370
FXUS02 KWBC 220657
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
156 AM EST SUN JAN 22 2023
VALID 12Z WED JAN 25 2023 - 12Z SUN JAN 29 2023
...HEAVY RAIN AND INLAND SNOW THREAT FROM THE OHIO VALLEY TO THE
INTERIOR NORTHEAST FOR WEDNESDAY THROUGH EARLY FRIDAY...
..SYNOPTIC OVERVIEW
A WELL ORGANIZED LOW PRESSURE SYSTEM TRACKING FROM THE GULF COAST
TO THE NORTHEAST U.S. DURING THE MIDDLE TO END OF THE WEEK WILL BE
THE MAIN STORY MAKING WEATHER HEADLINES DURING THIS FORECAST
PERIOD, WITH A WIND-DRIVEN RAIN NEAR THE COAST AND MODERATE TO
HEAVY SNOW ACROSS INTERIOR PORTIONS OF THE NORTHEAST. THIS WILL
BE IN RESPONSE TO AN AMPLIFYING SHORTWAVE TROUGH ALOFT THAT WILL
QUICKLY EXIT THE EAST COAST BY FRIDAY MORNING. IN THE WAKE OF
THIS STORM WILL BE A WEAKER ALBERTA CLIPPER THAT WILL TRACK
SOUTHEAST ACROSS THE GREAT LAKES REGION ON FRIDAY WITH A TRAILING
COLD FRONT BEHIND IT. BY NEXT WEEKEND, A NEW STORM SYSTEM WILL
LIKELY GET BETTER ORGANIZED ACROSS THE SOUTHERN PLAINS AS A MUCH
COLDER AIRMASS DROPS SOUTHWARD FROM CANADA ACROSS MUCH OF THE
MIDWEST AND NORTHERN PLAINS.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE 00Z MODEL GUIDANCE SUITE IS IN ABOVE AVERAGE SYNOPTIC SCALE
AGREEMENT THROUGH THURSDAY, INCLUDING THE TRACK OF THE STRONG
SURFACE LOW ACROSS THE EASTERN U.S. AND THE RIDGE AXIS ACROSS THE
WEST. ONE OF THE THINGS THE MODELS HAVE BEEN STRUGGLING WITH OVER
THE PAST COUPLE OF DAYS IS THE BREAKDOWN OF THE WEST COAST RIDGE
BY SHORTWAVE ENERGY ORIGINATING FROM THE GULF OF ALASKA, AND THE
PAST FEW GFS/GEFS RUNS HAVE MAINTAINED THE RIDGE LONGER THAN THE
CMC/ECMWF. THE ECMWF IS FASTER WITH THE ARRIVAL OF THE SHORTWAVE
REACHING THE PACIFIC NORTHWEST, WITH THE CMC BETWEEN THE TIMING OF
THE ECMWF AND GFS. BY NEXT SUNDAY, THE ECMWF IS SUPPORTING THE
DEVELOPMENT OF A CLOSED LOW NEAR THE WEST COAST, WHEREAS THE OTHER
GUIDANCE IS WEAKER WITH THIS. THE WPC FRONTS AND PRESSURES
FORECAST WAS PRIMARILY DERIVED FROM A NEARLY MULTI-DETERMINISTIC
MODEL BLEND FOR WEDNESDAY AND THURSDAY, FOLLOWED BY LESS OF THE
GFS OWING TO DIFFERENCES WITH THE WESTERN U.S. RIDGE GOING INTO
FRIDAY AND THE WEEKEND. THE ECENS WAS FAVORED MORE THAN THE GEFS
MEAN GOING INTO THE WEEKEND SINCE THE CMC MEAN WAS MUCH CLOSER TO
THE ECENS AND HAD A MORE FAVORABLE PATTERN EVOLUTION.
..WEATHER/HAZARD HIGHLIGHTS
THE NEXT MAJOR STORM SYSTEM IS FORECAST TO DEVELOP OVER
TEXAS/LOUISIANA ON TUESDAY AND THEN TRACK NORTHEAST ACROSS THE
OHIO VALLEY ON WEDNESDAY, AND THEN REACHING THE NORTHEAST U.S. BY
THURSDAY AS A NEW SURFACE LOW IS FORECAST TO DEVELOP NEAR THE
COAST AND BECOMES THE DOMINANT LOW. THE BEST HEAVY RAINFALL
POTENTIAL EXISTS FROM SOUTHERN GEORGIA AND ACROSS THE PIEDMONT OF
THE CAROLINAS AND VIRGINIA, WITH THE POTENTIAL FOR SOME 1 TO
LOCALLY 2 INCH RAINFALL TOTALS, AND ALSO ACROSS SOUTHERN NEW
ENGLAND AND LONG ISLAND, NY. THERE WILL LIKELY BE A NOTEWORTHY
SWATH OF WINTRY WEATHER FROM THE NORTHERN OHIO VALLEY/EASTERN
GREAT LAKES ON WEDNESDAY, WHERE A SWATH OF ENHANCED DEFORMATION
ZONE SNOWS WILL BE POSSIBLE. HEAVY SNOW IS THEN LIKELY ACROSS THE
APPALACHIANS THROUGH INTERIOR AREAS OF THE NORTHEAST AS THE
SECONDARY LOW DEVELOPS, WITH HEAVY RAIN AND GALES UP THE COAST AS
THE LOW CONTINUES TO INTENSIFY. MUCH OF THIS SNOW WILL BE FALLING
OVER AREAS THAT GET SIGNIFICANT ACCUMULATIONS FROM THE EVENT ON
SUNDAY-MONDAY.
A BROAD EXPANSE OF BELOW AVERAGE TEMPERATURES ARE EXPECTED FROM
THE INTERMOUNTAIN WEST TO THE CENTRAL GULF COAST ON WEDNESDAY IN
THE WAKE OF THE EASTERN U.S. LOW PRESSURE SYSTEM, AND MILD AIR
ALONG THE EAST COAST AHEAD OF THE FRONT. NOTHING TOO ANOMALOUS
APPEARS LIKELY GOING INTO FRIDAY, BUT A RETURN TO MUCH COLDER
CONDITIONS IS LOOKING LIKELY ACROSS THE NORTHERN PLAINS AND UPPER
MIDWEST AS AN ARCTIC AIRMASS MOVES IN BEHIND THE DEPARTING CLIPPER
LOW, WITH HIGHS RUNNING UP TO 15-25 DEGREES BELOW NORMAL
POTENTIALLY ACROSS PORTIONS OF MONTANA, THE DAKOTAS, AND NEBRASKA
ON SUNDAY. MEANWHILE, MILD CONDITIONS WILL LIKELY RETURN TO MUCH
OF THE SOUTHERN AND EASTERN U.S. WITH SOME RETURN FLOW OFF THE
GULF OF MEXICO.
HAMRICK
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, EXPERIMENTAL EXCESSIVE RAINFALL
OUTLOOK, WINTER WEATHER OUTLOOK PROBABILITIES AND HEAT INDICES 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
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