649  
FXUS02 KWBC 020700  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 AM EDT SAT JUL 02 2022  
 
VALID 12Z TUE JUL 05 2022 - 12Z SAT JUL 09 2022  
   
..OVERVIEW
 
 
A PERSISTENT UPPER LEVEL RIDGE/HIGH LOOKS TO BE IN PLACE NEXT WEEK  
OVER THE SOUTHERN TIER OF THE U.S. IN A COMMON SUMMER PATTERN,  
WITH RIDGING BUILDING FARTHER NORTHWARD IN THE ROCKIES/HIGH PLAINS  
AND CAUSING HOT TEMPERATURES ACROSS MUCH OF THE CENTRAL CONUS. THE  
STORM TRACK WILL THUS REMAIN FARTHER NORTH, WITH A RELOADING UPPER  
LOW ACROSS THE EASTERN PACIFIC/NORTHWEST U.S. AND GENERALLY WEST  
TO NORTHWEST FLOW WITH EMBEDDED SHORTWAVES ACROSS THE REST OF THE  
NORTHERN TIER. THIS FLOW PATTERN AND A QUASI-STATIONARY FRONTAL  
BOUNDARY DRAPED FROM THE NORTH-CENTRAL PLAINS TO THE MID-ATLANTIC  
WILL FOCUS SHOWERS AND STORMS, WITH SOME ORGANIZED CONVECTION AND  
LOCALLY HEAVY RAINFALL.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
RECENT MODEL GUIDANCE REMAINS IN GOOD AGREEMENT WITH THE SYNOPTIC  
PATTERN DESCRIBED ABOVE ESPECIALLY THROUGH THE MIDDLE OF NEXT  
WEEK, AND A BLEND OF THE DETERMINISTIC 12Z ECMWF, CMC, AND UKMET  
AND THE 12Z/18Z GFS WORKED WELL FOR THE FIRST HALF OF THE WPC  
MEDIUM RANGE FORECAST. INCREASING BUT RELATIVELY MINOR DIFFERENCES  
WERE SEEN AROUND THURSDAY, SUCH AS THE 12Z GFS BECOMING SOMEWHAT  
DIFFERENT WITH BROAD TROUGHING IN EASTERN CANADA AS IT WAS MORE  
AGGRESSIVE WITH A SHORTWAVE IN SOUTH-CENTRAL CANADA THAN OTHER  
GUIDANCE. REASONABLY LARGER SCALE DIFFERENCES ALSO ARISE BY  
FRIDAY-SATURDAY WITH THE EASTERN PACIFIC TROUGH/LOW, WITH THE  
12Z/18Z GFS RUNS HOLDING THE LOW OFFSHORE WHILE THE ECMWF AND CMC  
BRING TROUGHING INTO THE NORTHWEST BY THEN. THE WPC FORECAST  
FAVORED THE LATTER CLUSTER, SO THE MODEL BLEND LESSENED THE  
AMOUNTS OF GFS RUNS IN FAVOR OF THE AGREEABLE GEFS AND ECMWF  
ENSEMBLE MEAN GUIDANCE BY THE LATTER PART OF THE PERIOD, BUT  
MAINTAINED A MAJORITY OF THE OPERATIONAL GUIDANCE CONSIDERING THE  
REASONABLE AGREEMENT ON THE LARGE SCALE. THE NEW 00Z GFS IS FASTER  
THAN THE PREVIOUS RUNS AND MORE IN LINE WITH OTHER GUIDANCE,  
THOUGH THE 00Z GEFS MEAN SHOWS THAT A SLOWER TRACK IS STILL  
POSSIBLE. ALSO, OVERALL THE SMALLER SCALE FEATURES LIKE INDIVIDUAL  
SHORTWAVES SHOW CONSIDERABLY MORE VARIABILITY FROM MODEL TO MODEL,  
WHICH WILL LIKELY TAKE UNTIL THE SHORT RANGE PERIOD TO RESOLVE.  
UNFORTUNATELY THIS IS A PATTERN IN WHICH THESE MESOSCALE FEATURES  
MATTER GREATLY PARTICULARLY FOR QPF PLACEMENT AND AMOUNTS, SO  
CONTINUE TO FOLLOW UPDATES TO THE FORECAST FOR CHANGES GOING  
FORWARD.  
 
   
..SENSIBLE WEATHER AND HAZARDS
 
 
SCATTERED SHOWERS AND STORMS ARE LIKELY ACROSS MUCH OF THE U.S. AT  
TIMES NEXT WEEK, WITH ENHANCED TOTALS IN THE VICINITY OF A COUPLE  
OF FRONTAL BOUNDARIES STRETCHING GENERALLY WEST TO EAST ACROSS THE  
NORTHERN HALF OF THE COUNTRY. NORTHWESTERLY FLOW ALOFT AND  
ABUNDANT MOISTURE AND INSTABILITY WILL CREATE A FAVORABLE PATTERN  
FOR MESOSCALE CONVECTIVE SYSTEMS AND HIGH RAINFALL RATES FOR A  
BROAD AREA FROM THE NORTHERN PLAINS/MIDWEST/UPPER GREAT LAKES INTO  
THE OHIO VALLEY AND APPALACHIANS TO THE EAST COAST. THERE IS A  
SLIGHT RISK IN THE DAY 4 WPC EXPERIMENTAL EXCESSIVE RAINFALL  
OUTLOOK IN THE CENTRAL APPALACHIANS WHERE THIS ACTIVITY COULD  
FOCUS, AND HEAVY RAIN CAUSING FLASH FLOODING COULD CERTAINLY  
PERSIST INTO DAY 5 AND BEYOND BUT WITH CONSIDERABLE UNCERTAINTY IN  
THE PLACEMENT OF HEAVY RAIN AMOUNTS. SCATTERED THUNDERSTORMS ARE  
ALSO LIKELY IN THE SOUTHEAST THROUGH THE WEEK, AND SOME  
MID-ATLANTIC TO NORTHEAST RAIN EVENTS ARE POSSIBLE AS WELL  
DEPENDENT ON FRONTAL POSITIONS. MEANWHILE MONSOONAL MOISTURE COULD  
PERSIST THROUGH MUCH OF THE WEEK WITH MOIST SOUTHWESTERLY FLOW  
FROM THE EASTERN PACIFIC, LEADING TO MAINLY DIURNALLY DRIVEN  
SHOWERS AND STORMS OVER THE FOUR CORNERS STATES.  
 
THE GREATEST CONCERN FOR TEMPERATURES WILL BE WITH HEAT EXPECTED  
TO BUILD AGAIN ACROSS THE CENTRAL U.S. BY EARLY NEXT WEEK IN  
RESPONSE TO A STRENGTHENING UPPER LEVEL RIDGE. HIGHS OF 10-15  
DEGREES ABOVE NORMAL ARE FORECAST FOR THE CENTRAL PLAINS TO MIDDLE  
MISSISSIPPI VALLEY, EQUATING TO TEMPERATURES IN THE MID 90S TO LOW  
100S. SOUTHERN PLAINS LOCATIONS WILL SEE HOT TEMPERATURES AS WELL,  
BUT WITH LESS EXTREME ANOMALIES. WARMER THAN AVERAGE TEMPERATURES  
ARE LIKELY TO BUILD INTO THE NORTHERN ROCKIES TO NORTHERN PLAINS  
BY THURSDAY-SATURDAY. MEANWHILE THE WEST IS FORECAST TO BE COOLER  
THAN NORMAL IN RESPONSE TO TROUGHING ALOFT INITIALLY, BUT SHOULD  
MODERATE CLOSER TO NORMAL AND EVEN ABOVE NORMAL IN THE DESERT  
SOUTHWEST AND CALIFORNIA BY THE LATTER PART OF NEXT WEEK. THE EAST  
IS LIKELY TO BE NEAR AVERAGE TEMPERATURE-WISE.  
 
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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