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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