840  
FXUS64 KMOB 132011  
AFDMOB  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOBILE AL  
311 PM CDT THU AUG 13 2020  
   
NEAR TERM UPDATE /NOW THROUGH FRIDAY/
 
AFTERNOON FORECAST REMAINS  
ON TRACK WITH NO CHANGES NECESSARY AT THIS TIME. SLOW-MOVING  
SHOWERS AND THUNDERSTORMS CONTINUE TO DEVELOP OVER SOUTHEAST  
MISSISSIPPI THAT ARE FORECAST TO EXPAND TO THE SOUTHEAST INTO  
SOUTHWEST ALABAMA THROUGH THE REMAINDER OF THE DAY. IN ADDITION,  
ISOLATED SHOWERS AND A FEW STORMS HAVE FORMED ALONG A SEABREEZE  
PUSHING INLAND ACROSS OUR COASTAL COUNTIES. THESE SHOWERS AND  
STORMS WILL WILL CONTINUE TO EXPAND IN COVERAGE TO THE NORTH THIS  
AFTERNOON. MINOR/NUISANCE FLOODING CONTINUES TO BE THE MAIN THREAT  
TODAY AS THE DEEP STEERING FLOW REMAINS LIGHT COUPLED WITH DEEP  
MOISTURE IN PLACE OVER THE REGION. GUSTY OUTFLOW WINDS FROM SOME  
OF THE STRONGER THUNDERSTORMS ARE ALSO EXPECTED, WITH LOCALIZED  
WIND GUST BETWEEN 40 TO 50 MPH POSSIBLE.  
 
AN UPPER LEVEL SHORTWAVE OVER MISSISSIPPI WILL SLIDE EASTWARD  
THROUGH THE NEAR TERM, WITH THE AXIS REACHING CENTRAL ALABAMA BY  
NOON FRIDAY. A SECOND UPPER SHORTWAVE AND IMPULSES WILL APPROACH  
THE AREA FROM THE NORTHWEST ON FRIDAY, CARVING OUT A LARGER UPPER  
TROUGH OVER THE EASTERN CONUS BY LATE FRIDAY AFTERNOON. ISOLATED  
TO SCATTERED SHOWERS AND THUNDERSTORMS WILL PERSIST INTO THE EARLY  
EVENING HOURS, MAINLY ACROSS THE NORTHERN HALF OF THE FORECAST  
AREA, FOLLOWED BY A BRIEF LULL IN ACTIVITY FROM MID EVENING  
THROUGH ABOUT 4 AM. SCATTERED SHOWERS AND A FEW THUNDERSTORMS ARE  
THEN FORECAST TO REDEVELOP LATE TONIGHT THROUGH DAYBREAK WITH THE  
APPROACH OF THE SECOND UPPER SHORTWAVE. LOW TEMPERATURE TONIGHT  
WILL CONTINUE TO BE IN THE 70S.  
 
AN UNSETTLED WEATHER PATTERN WILL REMAIN THROUGH FRIDAY DUE TO  
DECREASING DAYTIME STABILITY, WITH SBCAPES CLIMBING BACK TO  
BETWEEN 1500 AND 2200 J/KG. ISOLATED POCKETS OF UP TO 3000 J/KG  
MAY OCCUR ACROSS OUR COASTAL ZONES BY EARLY AFTERNOON WHERE  
SURFACE DEWPOINTS WILL BE THE HIGHEST. DEEP MOISTURE WILL BE NO  
PROBLEM AS PRECIPITABLE WATER VALUES FLUCTUATE BETWEEN 2.0 TO 2.4  
INCHES THROUGH THE ENTIRE PERIOD.  
 
THEREFORE, KEPT NUMEROUS SHOWERS AND THUNDERSTORMS IN THE  
FORECAST ON FRIDAY, AND OUTFLOW WINDS FROM SOME OF THE STRONGER  
THUNDERSTORMS, WITH LOCALIZED WIND GUST BETWEEN 40 TO 50 MPH,  
REMAIN POSSIBLE. ADDITIONAL WIDESPREAD RAINFALL AMOUNTS THROUGH  
THE PERIOD WILL LIKELY RANGE FROM 0.5 TO 1.5 INCHES, WITH  
LOCALIZED HIGHER AMOUNTS UP TO 3 INCHES. HIGH TEMPERATURES FRIDAY  
WILL RANGE FROM 86 TO 91 DEGREES, WITH HEAT INDICES IN THE MID TO  
UPPER 90S. /22  
 

 
   
SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/
 
AN UPPER LEVEL  
TROUGH WILL BUILD OVER THE EASTERN CONUS THROUGH MUCH OF THE  
WEEKEND, WITH AN UPPER RIDGE PERSISTING OVER THE DESERT SOUTHWEST.  
BY LATE WEEKEND HOWEVER, THE TROUGH WILL LIFT TO THE NORTHEAST  
SOMEWHAT AND THE RIDGE TO THE WEST WILL BUILD INTO THE REGION.  
MEANWHILE, HIGH PRESSURE WILL CONTINUE OVER THE GULF OF MEXICO  
THROUGH THE WEEKEND. A SURFACE BOUNDARY WILL ALSO SLOWLY SLIDE  
OVER THE TENNESSEE VALLEY THROUGH SATURDAY. BY SUNDAY, THIS  
FEATURE WILL PROGRESS SOUTHEAST TOWARDS THE EAST COAST. ANOTHER  
COLD FRONT TO ITS NORTHWEST, WILL MOVE OVER THE MISSISSIPPI VALLEY  
AND APPROACH THE SOUTHEASTERN CONUS DURING THIS TIME.  
 
OVERALL, SCATTERED SHOWERS AND STORMS WILL BE THE THEME THROUGH  
THE SHORT TERM PERIOD. EXPECTING ACTIVITY TO BEGIN OVER THE OPEN  
GULF WATERS THROUGH THE LATE NIGHT/EARLY MORNING HOURS THEN  
TRANSITION OVER LAND THROUGH THE DAY. PWATS WILL BE ELEVATED,  
ESPECIALLY INITIALLY. VALUES WILL RANGE FROM 1.7-2.3 INCHES ON  
SATURDAY (HIGHER VALUES TOWARDS THE COAST); HOWEVER, DEEP LAYER  
MOISTURE WILL BE ON THE DECLINE BY LATE WEEKEND, WITH VALUES  
BETWEEN 1.3-1.7 INCHES ON SUNDAY. THIS IS DUE TO COOLER, DRIER AIR  
BEING BROUGHT DOWN FROM THE NORTH BY THE APPROACHING COLD FRONT.  
MODEL MLCAPE VALUES WILL RANGE FROM 700-1000 J/KG THROUGH THE  
WEEKEND AS WELL. THEREFORE, BETTER COVERAGE OF SHOWERS/STORMS IS  
EXPECTED SATURDAY, WITH LESS COVERAGE ON SUNDAY. THIS IS REFLECTED  
BY LIKELY POPS FOLLOWED BY CHANCE POPS, RESPECTIVELY. SHOWER AND  
STORM ACTIVITY WILL THEN WANE BY SUNDAY NIGHT, WITH ONLY SOME  
ISOLATED SHOWERS/STORMS ANTICIPATED.  
 
HIGH TEMPERATURES WILL BE IN THE UPPER 80S TO LOWER 90S SATURDAY  
BUT THEN WARM TO BE IN THE LOWER TO MID 90S BY SUNDAY AFTERNOON.  
LOWS FRIDAY NIGHT ARE EXPECTED TO BE IN THE LOWER TO MID 70S NORTH  
OF I-10 AND IN THE MID TO UPPER 70S SOUTH. LOWS THROUGH THE  
WEEKEND WILL THEN BE ONLY A TOUCH COOLER. LASTLY, A LOW RISK OF  
RIP CURRENTS CONTINUES THROUGH THE WEEKEND. /26  
 

 
   
EXTENDED TERM /MONDAY THROUGH THURSDAY/
 
THROUGH MONDAY, THE UPPER  
LEVEL TROUGH OVER THE EAST CONUS WILL BUILD OVER THE NORTHERN  
GULF COAST YET AGAIN AND EVENTUALLY OVER THE ARKLATEX REGION, WITH  
THE UPPER RIDGE OVER THE DESERT SOUTHWEST RETREATING BACK WEST.  
THIS TROUGH WILL THEN AMPLIFY THROUGH THE WEEK. EXPECTING COLD  
FROPA OVER THE NORTHERN GULF COAST THROUGH TUESDAY. A SURFACE LOW  
WILL ALSO FORM OVER THE PANHANDLE OF FLORIDA TUESDAY AND PERSIST  
OVER THIS AREA THROUGH THE REMAINDER OF THE EXTENDED TERM.  
ADDITIONALLY, THE COLD FRONT IS EXPECTED TO STALL AND LINGER SOUTH  
OF THE COAST OVER THE GULF DURING THIS TIME. A SHIFT TO A MORE  
NORTHERLY WIND FLOW IS ANTICIPATED LATE WEEKEND THROUGH EARLY NEXT  
WEEK WITH THIS COLD FROPA. SOUTHERLY FLOW IS NOT EXPECTED TO  
RETURN UNTIL LATE NEXT WEEK.  
 
THE AFOREMENTIONED PATTERN WILL RESULT IN DECREASING MOISTURE FOR  
THE REGION. THIS IS REFLECTED IN DECLINING DEW POINTS FROM THE  
LOWER TO MID 70S ON MONDAY TO THE MID TO UPPER 60S TO AROUND 70  
DEGREES BY TUESDAY MORNING. EXPECTING DEW POINTS THROUGH THURSDAY  
TO THEN MAINLY BE IN THE 60S NORTH OF I-10 AND IN THE UPPER 60S TO  
LOWER 70S SOUTH. FURTHERMORE, PWATS WILL ONLY RANGE FROM ABOUT  
1.2-1.6 INCHES DURING THIS TIME. THUS, CAPPED POPS GIVEN BY THE  
BLENDED SOLUTION AT CHANCE FOR THE DURATION OF THE EXTENDED TERM.  
MLCAPE VALUES SHOWN BY MODELS WILL ALSO RANGE FROM 500-1000 J/KG  
FROM MONDAY THROUGH THURSDAY. ALL OF THIS WILL LEAD TO DAILY  
CHANCES OF ISOLATED TO SCATTERED SHOWERS AND STORMS, BEGINNING  
OVER THE OPEN GULF WATERS AND RIGHT ALONG THE COAST DURING THE  
LATE NIGHT/EARLY MORNING HOURS THEN TRANSITIONING OVER LAND  
THROUGH THE DAY. THIS ACTIVITY WILL THEN DECREASE THROUGH THE  
EVENING EACH DAY.  
 
COLD FROPA WILL ALSO BRING SOME RELIEF IN THE FORM OF SLIGHTLY  
COOLER TEMPERATURES. AFTER HIGH TEMPERATURES IN THE LOWER 90S  
MONDAY AFTERNOON, HIGHS WILL GENERALLY BE IN THE UPPER 80S TO  
AROUND 90 DEGREES THROUGH THURSDAY. ALSO, LOWER DEW POINTS WILL  
CAUSE HEAT INDICES TO ONLY TOP OUT IN THE MID 90S TUESDAY THROUGH  
THURSDAY. LOWS WILL THEN BE IN THE UPPER 60S TO LOWER 70S OVER  
INLAND AREAS AND MAINLY IN THE MID 70S RIGHT ALONG THE COAST. /26  
 

 
   
MARINE
 
NO IMPACTS FORECAST EXCEPT WINDS AND WAVES HIGHER NEAR  
STORMS EACH DAY. ENVIRONMENTAL CONDITIONS SUPPORT THE DEVELOPMENT  
OF WATERSPOUTS EACH MORNING. /22  
 

 
   
MOB WATCHES/WARNINGS/ADVISORIES
 
 
AL...NONE.  
FL...NONE.  
MS...NONE.  
GM...NONE.  

 
 

 
 
THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT:  
HTTP://WEATHER.GOV/MOB  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab AL Page
The Nexlab FL Page
The Nexlab MS Page Main Text Page