077
FXUS02 KWBC 181928
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
328 PM EDT SUN OCT 18 2026
VALID 12Z WED OCT 21 2026 - 12Z SUN OCT 25 2026
..LINGERING NOR'EASTER OFFERS EAST COAST MARITIME IMPACTS
..SOUTHERN CALIFORNIA/SOUTHWEST/ROCKIES HEAVY PRECIPITATION
..OVERVIEW
A LINGERING NOR'EASTER WILL BRING WIND AND COASTAL FLOODING
IMPACTS TO THE EAST COAST INTO MID-LATE WEEK. A CUTOFF LOW WILL
SUPPORT HEAVY RAINFALL FROM SOUTHERN CALIFORNIA TO THE FOUR
CORNERS STATES MID-TO-LATE WEEK ALONG WITH SOME MOUNTAIN SNOWS.
ASSOCIATED ACTIVITY WILL SPREAD THROUGH THE WEST ROCKIES AND THEN
WORK DOWNSTREAM WITH PLAINS SYSTEM GENESIS. THERE IS ALSO AN
EMERGING ONSHORE WET PATTERN FOR FLORIDA TO MONITOR LATE PERIOD.
..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 MORE SIGNIFICANTLY HEADING
INTO NEXT WEEKEND, ESPECIALLY FOR STREAM SEPARATION WITH HANDLING
OF AMPLE PACIFIC ENERGIES SET TO WORK INTO A WESTERN U.S. MEAN
UPPER TROUGH. THE 12 UTC MODELS REMAIN MIXED. INSTEAD, FAVOR A
SOLUTION TRENDING MORE IN LINE WITH BETTER COMPATIBLE GEFS/ECMWF
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. THE STORM WILL INTENSIFY OFF THE
CAROLINAS OVER THE NEXT FEW DAYS 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 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. LEAD ANOMALOUS MOISTURE WILL FEED INTO
THE WEST TO SUPPORT INCREASINGLY WIDESPREAD RAIN/THUNDERSTORMS
OVER THE REGION AND THROUGH THE GREAT BASIN/ROCKIES. WPC EXCESSIVE
RAINFALL OUTLOOK MARGINAL RISK AREAS ARE IN PLACE FOR LOCAL RUNOFF
CONCERNS, BUT RAINFALL SHOULD ALSO AIDE LINGERING FIRE CONCERNS.
SOME HIGH ELEVATION SNOWFALL IS LIKELY FOR THE SIERRA THROUGH PARTS
OF THE INTERMOUNTAIN WEST TO THE ROCKIES. THE SLOW MOVING SYSTEM
WILL THEN EJECT DOWNSTREAM AND LEAD CYCLO/FRONTO GENESIS AND RETURN
FLOW SHOULD SUPPORT EMERGING SHOWERS/THUNDERSTORMS OVER THE PLAINS
BY NEXT WEEKEND, ALBEIT STILL WITH TIMING UNCERTAINTY TO NAVIGATE.
UPSTREAM, A CLOSED LOW WITH AMPLE UPPER TROUGHING WILL DIG FROM
THE GULF OF ALASKA TO APPROACH THE NORTHWEST AND/OR OFFSHORE LATE
WEEK. THIS SYSTEM COULD GENERATE MODERATE PRECIPITATION INCLUDING
HIGH ELEVATION SNOWS INTO THE NORTHWEST AS DEPENDENT ON ULTIMATE
INLAND PENETRATION TO MONITOR WITH UPCOMING GUIDANCE.
MEANWHILE, MEAN UPPER TROUGH DEVELOPMENT AND LINGERING DOWN THOUGH
THE SOUTHEAST U.S. MAY LEAD INTO A WET ONSHORE FLOW PERIOD FOR
ESPECIALLY SOUTHERN FLORIDA LATE PERIOD INTO NEXT WEEK.
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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