824  
FXUS02 KWBC 070652  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
252 AM EDT THU JUL 07 2022  
 
VALID 12Z SUN JUL 10 2022 - 12Z THU JUL 14 2022  
 
...A PROLONGED HEAT WAVE WILL LAST THROUGH EARLY NEXT WEEK ACROSS  
THE SOUTHERN PLAINS AND MID-SOUTH...  
   
..OVERVIEW
 
 
A PERSISTENT AND STRONG UPPER LEVEL HIGH DRIFTING WEST FROM THE  
SOUTHERN HIGH PLAINS AND THEN MEANDERING ATOP THE FOUR CORNERS  
STATES NEXT WEEK WILL KEEP VERY HOT TEMPERATURES IN PLACE ACROSS  
MUCH OF THE CENTRAL U.S. PARTICULARLY THROUGH AROUND TUESDAY.  
COMBINED WITH THE HUMIDITY, HEAT INDICES ARE LIKELY TO EXCEED  
105-110F IN PLACES AND WITH VERY LITTLE NIGHTTIME RELIEF IN  
TEMPERATURES, A PROLONGED HEAT WAVE IS EXPECTED TO CONTINUE ACROSS  
THE SOUTHERN HALF OF THE PLAINS AND MISSISSIPPI VALLEY. ON THE  
PERIPHERY OF THE UPPER RIDGE, TROUGHING IS FORECAST OVER THE  
NORTHEAST THIS WEEKEND WHILE ANOTHER TROUGH ACROSS THE NORTHWEST  
SUNDAY WILL TRACK QUICKLY ACROSS THE NORTH-CENTRAL U.S. AND  
REDEVELOP TROUGHING CENTERED IN THE NORTHEAST QUADRANT OF THE  
LOWER 48 BY TUESDAY-THURSDAY. RAIN AND THUNDERSTORMS ARE FORECAST  
FOR THE SOUTHEAST NEAR A COLD FRONT THAT SHOULD STALL AND  
DISSIPATE THROUGH THE FIRST HALF OF THE WEEK. THE NORTHERN PLAINS  
TO UPPER MIDWEST SHOULD ALSO SEE CHANCES OF RAIN AND POTENTIALLY  
SEVERE THUNDERSTORMS AHEAD OF ANOTHER COLD FRONT, AND SOME SHOWERS  
AND STORMS COULD SHIFT SOUTHEASTWARD WITH THE FRONT STRETCHING  
FROM THE NORTHEAST BACK INTO THE CENTRAL/SOUTHERN PLAINS  
TUESDAY-THURSDAY. MEANWHILE SOME MONSOONAL MOISTURE CONTINUES TO  
FLOW INTO THE SOUTHWEST.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
RECENT DETERMINISTIC AND ENSEMBLE GUIDANCE REMAINS IN GOOD  
AGREEMENT FOR THE LARGE SCALE SETUP AND EVOLUTION THROUGH THE  
FIRST HALF OF NEXT WEEK. SPECIFICALLY MODELS ARE QUITE AGREEABLE  
WITH THE UPPER HIGH/RIDGE STRETCHING FROM THE DESERT  
SOUTHWEST/NORTHERN MEXICO INTO THE NORTHERN PLAINS SUNDAY, THEN  
GETTING SUPPRESSED ON THE NORTHERN SIDE MONDAY BY TROUGHING/ENERGY  
MOVING QUICKLY EASTWARD FROM THE NORTHWEST/NORTHERN ROCKIES  
REGION. THERE ARE SOME MINOR SHORTWAVE AND FRONTAL/SURFACE LOW  
PLACEMENT DIFFERENCES ASSOCIATED WITH THE TROUGH, AFFECTING QPF AS  
WELL, AND IT MAY TAKE INTO THE SHORT RANGE PERIOD TO RESOLVE THESE  
ISSUES. BUT NO MAJOR DIFFERENCES WERE NOTED AND THE WPC FORECAST  
WAS RELATIVELY CLOSE TO CONTINUITY. MODELS THEN AGREE THAT THIS  
ENERGY SHOULD SERVE TO DEEPEN A TROUGH AXIS OVER THE GREAT LAKES  
AND OHIO VALLEY BY WEDNESDAY-THURSDAY. MEANWHILE FOR THE WEST, AN  
UPPER LOW SPINNING OVER THE NORTHEAST PACIFIC WILL SLOWLY PUSH  
TOWARD WESTERN CANADA THROUGH THE PERIOD, EVENTUALLY BRINGING  
TROUGHING TO THE PACIFIC NORTHWEST AROUND MIDWEEK. MOST MODELS AND  
ENSEMBLE MEANS WERE IN VERY GOOD AGREEMENT WITH THIS FEATURE, WITH  
THE EXCEPTION OF THE 12Z UKMET. THUS THE WPC FORECAST USED A BLEND  
OF THE 12Z/18Z GFS AND 12Z ECMWF AND CMC EARLY IN THE PERIOD,  
GRADUALLY ADDING IN SOME GEFS AND EC ENSEMBLE MEAN COMPONENT TO  
ABOUT A THIRD BY DAY 7 AS SOME SMALLER SCALE UNCERTAINTIES GROW.  
 
   
..SENSIBLE WEATHER AND HAZARDS
 
 
AS THE EASTERN PART OF A COLD FRONT CONTINUES TO DROP SOUTHWARD  
AND THEN STALL EARLY NEXT WEEK IN THE SOUTHEAST/CENTRAL GULF  
COAST/FLORIDA, IT WILL PROVIDE A FOCUS FOR ANOMALOUSLY HIGH  
MOISTURE TO POOL AND LEAD TO RAIN AND THUNDERSTORMS CHANCES  
CONTINUING FROM THE SHORT RANGE PERIOD. WHILE RAIN TOTALS ARE  
EXPECTED TO GRADUALLY DROP AS THE FRONT DISSIPATES, LOCALIZED  
AREAS OF FLASH FLOODING CANNOT BE RULED OUT ESPECIALLY IF MULTIPLE  
ROUNDS OF HEAVY RAIN AFFECT THE SAME AREAS. FARTHER NORTH,  
SHORTWAVE ENERGY AND A FRONTAL SYSTEM OR TWO ARE FORECAST TO LEAD  
TO RAIN AND THUNDERSTORMS ACROSS THE NORTHERN PLAINS AND UPPER  
MIDWEST SUNDAY-MONDAY. ALTHOUGH MOISTURE LEVELS WILL BE  
SUFFICIENT, THE POSSIBLY QUICKER STORM MOTIONS AND THE UNCERTAINTY  
IN THE DETAILS OF THE SHORTWAVES/FRONTAL PLACEMENT PRECLUDE SLIGHT  
RISK ISSUANCES IN THE WPC EXPERIMENTAL EXCESSIVE RAINFALL OUTLOOK  
THERE AT THIS POINT. HOWEVER, THE STORM PREDICTION CENTER  
CURRENTLY DELINEATES PARTS OF THE DAKOTAS INTO MUCH OF MINNESOTA  
IN A SLIGHT RISK FOR SEVERE WEATHER. RAINFALL ACTIVITY SHOULD  
SHIFT TOWARD THE GREAT LAKES REGION AND THEN THE NORTHEAST  
MONDAY-WEDNESDAY, WITH SCATTERED STORMS ALSO POSSIBLE ALONG THE  
TRAILING COLD FRONT IN THE OHIO VALLEY AND EVEN BACK INTO CENTRAL  
AND THEN SOUTHERN PARTS OF THE PLAINS AND MISSISSIPPI VALLEY.  
ELSEWHERE, MONSOONAL MOISTURE COULD PERSIST EVEN INTO NEXT WEEK  
WITH MOIST SOUTHWESTERLY FLOW/EMBEDDED SHORTWAVES LEADING TO  
MAINLY DIURNALLY DRIVEN SHOWERS AND STORMS OVER THE FOUR CORNERS  
STATES. THE WEST COAST SHOULD BE THE MOST CONSISTENTLY DRY AREA  
THROUGH THE PERIOD.  
 
VERY HOT WEATHER IS EXPECTED TO PERSIST ACROSS THE SOUTHERN HALF  
OF THE PLAINS/MISSISSIPPI VALLEY UNDERNEATH THE STRONG UPPER  
RIDGE/HIGH EARLY NEXT WEEK, BEFORE FINALLY SOME SLIGHT MODERATION  
AROUND MIDWEEK. 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 105-110F+ ARE LIKELY  
AT TIMES ACROSS THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY  
THROUGH EARLY NEXT WEEK. THE REPEATING DAYS OF HIGH HEAT/HUMIDITY  
AND LACK OF ANY APPRECIABLE NIGHTTIME RELIEF (LOWS IN THE UPPER  
70S TO LOW 80S FOR SOME AREAS) WILL INCREASE THE POTENTIAL FOR  
IMPACTS FROM THIS PROLONGED HEATWAVE TO THE MORE SENSITIVE AND  
VULNERABLE POPULATIONS. SEVERAL DAILY RECORD HIGH TEMPERATURES ARE  
POSSIBLE, PARTICULARLY FOR WARM LOWS BUT A FEW HIGHS MAY BE CLOSE  
TO RECORDS IN TEXAS. A BRIEFER PERIOD OF TEMPERATURES 10-20F ABOVE  
AVERAGE IS FORECAST FOR THE CENTRAL/NORTHERN PLAINS ON SUNDAY  
BEFORE APPROACHING CLOSER TO AVERAGE AS THE WORKWEEK BEGINS. AS  
THE UPPER RIDGE DRIFTS WESTWARD, THE WEST SHOULD SEE TEMPERATURES  
WARMING FROM SLIGHTLY BELOW NORMAL TO ABOVE NORMAL (BY 10+ DEGREES  
IN THE NORTHWEST) AS NEXT WEEK PROGRESSES. THE EAST CAN EXPECT  
SLIGHTLY COOLER THAN NORMAL TEMPERATURES EARLY IN THE WEEK BEHIND  
THE COLD FRONT, BEFORE WARMING TO NEAR/JUST ABOVE NORMAL.  
 
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  
 

 
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page