272  
FXUS64 KMOB 181130  
AFDMOB  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOBILE AL  
630 AM CDT FRI AUG 18 2017  
   
DISCUSSION
 
UPDATED FOR LATEST AVIATION DISCUSSION BELOW.  
 

 
   
AVIATION
 
 
18/12Z ISSUANCE...VFR CONDTIONS EXPECTED TO PREVAIL ACROSS THE REGION  
THROUGH MOST OF THE FORECAST PERIOD. EXPECT A PERSISTENCE FORECAST  
TODAY AND TONIGHT, WITH DEVELOPMENT OF ISOLATED TO SCATTERED SHRA/TSRA  
BY THIS AFTERNOON, ENDING AFTER SUNSET THIS EVENING. SURFACE WINDS  
GENERALLY LIGHT, PRIMARILY OUT OF THE WEST. 12/DS  
 

 
   
PREV DISCUSSION
 
/ISSUED 415 AM CDT FRI AUG 18 2017/  
 
NEAR TERM /NOW THROUGH FRIDAY NIGHT/...CONVECTION WAS RATHER LIMITED  
YESTERDAY AFTERNOON AS COMPARED TO PREVIOUS COUPLE OF DAYS, AS  
EXPECTED, ALTHOUGH THERE WERE A FEW SHOWERS AND STORMS AROUND. FOR  
TODAY, EXPECT SIMILAR CONDITIONS BUT PERHAPS A FEW MORE SHOWERS  
AND STORMS THIS AFTERNOON MAINLY CONFINED TO THE SOUTHERN HALF OF  
THE FORECAST AREA. UPPER RIDGING WEAKENS SLIGHTLY IN THE NEAR  
TERM, WITH THE TAIL END OF A WEAK MID/UPPER LEVEL SHORTWAVE MOVING  
WEST TO EAST ACROSS THE FORECAST AREA TODAY. MEANWHILE, A SURFACE  
HIGH PRESSURE RIDGE AXIS ALONG THE GULF COAST THIS MORNING IS  
EXPECTED TO DRIFT FURTHER OFFSHORE THROUGH TONIGHT AS A WEAK  
FRONT/TROF DRIFTS WELL SOUTH INTO THE AREA. SUBSIDENCE WILL BE A  
LITTLE LESS PRONOUNCED TODAY, AND THE SURFACE FRONT/TROF MOVING IN  
FROM THE NORTH WILL PROVIDE A LOW LEVEL FOCUS. THIS COMBINED WITH  
PWAT'S STILL RANGING FROM AROUND 1.3 INCHES OVER NORTHERN INLAND  
ZONES TO NEAR 2.0 INCHES AT THE COAST, SHOULD RESULT IN ISOLATED  
TO SCATTERED CONVECTION ACROSS SOUTHERN PORTIONS OF THE FORECAST  
AREA THIS AFTERNOON. NO SEVERE THREAT EXPECTED WITH THE ISOLATED  
TO SCATTERED STORMS, BUT LOCALIZED HEAVY RAIN, LIGHTNING AND BRIEF  
STRONG GUSTY WINDS CAN BE EXPECTED WITH ANY STORMS THAT DO  
DEVELOP. MOST OF THE CONVECTIVE ACTIVITY WILL BE THIS AFTERNOON,  
DIMINISHING QUICKLY AFTER SUNSET WITH LOSS OF INSTABILITY. WITH  
ABUNDANT SUNSHINE TODAY, ESPECIALLY EARLY, SHOULD BE ANOTHER HOT  
DAY TODAY, BUT HIGH TEMPS LIKELY A FEW DEGREES LOWER THAN  
YESTERDAY IN MOST LOCATIONS. MAX TEMPS THIS AFTERNOON ARE  
GENERALLY EXPECTED TO BE IN THE LOWER 90S FOR MOST LOCATIONS,  
EXCEPT FOR ALONG THE IMMEDIATE COAST WHERE SOME UPPER 80S ARE  
POSSIBLE. LOW TEMPS TONIGHT STILL WARM, IN THE LOW TO MID 70S  
INLAND AND MID TO UPPER 70S AT THE COAST. MUGGY CONDITIONS  
CONTINUE. 12/DS  
 
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...ON THE SOUTHERN  
PERIPHERY OF A MID LEVEL RIDGE NOSING WESTWARD OVER THE DEEP  
SOUTH OVER THE WEEKEND, A WELL DEFINED UPPER LEVEL TROF MOVES  
WESTWARD OVER THE GULF. DEEP LAYER MOISTURE, WITH PRECIPITABLE  
WATER (PWAT) VALUES AROUND 1.5 INCHES ON SATURDAY, LIES BETWEEN 1  
AND 2 STANDARD DEVIATIONS BELOW THE CLIMATOLOGICAL MEAN AS WE  
BEGIN THE LATTER HALF OF AUGUST. ALTHOUGH THERE IS SOME INFLUENCE  
OF LARGER SCALE SUBSIDENCE FROM RIDGE ALOFT AND ON THE NORTHERN  
AND WESTERN FLANK OF WESTWARD MOVING UPPER TROF TO THE SOUTH,  
CANNOT DISCOUNT A CHANCE OF SHOWERS AND STORMS DURING THE HEAT AND  
INSTABILITY OF THE DAY AS DEEP LAYER MOISTURE WILL BE ADEQUATE.  
DAYTIME HIGHS ON SATURDAY MOST LOCATIONS LOOK TO RISE TO BETWEEN  
93 AND 96. HEAT INDEX VALUES LIFT TO BETWEEN 102 AND 107.  
OVERNIGHT LOWS SATURDAY NIGHT 72 TO 75 INTERIOR TO MID TO UPPER  
70S COAST, WITH POTENTIAL OF LATE NIGHT SHOWERS AND STORMS CLOSER  
TO THE COAST AND OFFSHORE.  
 
AS THE AXIS OF THE UPPER TROF PIVOTS SLOWLY WEST OVER THE CENTRAL  
GULF ON SUNDAY, HIGHEST DEEP LAYER MOISTURE RECOVERS TO AROUND  
1.8 INCHES ALONG THE COAST THRU THE DAY. CONSIDERING THIS AND  
TRANSITIONING TO THE MORE FAVORED EASTERN SIDE OF THE TROF FOR  
BETTER SHOWER AND STORM POTENTIAL, WILL MENTION A MID RANGE CHANCE  
PROBABILITY. OVER THE INTERIOR, DEEP LAYER MOISTURE LOOKS TO  
REMAIN ABOUT A THIRD OF AN INCH LOWER IN PWAT AND LARGER SCALE  
SUBSIDENCE ASSOCIATED WITH MORE UPPER RIDGING THERE SUGGESTS A  
LOWER PROBABILITY THAN THAT ALONG THE COAST. DAYTIME HIGHS ON  
SUNDAY MID 90S ALONG AND NORTH OF I-10 TO LOWER 90S CLOSER TO THE  
COAST. HEAT INDEX VALUES 102 AND 107. /10  
 
LONG TERM /MONDAY THROUGH THURSDAY/...UPPER RIDGE AXIS OFF THE  
SOUTHEAST US COAST, BUILDS WEST THRU THE MIDDLE OF NEXT WEEK,  
PUSHING GULF UPPER TROF WESTWARD TO THE TEXAS COAST BY TUESDAY. A  
MARKED INCREASE IN PWAT IS SEEN MONDAY THRU WEDNESDAY WITH VALUES  
INCREASING TO BETWEEN 2.0 AND 2.1 INCHES ON AVERAGE. THUS, WILL  
MENTION A CHANCE OF DAILY STORMS DURING THE BETTER INSTABILITY OF  
EACH DAY. A DIURNAL DECREASE IN NIGHT-TIME CONVECTION OVER THE  
INTERIOR WHILE MAINTAINING SMALL PROBABILITIES CLOSER TO THE  
COAST AND OFFSHORE OVERNIGHT, WHICH IS COMMON IN SUMMER. HIGHS IN  
THE LOWER TO MID 90S INTERIOR TO 87 TO 90 COAST. HEAT INDEX VALUES  
TO MOSTLY RANGE 100 TO 105. OVERNIGHT LOWS IN THE MID 70S  
INTERIOR, 77 TO 80 CLOSER TO THE COAST. /10  
 
MARINE...A SURFACE HIGH PRESSURE RIDGE AXIS WILL CONTINUE TO EXTEND  
WEST ACROSS THE NORTHERN AND EASTERN GULF OF MEXICO THROUGH TODAY,  
BUT BEGIN TO WEAKEN SLIGHTLY BY SATURDAY AS A WEAK FRONT APPROACHES  
THE GULF COAST FROM THE NORTH. THIS PATTERN WILL RESULT IN A  
GENERALLY LIGHT WEST TO SOUTHWEST WIND FLOW THROUGH LATE SATURDAY,  
BUT AT TIMES A BRIEF NORTHWESTERLY COMPONENT IN THE LATE NIGHT AND  
EARLY MORNING HOURS. HIGH PRESSURE WILL AGAIN BUILD TO THE EAST OF  
THE MARINE AREA SUNDAY INTO THE EARLY PART OF NEXT WEEK WITH WINDS  
BECOMING MORE PREDOMINANT EAST TO SOUTHEAST. LITTLE CHANGE IN SEAS  
EXPECTED, GENERALLY REMAINING 2 FEET OR LESS THROUGH MOST OF THE  
PERIOD, INCREASING SLIGHTLY BY LATE MONDAY INTO TUESDAY. WINDS AND  
SEAS WILL HOWEVER BE LOCALLY HIGHER IN AND AROUND ISOLATED TO  
SCATTERED SHOWERS AND THUNDERSTORMS. 12/DS  
 

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

 
 

 
 
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