248  
FXUS02 KWBC 200702  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
301 AM EDT MON JUN 20 2022  
 
VALID 12Z THU JUN 23 2022 - 12Z MON JUN 27 2022  
 
...EXPANSIVE AREA OF EXCESSIVE HEAT LIKELY TO PERSIST ACROSS THE  
SOUTH INTO NEXT WEEKEND...  
 
   
..OVERVIEW
 
 
A BROAD UPPER LEVEL RIDGE PARKED OVER THE SOUTHERN U.S. THROUGH  
NEXT WEEKEND WILL BRING AN EXTENDED PERIOD OF EXCESSIVE HEAT AND  
RECORD TEMPS TO MANY ACROSS THE REGION. TO THE NORTH, WEAK AND  
PROGRESSIVE SYSTEMS WILL RIDE THE TOP OF THE RIDGE THROUGH THE  
NORTHWEST TO THE MIDWEST, EVENTUALLY AMPLIFYING AS IT REACHES THE  
GREAT LAKES/NORTHEAST LATER IN THE PERIOD, WHICH SHOULD HELP TO  
FINALLY BREAK DOWN THE MASSIVE SOUTHERN HEAT DOME. MONSOONAL  
MOISTURE WILL ALSO LIKELY CONTINUE THROUGH MUCH OF THE PERIOD  
ACROSS THE FOUR CORNERS REGION.  
 
   
..GUIDANCE/PREDICTABILITY EVALUATION
 
 
THERE IS DECENT AGREEMENT ON THE OVERALL PATTERN IN THE LATEST  
MODEL GUIDANCE, ESPECIALLY REGARDING A PERSISTENT AND EXPANSIVE  
UPPER RIDGE OVER THE SOUTHERN U.S. THE MOST UNCERTAIN PARTS OF THE  
FORECAST CONTINUES TO BE WITH INDIVIDUAL SYSTEMS ROUNDING THE TOP  
OF THE RIDGE, MOST OF WHICH ARE DETAIL DIFFERENCES AND TYPICAL RUN  
TO RUN VARIABILITY. ON THE EAST COAST, MODELS HAVE TRENDED AWAY  
FROM A CLOSED RETROGRADING LOW TOWARDS THE EAST COAST, RATHER  
FAVORING THE LOW BEING DRAWN NORTHWARD AND PUSHED EASTWARD INTO  
THE CANADIAN MARITIMES NEXT WEEKEND. THERE'S STILL QUITE A BIT OF  
UNCERTAINTY WITH THIS FEATURE AND VARIABILITY LEADING TO A VERY  
LOW CONFIDENCE FORECAST. REGARDLESS, MODELS DO AGREE ON SOME  
DEGREE OF ELONGATED TROUGHING ALONG OR OFF THE EAST COAST THROUGH  
THE PERIOD. TIMING HAS IMPROVED WITH A SHORTWAVE INTO THE  
NORTHWEST U.S. AND SKIRTING THE U.S./CANADIAN BORDER FRIDAY INTO  
SATURDAY. THE CMC IS SLOWER THAN THE ECMWF/GFS WHICH BECOMES MOST  
APPARENT BY SUNDAY AS THE FEATURE TRIES TO AMPLIFY SOME OVER THE  
GREAT LAKES.  
 
GOOD ENOUGH AGREEMENT THE FIRST HALF OF THE PERIOD ALLOWED FOR A  
MULTI-MODEL BLEND WHICH HELPED MITIGATE SOME OF THE DIFFERENCES  
ACROSS THE NORTHERN TIER AND EAST COAST. BY SUNDAY, INCORPORATED  
MORE OF THE ENSEMBLE MEANS ALONG WITH THE ECMWF AND GFS WHICH WERE  
CLOSEST TO THE ENSEMBLE MEANS.  
 
   
..SENSIBLE WEATHER/THREAT HIGHLIGHTS
 
 
ANOMALOUSLY HIGH MONSOONAL MOISTURE FOR THIS TIME OF YEAR, LIKELY  
TIED AT LEAST IN PART TO EASTERN PACIFIC TROPICAL SYSTEMS, WILL  
CONTINUE STREAMING INTO THE FOUR CORNERS STATES INTO NEXT WEEKEND.  
LOCALLY HEAVY TO EXCESSIVE RAINFALL IS POSSIBLE, PARTICULARLY OVER  
SENSITIVE BURN SCAR AREAS AND CONSIDERING THE MULTIPLE DAY  
REPEATING NATURE OF THIS ACTIVITY. A SHOWERY/STORMY PATTERN COULD  
ALSO SET UP THROUGH FRIDAY IN CENTRAL PARTS OF THE PLAINS AND  
MISSISSIPPI VALLEY AS A FRONT BECOMES ALIGNED WEST-EAST, WITH SOME  
POTENTIAL FOR RAIN AND STORMS TO TRAIN IN SOME AREAS. RAIN  
ACTIVITY IS THEN EXPECTED TO FOCUS FARTHER NORTH ACROSS THE  
NORTHERN PLAINS TO MIDWEST BY LATE IN THE WEEK IN THE VICINITY OF  
A COLD FRONT. FARTHER EAST, MOISTURE IS FORECAST TO STREAM AHEAD  
OF A FRONTAL SYSTEM ACROSS MUCH OF THE EAST COAST ON THURSDAY.  
THEN HOW MUCH RAIN LINGERS ACROSS THE EAST COAST WILL BE DEPENDENT  
ON THE AFOREMENTIONED UPPER LOW/TROUGH FEATURE'S EXISTENCE AND  
TRACK AS WELL AS A POSSIBLE FRONTAL BOUNDARY AT THE SURFACE.  
 
LIKELY THE BIGGEST THREAT OF THE MEDIUM RANGE PERIOD WILL BE A  
BROAD AREA OF POTENTIALLY RECORD-BREAKING HEAT ACROSS PARTS OF THE  
PLAINS EASTWARD LASTING THROUGH THE WEEK. THE SOUTHEASTERN  
QUADRANT OF THE COUNTRY IS MOST LIKELY TO SEE RECORD MAX OR MIN  
TEMPERATURES BE SET, WITH HIGHS EXCEEDING 100F AND LOWS WELL INTO  
THE 70S MEANING LITTLE RELIEF OVERNIGHT IN MANY AREAS.  
TEMPERATURES 10-15F ABOVE NORMAL COULD STRETCH FARTHER NORTH INTO  
MUCH OF THE PLAINS AND MISSISSIPPI AND OHIO VALLEYS AT TIMES AS  
WELL. TEMPEARTURES SHOULD FINALLY MODERATE ACROSS THE SOUTH BY  
NEXT WEEKEND AND ESPECIALLY EARLY NEXT WEEK AS THE UPPER PATTERN  
BEGINS TO AMPLIFY AGAIN. TEMPERATURES ALONG THE EAST COAST SHOW  
THE MOST FORECAST SPREAD, AND WILL BE DEPENDENT ON THE UPPER  
PATTERN. RELATIVELY COOLER TEMPERATURES WITH WELL BELOW NORMAL  
HIGHS ARE FORECAST PARTICULARLY FOR NEW MEXICO GIVEN THE MONSOONAL  
CLOUDS AND RAIN COVERAGE, WHILE NEAR NORMAL TEMPERATURES STRETCH  
THROUGH THE ROCKIES, AND THE WEST COAST STATES COULD BE A FEW  
DEGREES ABOVE AVERAGE.  
 
SANTORELLI  
 
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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