084  
FXUS02 KWBC 230712  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
312 AM 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 MODEL GUIDANCE FROM THE 18 UTC GFS AND 12  
UTC ECMWF/UKMET WEDNESDAY-FRIDAY, ALONG WITH INPUT FROM THE  
COMPATIBLE 01 UTC NATIONAL BLEND OF MODELS (NBM). LATEST 00 UTC  
GUIDANCE REMAINS IN LINE AND THIS SOLUITON SEEMS SUPPORTED BY  
GEFS/ECMWF ENSEMBLE MEANS AND WPC PRODUCT CONTINUITY. OPTED TO  
COMPOSE A LONGER RANGE SOLUTION CLOSEST TO THE 12 UTC GEFS MEAN  
AND ESPECIALLY THE MORE STREAM SEPARATED 12 UTC ECMWF ENSEMBLE  
MEAN NEXT WEEKEND GIVEN GROWING UNCERTAINTIES. ENSEMBLE MEAN USAGE  
WAS PART OF AN EFFORT TO MITIGATE GROWING INDIVIDUAL SYSTEM TIMING  
AND STRENGTH DIFFERENCES AT THESE LONGER TIME FRAMES, BUT  
INJECTION OF SOME INPUT FROM THE 12 UTC GFS/ECMWF ADDED IN  
PARTICULAR MORE SYSTEM DEFINITION AND WEATHER FOCUS CONSISTENT  
WITH ONGOING SEPARATED STREAM FLOW HISTORY. THE MAIN TARGETED  
CHANGE TO 01 UTC NBM QPF ACROSS THE FORECAST DOMAIN AND TIME  
SCALES WAS TO LESSEN NBM RUN TO RUN CONTINUITY VARIANCE BY  
INCORPORATING SOME WPC PRODUCT CONTINUITY.  
   
..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. TIMING  
AND AMPLITUDE ISSUES REMAIN IN THE GUIDANCE, BUT FORECAST SPREAD  
HAS STEADILY DECREASED OVER THE PAST FEW DAYS TO AFFORD A BLENDED  
GFS/ECMWF/UKMET MODEL FOREAST APPROACH. RECENT CANADIAN RUNS HAVE  
SEEMED A BIT TOO QUICK TO LIFT THE SYSTEM NORTH GIVEN INITIAL  
CLOSED SYSTEM NATURE. THE PATTERN MAY FOCUS 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 PATTTERN, 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 ESPECIALLY THURSDAY. 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.  
 
MEAWHILE, THE DOWNTREAM EJECTION OF A MAIN AND POSSIBLY  
CLOSED/WELL SEPARATED SOUTHERN STREAM SYSTEM IN THIS ACTIVE  
PATTERN REMAINS SLATED TO AGAIN MAINLY 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, SUGGESTING PRUDENCE WITH RAINFALL AMOUNTS  
AT THIS JUNCTURE DESPITE HIGHER POTENTIAL.  
 
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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