922
FXUS02 KWBC 030700
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
200 AM EST SAT DEC 03 2022
VALID 12Z TUE DEC 06 2022 - 12Z SAT DEC 10 2022
...HEAVY RAIN BECOMING MORE LIKELY FROM THE SOUTH-CENTRAL PLAINS
TO THE MID-SOUTH/TENNESSEE VALLEY EARLY-MID NEXT WEEK...
..GUIDANCE AND PREDICTABILITY ASSESSMENT
THE LATEST WPC MEDIUM RANGE PRODUCT SUITE WAS MAINLY 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 TUESDAY
INTO WEDNESDAY. THE LARGER SCALE UPPER FLOW PATTERN EVOLUTION
REMAINS GENERALLY COMPATIBLE IN GUIDANCE FOR MUCH OF NEXT WEEK
INCLUDING THE LATEST 00 UTC MODEL RUNS. HOWEVER, SMALLER SCALE
EMBEDDED SYSTEM FOCUS AND RUN TO RUN CONTINUITY ISSUES REMAIN
EVIDENT IN THIS SENSITIVE PATTERN WITH UNCERTAIN MULTI-STREAM
SYSTEM INTERACTIONS. ACCORDINGLY, TRANSITIONED TO USAGE OF A BLEND
OF COMPATIBLE GEFS/NAEFS/ECMWF ENSEMBLE MEANS LATER WEDNESDAY
THROUGH NEXT SATURDAY. THERE IS A GROWING SIGNAL FOR HEAVY RAINS
FROM THE SOUTH-CENTRAL PLAINS TO THE MID-SOUTH EARLY-MID NEXT
WEEK, BUT WAS HESITANT TO ISSUE ANY EXPERIMENTAL ERO "SLIGHT" RISK
AREAS DUE TO UNCERTAINTIES WITH LOCAL MAIN QPF FOCUS. FOR QPF,
TARGETED A BLEND TO THE 01 UTC NBM WITH LIMITED INCORPORATION OF
WPC CONTINUITY TO SOFTEN RUN TO RUN VARIANCE.
..PATTERN OVERVIEW AND WEATHER/HAZARD HIGHLIGHTS
IT REMAINS THE CASE THAT 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
SHOWS 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, FOLLOWED BY A POTENTIALLY VIGOROUS
SHORTWAVE TROUGH DIGGING INTO THE PACIFIC NORTHWEST
THURSDAY/FRIDAY TO RENEW PRECIPITATION INTO THE REGION, WITH AMPLE
SYSTEM ENERGIES WORKING OVER AN UNSETTLED WEST INTO NEXT WEEKEND.
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 SOUTH-CENTRAL PLAINS TO THE MID-SOUTH
ONWARD ACROSS 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 TO THE INTERIOR NORTHEAST
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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