539
FXUS02 KWBC 231804
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
204 PM EDT SUN OCT 23 2022
VALID 12Z WED OCT 26 2022 - 12Z SUN OCT 30 2022
..GUIDANCE AND PREDICTABILITY ASSESSMENT
MODEL AND ENSEMBLE SOLUTIONS CONTINUE TO TREND TOWARDS BETTER
AGREEMENT, BOLSTERING FORECAST CONFIDENCE LONGER INTO MEDIUM RANGE
TIME SCALES. THE WPC PRODUCT SUITE WAS MAINLY DERIVED FROM A BLEND
OF THE BEST CLUSTERED DETERMINISTIC MODEL GUIDANCE
WEDNESDAY-THURSDAY (WITH INPUT FROM THE 13Z NBM). BEYOND DAY
4/THURSDAY, THERE IS INCREASING UNCERTAINTY IN TIMING OF THE NEXT
SOUTHERN STREAM POSSIBLE CLOSED LOW ACROSS THE SOUTHERN PLAINS,
WITH THE GFS SEEMING TO SHOW MORE RUN TO RUN VARIABILITY AND A
LITTLE FASTER PROGRESSION WITH THE SYSTEM INTO THE WEEKEND. WPC
PREFERRED THE BETTER CLUSTERED AND SLIGHTLY SLOWER ECMWF/CMC AND
UKMET (THROUGH 5), AND AFTER THE FORECAST WAS GENERATED, THE 12Z
GFS DID COME IN A LITTLE SLOWER THAN IT'S 06Z RUN. THE LATE PERIOD
FORECAST IS LOW CONFIDENCE THOUGH BECAUSE THE ENSEMBLES DO SHOW A
WIDE VARIETY OF DIFFERENCES BOTH WITH TIMING AND
STRENGTH/AMPLITUDE LEADING TO THE MEAN SOLUTIONS QUITE WASHED OUT
COMPARED TO WHAT WILL LIKELY HAPPEN IN REALITY. WAS ABLE TO PAIR
THE ECMWF/CMC MODELS WITH MORE EC MEAN THOUGH LATE PERIOD BECAUSE
THE EC MEAN WAS MORE AMPLIFIED THAN THE REMAINDER OF THE ENSEMBLE
MEAN GUIDANCE. THE NEXT SHORTWAVE INTO THE WEST NEXT WEEKEND ALSO
SHOWS PLENTY OF UNCERTAINTY IN TERMS OF TIMING AND AMPLITUDE AND A
MORE ENSEMBLE HEAVY BLEND BY THEN SEEMS TO WORK WELL.
..PATTERN OVERVIEW AND WEATHER/HAZARD HIGHLIGHTS
A DYNAMIC UPPER TROUGH/CLOSED LOW WILL LIFT/SHEAR NORTHEASTWARD
FROM THE MIDWEST TO EASTERN CANADA WEDNESDAY INTO THURSDAY. THIS
SHOULD CONTINUE TO DIRECT SOME GULF OF MEXICO AND ATLANTIC
MOISTURE INTO THE LEADING FRONTAL SYSTEM ACROSS A BROAD REGION,
BUT PROGRESSION SHOULD MOSTLY FAVOR AN INCREASINGLY MORE SCATTERED
PRECIPITATION PATTERN COMPARED TO THE SHORT RANGE, ALBEIT WITH
SOME GREAT LAKE ENHANCEMENT POSSIBLE AFTER THE UPPER LOW MOVES
THROUGH.
AMPLE MIDWEEK UPPER TROUGH ENERGY INTO THE WEST COAST AND
SUBSEQUENT SOUTHERN STREAM FLOW AMPLIFICATION INLAND ACROSS THE
INTERIOR TO THE ROCKIES SETS THE STAGE FOR SOME MUCH BELOW NORMAL
COLD TEMPERATURES AND A MODERATE QPF COVERAGE RESPONSE TO INCLUDE
TERRAIN ENHANCED HEAVY SNOW THREATS FROM THE GREAT BASIN TO THE
ROCKIES WEDNESDAY INTO THURSDAY. LATE WEEK ADDITIONAL FLOW/DIGGING
OF UPSTREAM PACIFIC SYSTEM/UPPER ENERGIES INTO THE WEST BECOME TOO
CHAOTIC IN THE MODELS TO OFFER SURE FOCUS, BUT THE LESS DEFINED
ENSEMBLE MEANS AT LEAST SHOW POTENTIAL ENERGY AVAILABLE ALONG WITH
A MODEST MODEL, ENSEMBLE AND NBM QPF SIGNATURE BACK ACROSS MAINLY
THE NORTHWEST AND INLAND INTO THE NORTH-CENTRAL GREAT BASIN AND
ROCKIES NEXT WEEKEND.
MEANWHILE, THE DOWNSTREAM EJECTION OF A MAIN AND POSSIBLY
CLOSED/WELL SEPARATED SOUTHERN STREAM SYSTEM IN THIS ACTIVE
PATTERN REMAINS SLATED TO AGAIN EMERGE OVER THE SOUTH-CENTRAL TO
SOUTHERN U.S. LATE NEXT WEEK INTO NEXT WEEKEND TO RENEW
RAIN/CONVECTION, ALTHOUGH UNCERTAINTY ON PLACEMENT/AMOUNTS REMAIN
HIGHLY VARIABLE, THE SIGNAL/POTENTIAL FOR MODEST TO HEAVY RAINFALL
HAS INCREASED SOME WITH THIS CYCLE, COMPARED TO THE PREVIOUS
FORECAST, WHICH IS MORE CONSISTENT WITH CURRENT MODEL TRENDS FOR
THIS LOW.
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
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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