968
FXUS02 KWBC 210719
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
318 AM EDT FRI OCT 21 2022
VALID 12Z MON OCT 24 2022 - 12Z FRI OCT 28 2022
...MODEL AND PREDICTABILITY ASSESSMENT AND WEATHER/HAZARD
HIGHLIGHTS...
MODEL AND ENSEMBLE SOLUTIONS SEEM IN REASONABLY GOOD OVERALL
AGREEMENT MONDAY, BUT RAPIDLY EXHIBIT RUN TO RUN VARIABILTY AND
INCREASING FORECAST SPREAD THROUGH THE REST OF NEXT WEEK IN AN
ACTIVE PATTERN WITH LOWERING FORECAST CONFIDENCE. THE WPC MEDIUM
RANGE SURFACE AND 500 MB PROGS WERE MAINLY DERIVED FROM A
COMPOSITE BLEND OF THE 00 UTC GFS/ECMWF/UKMET/CANADIAN MONDAY INTO
EARLY TUESDAY BEFORE RAPIDLY TRANSITIONING TO A BLEND OF THE
COMPATIBLE GEFS/ECMWF ENSEMBLE MEANS FOR THE REST OF THE PERIOD.
IN THIS SCENARIO, AN EXITING UPPER TROUGH/LOW AND DEEPENED SURFACE
LOW/SYSTEM OVER THE NORTH-CENTRAL U.S. MONDAY OFFERS
WINDY/WRAPPING PRECIPITATION INCLUDING LEAD STRONG TO SEVERE
CONVECTION AS PER SPC AND SOME WRAPPING BACKSIDE SNOW. LEAD EARLY
WEEK PRE-FRONTAL WARMTH MODERATES THROUGH THE REST OF THE WEEK
OVER THE EAST-CENTRAL U.S. UPSTREAM, SYSTEM ENERGY PUSHING INLAND
ACROSS THE NORTHWEST TO THE ROCKIES WILL PRODUCE A SWATH OF
PRECIPITATION INCLUDING ELEVATION SNOWS ENHANCED BY TERRAIN BEFORE
REACHING THE NORTHERN PLAINS. POTENT TRAILING UPPER TROUGH
ENERGIES IN THIS STREAM ACROSS AN UNSETTLED SOUTHWEST MONDAY MAY
TAP MODESTLY WITH SOME MOISTURE FROM MEXICAN LANDFALLING AND
DECAYING ROSLYN. THE DRIVING UPPER TROUGH IS SLATED TO THEN EJECT
FROM THE SOUTHWEST AND LIFT NORTHEASTARD ACROSS THE CENTRAL U.S.
AND GREAT LAKES/MIDWET THOUGH MIDWEEK, BUT GUIDANCE IS VARIED WITH
STREAM SEPARATION AND TIMING ISSUES. THE PATTERN THOUGH SHOULD
FOCUS GULF MOISTURE AND INSTABILITY INTO THE DEVELOPING FRONT AND
WPC HAS ISSUED AN EXPERIMENTAL "SLIGHT" RISK OF EXCESSIVE RAINFALL
CENTERED OVER THE SOUTHERN PLAINS MONDAY WHERE MULTIPLE INCHES OF
CONVECTIVE RAINS MAY FOCUS.
SUBSEQUENT RENEWED UPPER TROUGH ENERGY FLOW INTO THE WEST COAST
INTO MID-LATER WEEK WAS BEEN HANDLED DIFFERENTLY BY THE MODELS,
BUT THE 00 UTC RUNS ARE MORE IN AGREEMENT WITH AN OVERALL TREND
FOR DIGGING. THIS SHOULD PROLONG A QUITE COLD PERIOD OVER THE
WEST/ROCKIES AND SYSTEM AMPLITUDE SHOULD FAVOR A DECENT AND
REPEATABLE MODERATE QPF COVERAGE RESPONSE TO INCLUDE ADDITIONAL
HEAVY SNOW THREATS WITH FOCUS OVER FAVORED TERRAIN FROM THE WEST
COAST STATES THROUGH THE GREAT BASIN AND THE ROCKIES. THIS SYSTEM
IS SLATED TO ENERGE OVER THE CENTRAL U.S. LATE PERIOD TO RENEW
RAIN/CONVECTIION.
ELSEWHERE, LINGERING UPPER TROUGHING OVER THE MID-ATLANTIC AND
OFFSHORE TROUGHING FOCUS THROUGH AT LEAST EARLY NEXT WEEK HAS
PROVEN HIGHLY UNCERTAIN IN GUIDANCE FROM RUN TO RUN. HOWEVER, THE
PATTERN DOES OFFER PROTRACTED SUPPORT FOR COASTAL AFFECT WITH
PREHAPS BEST FLOW FOCUS OVER NEW ENGLAND.
TARGETED CHANGES TO THE 01 UTC NBM 4.0 QPF WERE MAINLY TO INCREASE
AFTERNOON/EVENING CONVECTIVE RAINFALL TRAILING OVER THE
SOUTH-CENTRAL U.S. EARLY IN THE WEEK GIVEN FAVORABLE UPPER SUPPORT
AND FRONTAL POOLING MOISTURE/INSTABILITY, TO MODESTLY INCREASE
AMOUNTS AND COVERAGE DOWNSTREAM INTO MID-LATE WEEK WITH SWEEP
ACROSS THE EAST-CENTRAL STATES GIVEN LOW NBM BIAS AT THESE TIME
FRAMES WITH ORGANIZED SYSTEMS AND GIVEN FORECAST SPREAD
CONSOLIDATE/EXPAND OVERALL AREAL COVERAGE OF MID-LATER WEEK
PRECIPITATION OVER THE WEST/ROCKIES GIVEN FAVORABLE FLOW.
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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