810  
FXUS02 KWBC 080700  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 AM EDT MON AUG 08 2022  
 
VALID 12Z THU AUG 11 2022 - 12Z MON AUG 15 2022  
 
...MONSOONAL MOISTURE/RAINFALL THREAT CONTINUES FOR THE SOUTHWEST  
AND INTERMOUNTAIN WEST/ROCKIES THIS WEEK, WITH SOME LOCALIZED  
HEAVY RAIN POSSIBLE FOR THE GULF COAST STATES AS WELL...  
 
   
..OVERVIEW
 
 
A FAIRLY STAGNANT TROUGH-RIDGE-TROUGH PATTERN IS FORECAST LATER  
THIS WEEK INTO EARLY NEXT WEEK ACROSS THE CONTIGUOUS U.S., AS  
SHORTWAVES COMBINE TO DEEPEN A TROUGH IN THE EAST, AN UPPER LOW  
OFF THE WEST COAST LIFTS NORTHEASTWARD INTO BRITISH COLUMBIA, AND  
AN UPPER HIGH MEANDERS NEAR THE CENTRAL/SOUTHERN HIGH PLAINS. A  
COLD FRONT OR TWO STALLING AND APPROACHING THE GULF COAST WILL  
PROVIDE A FOCUS FOR MOISTURE AND RAIN/THUNDERSTORMS THERE AND  
LINGERING ACROSS MUCH OF FLORIDA INTO EARLY NEXT WEEK. MEANWHILE,  
PERSISTENT MONSOONAL MOISTURE LOOKS TO CONTINUE ACROSS THE  
SOUTHWEST AND EXPANDING INTO THE INTERMOUNTAIN WEST AND ROCKIES  
THIS WEEK.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
MODEL GUIDANCE HAS STABILIZED FOR THE MOST PART WITH THE TIMING OF  
THE EASTERN PACIFIC UPPER LOW COMING INTO SOUTHWESTERN CANADA,  
OPENING INTO A SHORTWAVE, AND MOVING EASTWARD THROUGH  
SOUTH-CENTRAL CANADA EARLY NEXT WEEK, WITH A GENERALLY SLOWER  
TRACK THAN SOME MODELS SHOWED A DAY OR SO AGO. THE 18Z GFS WAS  
SOMEWHAT FASTER THAN CONSENSUS, SO PREFERRED A BLEND INCORPORATING  
THE 12Z GFS AND OTHER 12Z GUIDANCE FOR THIS FEATURE. THE UPPER  
HIGH IN THE CENTRAL U.S. APPEARS WELL HANDLED IN THE MODELS,  
THOUGH WITH SOME UNCERTAINTY ON HOW MUCH IT COULD BE SUPPRESSED BY  
ENERGY ROUNDING THE RIDGE. THE 12Z CMC IN PARTICULAR SUPPRESSED  
THE RIDGE MORE THAN OTHER MODELS IN THE MIDWEST. MEANWHILE FARTHER  
EAST, MODELS AGREE UPON DEEPENING TROUGHING LATE THIS WEEK. BUT  
THERE ARE SOME DIFFERENCES WITH DISTRIBUTION OF ENERGY WITHIN THE  
TROUGH AND POTENTIAL FOR A CLOSED LOW AT TIMES AS SHOWN BY SOME  
DETERMINISTIC GUIDANCE LIKE THE ECMWF AND GFS. NO MODELS FROM THE  
12/18Z CYCLE SEEMED TO BE PARTICULAR OUTLIERS IN THE EAST, HOWEVER.  
 
GIVEN THE FAIRLY GOOD AGREEMENT IN THE OVERALL PATTERN, BUT WITH  
VARIOUS DETAILS STILL UP IN THE AIR (LITERALLY), THE MEDIUM RANGE  
FORECAST USED A BLEND OF THE 12/18Z DETERMINISTIC MODELS EARLY AND  
THEN INCORPORATED THE GEFS AND EC ENSEMBLE MEANS WITH GRADUALLY  
INCREASING PROPORTIONS TO ABOUT 50 PERCENT BY DAY 7 FOR THE WPC  
MASS FIELDS. ONCE AGAIN QPF WAS INCREASED OVER THE ALMOST ZERO NBM  
VALUES ACROSS THE MIDWEST FRIDAY INTO THE WEEKEND AS FRONTAL  
BOUNDARIES COME IN WEST OF THE HIGH AND MODELS SHOW POTENTIAL FOR  
RAIN.  
 
   
..WEATHER/HAZARDS HIGHLIGHTS
 
 
MOISTURE STREAMING AHEAD OF A COUPLE OF COLD FRONTS MOVING INTO  
THE SOUTHEAST AND TOWARD THE GULF COAST LATE THIS WEEK WILL  
PRODUCE RAIN AND THUNDERSTORMS IN THOSE AREAS, WHICH COULD PRODUCE  
LOCALLY HEAVY RAIN ESPECIALLY ALONG THE COAST. RAIN AMOUNTS WILL  
BE DEPENDENT ON HOW MUCH MOISTURE PROGRESSES ONSHORE, BUT WITH THE  
POTENTIAL FOR SLOW-MOVING STORMS, THE CHANCE OF FLOODING IS  
NONZERO. RAIN CHANCES ARE LIKELY TO CONTINUE ACROSS MUCH OF  
FLORIDA INTO THE WEEKEND AS THE FRONT STALLS. FARTHER NORTH, THE  
COLD FRONT SHOULD CLEAR OUT MOST RAINFALL FROM THE MID-ATLANTIC  
BUT SOME RAIN COULD REMAIN ACROSS THE NORTHEAST AS A LOW ALONG THE  
FRONT MAY LINGER NEARBY. MEANWHILE, MONSOONAL MOISTURE (THAT COULD  
BE ENHANCED DUE TO T.S. HOWARD) CONTINUES TO IMPACT THE SOUTHWEST  
INTO PARTS OF THE GREAT BASIN AND INTO THE ROCKIES WITH RAINFALL,  
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 DRIFTS THAT DIRECTION.  
HIGHS NEARING 100F ARE FORECAST EARLY NEXT WEEK IN THE  
CENTRAL/SOUTHERN PLAINS. FARTHER EAST, BELOW NORMAL HIGHS ARE  
POSSIBLE IN THE EAST-CENTRAL U.S. BEHIND THE COLD FRONT, WITH THE  
MOST PERSISTENT COOLER THAN AVERAGE WEATHER IN THE OHIO AND  
TENNESSEE VALLEYS. GIVEN THE RAINFALL AND CLOUDINESS OVER THE  
SOUTHWEST AND GREAT BASIN, HIGHS ARE LIKELY TO BE SEVERAL DEGREES  
BELOW NORMAL THERE THROUGH EARLY NEXT WEEK.  
 
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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