452
FXUS02 KWBC 281848
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
248 PM EDT TUE OCT 28 2025
VALID 12Z FRI OCT 31 2025 - 12Z TUE NOV 04 2025
..OVERVIEW
LATEST GUIDANCE CONTINUES TO ADVERTISE AN AMPLIFIED UPCOMING
MEDIUM RANGE PATTERN ALOFT WHICH FEATURES MEAN TROUGHING OVER THE
EASTERN U.S. AND A BUILDING RIDGE OUT WEST. AN INITIAL UPPER LOW
WILL BE EXITING THE NORTHEAST BY THE START OF THE PERIOD ON FRIDAY,
AS ANOTHER SHORTWAVE DROPS SOUTHWARD FROM THE UPPER MIDWEST BRING
RENEWED AMPLIFIED TROUGHING WITH LATEST GUIDANCE TRENDING TOWARD
A MORE STREAM SEPARATED TO CUTOFF CLOSED LOW OVER THE
SOUTHEAST ONCE AGAIN BY EARLY NEXT WEEK, ALBEIT WITH MUCH
UNCERTAINTY. THE NORTHWEST END THE WEEK WETTER AND MORE ACTIVE
FRIDAY/SATURDAY AHEAD OF AN UPPER SYSTEM MOVING INTO THE REGION,
WITH UPPER RIDGING BUILDING BACK IN AFTER. A NEW LOW MAY DEVELOP
TO INCREASING AFFECT THE SOUTHEAST TO EAST COASTS EARLY NEXT WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODELS ARE PRETTY AGREEABLE THAT THE INITIAL UPPER LOW OVER THE
NORTHEAST ON FRIDAY WILL LIFT NORTHWARD AND INTO EASTERN CANADA BY
SATURDAY, DRAGGING A STRONG SURFACE LOW WITH IT. SOME MINOR TIMING
INCONSISTENCIES CONTINUE WITH THIS, BUT A GENERAL MODEL BLEND WORKS
AS A GOOD STARTING POINT FOR NOW. THE MAIN FORECAST CONCERN THOUGH
IS WITH THE NEXT SHORTWAVE AS IT DROPS SOUTHWARD FROM THE UPPER
MIDWEST ON FRIDAY. AN EARLIER GUIDANCE CONCENSUS SAID THIS
SHORTWAVE WOULD ACT TO REINFORCE TROUGHING OVER THE EAST INTO THE
WEEKEND, BUT THERE IS A NOTEABLE GUIDANCE TREND NOW WITH CUT-OFF
LOW DEVELOMENT OVER THE SOUTH/GULF COAST. IN THIS UNCERTAIN TYPE
OF SCENARIO THAT BROADLY SEEMS INCREASINGLY REASONABLE GIVEN
UPSTREAM UPPER RIDGE AMPLIFICATION, WAVE DEVELOPMENT AND ENHANCED
QPF IS SLOWER TO EXIT THE REGION TO THE EAST COAST OR EVEN STALLED
TO THE SOUTH. SOME OF THE NEW 00/06/12 UTC GUIDANCE INCLUDING THE
GFS AND ECMWF AND AIFS HAVE TRENDED THIS DIRECTION, SO WPC PRODUCTS
WERE TRENDED FOR NOW IN THIS DIRECTION SUNDAY-TUESDAY. THE WPC
FORECAST WAS OTHERWISE BASED MORE ON THE ENSEMBLE MEANS INCLUDING
FOR OUT WEST AND INLAND WITH AN OVERALL SLOWED/AMPLIFIED NORTHERN
STREAM FLOW OVER SOUTHERN CANADA AND THE U.S. NORTHERN TIER.
..WEATHER/HAZARDS HIGHLIGHTS
WITH THE FIRST LOW, HEAVY RAIN LOOKS TO BE MOVING THROUGH MAINE
FRIDAY MORNING AND THEN EXITING THE NORTHEAST, THOUGH LAKE EFFECT
RAINS ARE LIKELY BEHIND THE PRIMARY SYSTEM. BY THE WEEKEND, UPPER
LEVEL ENERGY AND FRONTAL SYSTEMS COULD LEAD TO ROUNDS OF LIGHT
PRECIPITATION, PRIMARILY RAIN, IN THE MIDWEST, GREAT LAKES,
OHIO/TENNESSEE VALLEYS, AND REACHING TO THE CENTRAL GULF COAST.
HEAVY PRECIPITATION IS LIKELY FRIDAY INTO SATURDAY FOR THE PACIFIC
NORTHWEST AS A MODERATELY STRONG ATMOSPHERIC RIVER TAKES AIM AT
THE REGION AHEAD OF A LARGER NORTHEAST PACIFIC LOW. THERE REMAINS
A MARGINAL RISK IN THE DAY 4/FRIDAY ERO FOR THIS REGION. MOST
PRECIPITATION IS FORECAST TO STAY RAIN OTHER THAN SNOW EVEN IN THE
HIGHEST PEAKS OF THE OLYMPICS THROUGH FRIDAY, WITH MORE SNOW IN
THE CASCADES. THE REGION SHOULD TREND DRIER SUNDAY WITH POSSIBLY
ANOTHER INCREASE IN PRECIPITATION INTO EALRY NEXT WEEK AGAIN.
ELSEWHERE, THE SOUTHWEST TO THE PLAINS SHOULD STAY MOSTLY DRY
THROUGH THE PERIOD UNDER THE WARMING RIDGE ALOFT.
MUCH OF THE WEST CAN EXPECT WARMER THAN AVERAGE TEMPERATURES
UNDERNEATH UPPER RIDGING THROUGH THE PERIOD, EXPANDING INTO THE
CENTRAL U.S. SUNDAY AND BEYOND. MEANWHILE, THE EAST WILL BE MAINLY
NEAR OR BELOW NORMAL TEMPERATURES UNDERNEATH MEAN UPPER TROUGHING.
CONTINUITY IS LESS THAN STELLAR, BUT BROADLY REASONABLE RECENT
GUIDANCE TRENDS SEEM FAVORABLE FOR UPPER TROUGH/LOW DEVELOPMENT
OVER THE SOUTH/SOUTHEAST LATER WEEKEND INTO NEXT WEEK WITH
SUBSEQUENT AFFECTS INCLUDING ENHANCING RAINFALL AND UNSETTLED
WEATHER POTENTIAL QUITE UNCERTAIN OVER THE GULF AND/OR UP THE EAST
COAST TO MONITOR.
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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