084  
FXUS02 KWBC 261902  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
302 PM EDT FRI AUG 26 2022  
 
VALID 12Z MON AUG 29 2022 - 12Z FRI SEP 02 2022  
   
..OVERVIEW
 
 
THE UPPER-LEVEL PATTERN OVER THE CONUS IS FORECAST TO AMPLIFY NEXT  
WEEK, AFTER FAIRLY FLAT/ZONAL FLOW WITH EMBEDDED SHORTWAVES  
DOMINATE THE SHORT RANGE PERIOD. TROUGHING WILL DIG OVER THE  
EASTERN PACIFIC, POTENTIALLY REACHING THE NORTHWEST BY LATE NEXT  
WEEK, WHILE RIDGING AMPLIFIES OVER THE INTERIOR WEST AND THE  
CENTRAL U.S. AS ANOTHER POTENT TROUGH PUSHES FROM THE  
NORTH-CENTRAL TO NORTHEASTERN U.S. DURING THE PERIOD. A REASONABLY  
STRONG AND PROGRESSIVE COLD FRONT AHEAD OF THE LATTER TROUGH WILL  
PROVIDE A FOCUS FOR RAIN AND THUNDERSTORMS FOR THE EASTERN HALF OF  
THE U.S. AS IT TRACKS SOUTHEASTWARD, WITH COOLING TEMPERATURES  
BEHIND IT AS A SURFACE HIGH SETTLES IN. THE WEST IS LIKELY TO  
REMAIN RELATIVELY DRY NEXT WEEK, WITH WARM TO HOT TEMPERATURES  
UNDERNEATH THE UPPER RIDGE.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
FORTUNATELY MODEL GUIDANCE HAS SETTLED ON BETTER AGREEMENT FOR THE  
TRACK OF THE INITIAL SHORTWAVE IN THE NORTHERN PLAINS MONDAY AND  
AS IT PROGRESSES EASTWARD AND COMBINES WITH ADDITIONAL ENERGY TO  
PRODUCE A TROUGH AXIS SHIFTING THROUGH THE GREAT LAKES REGION WITH  
TIME, COMPARED TO A DAY OR TWO AGO. THE UPDATED WPC FORECAST FOR  
THE EARLY PART OF NEXT WEEK ENDED UP WITH A SLIGHTLY FASTER TRACK  
OF THE TROUGH AND THUS THE COLD FRONT POSITION OVER THE LOWER 48  
COMPARED TO THE PREVIOUS FORECAST, WHICH ALSO LOWERED QPF TOTALS  
IN THE CENTRAL U.S. SLIGHTLY. UTILIZED A BLEND OF THE  
DETERMINISTIC 00Z ECMWF/CMC/UKMET AND 06Z GFS IN THE FORECAST  
GIVEN THE REASONABLY GOOD MODEL AGREEMENT. BY WEDNESDAY-FRIDAY, A  
HANDFUL OF MODEL RUNS OVER THE LAST COUPLE OF DAYS HAVE BEEN  
SHOWING THE POSSIBILITY OF ENERGY TO SPLIT OFF INTO A SEPARATE  
UPPER LOW AND DRIFT SOMEWHERE OVER THE SOUTH-CENTRAL OR  
SOUTHEASTERN CONUS, INCLUDING THE 00Z CMC. THIS STILL SEEMS LIKE A  
LOWER PROBABILITY SOLUTION, SO REDUCED/ELIMINATED THE CMC FROM THE  
WPC FORECAST WITH TIME, IN FAVOR OF THE EC AND GEFS ENSEMBLE  
MEANS. THE PROPORTION OF THE MEANS VS. DETERMINISTIC MODELS (06Z  
GFS AND 00Z EC) WAS RIGHT AT HALF BY DAY 7. PREFERRED THE 06Z GFS  
OVER THE 00Z GIVEN THE 00Z WAS FASTER THAN CONSENSUS WITH THE  
EASTERN TROUGH LIFTING AWAY FROM THE NORTHEASTERN CONUS. THIS  
BLEND ALSO WORKED WELL FOR THE AGREEABLE RIDGE TO THE WEST AND THE  
TROUGH IN THE EASTERN PACIFIC EDGING TOWARD THE PACIFIC NORTHWEST,  
THOUGH IT IS LIKELY THAT THE DETAILS OF THE TIMING OF THE EASTERN  
EDGE OF THE TROUGH AND ASSOCIATED COLD FRONTS MAY VARY WITH TIME.  
THE NEWER 12Z GUIDANCE APPEARS GENERALLY IN LINE WITH THE PREVIOUS  
CYCLE, WITH NO DETERMINISTIC GUIDANCE SHOWING THE ROGUE SOUTHERN  
TIER UPPER LOW AS AGGRESSIVELY.  
 
   
..WEATHER/HAZARDS HIGHLIGHTS
 
 
A COLD FRONT AHEAD OF THE CENTRAL-EASTERN U.S. TROUGH WILL BE A  
PRIMARY FEATURE TO WATCH THROUGH NEXT WEEK WEATHER-WISE. MOISTURE  
POOLING ALONG AND AHEAD OF THE FRONT MAY LEAD TO POCKETS OF  
MODERATE TO LOCALLY HEAVY RAINFALL AT TIMES NEXT WEEK AS IT  
ADVANCES SOUTHEASTWARD FROM THE CENTRAL U.S. INTO THE EASTERN  
SEABOARD AND GULF COAST. SOUTH-CENTRAL PARTS OF THE PLAINS AND  
MISSISSIPPI VALLEY MAY BE ONE  
AREA OF FOCUS FOR HIGHER RAINFALL POTENTIAL AS INTERACTION WITH  
GULF MOISTURE MAY BOOST RAINFALL INTENSITY AND AMOUNTS, WHILE THE  
NORTHEAST HAS SEEN FORECAST RAIN TOTALS INCREASE AROUND  
WEDNESDAY-THURSDAY. THE WEST SHOULD GENERALLY STAY DRY UNTIL SOME  
SHOWERS MAY INCREASE FOR THE SOUTHERN/CENTRAL ROCKIES AND HIGH  
PLAINS, AND EVENTUALLY IN THE PACIFIC NORTHWEST DEPENDING ON COLD  
FRONTAL AND UPPER TROUGH POSITIONS.  
 
AHEAD OF THE FRONT, TEMPERATURES ARE LIKELY TO BE 5-15F ABOVE  
NORMAL FOR HIGHS IN THE NORTHEASTERN QUADRANT OF THE U.S., BUT  
TEMPERATURES SHOULD SWITCH TO BELOW NORMAL BEHIND THE FRONT FOR  
THE UPPER MIDWEST INTO THE GREAT LAKES AND OHIO VALLEY AS A COOL  
SURFACE HIGH SETTLES IN. THE SOUTHERN PLAINS MAY ALSO SEE  
TEMPERATURES A FEW DEGREES BELOW AVERAGE WITH THE RAIN AND  
CLOUDINESS POTENTIAL. MEANWHILE, RIDGING IN THE WEST AND A GRADUAL  
SHIFT EASTWARD WITH TIME WILL LEAD TO WARMER THAN AVERAGE  
TEMPERATURES FOR MUCH OF THE WEST, WITH THE HIGHEST ANOMALIES OF  
10-20F ABOVE NORMAL OCCURRING IN THE NORTHWEST AND NORTHERN HIGH  
PLAINS, BEFORE A COOLING TREND FOR THE PACIFIC NORTHWEST LATE NEXT  
WEEK WITH THE APPROACHING TROUGH. DAILY HIGH TEMPERATURE RECORDS  
FOR HIGHS AND WARM LOWS COULD BE CHALLENGED.  
 
TATE  
 
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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