657  
FXUS02 KWBC 160700  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 AM EDT SAT JUL 16 2022  
 
VALID 12Z TUE JUL 19 2022 - 12Z SAT JUL 23 2022  
 
...DANGEROUS HEAT TO PERSIST OVER MUCH OF THE WESTERN AND  
ESPECIALLY CENTRAL U.S. NEXT WEEK...  
   
..OVERVIEW
 
 
HOT TEMPERATURES WILL PREVAIL ACROSS A LARGE AREA OF THE  
CENTRAL/WESTERN U.S. UNDERNEATH A STRONG UPPER RIDGE CENTERED OVER  
THE FOUR CORNERS REGION. NEAR OR RECORD HIGHS WILL BE POSSIBLE AT  
TIMES, AND VERY WARM MORNING LOWS MAY ALSO CHALLENGE DAILY RECORDS  
OVER SOME AREAS. TOWARD THE END OF NEXT WEEK AND THE WEEKEND A  
POTENTIAL EASTWARD SHIFT IN THE UPPER RIDGE AND ARRIVAL OF A WEAK  
PACIFIC TROUGH TO THE WEST COAST MAY BRING WESTERN U.S. HIGH  
TEMPERATURES CLOSER TO NORMAL. FLOW AROUND THE RIDGE WILL CARRY  
SHORTWAVES THAT WILL HELP TO REINFORCE THE LONG TERM MEAN TROUGH  
OVER THE NORTHEASTERN U.S. AND PRODUCE EPISODES OF SHOWERS AND  
THUNDERSTORMS FROM THE NORTHERN TIER INTO THE EAST. FOR THE  
SOUTHWEST U.S. INTO THE ROCKIES, SOME MONSOONAL MOISTURE UNDER THE  
RIDGE WILL PROVIDE DAILY CHANCES OF SHOWERS AND STORMS, SOME OF  
WHICH COULD LEAD TO FLASH FLOODING.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
IN PRINCIPLE, LATEST GUIDANCE IS MOST AGREEABLE AND CONSISTENT  
WITH THE FOUR CORNERS UPPER RIDGE THROUGH ABOUT THURSDAY ALONG  
WITH THE IDEA OF A COMPACT UPPER LOW TRACKING EAST ALONG THE  
U.S.-CANADIAN BORDER, WITH THE OVERALL SHORTWAVE FEEDING INTO THE  
EASTERN NORTH AMERICA MEAN TROUGH. GUIDANCE IS STILL SHUFFLING  
AROUND WITH THE EXACT TIMING AND TRACK OF THE UPPER LOW/ASSOCIATED  
LOW PRESSURE AND THE 12Z ECMWF MOST NOTABLY STRAYS A BIT FASTER  
THAN CONSENSUS AFTER EARLY WEDNESDAY (00Z ECMWF HAS TRENDED  
SLOWER). OTHER ASPECTS OF THE FORECAST SHOW VARYING DEGREES OF  
SPREAD AND VARIABILITY. A SHORTWAVE PROGRESSING ALONG FROM WESTERN  
CANADA MAY BRING A FRONT INTO THE NORTHERN TIER AND POTENTIALLY  
INTERACT WITH THE LEADING SYSTEM EARLIER THAN PREVIOUSLY EXPECTED.  
MEANWHILE, MODELS HAVE BEEN ALL OVER THE PLACE FOR POTENTIAL  
EJECTION OF AN INITIAL WESTERN PACIFIC UPPER LOW WHOSE ENERGY MAY  
PLAY A ROLE IN THE FORECAST AROUND THE NORTHERN PERIPHERY OF THE  
RIDGE. ON THE EXTREMES, ECMWF RUNS HAVE BEEN QUITE FAST (00Z ECMWF  
FINALLY TRENDING SLOWER) AND THE 12Z CMC KEPT IT OVER THE PACIFIC  
THROUGH THE END OF THE PERIOD. THE NEW 00Z CMC HAS ADJUSTED CLOSER  
TO THE INTERMEDIATE GFS/UKMET. PREFER A CONSERVATIVE APPROACH FOR  
DEPICTING THIS FEATURE UNTIL BETTER AGREEMENT EMERGES. BY THE END  
OF THE WEEK, GUIDANCE DIVERGES FOR WHERE THE BEST UPPER RIDGE  
EMPHASIS WILL BE. CURRENT PREFERENCE IS CLOSEST TO THE  
INTERMEDIATE 12Z ECMWF AND LATEST GEFS/ECMWF MEAN RUNS, BETWEEN  
THE FARTHER WEST 12Z CMC AND FARTHER EAST GFS. ALSO OF NOTE, BY  
DAYS 5-7 THURSDAY-SATURDAY THE NEW 00Z GFS STRAYS INCREASINGLY OUT  
OF PHASE WITH OTHER MODEL/ENSEMBLE MEAN GUIDANCE FROM THE NORTH  
PACIFIC/ALASKA INTO WESTERN CANADA AND NORTHWESTERN U.S.  
 
BASED ON GUIDANCE AVAILABLE THROUGH THE 18Z CYCLE, THE UPDATED  
FORECAST INCORPORATED A COMPOSITE OF 12Z/18Z OPERATIONAL MODELS  
FOR ABOUT THE FIRST HALF OF THE PERIOD AND THEN ADDED INCREASING  
WEIGHT OF THE 18Z GEFS/12Z ECMWF MEANS SO THAT THEIR TOTAL WEIGHT  
REACHED 50 PERCENT BY THE END OF THE PERIOD. THE RESULTING  
FORECAST YIELDED GOOD CONTINUITY OVERALL WITH ONLY TYPICAL  
RUN-TO-RUN DETAIL/TIMING ADJUSTMENTS.  
   
..WEATHER/HAZARDS HIGHLIGHTS
 
 
THE CENTRAL PLAINS AND VICINITY SHOULD SEE THE GREATEST  
TEMPERATURE ANOMALIES DURING THE TUESDAY-SATURDAY PERIOD, WITH  
EACH DAY LIKELY TO FEATURE SOME HIGHS 10-15F ABOVE NORMAL. THIS  
REGION WILL BE WITHIN A BROADER AREA OF TRIPLE-DIGIT HIGHS  
EXPECTED TO PERSIST OVER MUCH OF THE SOUTHERN TWO-THIRDS OF THE  
PLAINS. IN LESS EXTREME FASHION, SOME OF THE HEAT MAY REACH THE  
NORTHERN PLAINS/UPPER MIDWEST AT TIMES. SOME DAILY RECORDS ARE  
POSSIBLE FOR HIGHS WHILE VERY WARM MORNING LOWS COULD ALSO  
CHALLENGE RECORDS ESPECIALLY AROUND WEDNESDAY-THURSDAY.  
 
OVER THE WEST, MONSOONAL MOISTURE AND ASSOCIATED DIURNALLY FAVORED  
SHOWERS/STORMS WITH LOCALLY HEAVY RAINFALL MAY KEEP PARTS OF THE  
FOUR CORNERS/GREAT BASIN REGION CLOSE TO NORMAL FOR HIGHS THROUGH  
THE PERIOD. OTHER PARTS OF THE WEST INLAND FROM THE PACIFIC COAST  
SHOULD START THE PERIOD UP TO 5-10F ABOVE NORMAL FOR HIGHS BUT  
THEN DECLINE MORE TOWARD NORMAL AS AN UPPER LOW/SHORTWAVE EJECT  
FROM THE PACIFIC AND THE FOUR CORNERS UPPER HIGH EVENTUALLY SHIFTS  
EASTWARD.  
 
LOCALLY HEAVY RAINFALL WILL BE POSSIBLE WITH A FAIRLY VIGOROUS  
SYSTEM FORECAST TO TRACK FROM THE NORTHERN PLAINS THROUGH THE  
GREAT LAKES AND EASTERN CANADA/NORTHEAST U.S. TUESDAY ONWARD.  
UNCERTAIN SPECIFICS OF ENERGY EJECTING FROM THE PACIFIC MAY PLAY A  
ROLE IN CONVECTIVE DETAILS ALONG A TRAILING FRONT THAT MAY SETTLE  
INTO THE FAR NORTHERN TIER LATE WEEK INTO THE WEEKEND. THE  
MID-ATLANTIC AND NORTHEAST WILL BE ON THE VERY WARM TO HOT SIDE,  
WITH SOME LOCATIONS POSSIBLY SEEING MORE CONSECUTIVE DAYS OF PLUS  
5-10F ANOMALIES FOR HIGHS THAN PREVIOUSLY EXPERIENCED SO FAR THIS  
SUMMER. PERSISTENT MOISTURE WILL ALLOW FOR MULTIPLE EPISODES OF  
SHOWERS/THUNDERSTORMS OVER THE SOUTHEAST/FLORIDA AND CENTRAL GULF  
COAST REGION. TEMPERATURES SHOULD BE NEAR NORMAL OVER THOSE AREAS.  
 
RAUSCH/TAYLOR  
 
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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