763
FXUS02 KWBC 191957
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
357 PM EDT MON OCT 19 2026
VALID 12Z THU OCT 22 2026 - 12Z MON OCT 26 2026
..LINGERING NOR'EASTER OFFERS EAST COAST MARITIME IMPACTS
..SOUTHERN CALIFORNIA/SOUTHWEST/ROCKIES HEAVY PRECIPITATION
..OVERVIEW
A POTENT LINGERING NOR'EASTER WILL BRING HIGH WIND/WAVE AND
COASTAL EROSION IMPACTS TO THE EAST COAST INTO MID-LATE WEEK. THIS
MARITIME STORM OFFERS SUBTROPICAL TRANSITION POTENTIAL. MEANWHILE,
A CUTOFF LOW WILL SUPPORT HEAVY RAINFALL FROM SOUTHERN CALIFORNIA
THROUGH THE GREAT BASIN/ROCKIES STATES MID-LATER WEEK ALONG WITH
SOME MOUNTAIN SNOWS. ACTIVITY WILL SPREAD DOWNSTREAM WITH PLAINS
SYSTEM GENESIS. AN UPPER RIDGE WEDGED BETWEEN OVER THE CENTRAL
U.S. WILL SUPPORT ABOVE AVERAGE TEMPERATURES THROUGH THE WEEKEND.
ELSEWHERE OF NOTE, BAHAMAS UPPER LOW/TROUGH SETTLING AND SURFACE LOW
PRESSURE GENESIS MAY FAVOR A WET ONSHORE FLOW PATTERN FOR THE
BAHAMAS AND BACK TO SOUTHERN FLORIDA FROM THIS WEEKEND/NEXT WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
GUIDANCE FORECAST CLUSTERING SEEMS REASONABLY GOOD FOR MID-LATER
THIS WEEK AND A BROAD BLEND WITH FOCUS ON THE MODELS SEEMS TO
PROVIDE A SOLID BASE FORECAST AND MESSAGING, BOLSTERING FORECAST
CONFIDENCE. MODEL DIFFERENCES INCREASE BY THE WEEKEND, ESPECIALLY
FOR STREAM SEPARATION WITH HANDLING OF AMPLE PACIFIC ENERGIES SET
TO WORK INTO AND DOWNSTREAM OUT FROM A WESTERN U.S. MEAN UPPER
TROUGH POSITIONS. CLUSTERING WOULD SEEM IMPROVED WITH DISCOUNT OF
RECENT GFS/GEFS RUNS WHOSE OUTLIER SOLUTIONS SHOW LESS THAN STELLAR
CYCLE TO CYCLE CONTINUITY. ACCORDINGLY, FAVOR A SOLUTION MORE IN
LINE WITH BETTER COMPATIBLE ECMWF/CANADIAN AND ECMWF/CANADIAN
ENSEMBLE MEANS FOR MAX CYCLE-CYCLE CONSISTENCY AND NBM CONTINUITY.
..WEATHER/HAZARDS HIGHLIGHTS
A NOR'EASTER WILL OFFER THREATS FOR HIGH WINDS AND COASTAL
FLOODING WITH STORMY MARITIME CONDITIONS FROM THE COASTAL MID-
ATLANTIC TO OFF THE NORTHEAST THIS WEEK. THE STORM WILL INTENSIFY
OFF THE CAROLINAS AND BRING STRONG WINDS BACK TO THE COASTLINE
INTO MID-LATE WEEK TO PROTRACT A THREAT FOR BEACH EROSION. THE
STORM OFFERS POTENTIAL SUBTROPICAL TRANSITION TO MONITOR LATER WEEK
PER NHC. PLEASE REFER TO WPC'S KEY MESSAGES ON OUR WEBSITE FOR
MORE INFORMATION: WWW.WPC.NCEP.NOAA.GOV.
A POTENT SHORTWAVE PASSING SOUTH OF THE GULF OF ALASKA IS FORECAST
TO DIG/AMPLIFY INTO A CUT-OFF LOW OVER THE EASTERN PACIFIC JUST
OFF THE WEST COAST INTO MIDWEEK AND WORK INLAND INTO CALIFORNIA AND
THE SOUTHWEST LATER WEEK. ANOMALOUS MOISTURE WILL FEED INTO THE
WEST TO SUPPORT INCREASINGLY WIDESPREAD RAIN/THUNDERSTORMS OVER THE
REGION AND THROUGH THE GREAT BASIN/ROCKIES. THERE'S A SLIGHT RISK
(AT LEAST 15% CHANCE) OF EXCESSIVE RAINFALL LEADING TO FLASH
FLOODING FOR PORTIONS OF THE FOUR CORNERS REGION, WITH A SIGNAL
FOR HEAVY PRECIPITATION OVER THE SAN JUAN MOUNTAINS AS WELL AS THE
GENERAL SOUTHWESTERN COLORADO AREA PEAKING ON THURSDAY. THE SLOW
MOVING SYSTEM WILL THEN EJECT DOWNSTREAM AND LEAD CYCLE/FRONTO
GENESIS AND RETURN FLOW SHOULD SUPPORT EMERGING SHOWERS/THUNDERSTORMS
OVER THE PLAINS, ESPECIALLY WITH FLOW FOCUS FOR THE SOUTHERN HIGH
PLAINS BY THE WEEKEND, ALBEIT WITH LINGERING TIMING UNCERTAINTIES.
UPSTREAM, A CLOSED LOW WITH AMPLE UPPER TROUGHING WILL DIG FROM
THE GULF OF ALASKA, AMPLIFY AND WORK TOWARD THE NORTHWEST THIS
WEEKEND INTO EARLY NEXT WEEK. THIS POTENTIALLY WELL ORGANIZED
SYSTEM COULD GENERATE MODERATE PRECIPITATION AND COOLING TO SUPPORT
SOME HIGH ELEVATION SNOWS ACROSS THE NORTHWEST AS DEPENDENT ON
ULTIMATE INLAND MOTION TO MONITOR WITH UPCOMING GUIDANCE.
MEANWHILE, MEAN UPPER TROUGH DEVELOPMENT AND LINGERING DOWN THOUGH
THE SOUTHEAST U.S. TO THE BAHAMAS MAY LEAD INTO A PROTRACTED WET
ONSHORE FLOW PERIOD FOR FLORIDA THIS WEEKEND INTO NEXT WEEK. THE
PATTERN MAY ESPECIALLY FAVOR URBAN RUNOFF ISSUE POTENTIAL, PERHAPS
WITH FOCUS FROM WEST PALM BEACH THROUGH MIAMI/SOUTHEAST FLORIDA.
KEBEDE/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, EXCESSIVE RAINFALL OUTLOOK,
WINTER WEATHER OUTLOOK PROBABILITIES, HEAT INDICES AND KEY MESSAGES
ARE AT:
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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