216
FXUS02 KWBC 020657
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
156 AM EST FRI DEC 02 2022
VALID 12Z MON DEC 05 2022 - 12Z FRI DEC 09 2022
..GUIDANCE AND PREDICTABILITY ASSESSMENT
THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A
COMPOSITE OF REASONABLY WELL CLUSTERED GUIDANCE FROM THE 18 UTC
GFS AND 12 UTC ECMWF/UKMET/CANADIAN MODELS ALONG WITH WPC
CONTINUITY AND THE 01 UTC NATIONAL BLEND OF MODELS VALID MONDAY.
THE LARGER SCALE UPPER FLOW PATTERN EVOLUTION REMAINS GENERALLY
COMPATIBLE IN GUIDANCE WELL INTO MEDIUM RANGE TIME SCALES AND
OFFERS SOME COMMON TREND FOR A SLOWER SOUTHERN STREAM SOLUTION IN
RECENT GUIDANCE INCLUDING THE LATEST 00 UTC RUNS. HOWEVER,
EMBEDDED SYSTEM TIMING/SURFACE FEATURE FOCUS AND RUN TO RUN
CONTINUITY ISSUES BUILD IN A SENSITIVE PATTERN WITH UNCERTAIN
MULTI-STREAM SYSTEM INTERACTIONS. THE 12 UTC ECMWF ENSEMBLES WERE
NOT AVAILABLE FOR THIS FORECAST PACKAGE DUE TO A TECHNICAL ISSUE,
BUT THE 12 UTC NAEFS MEAN THAT INCLUDES INPUT FROM BOTH GEFS AND
CANADIAN ENSEMBLES DOES SEEM TO PROVIDE A DECENT FORECAST BASIS
TUESDAY-NEXT FRIDAY WITH AND EXTENDING FROM A GENERAL COMPOSITE OF
VARIED MODEL GUIDANCE IN A PATTERN WITH LESS THAN STELLAR
CONTINUNITY WITH LOCAL SPECIFICS. ACCORDINGLY, FELT COMPELLED TO
ONLY BROADLY IMPLY THREAT AREAS AND TARGETED A BLEND OF NBM QPF
WITH SOME WPC CONTINUITY TO SOFTEN RUN TO RUN VARIANCE AND LOCAL
FOCUS.
..PATTERN OVERVIEW AND WEATHER/HAZARD HIGHLIGHTS
MUCH OF THE LOWER 48 WILL EXPERIENCE PROGRESSIVE FLOW ALOFT TO
CHANNEL BETWEEN A MEAN CLOSED LOW/TROUGH OVER CENTRAL CANADA AND A
RIDGE OVER THE GULF OF MEXICO NEXT WEEK. NORTHERN STREAM SHORTWAVE
AROUND THE CANADIAN VORTEX MAY FAVOR SOME PERIODS OF SNOW FROM THE
MIDWEST TO THE NORTHEAST. GUIDANCE HAS TRENDED TOWARDS A
POSITIVELY-TILTED UPPER-LEVEL TROUGH PERSISTING OVER THE EASTERN
PACIFIC AND WESTERN U.S. WITH ONLY A GRADUAL EASTWARD DRIFT DURING
THE EARLY-MID NEXT WEEK PRIOR TO LATER WEEK EJECTION INTO THE
FLOW. AN UPSTREAM RIDGE SHOULD MOVE INTO THE NORTHWEST
U.S./WESTERN CANADA BY MIDWEEK OR SO, FOLLOWED BY A SHORTWAVE
TROUGH APPROACHING THE PACIFIC NORTHWEST AROUND THURSDAY TO RENEW
PRECIPITATION INTO THE REGION. THIS PATTERN SHOULD PROMOTE BELOW
NORMAL TEMPERATURES OVER MOST OF THE WEST AND NORTH-CENTRAL STATES
ON MOST DAYS, WITH RAIN AND MOUNTAIN SNOW AFFECTING SOME PARTS OF
THE WEST. THE PATTERN ALSO LOOKS TO OFFER A FAVORABLE SETUP FOR
SOME HEAVIER RAINFALL OVER PORTIONS OF THE EAST-CENTRAL U.S. NEXT
WEEK AS MULTIPLE LEAD MOISTURE SOURCES UNCERTAINLY INTERACT WITH A
COUPLE FRONTS, PERHAPS WITH A FOCUS FROM THE TENNESSEE VALLEY TO
THE SOUTHERN APPALACHIANS. A MAINLY DOMINANT NORTHERN STREAM FLOW
AND ASSOCIATED SETTLING OF COLDER AIR TO THE NORTH OF THESE FRONTS
MAY ALSO PROVIDE A POSSIBILITY FOR AN OVERRUNNING SWATH OF
SNOW/ICE/FREEZING RAIN ON THE NORTH SIDE OF THE RAIN SHIELDS,
PERHAPS FROM THE SOUTH-CENTRAL PLAINS THROUGH THE OHIO VALLEY
STATES MID-LATER NEXT WEEK.
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, 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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