340
FXUS02 KWBC 300710
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
310 AM EDT WED OCT 30 2024
VALID 12Z SAT NOV 02 2024 - 12Z WED NOV 06 2024
...MULTI-DAY HEAVY RAIN/FLOODING THREAT FROM THE SOUTHERN PLAINS
TO THE MID-MISSISSIPPI VALLEY THIS WEEKEND INTO EARLY NEXT WEEK...
..GENERAL OVERVIEW
AN EMERGING EXCESSIVE RAINFALL EVENT IS EXPECTED TO DEVELOP IN
EARNEST BY THE WEEKEND INTO EARLY NEXT WEEK OVER THE SOUTH-
CENTRAL U.S. WITH RETURN GULF OF MEXICO INFLOW IN A DEEPENING
MOISTURE CHANNEL BETWEEN A EAST/SOUTHEAST UPPER RIDGE AND SLOW
APPROACH OF AMPLIFIED UPPER TROUGH/LOW ENERGY AND FRONT FROM THE
WEST. TOWARDS THAT END, AFOREMENTIONED UPSTREAM UPPER TROUGH ENERGY
WILL DIG SHARPLY INTO AN UNSETTLED WEST THIS WEEKEND, WITH
MODERATE RAINS AND ELEVATION SNOWS FROM THE NORTHWEST SOUTHWARD TO
CALIFORNIA. ACTIVITY SHOULD SPREAD MORE MODESTLY TO THE SOUTHWEST
AND THE INTERMOUTAIN WEST/ROCKIES BY EARLY NEXT WEEK WITH SLOW AND
AMPLIFIED FLOW TRANSLATION AND ENERGY REINFORCEMENT AND CLOSED LOW
DEVELOPMENT AT THE BASE OF THE QUITE COOLING UPPER TROUGH/FRONTS.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODELS AND ENSEMBLES HAVE TRENDED TOWARD A BETTER CLUSTERED OVERALL
SOLUTION OVER THE COMING WEEKEND IN A PATTERN SEEMINGLY NOW WITH
CLOSER TO AVERAGE PREDICTABILITY. A COMPOSITE MODEL BLEND TENDS TO
MITIGATE STILL LINGERING INDIVIDUAL SYSTEM TIMING ISSUES TO OFFER A
SEEMINGLY REASONABLE FORECAST STARTING POINT, GENERALLY IN LINE
WITH THE NATIONAL BLEND OF MODELS AND THREAT MESSAGING CONTINUITY.
FORECAST SPREAD INCREASES INTO LONGER TIME FRAMES, SO PIVOTED TO A
COMPOSITE BLEND OF BEST CLUSTERED AND CYCLE TO CYCLE CONSISTENT
GUIDANCE FROM THE 12 UTC ECMWF/CANADIAN AND THEIR ENSEMBLE MEANS.
..WEATHER/HAZARDS HIGHLIGHTS
A HEAVY RAINFALL PATTERN SEEMS LIKELY ON TAP BY THE WEEKEND WITH
MAIN FOCUS FROM THE SOUTHERN PLAINS THROUGH THE MID-MISSISSIPPI
VALLEY AND VICINITY. THE WPC DAY 4/SATURDAY AND DAY 5/SUNDAY
EXCESSIVE RAINFALL OUTLOOKS (EROS) OFFER MARGINAL AND SLIGHT RISK
THREAT AREAS GIVEN CONSISTENT GUIDANCE SIGNALS. EXPECT ACTIVITY TO
EXPAND AND FOCUS ALONG A SOUTHWEST TO NORTHEAST AXIS AHEAD OF
ADDITIONAL FRONTAL BOUNDARIES THIS WEEKEND AND INTO EARLY NEXT WEEK
AS ROBUST UPPER TROUGH/CLOSED LOW ENERGY DIGS UPSTREAM INTO THE
WEST COAST TO RE-AMPLIFY THE FLOW OVER THE LOWER 48 AND VICINITY.
MULTIPLE DAYS OF SOUTHERLY, MOIST GULF INFLOW LOOK TO INCREASE THE
CHANCES OF MORE WIDESPREAD, HEAVY RAINFALL WITH FLOODING CONCERNS
DESPITE DRY ANTECEDENT CONDITIONS, WITH A RISK OF REPEAT/TRAINING
CONVECTION IN A SLOW TO DISLODGE AND DEEPENED MOISTURE CHANNEL
BETWEEN THE WEST/SOUTHWEST U.S. UPPER TROUGH AND EAST/SOUTHEAST
U.S. WARMING UPPER RIDGE. THE MULTI-DAY THREAT WILL LIKELY CONTINUE
INTO EARLY NEXT WEEK WHILE SPREADING NORTHEASTWARD OVER THE
MIDWEST IN THIS PATTERN WITH THE DEEP MOISTURE LEADING TO SOME WARM
SECTOR RECORD HIGH OVERNIGHT TEMPERATURES.
PRECIPITATION WITH PACIFIC SYSTEM DIGGING WILL BE LOCALLY ENHANCED
BY TERRAIN AS MODERATE LONG-FETCH MOISTURE IS FORECAST TO WORK
SOUTHWARD OVER THE WEST COAST THIS WEEKEND, WITH HIGH-ELEVATION
SNOW ALSO REACHING FAVORED TERRAIN OF THE NORTHERN INTERMOUNTAIN
WEST/ROCKIES AND ENHANCED RAINS REACHING DOWN INTO CALIFORNIA.
REGARDLESS, THE COLD FRONTAL SURGE AND POSSIBLE CLOSED LOW
DEVELOPMENT AT THE SOUTHERN BASE OF THE MAIN UPPER TROUGH WILL
BRING IN COOLER TEMPERATURES TO MUCH OF THE WEST. THIS AND SLOW AND
AMPLIFIED FLOW TRANSLATION WILL ALSO ACT TO SPREAD MORE MODEST
RAINS OVER THE SOUTHWEST AND INTO THE SOUTH-CENTRAL GREAT BASIN AND
ROCKIES INTO EARLY NEXT WEEK. MEANWHILE, ADITIONAL PACIFIC SYSTEM
ENERGY UPSTREAM MAY ALSO BRING ANOTHER ROUND OF MODERATE
PRECIPITATION BACK INTO THE NORTHWEST.
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 FORECAST (QPF), EXCESSIVE RAINFALL
OUTLOOK (ERO), WINTER WEATHER OUTLOOK (WWO) PROBABILITIES, HEAT
INDICES, AND KEY MESSAGES CAN BE ACCESSED FROM:
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
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW
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