982
FXUS02 KWBC 240735
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
335 AM EDT FRI OCT 24 2025
VALID 12Z MON OCT 27 2025 - 12Z FRI OCT 31 2025
..HEAVY RAIN POSSIBLE UP THE EAST COAST NEXT WEEK
..OVERVIEW
THE MEDIUM RANGE PATTERN OVER THE LOWER 48 NEXT WEEK LOOKS VERY
AMPLIFIED AND ACTIVE. DEEP TROUGHING OVER THE WEST WILL CONTINUE TO
BRING UNSETTLED COOL CONDITIONS TO THE REGION THROUGH MONDAY, WITH
A COMPACT UPPER LOW OVER THE NORTHEAST, AND A WEAKENING LOW ACROSS
THE MID- SOUTH. ENERGY FROM THESE THREE SYSTEMS WILL INTERACT INTO
MID WEEK EVENTUALLY RESULTING IN A LIKELY LARGE AND DEEP UPPER LOW
OVER THE EASTERN U.S. WHICH WILL BRING WIDESPREAD RAIN TO THE OHIO
VALLEY, APPALACHIANS, AND EAST COAST. WEAKER SHORTWAVES AND
FRONTAL BOUNDARIES WILL KEEP PARTICULARLY THE PACIFIC NORTHWEST WET
THROUGH MUCH OF THE NEXT WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE IS IN REASONABLY GOOD AGREEMENT THROUGH ABOUT
TUESDAY, BUT QUICKLY BECOME MORE AND MORE UNCERTAIN REGARDING THE
SPECIFICS OF THE DEVELOPING EAST COAST LOW LATER IN THE WEEK. THERE
IS A LOT OF UNCERTAINTY SURROUNDING HOW THE ENERGY FROM THE WEST-
CENTRAL U.S. TROUGH AND INITIAL NORTHEAST LOW WILL INTERACT. THE
GFS AND ECMWF HAVE BETTER SUPPORT FROM THE ENSEMBLE MEANS IN
SHOWING INTERACTION OF THESE TWO FEATURES AND A DUE EAST TRACK OF
THE NEW RESULTING LOW FROM THE OHIO VALLEY TO THE NORTHEAST NEXT
WEDNESDAY-FRIDAY. THE CMC (AND TO SOME EXTENT THE UKMET) KEEP THE
TWO FEATURES SEPARATE WITH A FURTHER SOUTH OR SOUTHEASTWARD TRACK
OF THE UPPER LOW THROUGH THE MID-SOUTH TO SOUTHEAST. THIS AFFECTS
ANY KIND OF COASTAL LOW DEVELOPMENT OFF THE EAST COAST, WITH THE EC
AND ECENS CONTINUING TO FAVOR MORE DEVELOPMENT. THE WPC FORECAST
FAVORED THE EC/GFS SOLUTIONS WHICH WAS CLOSEST TO CONTINUITY.
TROPICAL STORM MELISSA IN THE CARIBBEAN IS FORECAST TO BE A SLOW
MOVING MAJOR HURRICANE BY THE START OF THE MEDIUM RANGE PERIOD NEAR
JAMAICA. ITS TRACK IS ALSO HIGHLY INFLUENCED BY THE DEVELOPING
TROUGH/LOW OVER THE EAST NEXT WEEK, WITH THE CMC FURTHEST WEST
BEFORE IT GETS PUSHED OVER THE BAHAMAS AND OUT TO SEA. THE GFS
REMAINS MUCH FASTER THAN THE CONSENSUS. DESPITE THE UNCERTAINTY IN
THE EXACT TRACK, MELISSA IS NOT EXPECTED TO BRING MUCH IF ANY
IMPACTS TO THE U.S. EAST COAST OUTSIDE OF SOME WAVES AND RIP
CURRENTS, BUT GIVEN DEPENDENCE ON THE EASTERN U.S. EVOLUTION,
MELISSA IS WORTH MONITORING FOR ANY POTENTIAL CHANGES TO THE
FORECAST. THE WPC FORECAST WILL FOLLOW THE OFFICIAL FORECAST TRACK
FROM THE NATIONAL HURRICANE CENTER.
THE WPC FORECAST BEGINS WITH A BLEND OF THE 18Z GFS, 12Z ECMWF,
AND LESSER PROPORTION OF THE 12Z UKMET. INTO THE MID AND LATE
PERIOD, QUICKLY INCREASED THE PROPORTION OF ENSEMBLE MEANS TO 70
PERCENT OF THE BLEND BY DAY 7 GIVEN THE INCREASING SPREAD.
..WEATHER/HAZARDS HIGHLIGHTS
WITH A LOW PRESSURE SYSTEM OVER THE MID-SOUTH BY MONDAY, AND
ANOTHER POSSIBLY DEVELOPING OFFSHORE, RAIN CHANCES ARE FORECAST TO
SPREAD INTO THE APPALACHIANS AND CAROLINAS INTO THE SOUTHERN MID-
ATLANTIC. CONTINUED A MARGINAL RISK IN THE DAY 4/MONDAY ERO TO
INCLUDE NOT JUST THE COASTAL RAIN BUT BACK INTO THE SOUTH- CENTRAL
APPALACHIANS THAT CAN BE SENSITIVE TO HEAVY RAIN CAUSING FLASH
FLOODING. AS THESE FEATURES INTERACT WITH ADDITIONAL ENERGY TO THE
WEST, MORE RAIN LOOKS TO OVERSPREAD THE OHIO VALLEY AND
APPALACHIANS TO MID- ATLANTIC BY MIDWEEK, WITH MARGINAL RISK ALSO
IN PLACE ON THE DAY 5/TUESDAY ERO FOR THE MID-ATLANTIC REGION.
THERE REMAINS A LOT OF UNCERTAINTY IN AMOUNTS AND PLACEMENT OF THIS
RAIN AND FORECAST DETAILS ARE LIKELY TO CHANGE GIVEN THE MODEL
SPREAD AT THIS POINT. EXPECT RAIN TO CONTINUE TRACKING UP THE EAST
COAST WEDNESDAY-FRIDAY.
TROUGHING ACROSS THE NORTHWEST AND THE TAIL END OF AN ATMOSPHERIC
RIVER WILL LEAD TO PRECIPITATION THERE, INCLUDING HIGHER ELEVATION
SNOW THAT WILL LIKELY BE HEAVY IN THE CASCADES AND PERHAPS INTO THE
NORTHERN ROCKIES INTO MONDAY, WITH 1 TO 2 FEET OF SNOW POSSIBLE.
ENERGY FROM THE WESTERN TROUGH SHOULD PUSH A FRONT THROUGH THE
NORTH-CENTRAL U.S. FOR RAIN CHANCES IN THE DAKOTAS AND UPPER
MIDWEST ESPECIALLY ON MONDAY. THIS RAIN LOOKS TO HAVE LOW RATES
GIVEN LACK OF INSTABILITY, AND SINCE THIS DOES NOT TEND TO BE AN
AREA THAT IS SENSITIVE TO FLOODING, DO NOT HAVE ANY SORT OF ERO
RISK IN THE OUTLOOK AT THIS TIME. GUSTY WINDS ARE POSSIBLE IN THE
NORTH- CENTRAL ROCKIES TO PLAINS EARLY NEXT WEEK WITH THIS SYSTEM
AS WELL. ADDITIONAL WEAKER SHORTWAVES/FRONTS INTO THE WEST WILL
KEEP RAIN AND MOUNTAIN SNOW CHANCES IN THE FORECAST FOR
PARTICULARLY THE PACIFIC NORTHWEST THROUGH MUCH OF THE WEEK.
COOLER WEATHER WILL BE IN PLACE ACROSS THE WEST EARLY NEXT WEEK,
ESPECIALLY THE NORTHWEST THROUGH MONDAY WHERE HIGHS ARE FORECAST TO
BE 10 TO 15 DEGREES BELOW AVERAGE. TEMPERATURES SHOULD MODERATE
AFTER MONDAY BACK TO NORMAL OR EVEN A LITTLE ABOVE NORMAL.
MEANWHILE, PARTS OF THE PLAINS WILL BE NEAR TO ABOVE AVERAGE EARLY
NEXT WEEK BEFORE A COOL DOWN MIDWEEK AS COLDER HIGH PRESSURE BUILDS
IN BEHIND A COLD FRONT. MUCH OF THE EAST COAST REGION SHOULD
GENERALLY BE SLIGHTLY BELOW AVERAGE THROUGH MOST OF THE FORECAST
PERIOD.
SANTORELLI
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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