384  
FXUS02 KWBC 091818  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
217 PM EDT SAT JUL 09 2022  
 
VALID 12Z TUE JUL 12 2022 - 12Z SAT JUL 16 2022  
 
...HEAT WAVE TO LAST THROUGH EARLY NEXT WEEK ACROSS THE SOUTHERN  
PLAINS AND MID-SOUTH AS A HEAVY RAINFALL THREAT EMERGES FOR THE  
CENTRAL GULF COAST STATES...  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
ON THE LARGE SCALE, THE GUIDANCE SHOWS FAIRLY GOOD AGREEMENT ON  
THE UPPER PATTERN DURING THE MEDIUM RANGE THROUGH AT LEAST DAY 5.  
THERE APPEARS TO BE BETTER AGREEMENT ON QPF PLACEMENT NEAR THE  
CENTRAL GULF COAST WHERE AN UPPER DISTURBANCE/MOISTURE FROM THE  
GULF OF MEXICO WILL INTERACT WITH A STALLED FRONT TO PRODUCE  
MULTIPLE DAYS OF HEAVY RAINFALL. THE GFS/GEFS REMAIN FARTHER WEST  
WITH THE HEAVIER QPF BOTH ON DAYS 4 AND 5, BUT MUCH OF THE  
REMAINDER OF THE GUIDANCE NOW SHOWS BETTER CONSENSUS FARTHER EAST  
TOWARDS SOUTHERN LA/MS/AL, EVEN INTO WESTERN FL PANHANDLE, WHICH  
IS WHERE THE WPC QPF IS HEAVILY WEIGHTED TOWARDS TODAY. FOR THE  
MASS FIELDS, A CONSENSUS OF DETERMINISTIC GUIDANCE WORKED FINE  
THROUGH DAY 5.  
 
BY DAYS 6 AND 7, THERE IS SOME MORE LARGER SCALE DIFFERENCES IN  
TIMING THAT ARISE AROUND AMPLIFIED TROUGHING ACROSS THE EASTERN  
U.S., AS WELL AS A COMPACT CLOSED LOW INTO THE PACIFIC  
NORTHWEST/SOUTHWEST CANADA. IN THE EAST, THE GFS GETS MUCH QUICKER  
WITH THE TROUGH EXITING THE EAST COAST, WHERE AS THE ECMWF/CMC AND  
THE ENSEMBLE MEANS SHOW THE TROUGH/FRONT LINGERING ACROSS THE EAST  
COAST REGION. IN THE WEST, THE CMC IS FARTHEST NORTH WITH A  
COMPACT CLOSED LOW MOVING IN TOWARDS THE PACIFIC NORTHWEST, BUT  
THE GFS AND THE ECMWF ARE FARTHER SOUTH. THE ENSEMBLE MEANS  
SUPPORT SOMETHING IN THE MIDDLE OF THESE TWO CAMPS. FORECAST  
UNCERTAINTY ISN'T HUGE, BUT IT IS NOTABLE FOR THESE LATER TIME  
PERIODS, SO A BLEND TOWARDS THE ENSEMBLE MEANS AND ECMWF SEEMED  
BEST FOR TODAY. THIS APPROACH ALSO MAINTAINS GOOD WPC PRODUCT  
CONTINUITY FROM OVERNIGHT.  
 
   
..OVERVIEW AND WEATHER/HAZARDS HIGHLIGHTS
 
 
A MEAN UPPER TROUGH POSITION WILL DEVELOP OFF THE PACIFIC  
NORTHWEST BY EARLY NEXT WEEK WITH LEAD MIDWEST UPPER TROUGHING  
ALSO DIGGING INTO THE EAST WHERE ASSOCIATED FRONTAL PASSAGES WILL  
FOCUS RAIN AND THUNDERSTORMS. HOWEVER, DEEPER MOISTURE IS EXPECTED  
TO TRAIL FROM THE EASTERN MID-ATLANTIC TO THE SOUTHEAST ALONG A  
WAVY STALLED LEAD FRONT FORECAST TO INTERACT WITH AN UPPER LOW  
FROM THE SUB-TROPICS TO SUPPORT HEAVY RAIN POTENTIAL NEAR THE  
CENTRAL GULF COAST. THIS SYSTEM COULD FOCUS SLOW-MOVING/REPEAT  
CELLS WITH VERY HEAVY DOWNPOURS LEADING TO A LOCAL RUNOFF RISK.  
THE NORTHERN PLAINS TO UPPER MIDWEST SHOULD ALSO SEE CHANCES OF  
RAIN AND STRONG THUNDERSTORMS AS EJECTING IMPULSES ROUND THE  
RIDGE. A SMALL SLIGHT RISK WAS ADDED TO THE DAY 5 EXPERIMENTAL  
EXCESSIVE RAINFALL OUTLOOK ACROSS EASTERN TN/CENTRAL APPALACHIANS  
WHERE MOISTURE AND INSTABILITY MAY POOL ALONG A FRONTAL BOUNDARY  
WITH AT LEAST LOCALLY HEAVY RAINFALL OVER AN AREA WITH RECENT  
RAINFALL AND HIGHER SUSCEPTIBILITY TO NEW RAINS. MEANWHILE, A  
PERSISTENT MONSOONAL MOISTURE FLOW INTO THE SOUTHWEST OFFERS  
CHANCES FOR SOME LOCALLY HEAVY DOWNPOURS.  
 
VERY HOT WEATHER IS EXPECTED TO PERSIST ACROSS THE SOUTHERN  
PLAINS/LOWER MISSISSIPPI VALLEY UNDERNEATH LINGERING UPPER RIDGING  
EARLY NEXT WEEK, BEFORE EASING SLIGHTLY FOLLOWING A FRONTAL  
PASSAGE. EARLY WEEK HIGH TEMPERATURES NEAR OR EXCEEDING 100F ARE  
EXPECTED, WHICH IS BETWEEN 5 AND 15 DEGREES ABOVE NORMAL. COMBINED  
WITH THE HUMIDITY, DAILY MAXIMUM HEAT INDICES UPWARDS TO 105-110F+  
ARE LIKELY AND THE REPEATING DAYS OF HIGH HEAT/HUMIDITY AND LACK  
OF APPRECIABLE NIGHTTIME RELIEF (LOWS IN THE UPPER 70S TO LOW 80S  
FOR SOME AREAS) WILL INCREASE THE POTENTIAL FOR IMPACTS FROM THIS  
HEATWAVE TO THE MORE VULNERABLE POPULATIONS. SEVERAL DAILY RECORD  
HIGH TEMPERATURES ARE POSSIBLE, PARTICULARLY FOR WARM LOWS, BUT A  
FEW HIGHS MAY BE CLOSE TO RECORDS IN TEXAS. AS THE UPPER RIDGE  
DRIFTS WESTWARD TOWARDS THE FOUR CORNERS BY LATE WEEK, ANOMALOUS  
HEAT IS FORECAST TO DEVELOP AND OVERSPREAD THE NORTHERN PLAINS AS  
UPPER RIDGING BUILDS OVER THE NORTHERN ROCKIES AHEAD OF AN UPPER  
TROUGH ADVANCING INTO SOUTHWESTERN CANADA. DOWNSTREAM, THE EAST  
MAY INITIALLY SEE WARM TEMPS/HUMIDITY ON TUESDAY IN BETWEEN  
FRONTS, BUT CAN EXPECT SLIGHTLY COOLER THAN NORMAL TEMPERATURES  
BEHIND THE COLD FRONT, BEFORE WARMING TO NEAR/JUST ABOVE NORMAL BY  
THE END OF THE WEEK.  
 
SANTORELLI/SCHICHTEL  
 
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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