745  
FXUS02 KWBC 111847  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
246 PM EDT THU AUG 11 2022  
 
VALID 12Z SUN AUG 14 2022 - 12Z THU AUG 18 2022  
 
...MONSOONAL MOISTURE/RAINFALL THREAT CONTINUES FOR THE SOUTHWEST  
AND INTERMOUNTAIN WEST/ROCKIES...  
 
...EXCESSIVE HEAT THREAT ACROSS THE PLAINS, WITH WARMING  
TEMPERATURES IN THE NORTHWEST NEXT WEEK...  
 
   
..OVERVIEW
 
 
THE MEDIUM RANGE PERIOD WILL BEGIN SUNDAY WITH A CONTINUED  
TROUGH-RIDGE-TROUGH PATTERN ACROSS THE LOWER 48. AS NEXT WEEK  
PROGRESSES, THERE SHOULD BE A TREND TOWARD THE UPPER HIGH/RIDGE  
EXPANDING INTO THE WEST, LEADING TO WELL ABOVE AVERAGE  
TEMPERATURES IN THE NORTHWEST. THE RIDGE ALOFT WITH EMBEDDED  
SHORTWAVE ENERGY WILL ALSO CONTINUE TO SUPPORT MONSOONAL MOISTURE  
STREAMING INTO THE SOUTHWEST, INTERMOUNTAIN WEST, AND ROCKIES  
THROUGH THE WEEK, WITH RAIN EVENTUALLY SPREADING INTO PORTIONS OF  
THE PLAINS AND MISSISSIPPI VALLEY. MEANWHILE THE TROUGH ACROSS THE  
EAST MAY DEEPEN AND CLOSE OFF AN UPPER LOW AROUND MIDWEEK, WHICH  
COULD CAUSE MULTIPLE DAYS OF RAINFALL IN THE NORTHEAST, BUT  
DEPENDENT ON THE POSITION OF THE UPPER LOW AND THE ASSOCIATED  
SURFACE LOW/FRONTS, WHICH REMAIN UNCERTAIN AT THIS POINT.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
THERE WAS A BIT MORE UNCERTAINTY WITH THE SYNOPTIC PATTERN  
COMPARED TO YESTERDAY, PARTICULARLY WITH RESPECT TO THE EASTERN  
U.S. TROUGH. THE TROUGH-RIDGE-TROUGH PATTERN WAS CAPTURED WELL BY  
THE LATEST GUIDANCE, THOUGH. A GENERAL MODEL BLEND OF THE 00Z  
EC/UK/CMC AND 06Z GFS WAS UTILIZED ON DAYS 3 AND 4 WITH THE 00Z EC  
BEING FAVORED THROUGH DAY 5 DUE TO A MORE CONSISTENT SIGNAL AND  
REASONABLE APPROACH TO THE SOUTHERN RIDGE AND EASTERN TROUGH.  
MODELS, INCLUDING THE LATEST 13Z NBM, HAVE TRENDED DRYER SINCE  
OVERNIGHT WITH RESPECT TO THE QPF PRODUCED BY THE EASTERN TROUGH  
OVER PARTS OF THE COASTAL NORTHEAST ON DAYS 4-6. THE 00Z ECE/CMCE  
WERE INCORPORATED INTO THE GMB ON DAY 5 TO SMOOTH OUT SMALL SCALE  
DISCREPANCIES FOUND IN THE WESTERN RIDGE AXIS. THE ENSEMBLES WERE  
FAVORED THROUGH THE REST OF THE PERIOD.  
 
   
..WEATHER/HAZARDS HIGHLIGHTS
 
 
PARTS OF THE WEST HAVE SEEN PERSISTENT MONSOONAL MOISTURE OVER THE  
PAST COUPLE OF MONTHS, AND NEXT WEEK WILL CONTINUE THAT PATTERN AS  
ANOMALOUSLY HIGH MOISTURE STREAMS INTO THE SOUTHWEST, GREAT BASIN,  
AND ROCKIES IN CONJUNCTION WITH SMALL-SCALE SHORTWAVE ENERGY TO  
PRODUCE RAIN AND THUNDERSTORMS, PARTICULARLY IN THE AFTERNOON AND  
EVENING HOURS. SLIGHT RISKS OF EXCESSIVE RAINFALL ARE IN PLACE FOR  
PORTIONS OF THE DESERT SOUTHWEST ON SUNDAY AND THE CENTRAL ROCKIES  
ON MONDAY, WHERE CURRENT FORECASTS SHOW THE BEST CHANCES FOR HEAVY  
RAINFALL. HEAVY RAIN AMOUNTS LOOK TO CONTINUE THROUGH MIDWEEK IN  
THE CENTRAL ROCKIES. THERE ARE INCREASING CHANCES FOR RAINFALL TO  
SPREAD INTO PARTS OF THE CENTRAL/SOUTHERN PLAINS AND MISSISSIPPI  
VALLEY AS THE WEEK PROGRESSES. ELSEWHERE, THE GULF COAST AND INTO  
FLORIDA COULD SEE SCATTERED STORMS WITH A MOIST AIRMASS AND A  
COUPLE OF FRONTAL BOUNDARIES. THEN AS A SURFACE LOW IS CURRENTLY  
FORECAST TO TRACK ACROSS THE OHIO VALLEY THROUGH THE MID-ATLANTIC  
TOWARD THE NORTHEAST, RAIN IS FORECAST FOR THOSE AREAS. THERE'S  
INCREASING CONFIDENCE IN A MULTI-DAY RAIN EVENT OCCURRING FOR MUCH  
OF THE COASTAL NORTHEAST, FROM NEW JERSEY UP TO MAINE THROUGH  
MID-WEEK.  
 
VERY WARM TO HOT TEMPERATURES AROUND 10-15F ABOVE AVERAGE, THOUGH  
MAINLY NOT TO RECORD-BREAKING LEVELS, ARE FORECAST ACROSS THE  
CENTRAL PLAINS SUNDAY INTO MONDAY, WITH A GRADUALLY MODERATING  
TREND TUESDAY ONWARD YIELDING BELOW NORMAL HIGHS. AS THE UPPER  
RIDGE EXPANDS INTO THE NORTHWEST, THIS WILL WARM UP TEMPERATURES  
THERE AND CAUSE HIGHS 10-20F ABOVE NORMAL FOR TUESDAY-THURSDAY.  
MEANWHILE, BELOW NORMAL HIGHS ARE EXPECTED IN THE EAST-CENTRAL  
U.S. BEHIND THE COLD FRONT, WITH THE MOST PERSISTENT COOLER THAN  
AVERAGE WEATHER IN THE OHIO AND TENNESSEE VALLEYS TOWARD THE  
MID-ATLANTIC. GIVEN THE RAINFALL AND CLOUDINESS OVER THE SOUTHWEST  
AND GREAT BASIN INTO THE ROCKIES, HIGHS ARE LIKELY TO BE SEVERAL  
DEGREES BELOW NORMAL THERE THROUGH MUCH OF NEXT WEEK.  
 
KEBEDE/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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