865  
FXUS02 KWBC 071707  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
106 PM EDT SUN AUG 07 2022  
 
VALID 12Z WED AUG 10 2022 - 12Z SUN AUG 14 2022  
 
...HEAVY RAINFALL/FLASH FLOODING THREAT FOR THE OHIO/TENNESSEE AND  
LOWER MISSISSIPPI VALLEYS AND SOUTH-CENTRAL APPALACHIANS...  
 
...MONSOONAL MOISTURE/RAINFALL THREAT CONTINUES FOR THE SOUTHWEST  
AND SOUTH-CENTRAL GREAT BASIN/ROCKIES THIS WEEK...  
 
   
..OVERVIEW
 
 
IT REMAINS THE CASE THAT THE OVERALL WEATHER PATTERN ACROSS THE  
CONTIGUOUS U.S. THROUGH THE LATTER HALF OF THIS WEEK IS FORECAST  
TO AMPLIFY INTO A TROUGH-RIDGE-TROUGH PATTERN, AS SHORTWAVES  
COMBINE TO DEEPEN A TROUGH IN THE EAST, AN UPPER LOW OFF THE WEST  
COAST LIFTS NORTHEASTWARD TOWARD THE PACIFIC NORTHWEST, 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 INTO THE APPALACHIANS/MID-ATLANTIC AND NORTHEAST  
WEDNESDAY, WITH SCATTERED CONVECTION POSSIBLE FARTHER SOUTH AS  
WELL. MEANWHILE, PERSISTENT MONSOONAL MOISTURE LOOKS TO CONTINUE  
ACROSS THE SOUTHWEST AND SOUTH-CENTRAL GREAT BASIN/ROCKIES THIS  
WEEK.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
MODEL GUIDANCE REMAINS QUITE AGREEABLE WITH THE UPPER HIGH/RIDGE  
PERSISTING AND MEANDERING A BIT ACROSS THE CENTRAL U.S. THROUGH  
THE WEEK INTO NEXT WEEKEND, AND ALSO AGREES UPON THE TROUGH  
DEEPENING ACROSS THE EAST LATE WEEK, WITH DETAIL DIFFERENCES  
DECREASED FROM PAST RUNS OEVR MEDIUM RANGE TIME SCALES. THIS  
BOLSTERS PATTERN FORECAST CONFIDENCE.  
 
THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A  
COMPOSITE BLEND OF NOW OVERALL WELL CLUSTERED GUDIANCE FROM THE  
LATEST GFS/ECMWF/UKMET/CANADIAN AND GEFS/ECMWF ENSEMBLES ALONG  
WITH THE 13 UTC NATIONAL BLEND OF MODELS AND WPC PRODUCT  
CONTINUITY. TARGETED CHANGES TO THE 13 UTC NBM  
QPF INCLUDED SOME INCREASE OF AFTERNOON/EVENING CONVECTIVE AMOUNTS  
OVER THE WEST BUT IN PARTICULAR ACROSS THE CENTRAL GULF OF MEXICO  
COAST MID-LATER THIS WEEK AND WITH FRONTAL PASSAGE ACROSS THE  
UPPER MIDWEST/GREAT LAKES NEXT WEEKEND.  
   
..WEATHER/HAZARDS HIGHLIGHTS
 
 
AS THE MEDIUM RANGE PERIOD BEGINS 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 MOVEMENT 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, AS  
THEY HAVE RECEIVED ABUNDANT RAINFALL RECENTLY AND ARE SENSITIVE TO  
ADDITIONAL RAIN AMOUNTS, SO A SLIGHT RISK REMAINS IN THE  
EXPERIMENTAL DAY 4 ERO. THE NORTHEAST/NEW ENGLAND ALSO MAY RECEIVE  
HEAVY RAIN THAT COULD CAUSE FLASH FLOODING GIVEN A SHARPENING  
TROUGH ALOFT PROVIDING UPPER LEVEL SUPPORT AND ABOVE AVERAGE  
MOISTURE, BUT MODEL SPREAD IN THE EXACT PLACEMENT OF THE HEAVIEST  
RAINFALL PRECLUDED ADDING A SLIGHT RISK. 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. IN THIS PATTERN THERE IS ALSO INCREASED POTENTIAL FOR  
LOCALLY ENHANCED LEAD RAINS ACROSS THE LOWER MS VALLEY/CENTRAL  
GULF COAST MID-LATE WEEK WITH MOIST FLOW AND SLOW CELL  
TRANSLATION. MEANWHILE, MONSOONAL MOISTURE (THAT COULD BE ENHANCED  
DUE TO T.D. NINE-E) CONTINUES TO IMPACT THE SOUTHWEST WITH  
RAINFALL, WITH A TREND TOWARD INCREASING CHANCES FOR RAIN FARTHER  
NORTH AS THE MOISTURE PLUME EXPANDS INTO THE INTERMOUNTAIN  
WEST/GREAT BASIN AND THE ROCKIES, WITH SOME LOCALLY HEAVY TOTALS  
POSSIBLE.  
 
VERY WARM TO HOT TEMPERATURES AROUND 10-15F ABOVE AVERAGE, THOUGH  
NOT QUITE TO RECORD-BREAKING LEVELS, ARE FORECAST ACROSS THE  
NORTHERN/CENTRAL PLAINS THROUGH THE LATTER PART OF THE WEEK, WITH  
A SLIGHT EASTWARD TREND AS THE UPPER HIGH MOVES THAT DIRECTION.  
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 NEXT WEEKEND.  
 
TATE/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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