051
FXUS02 KWBC 150709
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
309 AM EDT THU OCT 15 2026
VALID 12Z SUN OCT 18 2026 - 12Z THU OCT 22 2026
...FROST/FREEZE THREATS ACROSS PARTS OF THE MID-ATLANTIC AND
NORTHEAST SUNDAY AND MONDAY...
...A POSSIBLE EAST COAST LOW EARLY TO MID NEXT WEEK COULD BRING
COASTAL IMPACTS...
..OVERVIEW
A CHILLY SURFACE HIGH OVER THE EASTERN U.S. WILL BRING FROST AND
FREEZE CONCERNS TO PARTS OF THE MID-ATLANTIC AND NORTHEAST EARLY IN
THE PERIOD. A COLD FRONT SINKING THROUGH FLORIDA MAY BRING A
THREAT FOR LOCALLY HEAVY RAINFALL ON SUNDAY. THERE IS ALSO
INCREASING POTENTIAL FOR A LOW OFF THE EAST COAST TO FORM ALONG
THIS FRONT, AND MAY BRING SHOWERS OR A LOCALLY HEAVY RAINFALL
THREAT TO PARTS OF THE COASTAL MID- ATLANTIC, DEPENDING ON HOW
CLOSE TO THE COAST THE LOW GETS. OUT WEST, AN UPPER LOW WILL DROP
DOWN THE WEST COAST WITH DEEP TROUGHING LIKELY OVER THE WEST BY
NEXT THURSDAY. THIS BRINGS THE POTENTIAL FOR WIDESPREAD RAIN AND
HIGH ELEVATION SNOWS ESPECIALLY TUESDAY AND WEDNESDAY NEXT WEEK,
WITH SOME SHOWERS INCREASING ACROSS THE CENTRAL U.S. AS WELL LATE
PERIOD.
..GUIDANCE/PREDICTABILITY ASSESSMENT
ASPECTS OF THE MEDIUM RANGE FORECAST HAVE BECOME INCREASINGLY
UNCERTAIN OVER THE LAST DAY OR SO. WITH YESTERDAYS 12Z RUNS AND
ESPECIALLY TONIGHTS 00Z RUNS, THERE SEEMS TO NOW BE A CLEAR TREND
TOWARDS SOME SORT OF LOW OR ENERGY FROM A TROUGH WELL OFF THE EAST
COAST TO LINGER SOMEWHERE OFF THE MID- ATLANTIC COAST MOST OF THE
PERIOD. THERE IS CONSIDERABLE UNCERTAINTY ON THE PLACEMENT OF ANY
UPPER AND SURFACE LOW, AND ITS IMPACTS ON COASTAL LOCATIONS IN THE
MID- ATLANTIC. THE ECMWF, ECAIFS, AND UKMET ARE CLOSEST TO THE
COAST, WITH THE CMC A BIT MORE OFFSHORE AND THE GFS WELL OFFSHORE.
THERE IS INCREASING SUPPORT FOR THIS AS WELL IN THE LATEST
ENSEMBLES AS WELL. THE WPC FORECAST TRIED TO TAKE A MIDDLE GROUND
APPROACH, BUT DOES PRESENT A SHIFT IN CONTINUITY FROM THE PREVIOUS
SHIFT WHICH DID NOT SHOW THE PRESENCE OF THE LOW AT ALL.
SIGNIFICANT UNCERTAINTY WITH THE TRACK AND IMPACTS OF THIS LOW, BUT
WILL NEED TO BE WATCHED CLOSELY.
OUT WEST, THE 00Z GUIDANCE TONIGHT HAS COME INTO BETTER AGREEMENT
WITH THE EVOLUTION OF AN UPPER LOW THAT DROPS SOUTHWARD ALONG THE
COAST AND EVENTUALLY MOVES INTO THE SOUTHWEST. PREVIOUS RUNS OF THE
ECMWF HAD BEEN FARTHER OFFSHORE, AND SLOWER TO BRING THE TROUGH
INLAND, BUT THE 00Z RUN TRENDED FASTER. CONVERSELY, YESTERDAYS 12Z
GFS CAME IN MUCH FASTER, BUT THE NEW 00Z RUN WAS SLOWER AGAIN. THIS
IS ALSO GENERALLY IN LINE WITH THE CMC AND ECAIFS, AND IT SEEMS A
GENERAL MODEL COMPROMISE (WITH THE ENSEMBLE MEANS) SHOULD SERVE AS
A GOOD STARTING POINT FOR THE FORECAST.
..WEATHER/HAZARDS HIGHLIGHTS
A COLD FRONT MOVING SLOWLY THROUGH FLORIDA WILL ALLOW FOR
INCREASED ONSHORE FLOW AND LOCALLY HEAVY RAINFALL, ESPECIALLY ALONG
THE EAST COAST. WPC HAS THIS REGION IN A MARGINAL RISK FOR SUNDAY.
COASTAL LOW PRESSURE DEVELOPMENT OFF THE MID-ATLANTIC COAST MAY
ALLOW FOR MORE SHOWERS AND LOCALLY HEAVY RAINFALL FOR ESPECIALLY
THE EASTERN CAROLINAS AND SOUTHEAST VIRGINIA, WITH POSSIBLE GUSTY
WINDS. ALL OF THIS IS HIGHLY DEPENDENT ON HOW CLOSE TO THE COAST
THIS LOW IS, AND A CLOSER LOCATION WOULD MEAN MUCH GREATER IMPACTS,
ESPECIALLY IF THE LOW LINGERS FOR ANY PERIOD OF TIME. OUT WEST,
PRECIPITATION CHANCES INCREASE BY MONDAY AND ESPECIALLY TUESDAY
INTO WEDNESDAY WITH RAIN AND HIGH ELEVATION SNOW. SOME RAINFALL MAY
BEGIN TO DEVELOP ACROSS THE SOUTH-CENTRAL U.S. BY MID NEXT WEEK AS
WELL.
CANADIAN HIGH PRESSURE WILL BE IN PLACE ACROSS MUCH OF THE EAST ON
SUNDAY, WITH FROST/FREEZE CONCERNS FOR PARTS OF THE MID-ATLANTIC
AND THE NORTHEAST. ELSEWHERE, ABOVE NORMAL TEMPERATURES WILL EXPAND
ACROSS THE CENTRAL U.S. AS CONDITIONS TREND COOLER ACROSS THE WEST
UNDERNEATH DEEP TROUGHING NEXT WEEK.
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, 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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