870  
FXUS02 KWBC 090700  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 AM 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
 
 
AN UNCERTAIN ASPECT IN THE MEDIUM-RANGE PERIOD REMAINS NEAR THE  
CENTRAL GULF COAST WHERE AN UPPER FEATURE FROM THE GULF OF MEXICO  
AND POSSIBLE SURFACE LOW MAY INTERACT WITH A STALLED FRONT AND  
COULD RESULT IN HEAVY RAINFALL IN THE VICINITY. THE ECMWF/ECMWF  
ENSEMBLE MEAN AND ESPECIALLY NOW THE UKMET FOCUS THE HEAVIEST  
RAINS FARTHER EAST TOWARD MS/AL COASTS AND WESTERN FLORIDA  
PANHANDLE THAN THE GFS AND GEFS MEAN. THE CMC ALSO INDICATES SUCH  
INTERACTION, BUT WITH LESS QPF. EVEN A COMPOSITE BLEND ACTS TO  
EMPHASIZE A THREAT THAT SEEMS PLAUSIBLE GIVEN SURFACE  
PATTERN/TROPICAL MOISTURE POTENTIAL ALONG WITH THE SLOW MOVING AND  
AMPLIFIED NATURE OF THE UPPER FLOW THAT WOULD TEND TO KEEP A DEEP  
MOISTURE AND HEAVY RAIN THREAT NEAR THE CENTRAL GULF COAST REGION  
NEXT WEEK. ANOTHER RECENT MODEL DIFFERENCE OF NOTE CONCERNED  
CONSISTENCY WITH LATER PERIOD AMPLITUDE OF UPPER TROUGH ENERGY  
NEAR THE PACIFIC NORTHWEST, BUT FORECAST SPREAD HAS DECREASED,  
WITH MOST GUIDANCE NOW SHOWING MODERATE OR BETTER AMPLIFICATION  
AND NEAR NEUTRAL TILT.  
 
THE WPC MEDIUM RANGE PRODUCT SUITE WAS MAINLY DERIVED FROM A  
COMPOSITE OF THE 18 UTC GFS AND 12 UTC ECMWF/UKMET/CANADIAN ALONG  
WITH 01 UTC NATIONAL BLEND OF MODELS TUESDAY INTO THURSDAY.  
GRADUALLY INCREASING FORECAST SPREAD INTO DAYS 6/7 (FRIDAY/NEXT  
SATURDAY) PROMPTED A PREFERENCE TRANSITION TOWARD THE 12 UTC ECMWF  
ENSEMBLE MEAN ALOFT, WHOSE MOST AMPLIFIED ENSEMBLE MEAN SOLUTION  
SEEMED TO BEST FIT THE PATTERN. WPC PRODUCT CONTINUITY IS GOOD IN  
A PATTERN WITH ABOVE NORMAL PREDICTABILITY AND 00 UTC GUIDANCE  
GENERALLY REMAINS IN LINE.  
   
..OVERVIEW AND WEATHER/HAZARDS HIGHLIGHTS
 
 
A MEAN UPPER TROUGH POSITION WILL DEVELOP OFF THE PACIFIC  
NORTHWEST BY EARLY NEXT WEEK AS LEAD MIDWEST UPPER TROUGHING DIGS  
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. 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 WITH FRONTAL APPROACH.  
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. 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 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 TOWARD FOUR CORNERS, MUCH OF THE WEST. BY LATE WEEK, HEAT  
IS FORECAST TO DEVELOP AND OVERSPREAD THE NORTHERN PLAINS AS AN  
UPPER RIDGE EXITS THE NORTHERN ROCKIES AHEAD OF AN UPPER TROUGH  
ADVANCING INTO SOUTHWESTERN CANADA. DOWNSTREAM, THE EAST CAN  
EXPECT SLIGHTLY COOLER THAN NORMAL TEMPERATURES EARLY IN THE WEEK  
BEHIND THE COLD FRONT, BEFORE WARMING TO NEAR/JUST ABOVE NORMAL.  
 
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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