427
FXUS02 KWBC 240655
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
154 AM EST WED JAN 24 2024
VALID 12Z SAT JAN 27 2024 - 12Z WED JAN 31 2024
..OVERVIEW
ORGANIZED RAINFALL TO LIFT UP THE LENGTH OF THE EASTERN SEABOARD
AND VICINITY WITH A DEEPENING LOW PRESSURE SYSTEM/COASTAL LOW
TRACK THIS WEEKEND MAY ALSO PRODUCE A SWATH OF PLOWABLE INTERIOR
NORTHEAST SNOWS BY SUNDAY. FAR UPSTREAM, A LONG DURATION WET
PATTERN IS LIKELY TO PERSIST THROUGH THE NEXT WEEK WITH FOCUS FROM
NORTHERN CALIFORNIA THROUGH THE PACIFIC NORTHWEST. MUCH OF THE
REST OF OUR FINE NATION IN BETWEEN SHOULD EXPERIENCE A TRANQUIL
BREAK FROM SIGNIFICANT RECENT BOUTS OF COLD AIR/WINTRY CONDITIONS
TO INUDATING WET WEATHER, INSTEAD IN A RELATIVELY WARM AND DRY
LATE JANUARY PATTERN.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE WPC MEDIUM RANGE PRODUCT SUITE WAS MAINLY DERIVED FROM A
COMPOSITE BLEND OF REASONABLY WELL CLUSTERED GUIDANCE FROM THE 18
UTC GFS AND 12 UTC ECMWF/UKMET/CANADIAN FOR SATURDAY INTO MONDAY
IN AN OVERALL PATTERN WITH SEEMINGLY ABOVE NORMAL PREDICTABILITY.
THIS BLENDED SOLUTION IS ALSO QUITE COMPATIBLE WITH ENSEMBLES, THE
NATIONAL BLEND OF MODELS AND WPC CONTINUITY. A COMPOSITE OF NEWER
00 UTC GUIDANCE REMAINS IN LINE FOR THIS FORECAST PERIOD. PREFER
TO SWITCH TO A FORECAST BASED ON LATEST COMPATIBLE GEFS/ECMWF
ENSEMBLE MEANS THROUGH EARLY TO MID NEXT WEEK AMID GROWING MODEL
FORECAST SPREAD AND CYCLE TO CYCLE CONTINUITY ISSUES WITH THE
TIMING/AMPLITUDE OF EMBEDDED SYSTEMS. MODEL ISSUES AND
UNCERTAINTIES REMAIN EVIDENT WITH THE NEWER 00 UTC CYCLE AT THESE
LESS CERTAIN LONGER TIME FRAMES.
..WEATHER/HAZARDS HIGHLIGHTS
DEEP LAYERED SOUTHERLY FLOW IN ADVANCE OF A SLOW MOVING AND
AMPLIFIED EASTERN PACIFIC UPPER TROUGH WILL LIFT DEEP AND LONG
FETCH MOISTURE UP ACROSS THE EASTERN PACIFIC AND TANGENTLY INTO
NORTHERN CALIFORNIA AND THROUGH THE PACIFIC NORTHWEST. THIS WILL
FUEL A PROTRACTED WET PERIOD OVER THE NEXT WEEK, WITH CONDITIONS
ERODING OVER TIME WITH THE CUMULATIVE BUILDING OF RAINFALL TOTALS.
LIFTING SYSTEMS EMBEDDED WITHIN THE LARGER SCALE FLOW WILL
PERIODICALLY ENHANCE ACTIVITY RIDING THE WESTERN PERIPHERY OF AN
AMPLIFIED DOWNSTREAM UPPER RIDGE OVER THE WEST, AND MAY OVER TIME
LEAD TO RUNOFF ISSUES MAINLY FOR FAVORED FACING TERRAIN. WPC
EXCESSIVE RAINFALL OUTLOOKS (EROS) FOR DAY 4/SATURDAY AND DAY
5/SUNDAY SHOW SMALL MARGINAL RISK THREAT AREAS CENTERED OVER NW
CALIFORNIA/SW OREGON AND FOR BOTH DAYS OVER THE OLYMPICS TO
HIGHLIGHT BEST GUIDANCE SIGNALS AND TOPOGRAPHY.
AN ONGOING AND SIGNIFICANT RAINFALL EPISODE OVER THE SOUTH WILL
FINALLY END SATURDAY. DEEP GULF OF MEXICO TO ATLANTIC MOISTURE
FEED AHEAD OF THE LAST MAJOR SOUTHERN STREAM SHORTWAVE IN THE
SERIES WILL LIFT NORTHEASTWARD ON THE WESTERN PERIPHERY OF AN
AMPLIFIED DOWNSTREAM UPPER RIDGE. A REMAINING THREAT FOR HEAVY
RAIN UP FROM THE SOUTHEAST THROUGH THE SOUTHERN APPALACHIANS AND
VICINITY WITH SYSTEM APPROACH/PASSAGE AND DEEPENING LOW FOCUS HAS
PROMPTED A DAY 4/SATURDAY ERO MARGINAL RISK AREA. THE LIFTING OF
THIS FEATURE AND LOW ALSO FAVORS A MODERATE WRAPPED PRECIPITATION
SWATH ACROSS THE OHIO VALLEY, APPALACHIANS AND MID-ATLANTIC
THROUGH THE NORTHEAST THIS WEEKEND. WHILE WITHIN A WIDESPREAD AND
SIGNIFICANTLY WARMER PATTERN, ENOUGH COOLED AIR MAY REMAIN IN
PLACE TO ALLOW FOR SNOW ALONG WITH SOME WINDY CONDITIONS ON THE
NORTHERN EDGE OF THE BROAD PRECIPITATION SHIELD OVER THE INTERIOR
NORTHEAST BY SUNDAY AS AIDED WITH A DEEPENING LOW TRACK UP/OFF THE
EAST COAST. THIS EMERGING COASTAL STORM WILL ALSO OFFER A MARITIME
RISK OFFSHORE THE MID-ATLANTIC THEN NEW ENGLAND SUNDAY INTO
MONDAY.
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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