THERE REMAINS MUCH UNCERTAINTY WITH THIS SYSTEM
AS EARLY AS SHORT RANGE TIME SCALES INCLUDING SOME OF THE LATEST
12 UTC GUIDANCE THAT SPLITS THE SYSTEM SOUTH AND EAST TO PONDER.
MEANWHILE, NORTHERN STREAM ENERGY WILL SWING THROUGH THE GREAT
LAKES AT THE SAME TIME. OUT WEST, AN INITIAL WEAKER ATMOSPHERIC
RIVER SHOULD KEEP THE REGION SHOWERY, BUT A STRONGER AR LOOKS TO
MOVE INTO THE REGION BY THE MIDDLE OF NEXT WEEK BRINGING A THREAT
FOR MODERATE TO HEAVY RAINFALL AND MOUNTAIN SNOWS FOR PARTS OF
WASHINGTON, OREGON, NORTHERN CALIFORNIA, AND THE SIERRA NEVADA.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE MAIN FORECAST CONCERN CONTINUES TO BE WITH THE SHORTWAVE
TROUGH DROPPING SOUTHWARD, WITH POSSIBLE CUTOFF CLOSED LOW
DEVELOPMENT OVER THE MISSISSIPPI VALLEY TO GULF COAST ON SUNDAY
INTO MONDAY. GUIDANCE STILL SHOW CONSIDERABLE TIMING AND PHASING
CONCERNS, EVEN AS EARLY AS DAY 3/SUNDAY WITH HOW QUICKLY IT EXITS
THE GULF COAST/SOUTHEAST REGION AND/OR SPLITS SOME SYSTEM ENERGY
MORE SOUTHWARD AND PROGRESSIVELY EASTWARD TO MONITOR. MODELS AND
MACHINE LEARNING GUIDANCE HAS BEEN WAY LESS THAN STELLAR WITH CYCLE
TO CYCLE CONTINUITY/SENSITIVITY. THE ENSEMBLE MEANS, BY NATURE,
HAVE BEEN MORE CONSISTENT WITH DEVELOPMENT OF A SEPARATED SOUTHERN
STREAM SYSTEM WITH A SLOWLY PROGRESSIVE TREND. OUT WEST, A WEAK
SHORTWAVE WILL SWING THROUGH EARLY IN THE PERIOD, WITH A MUCH
STRONGER AND DEEPER TROUGH TO THE WEST COAST WEDNESDAY/THURSDAY OF
NEXT WEEK IN A RENEWED WET PATTERN WITH FOCUS INTO THE NORTHWEST.
ACCORDINGLY, WPC MEDIUM-RANGE GUIDANCE WAS MAINLY DERIVED FROM THE
LATEST AND BEST COMPATIBLE GEFS/ECMWF ENSEMBLE MEANS AND NATIONAL
BLEND OF MODELS TO MAINTAIN MAX PRODUCT CONTINUIY AMID UNCERTAINTY.
..WEATHER/HAZARDS HIGHLIGHTS
IT IS STILL AN EXPECTATION THAT RAINFALL WILL DEVELOP ALONG THE
GULF COAST WITH WEAK SURFACE LOW DEVELOPMENT ALONG A TRAILING
FRONTAL BOUNDARY IN THE GULF BY SUNDAY. RAIN COVERAGE MAY EXPAND
FOR THE SOUTHEAST EARLY NEXT WEEK, BUT WITH MUCH UNCERTAINTY AND
HIGHLY DEPENDENT ON THE PATTERN EVOLUTION INTO THIS REGION. AT THIS
POINT, MODELS ARE MAINLY NOT SHOWING MUCH MORE THAN MODERATE
SHOWERS ONSHORE, BUT THIS COULD CHANGE DEPENDING ON THE STRENGTH OF
THE UPPER LOW. THE NORTHERN STREAM ENERGY THROUGH THE GREAT LAKES
MAY BRING LIGHT RAIN TO THIS REGION EARLY IN THE PERIOD AS WELL.
THE NORTHWEST SHOULD TREND DRIER SUNDAY BEHIND AN INITIAL
ATMOSPHERIC RIVER INTO THE REGION. ANOTHER INCREASE IN
PRECIPITATION EARLY WEEK IS EXPECTED, BUT A MORE FAVORABLE AR
PATTERN AND INCREASED MOISTURE LOOKS TO MOVE IN NEXT WEDNESDAY WITH
LOCALLY MODERATE TO HEAVY RAINFALL POSSIBLE AND SNOW IN THE
HIGHEST ELEVATIONS. ELSEWHERE, THE SOUTHWEST TO THE PLAINS SHOULD
STAY DRY THROUGH THE PERIOD UNDER A MEAN UPPER RIDGE.
MUCH OF THE SOUTHWEST/INTERIOR WEST TO CENTRAL U.S. AND MIDWEST
WILL BE WARMER THAN AVERAGE WITH STRONG UPPER LEVEL RIDGING THROUGH
THE PERIOD. DAYTIME HIGHS COULD AVERAGE 10 TO 20 DEGREES ABOVE
NORMAL EACH DAY. MEANWHILE, BELOW NORMAL TEMPERATURES NEAR THE GULF
COAST/SOUTHEAST ASSOCIATED WITH THE UPPER CUTOFF LOW SHOULD
MODERATE AFTER MONDAY.
SANTORELLI/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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