413  
FXUS02 KWBC 040700  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
259 AM EDT THU AUG 4 2022  
 
VALID 12Z SUN AUG 7 2022 - 12Z THU AUG 11 2022  
 
***MONSOONAL PATTERN REMAINS ACTIVE ACROSS THE SOUTHWEST WITH  
ADDITIONAL HEAVY RAINFALL EXPECTED***  
 
   
..GENERAL OVERVIEW
 
 
THE CORE OF THE WESTERLIES ALOFT WILL BE OVER SOUTHERN CANADA,  
WITH A TROUGH AND COLD FRONT CROSSING THE NORTHERN PLAINS AND  
GREAT LAKES REGION BY EARLY NEXT WEEK. THE CORE OF THE UPPER  
RIDGE IS EXPECTED TO RETROGRADE WESTWARD AND BECOME ESTABLISHED  
OVER THE INTERMOUNTAIN WEST BY MONDAY, AND LIKELY PERSISTING THERE  
THROUGH NEXT THURSDAY. MEANWHILE, A BROAD UPPER LEVEL TROUGH IS  
EXPECTED ACROSS THE NORTHEASTERN QUADRANT OF THE NATION AS THE  
UPPER LEVEL PATTERN BECOMES A BIT MORE AMPLIFIED. THE UPPER LOW  
WELL OFF THE WEST COAST IS FORECAST TO CONTINUE SLOWLY LIFTING  
NORTHWARD NEXT WEEK.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
THE 00Z MODEL GUIDANCE SUITE IS INITIALLY IN GOOD SYNOPTIC SCALE  
AGREEMENT ACROSS THE NATION THROUGH AT LEAST MONDAY. THERE ARE  
SOME MINOR TIMING DIFFERENCES WITH THE SHORTWAVE CROSSING THE  
NORTHERN GREAT LAKES, WITH THE 00Z ECMWF SLIGHTLY AHEAD OF THE  
CMC/GFS, BUT STILL CLOSE ENOUGH TO MERIT A THREE-WAY BLEND OF  
THESE MODELS. MODEL DIFFERENCES BECOME MORE SIGNIFICANT BY THE  
MIDDLE OF NEXT WEEK, WITH THE ECMWF FARTHER INLAND WITH THE CLOSED  
LOW OVER BRITISH COLUMBIA, AND THE GFS/CMC ARE STRONGER WITH THE  
TROUGH BUILDING IN ACROSS THE EASTERN U.S. BY NEXT THURSDAY. THE  
UPPER RIDGE ACROSS THE ROCKIES STILL HAS VERY GOOD AGREEMENT  
THROUGH THE FORECAST PERIOD. THE WPC FORECAST WAS PRIMARILY BASED  
ON A CMC/ECMWF/GFS/SOME ENSEMBLE MEANS THROUGH TUESDAY, FOLLOWED  
BY GRADUALLY INCREASING CONTRIBUTIONS FROM THE GEFS/ECENS WHILST  
STILL KEEPING SOME OF THE DETERMINISTIC GUIDANCE.  
 
   
..WEATHER/HAZARDS HIGHLIGHTS
 
 
TEMPERATURES ARE EXPECTED TO BE SLIGHTLY ABOVE NORMAL ACROSS  
PORTIONS OF THE NORTHEAST AND ALSO THE PACIFIC NORTHWEST ON  
SUNDAY, BUT NO MAJOR HEAT WAVES ARE CURRENTLY EXPECTED AT THIS  
TIME. READINGS WILL BE RUNNING A FEW DEGREES BELOW NORMAL ACROSS  
MUCH OF THE SOUTHWEST AND THE ROCKIES WITH THE ADDITIONAL CLOUDS  
AND SHOWERS. BY THE MIDDLE OF THE WEEK, HEAT BUILDS AGAIN ACROSS  
THE CENTRAL AND NORTHERN PLAINS, BUT THE ANOMALIES SHOULD BE TEN  
DEGREES ABOVE AVERAGE OR LESS IN MOST CASES.  
 
FOR PRECIPITATION, THE MAIN THREATS FOR FLASH FLOODING WILL BE  
ASSOCIATED WITH ENHANCED MONSOONAL MOISTURE OVER THE SOUTHWEST AND  
FOUR CORNERS REGION, IN ADDITION TO FRONTS/SHORTWAVES FROM  
MICHIGAN TO THE NORTHEAST U.S. AS NORTHERN STREAM SHORTWAVE  
TROUGHS PROGRESS DOWN STREAM. THE COMBINED SIGNALS FOR RAINFALL  
AND ALREADY WET CONDITIONS OVER THE DESERT SOUTHWEST INTO THE  
CENTRAL ROCKIES/GREAT BASIN LATE INTO THE WEEKEND SUPPORT A FEW  
SLIGHT RISK AREAS FOR THE DAY 4 EXCESSIVE RAINFALL OUTLOOK.  
DESPITE FRONTAL PROGRESSION, DEEP MOISTURE AND INSTABILITY ALSO  
MERITS MAINTAINING THE SLIGHT RISK AREA ACROSS THE NORTHERN GREAT  
LAKES IN A REGION WITH ENHANCED/ONGOING SHORT RANGE QPF.  
 
HAMRICK  
 
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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