973
FXUS02 KWBC 190653
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
253 AM EDT WED MAR 19 2025
VALID 12Z SAT MAR 22 2025 - 12Z WED MAR 26 2025
..OVERVIEW AND GUIDANCE/PREDICTABILITY ASSESSMENT
PROGRESSIVE UPPER FLOW WITH MULTIPLE EMBEDDED SYSTEMS THIS WEEK IN
TWO MAIN STREAMS WILL AMPLIFY INTO NEXT WEEK WITH THE DEVELOPMENT
OF A WARMING/BUILDING WEST COAST RIDGE AND A COOLING/DEEPENING AND
UNSETTLING EAST-CENTRAL U.S. TROUGH.
MODELS AND ENSEMBLES SEEM WELL CLUSTERED WITH THE WEATHER PATTERN
EVOLUTION THROUGH THE MEDIUM RANGE PERIOD, WITH REASONABLY GOOD
AGREEMENT ON INDIVIDUAL STORM SYSTEMS AS WELL. FORECAST CONFIDENCE
REMAINS ABOVE AVERAGE OVERALL WITH A GUIDANCE BLEND, ALBEIT WITH
MORE UNCERTAINTY IN DETAILS LATER PERIOD. HOWEVER, THESE SEEM WELL
MITIGATED CONSISTENT WITH PREDICTABILITY BY THE BLEND PROCESS AND
TARGETED MANUAL ADJUSTMENTS. THE WPC FORECAST WAS MAINLY DERIVED
FROM A GFS/ECMWF/CMC/UKMET COMPOSITE SATURDAY INTO MONDAY BEFORE
SWITCHING TO A BLEND OF BEST CLUSTERED GFS/ECMWF/CANADIAN MODEL
AND ENSEMBLE MEAN GUIDANCE INTO LONGER TIME FRAMES. THIS SOLUTION
PLAN IS MAINLY IN LINE WITH THE NATIONAL BLEND OF MODELS, MACHINE
LEARNING/00 UTC GUIDANCE AND OFFERS GOOD WPC PRODUCT CONTINUITY.
..WEATHER/HAZARDS HIGHLIGHTS
A SERIES OF PACIFIC SYSTEMS AND MODERATE MOISTURE FEEDS WILL FUEL
PERIODS OF UNSETTLED WET WEATHER TO THE WEST/NORTHWEST, WITH AN
ENHANCED MOISTURE/RAIN FOCUS FOR THE PACIFIC NORTHWEST AND TERRAIN
ENHANCED HEAVY SNOWS INLAND TO THE ROCKIES. THE WPC DAY 5/SUNDAY
EXCESSIVE RAINFALL OUTLOOK (ERO) INTRODUCES A MARGINAL RISK AREA
FOR COASTAL NORTHWEST OREGON/WASHINGTON AS COMPOUNDING EFFECTS OF
MULTIPLE BOUTS OF PRECIPITATION MAY LEAD TO LOCAL RUNOFF ISSUES.
DOWNSTREAM, LESS DEFINED PERIODS OF PRECIPITATION OVER THE CENTRAL
TO EASTERN U.S. INTO THE WEEKEND ARE EXPECTED TO BECOME MUCH
BETTER ORGANIZED STARTING SUNDAY AS A DEEPENING CYCLONE IS FORECAST
TO TRACK NORTHEASTWARD FROM THE PLAINS TO THE GREAT LAKES AND THE
NORTHEAST/EASTERN CANADA INTO EARLY NEXT WEEK. RETURN FLOW FROM
THE GULF APPEARS TO SUPPORT A HEAVY RAIN AND A SEVERE WEATHER
THREAT FOR PARTS OF THE SOUTH SUNDAY INTO MONDAY. A WPC DAY 5 ERO
MARGINAL RISK AREA WAS INTRODUCED FOR THE LOWER MISSISSIPPI AND
TENNESSEE VALLEYS. ENHANCED RAINS THEN SPREAD AS A WAVY COLD FRONT
SWEEPS ACROSS THE SOUTHEAST/EASTERN SEABOARD MONDAY INTO TUESDAY.
MEANWHILE, REINFORCING COLD AIR WRAPPING AROUND THE MAIN LOW
APPEARS TO SUPPORT A HEAVY SNOW THREAT FOR THE GREAT LAKES REGION
SUNDAY INTO MONDAY, POSSIBLY SPREADING OVER THE NORTHERN AND
INTERIOR NORTHEAST INTO MONDAY AND TUESDAY WITH CLOSED UPPER
LOW/TROUGH APPROACH AND AS TRIPLE-POINT LOW DEVELOPMENT IS
ADDITIONALLY POSSIBLE NEAR THE COAST OF NEW ENGLAND.
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 (QPF), EXCESSIVE RAINFALL
OUTLOOK (ERO), WINTER WEATHER OUTLOOK (WWO) PROBABILITIES, HEAT
INDICES, AND KEY MESSAGES CAN BE ACCESSED FROM:
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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