350  
FXUS02 KWBC 061901  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 PM EDT SAT AUG 06 2022  
 
VALID 12Z TUE AUG 09 2022 - 12Z SAT AUG 13 2022  
 
...POTENTIALLY HEAVY RAINFALL AND FLASH FLOODING ARE POSSIBLE IN  
THE OHIO/TENNESSEE VALLEYS TUESDAY-WEDNESDAY WHILE MONSOONAL  
MOISTURE CONTINUES IN THE WEST...  
 
   
..OVERVIEW
 
 
THE OVERALL WEATHER PATTERN ACROSS THE CONTIGUOUS U.S. NEXT WEEK  
IS FORECAST TO AMPLIFY INTO A TROUGH-RIDGE-TROUGH PATTERN, AS  
SHORTWAVES COMBINE TO DEEPEN A TROUGH IN THE EAST, A SLOW-MOVING  
UPPER LOW OFF THE WEST COAST LIFTS NORTHEASTWARD INTO THE PACIFIC  
NORTHWEST AROUND WEDNESDAY-THURSDAY, AND AN UPPER HIGH NUDGES  
EASTWARD FROM THE CENTRAL ROCKIES INTO THE CENTRAL/SOUTHERN  
PLAINS. MOISTURE LIFTED AHEAD OF THE EASTERN TROUGH AND  
ASSOCIATED COLD FRONT WILL LIKELY LEAD TO AREAS OF HEAVY RAIN AND  
THUNDERSTORMS MAINLY ACROSS THE OHIO AND TENNESSEE VALLEYS  
TUESDAY-WEDNESDAY WITH SCATTERED CONVECTION SPREADING INTO THE  
EASTERN SEABOARD AS WELL. MEANWHILE, PERSISTENT MONSOONAL  
MOISTURE LOOKS TO CONTINUE ACROSS PORTIONS OF THE WEST, LEADING TO  
ADDITIONAL RAINFALL WITH A GRADUAL NORTHWARD EXPANSION OF THE RAIN  
TOWARD THE NORTHERN ROCKIES AS THE WEEK PROGRESSES.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
ENSEMBLE MEANS FROM THE GEFS, ECMWF, AND CMC CONTINUE TO SHOW GOOD  
AGREEMENT WITH ONE ANOTHER WITH RESPECT TO THE AFOREMENTIONED  
SYNOPTIC SCALE EVOLUTION FOR NEXT WEEK. THE LARGEST MODEL SPREAD  
CONTINUES TO BE LOCATED FROM OFF THE WEST COAST TO THE PACIFIC  
NORTHWEST WHERE AN UPPER LOW IS FORECAST TO TRACK THROUGH.  
ENSEMBLE MEANS HAVE GENERALLY SLOWED DOWN THE LOW TRACK SLIGHTLY  
IN THE PAST FEW RUNS WHILE THE FAST DETERMINISTIC SOLUTIONS FROM  
THE ECMWF AND GFS HAVE SLOWED DOWN CONSIDERABLY TO BETTER AGREE  
WITH THEIR RESPECTIVE ENSEMBLE MEAN POSITIONS. ON THE OTHER HAND,  
THE CMC'S FORECAST POSITIONS OF THE UPPER LOW IS SLIGHTLY SLOWER  
THAN ITS ENSEMBLE MEAN. MEANWHILE, MODEL SPREAD REMAINS MODEST  
WITH THE EVOLUTION OF THE EAST COAST TROUGH LATE NEXT WEEK. NEAR  
THE GULF COAST, THE GFS WAS MOST ENTHUSIASTIC WITH A TROPICAL LOW  
BRINGING TROPICAL MOISTURE ONSHORE TOWARD THE LATTER PART OF NEXT  
WEEK.  
 
THE WPC MEDIUM-RANGE FORECAST PACKAGE WAS BASED ON, 40% FROM THE  
00Z ECMWF/00Z MEAN, 40% FROM THE 06Z GFS/GEFS, AND 20% FROM THE  
00Z CMC/CMC MEAN, TRANSITIONING TO MOSTLY A CONSENSUS OF THE  
ENSEMBLE MEANS BY DAY 7, AND CONSENSUS WITH THE NBM. THE RESULTS  
SHOW GOOD CONTINUITY WITH THE PREVIOUS FORECAST PACKAGE.  
 
   
..WEATHER/HAZARDS HIGHLIGHTS
 
 
FOR THE EARLY PART OF THE MEDIUM RANGE PERIOD TUESDAY-WEDNESDAY,  
AN AXIS OF LOCALLY HEAVY RAIN AND THUNDERSTORMS AHEAD OF A COLD  
FRONT IS EXPECTED TO CONTINUE PUSHING SOUTHEASTWARD ACROSS THE  
OHIO VALLEY TO NORTHEAST INTO THE TENNESSEE VALLEY AND  
MID-ATLANTIC REGION. THE RELATIVELY SLOW PUSH OF THE FRONT COULD  
LEAD TO TRAINING STORMS THAT COULD CAUSE FLASH FLOODING. FLOODING  
CONCERNS ARE PARTICULARLY ENHANCED ACROSS PORTIONS OF  
KENTUCKY/TENNESSEE/WEST VIRGINIA ON WEDNESDAY, AS THEY HAVE  
RECEIVED ABUNDANT RAINFALL RECENTLY AND ARE SENSITIVE TO  
ADDITIONAL RAIN AMOUNTS. THE FRONT CONTINUING TO PUSH  
SOUTHEASTWARD INTO THE LATTER HALF OF THE WEEK SHOULD CLEAR  
RAINFALL OUT OF THE NORTHEASTERN QUADRANT OF THE COUNTRY, BUT  
SCATTERED CONVECTIVE ACTIVITY IS FORECAST TO CONTINUE IN THE  
SOUTHEAST. MEANWHILE, MONSOONAL MOISTURE CONTINUES TO IMPACT THE  
SOUTHWEST WITH ENHANCED RAINFALL, WITH A TREND TOWARD GRADUALLY  
LESS RAINFALL IN AREAS LIKE NEW MEXICO BUT INCREASING CHANCES FOR  
RAIN FARTHER NORTH AS THE MOISTURE PLUME EXPANDS INTO THE  
INTERMOUNTAIN WEST AND GREAT BASIN, WITH SOME LOCALLY HEAVY TOTALS  
POSSIBLE HERE AS WELL.  
 
VERY WARM TO HOT TEMPERATURES AROUND 10-15F ABOVE AVERAGE, THOUGH  
NOT QUITE TO RECORD-BREAKING LEVELS, ARE FORECAST TO SHIFT FROM  
THE NORTHWEST TUESDAY INTO THE NORTHERN AND THEN CENTRAL PLAINS AS  
THE WORKWEEK PROGRESSES WITH THE EASTWARD NUDGE OF THE UPPER HIGH.  
FARTHER EAST, SLIGHTLY BELOW NORMAL HIGHS ARE POSSIBLE IN THE OHIO  
AND TENNESSEE VALLEYS BEHIND THE COLD FRONT, WHILE TEMPERATURES  
ALONG THE EASTERN SEABOARD WILL FLIP FROM SLIGHTLY ABOVE TO  
SLIGHTLY BELOW AVERAGE. GIVEN THE RAINFALL AND CLOUDINESS OVER THE  
SOUTHWEST AND GREAT BASIN, HIGHS ARE LIKELY TO BE SEVERAL DEGREES  
BELOW NORMAL THERE THROUGH LATE WEEK.  
 
KONG/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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