347
FXUS02 KWBC 261649
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1248 PM EDT WED OCT 26 2022
VALID 12Z SAT OCT 29 2022 - 12Z WED NOV 02 2022
...HEAVY RAIN/SNOW THREAT FOR THE NORTHWEST/ROCKIES SUNDAY THROUGH
EARLY-MID NEXT WEEK...
...WEEKEND CLOSED LOW HEAVY RAIN THREAT FROM THE LOWER MISSISSIPPI
VALLEY THROUGH THE SOUTHERN APPALACHIANS...
..GUIDANCE AND PREDICTABILITY ASSESSMENT
THE GLOBAL MODEL GUIDANCE WAS IN REASONABLE AGREEMENT REGARDING
THE EVOLUTION OF THE SYNOPTIC PATTERN THROUGHOUT THE MEDIUM RANGE.
A SLIGHTLY MORE PROGRESSIVE TREND IN THE PATTERN WAS REALIZED
SINCE THE OVERNIGHT FORECAST. THIS TRANSLATED INTO NOTABLY LESS
QPF FOR PARTS OF THE NORTHWEST AND SOUTHEAST/SOUTHERN
APPALACHIANS. A GENERAL MODEL BLEND CONSISTING OF THE 00Z
EC/UK/CMC AND 06 GFS WAS APPLIED THROUGH DAY 4 SINCE THEY ALL
CAPTURED THE WEAKENING CLOSED LOW'S PROGRESSION THROUGH THE LOWER
MISSISSIPPI AND TENNESSEE VALLEYS FAIRLY WELL. THE 00Z ECE AND 06Z
GEFS MEANS WERE INTRODUCED TO THE BLEND ON DAY 5 TO ACCOUNT FOR
UNCERTAINTY REVOLVING AROUND THE EVOLUTION OF A PIECE OF SHORTWAVE
ENERGY MOVING TOWARD SOUTHERN CALIFORNIA/BAJA PENINSULA. THE
ENSEMBLE MEANS MAKE UP A MAJORITY OF THE BLEND BY DAYS 6 AND 7 DUE
TO UNCERTAINTY SURROUNDING AN UPPER TROUGH WHICH WILL APPROACH THE
PACIFIC NORTHWEST. THE ENSEMBLES THEMSELVES HAVE QUITE A BIT OF
SPREAD WITH RESPECT TO THIS TROUGH.
..PATTERN OVERVIEW AND WEATHER/HAZARD HIGHLIGHTS
THE DETAILS WITH A POTENT SERIES OF PACIFIC SYSTEMS TO WORK INTO
THE WEST/NORTHWEST THIS WEEKEND AND THROUGH EARLY-MID NEXT WEEK
REMAINS MORE RUN TO RUN VARIED THAN NORMAL IN RECENT MODEL
GUIDANCE, BUT THE COMPATIBLE GEFS/ECMWF ENSEMBLE MEANS OFFER A
INCREASINGLY STRONG SIGNAL FOR A PATTERN WITH LONG FETCH MOISTURE
TO FUEL PERIODIC MODERATE TO LOCALLY ENHANCED PRECIPITATION FROM
NORTHERN CALIFORNIA AND THE PACIFIC NORTHWEST INLAND ACROSS THE
NORTH-CENTRAL GREAT BASIN/ROCKIES. THIS WILL OFFER HEAVIEST
RAINFALL POTENTIAL FOR THE COASTAL RANGES/OLYMPICS AND CASCADES OF
THE PACIFIC NORTHWEST ALONG WITH A SIGNIFCIANT THREAT FOR TERRAIN
ENHANCED ELEVATION SNOW SET TO ALSO SPREAD EARLY-MID NEXT WEEK
INTO THE MOUNTAINS OF NORTHERN CALIFORNIA INLAND ACROSS THE
NORTH-CENTRAL GREAT BASIN/ROCKIES AS DEPICTED IN THE WPC WINTER
WEATHER OUTLOOK PROBABILITIES IN NDFD.
MEANWHILE, AN INTIALLY CLOSED/SEPARATED SOUTHERN STREAM SYSTEM IS
SLATED TO LIFT FROM THE SOUTHERN PLAINS THROUGH THE OHIO VALLEY
THIS WEEKEND. THIS WILL ACT TO FOCUS ACROSS THE SOUTH ENHANCED
RAIN/CONVECTION GIVEN UPPER AND SURFACE SYSTEM SUPPORT TO POOL
MOISTURE/INSTABILITY TO FUEL ACTIVITY. THERE IS SOME GUIDANCE
SIGNAL FOR LOCALLY MODERATE TO HEAVY RAINFALL GIVEN THE RISK OF
REPEAT/TRAINING CELLS. WHILE LOCALLY HEAVY RAINFALL IS POSSIBLE
THIS WEEKEND, NOT RATES ARE NOT EXPECTED TO BE SUBSTANTIAL ENOUGH
TO OVERCOME HIGH FLASH FLOOD GUIDANCE. NEVERTHELESS, ALSO EXPECT A
SWATH OF MODERATELY HEAVY RAINFALL TO LIFT ACROSS THE OHIO
VALLEY/APPALACHAINS AND ACROSS THE EASTERN SEABOARD THROUGH EARLY
NEXT WEEK WITH THE LEAD SYSTEM AND WITH REJUVINATING BACKSIDE
UPPER TROUGH ENERGY FEED THAT MAY SPAWN MODEST COASTAL/FRONTAL
GENESIS AND MOISTURE FROM THE ATLANTIC IN ADDITION TO LINGERING
GULF MOISTURE.
KEBEDE/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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