839  
FXUS02 KWBC 121854  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
252 PM EDT SUN JUN 12 2022  
 
VALID 12Z WED JUN 15 2022 - 12Z SUN JUN 19 2022  
 
...DANGEROUS/RECORD HEAT OVER THE EAST-CENTRAL/SOUTHEASTERN U.S.  
THROUGH AT LEAST WEDNESDAY...  
 
...HEAT LIKELY TO BECOME ESTABLISHED OVER THE NORTHERN-CENTRAL  
PLAINS FRIDAY-SUNDAY...  
 
19Z UPDATE: MODELS AND ENSEMBLES HAVE A GOOD OVERALL HANDLE ON THE  
SYNOPTIC SCALE PATTERN ACROSS THE MAJORITY OF THE NATION THROUGH  
THE END OF THE WEEK. THE EXCEPTION IS WITH THE TROUGH CROSSING  
THE NORTH-CENTRAL U.S. AND GREAT LAKES REGION, WITH THE 12Z GFS  
MORE AMPLIFIED INITIALLY ACROSS MICHIGAN AND VICINITY. GOING  
FORWARD INTO THE WEEKEND, THE 12Z ECMWF IS SLOWER AND MORE  
AMPLIFIED WITH A DEEP TROUGH SITUATED OVER THE NORTHEAST U.S.,  
WHEREAS THE CMC/GFS TAKE THE TROUGH AXIS WELL OFFSHORE, THUS  
MAKING THE FORECAST CONFIDENCE FOR THIS REGION SLIGHTLY REDUCED.  
THERE IS BETTER OVERALL TIMING REGARDING THE NEXT SYNOPTIC SCALE  
TROUGH ENTERING THE WESTERN U.S. THIS WEEKEND. SOME OF THE  
DETERMINISTIC DETERMINISTIC GUIDANCE WAS MAINTAINED THROUGH NEXT  
SUNDAY, WITH ABOUT HALF OF THE BLEND WEIGHTED TO THE ENSEMBLE  
MEANS AND PREVIOUS WPC CONTINUITY. THE PREVIOUS WPC FORECAST  
DISCUSSION FOLLOWS BELOW. /HAMRICK  
---------------  
   
..OVERVIEW AND GUIDANCE/PREDICTABILITY EVALUATION
 
 
THE START OF THE PERIOD EARLY WEDNESDAY WILL FEATURE A STRONG  
UPPER RIDGE OVER THE EAST, ANCHORED BY A HIGH OVER THE SOUTHERN  
APPALACHIANS, WHILE AN EJECTING WESTERN TROUGH REACHES THE HIGH  
PLAINS. THEN OVER THE NEXT TWO TO THREE DAYS THE UPPER PATTERN  
WILL TRANSITION TO AN AMPLIFIED WEST COAST TROUGH/PLAINS RIDGE,  
WITH THE LATTER ULTIMATELY HELPING TO DIG INITIALLY PROGRESSIVE  
SOUTHERN CANADA/NORTHERN U.S. ENERGY THROUGH THE NORTHEAST AND  
INTO THE ATLANTIC. THIS CONFIGURATION MAY NUDGE A BIT TO THE EAST  
DURING THE WEEKEND. THE CHANGE IN PATTERN WILL SHIFT THE EMPHASIS  
FOR MOST ANOMALOUS HEAT FROM THE EAST-CENTRAL/SOUTHEAST U.S. AS OF  
WEDNESDAY MORE INTO THE NORTHERN-CENTRAL PLAINS DURING  
FRIDAY-SUNDAY. A COLD FRONT PUSHING EASTWARD FROM THE  
PLAINS/UPPER MIDWEST WILL FOCUS SHOWERS AND THUNDERSTORMS MID-LATE  
WEEK, AND POSSIBLY INTO THE WEEKEND OVER THE SOUTH. A LEADING  
FRONT OVER PARTS OF THE EAST MAY ALSO PROMOTE AREAS OF RAINFALL  
DURING WEDNESDAY-THURSDAY. THE WAVY FRONT AHEAD OF THE WEST COAST  
UPPER TROUGH SHOULD BRING AREAS OF RAINFALL TO THE NORTHWEST,  
WHILE RAINFALL MAY EXPAND THROUGH PARTS OF THE FOUR CORNERS STATES  
LATE WEEK THROUGH THE WEEKEND AS MOISTURE FLOWS NORTHWARD AHEAD OF  
THIS SYSTEM.  
 
MOST OF THE LATEST GUIDANCE CONTINUES TO AGREE UPON MOST ASPECTS  
OF THE LARGE SCALE PATTERN EVOLUTION BUT SOME INDIVIDUAL RUNS  
STILL OFFER MEANINGFUL DIFFERENCES WITH ONE OR MORE ASPECTS OF THE  
FORECAST. UKMET RUNS HAVE BEEN LESS AGREEABLE THAN OTHER  
MODELS/MEANS WITH DETAILS OF FLOW ACROSS THE NORTHERN  
U.S./SOUTHERN CANADA SO THE UPDATED FORECAST DID NOT INCORPORATE  
THAT MODEL'S INPUT. MEANWHILE THE OPERATIONAL MODELS HAVE BEEN  
SHOWING A LOT OF RUN-TO-RUN VARIABILITY FOR DETAILS WITHIN THE  
WEST COAST TROUGH AFTER THURSDAY OR SO, FAVORING MAINTENANCE OF A  
BLEND/ENSEMBLE MEAN APPROACH FOR DEPICTING THAT FEATURE. FINALLY,  
INCREASINGLY SIGNIFICANT DIFFERENCES ARISE WITH FLOW DETAILS OVER  
THE NORTHEAST INTO WESTERN ATLANTIC BY NEXT WEEKEND. OVERALL THE  
ECMWF/CMC AND THEIR MEANS DEVELOP STRONGER/WESTWARD TROUGHING THAN  
FORECAST BY GFS/GEFS MEAN RUNS. THE NEW 00Z GFS HAS BECOME THE  
MOST EXTREME WITH ITS HIGHER HEIGHTS OVER THE NORTHEAST AND  
VICINITY, ACTUALLY EXTENDING ITS RIDGE INTO THIS REGION IN  
CONTRAST TO THE GEFS MEAN WHICH AT LEAST HAS NORTHWESTERLY FLOW  
(BUT WITH HIGHER HEIGHTS THAN OTHER GUIDANCE). TELECONNECTIONS  
RELATIVE TO UPPER MIDWEST AND NORTHEAST ATLANTIC POSITIVE HEIGHT  
ANOMALY CENTERS IN THE D+8 MULTI-DAY MEANS FAVOR SOME UPPER  
TROUGHING ALONG OR A LITTLE OFFSHORE THE NORTHEAST U.S. COAST BUT  
PERHAPS NOT QUITE AS AMPLIFIED AS IN THE ECMWF CLUSTER. ABOVE  
CONSIDERATIONS LED TO USING THE 18Z GFS AND 12Z ECMWF/CMC IN A  
BLEND TO START THE UPDATED FORECAST EARLY IN THE PERIOD, FOLLOWED  
BY A TRANSITION TO SLIGHTLY MORE THAN HALF TOTAL WEIGHT OF THE 18Z  
GEFS/12Z ECMWF MEANS BY DAY 7 SUNDAY.  
   
..SENSIBLE WEATHER/THREAT HIGHLIGHTS
 
 
THE COLD FRONT PUSHING EASTWARD FROM THE UPPER MIDWEST/GREAT  
LAKES/PLAINS WILL PRODUCE AREAS OF SHOWERS AND THUNDERSTORMS  
DURING THE MID-LATE WEEK TIME FRAME. IT WILL TAKE ADDITIONAL TIME  
TO RESOLVE THE DETAILS BUT FOR NOW THERE IS AT LEAST SOME SIGNAL  
FOR LOCALLY MODERATE TO HEAVY ACTIVITY OVER THE UPPER MIDWEST AS  
WELL AS PORTIONS OF THE APPALACHIANS AND MID-ATLANTIC. A LEADING  
FRONT DRAPED OVER PARTS OF THE EAST WEDNESDAY-THURSDAY COULD FOCUS  
OTHER AREAS OF RAINFALL. THE INITIAL PLAINS/MIDWEST FRONT SHOULD  
REACH THE SOUTH BY NEXT WEEKEND. EVEN BEFORE THIS FRONT'S  
ARRIVAL, LOCATIONS ACROSS THE SOUTHEAST AND GULF COAST MAY SEE  
DIURNALLY FAVORED SHOWERS AND THUNDERSTORMS ON ONE OR MORE DAYS.  
THE UPPER TROUGH NEARING THE WEST COAST TOWARD THE END OF THE WEEK  
SHOULD BRING MAINLY LIGHT RAINFALL TO PARTS OF THE NORTHWEST, WITH  
SOME INCREASE IN AMOUNTS POSSIBLE OVER THE NORTHERN ROCKIES BY THE  
WEEKEND AS THE SYSTEM DRIFTS INLAND. MEANWHILE THE AMPLIFIED  
PATTERN WILL LIKELY BRING MUCH ABOVE NORMAL AMOUNTS OF MOISTURE  
FOR THE TIME OF YEAR NORTHWARD THROUGH THE FOUR CORNERS STATES AND  
VICINITY FRIDAY THROUGH THE WEEKEND, SUPPORTING AN INCREASE IN  
COVERAGE/INTENSITY OF RAINFALL ACROSS THE REGION.  
 
AROUND MIDWEEK EXPECT HIGHS TO BE 10-20F ABOVE NORMAL FROM THE  
GREAT LAKES INTO THE CAROLINAS, WITH NUMEROUS LOCATIONS  
CHALLENGING RECORD HIGHS. A BROAD AREA OF RECORD WARM LOWS WILL  
BE POSSIBLE AS WELL. THE HEAT MAY PERSIST TO SOME EXTENT INTO  
THURSDAY BUT HIGHS WILL TEND TO BE A FEW DEGREES COOLER, SO ANY  
DAILY RECORDS SHOULD BE MORE ISOLATED. THE NORTHERN TWO-THIRDS OF  
THE EAST WILL SEE A STEADY COOLING TREND INTO THE WEEKEND. THE  
EASTERN GREAT LAKES/NORTHEAST MAY EVEN SEE MODESTLY BELOW NORMAL  
HIGHS. UNCERTAINTY WITH THE UPPER FLOW PATTERN OVER THE NORTHEAST  
AT THAT TIME LOWERS CONFIDENCE IN THE FORECAST THOUGH. AREAS FROM  
THE SOUTHERN PLAINS INTO THE SOUTHEAST WILL BE ON THE HOT SIDE  
THROUGH THE PERIOD WITH HIGHS PERSISTENTLY 5-10F ABOVE NORMAL.  
LINGERING COOL HIGHS OVER THE NORTHERN ROCKIES/PLAINS ON WEDNESDAY  
WILL QUICKLY GIVE WAY TO A PRONOUNCED WARMING TREND THAT INITIALLY  
BRINGS A DAY OR SO OF PLUS 5-15F ANOMALIES ACROSS CALIFORNIA AND  
THE GREAT BASIN MID-LATE WEEK, FOLLOWED BY HIGHS OF 15-25F ABOVE  
NORMAL SETTLING OVER THE NORTHERN-CENTRAL PLAINS BY FRIDAY-SUNDAY.  
MAX TEMPERATURES COULD REACH HIGH ENOUGH TO CHALLENGE DAILY  
RECORDS OVER PARTS OF THE CENTRAL PLAINS BY NEXT SUNDAY.  
MEANWHILE THE UPPER TROUGH NEAR THE WEST COAST SHOULD SPREAD  
MODESTLY BELOW NORMAL HIGHS GRADUALLY FARTHER INLAND BY NEXT  
WEEKEND.  
 
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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