778
FXUS02 KWBC 121901
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
200 PM EST SAT NOV 12 2022
VALID 12Z TUE NOV 15 2022 - 12Z SAT NOV 19 2022
...MUCH BELOW NORMAL TEMPERATURES TO SETTLE OVER MUCH OF THE
NATION ALONG WITH A THREAT FOR APPALACHIANS/INTERIOR NORTHEAST AND
GREAT LAKE EFFECT SNOWS...
..SYNOPTIC OVERVIEW
A RATHER COLD PATTERN IS EXPECTED TO BE IN PLACE ACROSS MUCH OF
THE NATION FOR NEXT WEEK WITH BROAD CYCLONIC FLOW ALOFT AROUND A
DEEP UPPER LEVEL TROUGH CENTERED NEAR THE NORTH-CENTRAL U.S. AND
EXTENDING INTO CENTRAL CANADA. MULTIPLE REINFORCING COLD
FRONTS/SHORTWAVES WILL HELP TO MAINTAIN THIS PATTERN, AND A STRONG
UPPER RIDGE AXIS SHOULD PREVAIL JUST OFF THE WEST COAST. THERE
WILL LIKELY BE TWO SEPARATE GULF COAST STORM SYSTEMS THAT DEVELOP
IN RESPONSE TO SHORTWAVES TRACKING AROUND THE SOUTHERN PERIPHERY
OF THE DEEP TROUGH, AND THESE ARE EXPECTED TO PRODUCE ROUNDS OF
RAIN FROM THE DEEP SOUTH TO THE EAST COAST. THE COLD AIR WILL ALSO
FAVOR SWATHS OF ENHANCED SNOW/ICE ON THE WESTERN PERIPHERY OF THE
ASSOCIATED PRECIPITATION SHIELD FROM THE CENTRAL TO THE NORTHERN
APPALACHIANS/INTERIOR MOUNTAINS OF THE NORTHEAST. THIS PATTERN
WILL ALSO FAVOR A PROTRACTED OPPORTUNIUTY FOR PERIODS OF LAKE
ENHANCED SNOWS TO THE LEE OF THE GREAT LAKES.
..GUIDANCE AND PREDICTABILITY ASSESSMENT
MODELS AND ENSEMBLE SOLUTIONS OVERALL SEEM WELL CLUSTERED
TUESDAY/WEDNESDAY FOR MUCH OF THE LOWER 48 STATES, BOLSTERING
FORECAST CONFIDENCE IN A COMPOSITE SOLUTION TO MITIGATE LINGERING
SMALLER SCALE VARIANCE. GUIDANCE DIFFERENCES BECOME INCREASINGLY
EVIDENT THROUGH THE REMAINDER OF NEXT WEEK, ESPECIALLY OVER THE
WEST WHERE THE 00/06 UTC GFS AND 00 UTC CANADIAN DUG MUCH MORE
AMPLE UPPER TROUGH/LOW ENERGIES IN SEPARATED FLOW THAN THE 00 UTC
ECMWF AND GEFS/ECMWF ENSEMBLES. THE 12 UTC GFS HAS COMPLETELY
FLIPPED TO FOCUS MOST UPPER ENERGIES INTO THE CENTRAL U.S., BUT
THE 12 UTC CANADIAN HAS NOT CHANGED CONTINUITY AND INCREDIBLY NOW
THE 12 UTC ECMWF HAS DRAMTICALLY SWITCHED TO SHOW MUCH MORE UPPER
TROUGHING OVER THE WEST. THE WPC MEDIUM RANGE PRODUCT SUITE WAS
PRIMARILY DERIVED FROM THE 06 UTC GEFS AND 00 UTC ECMWF ENSEMBLE
MEANS GIVEN GREATER THAN NORMAL PATTERN EVOLUTION UNCERTAINTY.
THIS STILL SEEMS SUPPORTED BY THE 12 UTC GEFS.
WITH RESPECT TO TARGETED CHANGES TO 13 UTC NBM QPF, WPC QPF
INCREASED AMOUNTS TO THE LEE OF THE GREAT LAKES IN QUITE FAVORABLE
FLOW NEXT WEEK AND ALSO FAVORED POTENTIAL FOR MODESTLY MORE
AMOUNTS FOR THE GULF COAST/SOUTHEAST CONSIDERING ORGANIZATION OF
THE MAIN TWO SUPPORTING LOWS/FRONTAL SYSTEMS EXPECTED TO TRAVERSE
THE REGION THIS PERIOD.
..WEATHER/HAZARD HIGHLIGHTS
TWO ORGANIZING SYSTEM NEAR THE GULF COAST EARLY AND THEN LATER
NEXT WEEK ARE EXPECTED TO LIFT NORTHEASTWARD AND PRODUCE MODERATE
SWATHS OF RAIN ACROSS MUCH OF THE SOUTH AND SOUTHEAST. LEAD SYSTEM
TRACK AND COASTAL LOW TRANSITION UP THE EAST COAST MIDWEEK ALSO
OFFERS A THREAT FOR ENHANCED SNOW/ICE ON THE WESTERN PERIPHERY OF
THE ASSOCIATED PRECIPITATION SHIELD FROM THE CENTRAL TO THE
NORTHERN APPALACHIANS/INTERIOR MOUNTAINS OF THE NORTHEAST.
NORTHERN STREAM ENERGY PASSAGES AND COLD AIR ADVECTION OVER THE
GREAT LAKES IS EXPECTED TO PRODUCE GREAT LAKE EFFECT SNOW AT
TIMES, AND SOME OF THIS SNOW COULD BE LOCALLY HEAVY IN A
REINFORCING COLD FLOW PATTERN FOR MUCH OF NEXT WEEK.
THE OTHER NOTEWORTHY ASPECT OF THE EXTENDED FORECAST WILL BE THE
WIDESPREAD ANOMALOUS COLD WEATHER ACROSS A GREAT DEAL OF THE
NATION FOR BASICALLY ALL OF NEXT WEEK, ESPECIALLY FROM THE
UNSETTLED INTERIOR WEST TO THE HIGH PLAINS/MIDWEST WHERE
TEMPERATURES MAY RUN 15-30 DEGREES BELOW MID-NOVEMBER AVERAGES.
SOME SPOTTY DAILY RECORDS ARE ALSO POSSIBLE. EXCEPTIONS TO THE
COLD WEATHER MAY BE THE FLORIDA PENINSULA AND POSSIBLY THE WEST
COAST, WITH READINGS NEAR OR SLIGHTLY ABOVE AVERAGE.
HAMRICK/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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