830
FXUS02 KWBC 212040
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
439 PM 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 HAVE TRENDED TOWARDS BETTER AGREEMENT
SINCE EVEN JUST 24 HOURS AGO, AND NOW SHOW FAIRLY GOOD AGREEMENT
ON THE OVERALL PATTERN, BUT PLENTY OF RUN TO RUN VARIABILITY AND
INCREASING SPREAD ON THE DETAILS NEXT WEEK. WPC LEANED ON A
COMPOSITE BLEND OF THE 00Z CMC/ECMWF AND 06Z GFS THE FIRST HALF OF
THE PERIOD, WITH INCREASING CONTRIBUTIONS FROM THE ENSEMBLE MEANS
THE LATER HALF AMIDST INCREASING SPREAD/UNCERTAINTY. THIS
GENERALLY MAINTAINED GOOD CONTINUITY WITH THE PREVIOUS SHIFT.
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/CLOSED LOW IS SLATED TO
THEN EJECT FROM THE SOUTHWEST AND LIFT NORTHEASTWARD ACROSS THE
CENTRAL U.S. AND GREAT LAKES/MIDWEST THOUGH MIDWEEK. TIMING AND
AMPLITUDE ISSUES REMAIN IN THE GUIDANCE. THE MAIN OUTLIER AT THIS
POINT IS THE GFS WHICH IS SLOWER AND MAINTAINS A CLOSED LOW LONGER
THAN THE REST OF THE GUIDANCE WOULD SUGGEST. 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 LATEST RUNS THIS MORNING 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 EMERGE OVER THE CENTRAL U.S. LATE PERIOD
TO RENEW RAIN/CONVECTION, ALTHOUGH UNCERTAINTY ON PLACEMENT AND
AMOUNTS ARE HIGHLY VARIABLE AT THIS TIME.
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 EFFECT WITH
PERHAPS BEST FLOW FOCUS OVER NEW ENGLAND.
IN TERMS OF QPF ACROSS THE COUNTRY COMPARED TO THE 13Z NBM,
INCREASED AMOUNTS AND SOMEWHAT THE GENERAL COVERAGE BASED ON A
MULTI-MODEL ENSEMBLE BLEND, ESPECIALLY EARLY WEEK ACROSS THE
SOUTHERN/CENTRAL PLAINS INTO THE MIDWEST.
SANTORELLI/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
- HEAVY RAIN ACROSS PORTIONS OF CALIFORNIA, THE PACIFIC NORTHWEST,
AND THE NORTHERN GREAT BASIN,
MON-TUE, OCT 24-OCT 25 AND THU-FRI, OCT 27-OCT 28.
- HEAVY RAIN ACROSS PORTIONS OF THE CENTRAL PLAINS, THE LOWER
MISSISSIPPI VALLEY, THE GREAT LAKES,
THE MIDDLE MISSISSIPPI VALLEY, THE UPPER MISSISSIPPI VALLEY, THE
SOUTHERN PLAINS, AND THE OHIO
VALLEY, MON-TUE, OCT 24-OCT 25.
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE SOUTHEAST.
- HIGH WINDS ACROSS PORTIONS OF THE CENTRAL PLAINS AND THE
NORTHERN PLAINS, MON, OCT 24.
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE CENTRAL
ROCKIES, THE CENTRAL GREAT BASIN,
THE NORTHERN ROCKIES, THE SOUTHERN ROCKIES, CALIFORNIA, THE
NORTHERN GREAT BASIN, THE PACIFIC
NORTHWEST, AND THE SOUTHWEST, MON, OCT 24.
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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