786
FXUS02 KWBC 291855
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
255 PM EDT WED OCT 29 2025
VALID 12Z SAT NOV 01 2025 - 12Z WED NOV 05 2025
..OVERVIEW
GUIDANCE CONTINUES TO ADVERTISE AN AMPLIFIED UPCOMING MEDIUM RANGE
PATTERN ALOFT, AT LEAST THROUGH THIS WEEKEND, WHICH FEATURES MEAN
TROUGHING OVER THE EASTERN U.S. AND A BUILDING RIDGE OUT WEST. A
POTENT SHORTWAVE DROPS SOUTHWARD FROM THE UPPER MIDWEST ON
SATURDAY TO BRING RENEWED AMPLIFIED TROUGHING OVER THE EAST WITH
STILL VARIED RECENT GUIDANCE OVERALL STILL CONTINUING TO TREND
TOWARD MORE STREAM SEPARATION WITH A POSSIBLE CUTOFF CLOSED LOW
OVER OR NEAR THE GULF COAST REGION/VICINITY BY EARLY NEXT WEEK.
THE TAIL END OF AN ATMOSPHERIC RIVER WILL KEEP THE NORTHWEST STILL
WET INTO SATURDAY, BUT DRIER INTO EARLY NEXT WEEK WITH UPPER
RIDGING. ANOTHER DEEP TROUGH WILL APPROACH THE WEST COAST BY AROUND
WEDNESDAY OF NEXT WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
A MAIN FORECAST CONCERN CONTINUES TO BE WITH THE SHORTWAVE TROUGH
DROPPING SOUTHWARD TO THE MIDWEST INTO SATURDAY, WITH POSSIBLE
CUTOFF CLOSED LOW DEVELOPMENT OVER THE MISSISSIPPI VALLEY TO GULF
COAST BY SUNDAY OR MONDAY. LATEST GUIDANCE TRENDS CONTINUE TO BE
FOR THIS SCENARIO. RECENT CMC RUNS ADVERTISED A MORE PROGRESSIVE
AMPLIFIED TROUGH THROUGH THE REGION, BUT THE LATEST 12 UTC RUN HAS
AT LEAST TRENDED MORE AMPLIFIED/LESS PROGRESSIVE. THERE IS ALSO
UNCERTAINTY IN WHETHER ANY SORT OF CLOSED LOW WILL LINGER NEAR THE
GULF COAST OR LIFT OFF THE SOUTHEAST COAST. A FEW GFS AND ECMWF
RUNS HAVE RECENTLY OFFERED THIS LATTER POSSIBILITY, BUT IT IS NOT
SHOWN IN EITHER'S NEW 12 UTC RUN THAT ARE MORE IN LINE WITH THE
GEFS/ECMWF ENSEMBLE MEANS. THE AIFS IS MORE PROGRESSIVE THAN THAT
SOLUTION NOW, BUT THE AIFS ENSEMBLE MEAN IS SLOWER. ACCORDINGLY
WITH UNCERTAINTY, THE WPC FORECAST IS CLOSE TO THE GEFS/ECMWF
ENSEMBLE MEANS THAT SHOW STREAM SEPARATION AND FAIRLY SLOW
PROGRESSION THAT SEEMS A GOOD MATCH TO THE LARGER SCALE FLOW. OUT
WEST, THERE IS QUESTION ON THE TIMING OF THE NEXT TROUGH TOWARDS
THE COAST LATE PERIOD AND AN ENSEMBLE MEAN BLEND SEEMED A GOOD
STARTING POINT WITH A GRADUAL SLOWER TREND RECENTLY THAT SEEMS
CONSISTENT WITH AMPLIFYING FLOW.
..WEATHER/HAZARDS HIGHLIGHTS
A DEPARTING STRONG SURFACE LOW OUT OF THE NORTHEAST/CANADIAN
MARITIMES WILL INDUCE LAKE EFFECT RAINS BEHIND IT. THE SHORTWAVE
DROPPING THROUGH THE MIDWEST MAY BRING SOME UNCERTAIN LIGHT RAIN
SHOWERS WITH IT, BUT ADDITIONAL RAINFALL MAY DEVELOP ALONG THE GULF
COAST WITH WEAK SURFACE LOW DEVELOPMENT ALONG A TRAILING FRONTAL
BOUNDARY IN THE GULF. RAIN COVERAGE MAY EXPAND FOR THE SOUTHEAST
AND EAST COAST EARLY NEXT WEEK, BUT WITH MUCH UNCERTAINTY AND
HIGHLY DEPENDENT ON THE PATTERN EVOLUTION INTO THIS REGION.
LOCALLY MODERATE TO HEAVY PRECIPITATION MAY LINGER INTO SATURDAY
ON THE BACK END OF A MODERATELY STRONG ATMOSPHERIC RIVER INTO THE
NORTHWEST LATE THIS WEEK. BUT BY SATURDAY, INSTABILITY SHOULD BE
LESS AND THE BETTER MOISTURE ANOMALIES WILL BE QUICKLY SHIFTING
EASTWARD, SO NO MARGINAL RISK IS PLANNED AT THIS TIME ON THE ERO
SINCE FRIDAY SHOULD BE THE BIGGER DAY. MOST PRECIPITATION IS
FORECAST TO STAY RAIN OTHER THAN SNOW IN THE HIGHEST PEAKS OF THE
OLYMPICS AND THE CASCADES. THE REGION SHOULD TREND DRIER SUNDAY
WITH POSSIBLY ANOTHER INCREASE IN PRECIPITATION EARLY-MID 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 ONWARD. MEANWHILE, THE EAST WILL BE NEAR TO
JUST BELOW NORMAL TEMPERATURES UNDERNEATH MEAN UPPER TROUGHING.
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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