022  
FXUS02 KWBC 081919  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
318 PM EDT FRI JUL 08 2022  
 
VALID 12Z MON JUL 11 2022 - 12Z FRI JUL 15 2022  
 
...A PROLONGED HEAT WAVE WILL LAST THROUGH EARLY NEXT WEEK ACROSS  
THE SOUTHERN PLAINS AND MID-SOUTH...  
   
..OVERVIEW
 
 
IT REMAINS THE CASE THAT 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, OPPRESSIVE  
HEAT INDICES ARE LIKELY 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 THROUGH MIDWEEK BEFORE HEAT OVERSPREADS THE NORTHERN PLAINS  
BY LATE WEEK. 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-FRIDAY. RAIN AND  
THUNDERSTORMS ARE FORECAST TO BE HEAVIEST NEAR THE SOUTHEAST U.S.  
COAST AS A COLD FRONT STALLS. THE STALLED FRONT IS FORECAST TO  
INTERACT WITH AN UPPER LOW FROM THE SUB-TROPICS AND MAY RESULT IN  
HEAVY RAIN POTENTIAL NEAR THE CENTRAL GULF COAST MIDWEEK. 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-LATER NEXT WEEK. MEANWHILE, A PERSISTENT MONSOONAL  
MOISTURE FLOW INTO THE SOUTHWEST OFFERS MULTI-DAY CHANCES FOR  
PERIODS OF LOCALLY ENHANCED RAINFALL.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
THE MOST UNCERTAIN ASPECT IN THE MEDIUM-RANGE PERIOD IS NEAR THE  
CENTRAL GULF COAST WHERE AN UPPER LOW MOVING NORTHWEST ACROSS THE  
GULF OF MEXICO IS FORECAST TO INTERACT WITH A STALLED FRONT AND  
COULD RESULT IN HEAVY RAINFALL IN THE VICINITY. THE ECMWF AND EC  
MEAN HAVE BEEN PLACING THE HEAVIEST RAINS FARTHER EAST TOWARD  
MS/AL COASTS AND WESTERN FLORIDA PANHANDLE THAN THE GFS AND GEFS.  
THE CMC ALSO INDICATES SUCH INTERACTION BUT WITH LESS QPF. THE  
ECMWF MIGHT INTRODUCE TOO MUCH CONVECTIVE FEEDBACK ON THIS SYSTEM  
SO THAT A TROPICAL CYCLONE WAS FORECAST TO RACE UP THE EAST COAST  
IN YESTERDAY'S 12 UTC RUN, AND WITH A SIMILAR TENDENCY IN  
SUBSEQUENT RUNS. A BLEND OF THE GFS/GEFS WITH ECMWF/EC MEAN  
TOGETHER WITH THE ENSEMBLE BIAS-CORRECTED QPF WAS USED, WHICH  
TENDS TO KEEP A HEAVY RAIN THREAT NEAR THE CENTRAL GULF COAST  
REGION MIDWEEK.  
 
THE WPC MEDIUM RANGE PRODUCT SUITE WAS DERIVED FROM A COMPOSITE  
BLEND OF THE REASONABLY WELL-CLUSTERED MODEL GUIDANCE WITH 40%  
FROM THE 06 UTC GFS/GEFS, 40% FROM THE 00Z UTC ECMWF/EC MEAN, AND  
20% FROM THE 00Z CMC/CMC MEAN, USING MORE OF THE ENSEMBLE MEANS  
WITH INCREASING FORECAST LEAD TIME. THIS FORECAST STRATEGY  
MAINTAINS GOOD WPC PRODUCT CONTINUITY IN A PATTERN WITH OVERALL  
ABOVE NORMAL PREDICTABILITY.  
   
..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 SLOWLY WEAKENS AND  
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 INTO MONDAY. ALTHOUGH MOISTURE AND  
INSTABILITY LEVELS WILL BE SUFFICIENT, THE POSSIBLY QUICKER STORM  
MOTIONS AND THE UNCERTAINTY IN THE DETAILS OF THE  
SHORTWAVES/FRONTAL PLACEMENT PRECLUDE SLIGHT RISK ISSUANCE IN THE  
WPC EXPERIMENTAL EXCESSIVE RAINFALL OUTLOOK AT THIS POINT.  
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  
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.  
 
AN UPPER LEVEL WEAKNESS NEAR THE CENTRAL GULF COAST INTERACTING  
WITH THE STALLED FRONT AND AN UPPER LOW MOVING ACROSS THE GULF OF  
MEXICO COULD BRING SOME LOCALLY HEAVY RAINFALL TO COASTAL  
LOCATIONS FROM EARLY TO MIDDLE OF NEXT WEEK. THIS SYSTEM COULD  
FOCUS SLOW-MOVING/REPEAT CELLS WITH VERY HEAVY DOWNPOURS LEADING  
TO LOCAL RUNOFF RISK. A SLIGHT RISK OF EXCESSIVE RAINFALL HAS  
BEEN INTRODUCED NEAR THE LOUISIANA COAST ON DAY 4.  
 
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 NEXT 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. 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. 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.  
 
KONG/SCHICHTEL, ET AL.  
 
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  
 
HAZARDS:  
- HEAVY RAIN ACROSS PORTIONS OF THE CENTRAL GULF COAST, MON-THU,  
JUL 11-JUL 14.  
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHEAST, MON, JUL 11.  
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHEAST AND THE SOUTHERN  
MID-ATLANTIC, THU-FRI, JUL 14-JUL 15.  
- FLOODING POSSIBLE ACROSS PORTIONS OF THE MIDDLE MISSISSIPPI  
VALLEY AND THE UPPER MISSISSIPPI VALLEY.  
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE CENTRAL  
PLAINS, THE UPPER MISSISSIPPI VALLEY, AND THE NORTHERN PLAINS.  
- FLOODING LIKELY ACROSS PORTIONS OF THE MIDDLE MISSISSIPPI VALLEY.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE CENTRAL AND SOUTHERN  
PLAINS, MON, JUL 11.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE LOWER AND MIDDLE  
MISSISSIPPI VALLEY AND THE SOUTHERN PLAINS, MON-WED, JUL 11-JUL 13.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE SOUTHERN PLAINS, MON-THU,  
JUL 11-JUL 14.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE CENTRAL AND NORTHERN  
PLAINS, THU-FRI, JUL 14-JUL 15.  
 
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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