376  
FXUS02 KWBC 191858  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
257 PM EDT SUN JUN 19 2022  
 
VALID 12Z WED JUN 22 2022 - 12Z SUN JUN 26 2022  
 
...EXPANSIVE AREA OF EXCESSIVE HEAT LIKELY TO PERSIST ACROSS THE  
SOUTH INTO NEXT WEEKEND...  
 
   
..OVERVIEW
 
 
A BROAD UPPER LEVEL RIDGE CENTERED OVER THE LOWER MISSISSIPPI  
VALLEY MIDWEEK AND DRIFTING WESTWARD INTO THE SOUTHERN PLAINS FOR  
THE LATTER HALF OF THE WEEK WILL BE THE MOST PROMINENT FEATURE  
DURING THE MEDIUM RANGE PERIOD AND WILL CAUSE WIDESPREAD EXCESSIVE  
HEAT ACROSS MUCH OF THE SOUTH. TO THE NORTH, EXPECT WEAK AND  
PROGRESSIVE SYSTEMS TO RIDE THE TOP OF THE RIDGE THROUGH THE  
NORTHWEST TO MIDWEST, WHILE TROUGHING IS LIKELY FOR BOTH THE EAST  
AND WEST COASTS. MONSOONAL MOISTURE WILL LIKELY CONTINUE THROUGH  
MUCH OF THE WEEK ACROSS THE FOUR CORNERS REGION, AND SOME SHOWERS  
AND STORMS ARE ALSO POSSIBLE IN THE NORTH-CENTRAL U.S. AND THE  
EAST COAST.  
 
   
..GUIDANCE/PREDICTABILITY EVALUATION
 
 
GOOD MODEL AGREEMENT PERSISTS WITH THE RIDGE/UPPER HIGH ANCHORED  
ACROSS THE SOUTH, BUT MODELS SHOW GENERALLY MORE VARIABILITY WITH  
TROUGHING FEATURES SURROUNDING THE RIDGE. THE MOST UNCERTAIN PART  
OF THE FORECAST CONTINUES TO BE THE POSSIBILITY FOR ENERGY TO CUT  
OFF AND CREATE A CLOSED LOW OVER THE WESTERN ATLANTIC, WHICH COULD  
THEN RETROGRADE TOWARD THE EAST COAST DURING THE LATTER PART OF  
THE WEEK. THERE IS STILL CONSIDERABLE SPREAD WITH RECENT MODEL  
GUIDANCE REGARDING PLACEMENT OF THE LOW POSSIBLY EMBEDDED IN BROAD  
TROUGHING--GFS RUNS REMAIN THE FASTEST/FARTHEST NORTH WITH THE  
UPPER LOW GETTING ABSORBED BACK INTO THE MEAN FLOW OVER THE  
NORTHEAST BEFORE FRIDAY, WHILE MOST OTHER GUIDANCE SHOWED THE LOW  
LINGERING FARTHER SOUTH INTO NEXT WEEKEND. AT THE TIME OF FORECAST  
CREATION, THE 00Z ECMWF, CMC, AND UKMET ALONG WITH MANY EC  
ENSEMBLE MEMBERS AND A FEW GEFS ENSEMBLE MEMBERS ALL AGREED UPON A  
FARTHER SOUTH POSITION OF THE LOW (THOUGH THE CMC WAS CONSIDERED  
TOO FAR SOUTH, WITH OTHER GUIDANCE NEAR THE CAROLINAS FRI-SAT  
WHILE THE CMC WAS NEAR FLORIDA). THE WPC FORECAST WAS CLOSER TO  
THIS CLUSTER OF GUIDANCE, THOUGH TEMPERED BY FAVORING THE EC AND  
GEFS ENSEMBLE MEANS ESPECIALLY LATER IN THE PERIOD, WHICH WERE  
WEAKER DUE TO INCREASED VARIABILITY IN INDIVIDUAL MEMBER  
SOLUTIONS. HOWEVER, AFTER THREE FULL MODEL CYCLES INDICATING THE  
CLOSED LOW POTENTIAL, THE 12Z MODEL SUITE THAT HAS ARRIVED SO FAR  
HAS NOTABLY BACKED OFF ON THE POSSIBILITY OF AN UPPER LOW THAT FAR  
SOUTH--THE 12Z ECMWF, UKMET, AND CMC LOOK CLOSER TO THE NORTHEAST  
SOLUTION THAT THE GFS HAS BEEN SHOWING, THOUGH MAINTAINING  
TROUGHING LONGER THERE (ESPECIALLY THE CMC). THE FEATURE HAS VERY  
LOW PREDICTABILITY GIVEN IT IS RELIANT ON ENERGY DISTRIBUTION  
WITHIN A NARROW TROUGH, AND SOME ENERGY COULD STEM FROM FEATURES  
AS SMALL AS MCSS AND MCVS, SO FUTURE REFINEMENTS IN THE FORECAST  
ARE LIKELY. OTHER SYSTEMS SUCH AS A COMPACT UPPER LOW NEAR  
CALIFORNIA WED-THU WITH LINGERING WEAKER ENERGY MOVING EASTWARD  
SOMEWHAT, AS WELL AS A NORTHERN STREAM LOW MOVING ACROSS SOUTHERN  
CANADA WITH TROUGHING INTO THE NORTHWESTERN TO NORTH-CENTRAL U.S.,  
FORTUNATELY SHOW BETTER AGREEMENT THAT COULD BE HANDLED WITH A  
MULTI-MODEL BLEND OF GUIDANCE.  
 
   
..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 THROUGH MIDWEEK  
AND BEYOND. 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  
WEDNESDAY-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. BUT 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.  
 
TATE  
 
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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