916  
FXUS02 KWBC 100701  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 AM EDT TUE MAY 10 2022  
 
VALID 12Z FRI MAY 13 2022 - 12Z TUE MAY 17 2022  
 
...LINGERING BLOCKY PATTERN TO EXTEND RECORD HEAT FROM THE  
SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY TO THE MIDWEST/NORTHEAST  
LATE WEEK ALONG WITH EPISODES OF CENTRAL U.S. CONVECTION AND AN  
EMERGING ONSHORE RAINFALL FOCUS TO THE CAROLINAS...  
...DEVELOPING HEAT THREAT FOR CALIFORNIA AND THE SOUTHWEST FROM  
THE WEEKEND INTO NEXT WEEK WHILE HEAT PERSISTS EASTWARD OVER FAR  
SOUTHERN TIER AREAS...  
 
   
..OVERVIEW
 
 
GUIDANCE CONTINUES TO SHOW THE LARGE SCALE UPPER PATTERN  
TRANSITIONING FROM A BLOCKY REGIME LATE THIS WEEK TOWARD AN  
EASTERN PACIFIC TROUGH, WESTERN U.S. INTO HIGH PLAINS RIDGE, AND  
EASTERN U.S. TROUGH. A BROAD AREA OF MUCH ABOVE NORMAL  
TEMPERATURES INTO LATE THIS WEEK FROM THE SOUTHERN PLAINS INTO  
GREAT LAKES/NORTHEAST, WITH NUMEROUS DAILY RECORDS POSSIBLE, WILL  
EVENTUALLY MODERATE OVER THE NORTHERN TWO-THIRDS OF THE COUNTRY AS  
A WAVY FRONT OVER THE PLAINS (A POSSIBLE FOCUS FOR AT LEAST SOME  
LOCALLY HEAVY RAINFALL) PUSHES FARTHER EASTWARD AHEAD OF THE  
APPROACHING TROUGH. MEANWHILE AN UPPER LOW REACHING THE SOUTHEAST  
BY FRIDAY WILL QUICKLY OPEN UP AS IT LIFTS NORTHWARD, SPREADING  
RAINFALL INTO AND NORTH FROM THE CAROLINAS. THE UPPER RIDGE  
BUILDING INTO/THROUGH THE WEST WILL MODERATE INITIALLY CHILLY  
TEMPERATURES OVER THE NORTHWEST WHILE BRINGING A PERIOD OF VERY  
WARM TO HOT WEATHER ACROSS THE SOUTHERN HALF OF THE WEST SATURDAY  
ONWARD, CONNECTING WITH THE HEAT EXPECTED TO PERSIST OVER AND NEAR  
THE SOUTHERN PLAINS. HIGHS MAY CHALLENGE DAILY RECORDS OVER SOME  
LOCATIONS ACROSS THESE AREAS.  
   
..GUIDANCE EVALUATION/PREFERENCES
 
 
THE 12Z/18Z OPERATIONAL MODEL COMPOSITE USED AS THE BASIS OF THE  
UPDATED FORECAST EARLY IN THE PERIOD TRANSITIONED TO A BLEND OF  
THE 18Z GFS/12Z ECMWF AND THEIR ENSEMBLE MEANS BY MID-LATE PERIOD.  
THE UKMET/CMC HAVE CONTINUED THEIR GENERAL TREND TOWARD RECENT  
GFS/ECMWF IDEAS FOR THE STORM EXPECTED TO REACH JUST NORTH OF THE  
NORTHERN PLAINS AS OF EARLY FRIDAY. HOWEVER THE UKMET/CMC HAVE  
BEEN STRAYING FROM THE OTHER GUIDANCE FOR THE ULTIMATE EVOLUTION  
OF TRAILING SHORTWAVE ENERGY INITIALLY OVER THE NORTHWEST, PULLING  
IT FARTHER SOUTH THAN CONSENSUS. THIS TRAIT OF THOSE MODELS  
CONTRASTS WITH RECENT GFS/ECMWF AND GEFS/ECMWF MEAN TRENDS TOWARD  
SOMEWHAT LESS AMPLITUDE OF THE EVENTUAL EASTERN TROUGH ALOFT AND A  
STRONGER UPPER RIDGING BUILDING BACK OVER THE SOUTHERN  
PLAINS--LEADING TO GREATER PERSISTENCE OF THE HEAT OVER THAT  
REGION. MEANWHILE INDIVIDUAL MODELS AND ENSEMBLE MEMBERS DIVERGE  
FOR DETAILS OF EASTERN PACIFIC SHORTWAVE ENERGY PUSHING INTO  
WESTERN NORTH AMERICA. IN GENERAL THE LATEST GFS RUNS HAVE LEANED  
TOWARD BRINGING LOWER HEIGHTS INTO THE WEST VERSUS MOST OTHER  
GUIDANCE BUT NOT TO AN EXTREME DEGREE VERSUS TYPICAL  
PREDICTABILITY/ERROR RANGES AT THE TIME FRAME OF INTEREST. ALSO  
THE NEW 00Z UKMET BEARS SOME SIMILARITY TO THE GFS. THESE  
SHORTWAVE DETAILS WILL BE IMPORTANT FOR DETERMINING THE COVERAGE  
AND INTENSITY OF PRECIPITATION OVER THE NORTHWEST.  
   
..WEATHER/THREAT HIGHLIGHTS
 
 
WITHIN THE BROAD AREA OF ABOVE NORMAL TEMPERATURES FROM THE  
SOUTHERN PLAINS THROUGH GREAT LAKES AND NORTHEAST ON FRIDAY, THE  
BEST POTENTIAL FOR SOME DAILY RECORDS WILL BE ACROSS THE SOUTHERN  
TIER AND GREAT LAKES/NORTHEAST. HIGHEST ANOMALIES OF PLUS 10-20F  
OR SLIGHTLY HIGHER SHOULD BE ACROSS NORTHERN AREAS FROM FRIDAY  
INTO THE WEEKEND. MEANWHILE POTENTIAL RECORD HEAT COULD PERSIST  
OVER/NEAR EASTERN TEXAS INTO NEXT WEEK, AND MAY EXPAND OVER MORE  
OF THE SOUTHERN PLAINS/SOUTH EARLY NEXT WEEK.  
 
THE RIDGE BUILDING OVER THE WEST WILL LEAD TO A PRONOUNCED WARMING  
TREND DURING THE WEEKEND, WITH BROAD COVERAGE OF HIGHS 10-15F  
ABOVE NORMAL OVER THE SOUTHERN HALF OF THE REGION BY SUNDAY AND  
PERSISTING INTO TUESDAY. THIS HEAT COULD CHALLENGE DAILY RECORD  
HIGHS OVER SOME SOUTHERN AREAS AND ULTIMATELY INCREASE  
TEMPERATURES OVER THE SOUTHERN PLAINS ONCE AGAIN NEXT WEEK. THE  
PACIFIC NORTHWEST AND NORTHERN ROCKIES WILL BE CHILLY ON FRIDAY  
WITH HIGHS 5-15F BELOW NORMAL, FOLLOWED BY SOME MODERATION.  
SHORTWAVES EJECTING FROM THE EASTERN PACIFIC UPPER TROUGH AND  
ASSOCIATED SURFACE FRONTS MAY PRODUCE MULTIPLE EPISODES OF  
PRECIPITATION OVER THE NORTHWEST. SOME OF THIS ACTIVITY COULD BE  
LOCALLY MODERATE/HEAVY DEPENDING ON EXACT DETAILS WHICH HAVE LOW  
PREDICTABILITY AT THIS TIME.  
 
A WAVY FRONT EXTENDING SOUTH FROM AN INITIAL STORM SYSTEM OVER  
SOUTHERN CANADA MAY HANG UP OVER THE UPPER MIDWEST THROUGH  
SOUTHERN PLAINS FOR A TIME LATE THIS WEEK AS IT AWAITS THE ARRIVAL  
OF DYNAMICS FROM THE NORTHWEST, LEADING TO THE POSSIBILITY OF SOME  
MODERATE TO HEAVY SHOWERS AND THUNDERSTORMS OVER OR JUST WEST OF  
THE MISSISSIPPI VALLEY. THEN THIS FRONT WILL BECOME MORE  
PROGRESSIVE AS UPPER TROUGHING HEADS TOWARD AND INTO THE EAST.  
SOME RAINFALL ALONG THE FRONT COULD STILL BE FAIRLY INTENSE BUT  
THE GREATER PROGRESSION MAY TEMPER MAXIMUM TOTALS OVER THE EAST.  
THE TRAILING PART OF THE FRONT SHOULD STALL AND MAY LIFT BACK AS A  
WARM FRONT EARLY NEXT WEEK, POTENTIALLY SERVING AS A FOCUS FOR  
SOME CONVECTION. THE SOUTHEAST UPPER LOW THAT QUICKLY OPENS UP  
FRIDAY INTO SATURDAY WILL SPREAD AN AREA OF RAIN INTO THE  
CAROLINAS AND AREAS TO THE NORTH. SOME LOCALIZED ENHANCEMENT WILL  
BE POSSIBLE OVER THE CAROLINAS/VIRGINIA BUT RAPID OPENING OF THE  
UPPER LOW SHOULD TEND TO DECREASE THE FOCUS OF MOISTURE FARTHER  
NORTHWARD.  
 
RAUSCH  
 
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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