741  
FXUS64 KMOB 222322  
AFDMOB  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOBILE AL  
622 PM CDT FRI JUN 22 2018  
   
DISCUSSION
 
UPDATED FOR LATEST AVIATION DISCUSSION BELOW.  
 

 
   
AVIATION
 
 
00Z ISSUANCE...A CLUSTER OF THUNDERSTORMS CURRENTLY OVER CENTRAL  
MISSISSIPPI WILL CONTINUE TO MAKE ITS WAY SOUTHEAST INTO THE LOCAL  
AREA THROUGH LATE THIS EVENING. THIS ACTIVITY WILL EVENTUALLY  
DISSIPATE AND GIVE WAY TO VFR CONDITIONS OVERNIGHT TONIGHT.  
EXCEPTION MAY BE SOME MVFR CIGS NEAR THE COAST RIGHT AROUND  
SUNRISE. OTHERWISE, VFR CONDITIONS AND LIGHT SOUTHWEST WINDS  
CONTINUE THROUGH THE REMAINDER OF THE PERIOD. /49  
 

 
   
PREV DISCUSSION
 
/ISSUED 333 PM CDT FRI JUN 22 2018/  
 
NEAR TERM /NOW THROUGH SATURDAY/...A SEASONABLY VERY PRONOUNCED AND  
DEEPLY-REFLECTED CYCLONE CURRENTLY OVER THE OHIO VALLEY LIFTS  
FURTHER TO THE NORTHEAST DURING THE NEXT 24 HOURS. THE NET EFFECT IS  
THAT OUR REGION REMAINS, AT FIRST (I.E., THE FIRST 12 H) WITHIN A  
ZONAL FLOW AND THEN GRADUALLY DEVELOPING DEEP-LAYER RIDGING BY LATE  
SATURDAY AFTERNOON. THE FIRST THING TO DEAL WITH IS INTENSE TO  
SEVERE THUNDERSTORMS (MAINLY NORTH OF HIGHWAY 84) WILL DECAY AS THEY  
ATTEMPT TO PROPAGATE SOUTHWARD AGAINST A DEEP-LAYER MEAN ZONAL FLOW.  
THERE IS ENOUGH VERTICAL WIND SHEAR FOR SOME OF THESE STORMS TO  
EVOLVE UPSCALE AND EXHIBIT MULTICELLULAR TRAITS, AND WITH FORECAST  
DOWNDRAFT-INDUCED COLD POOLS, SOME MAY EVEN BOW A BIT INTO THE  
EVENING HOURS. IN ADDITION, DRY AIR ALOFT WILL AID DOWNDRAFT  
ACCELERATION. VERY LOCALIZED WIND DAMAGE WILL BE THE MAIN THREAT.  
AMPLE THERMODYNAMIC INSTABILITY WILL WANE DURING THE EVENING HOURS.  
BEST RAIN CHANCES REMAIN ALONG AND NORTH OF HIGHWAY 84 THIS EVENING  
AND THIS SHIFTS TO NORTH OF HIGHWAY 84 AND EAST OF I-65 OVERNIGHT.  
PARTLY CLOUDY ELSEWHERE. ANOTHER WARM AND MUGGY NIGHT IN STORE. ON  
SATURDAY, THERE IS A VERY SMALL CHANCE OF RAIN ALONG THE MS/AL  
COASTAL ZONES (NEAR THE SEA-BREEZE AND MAINLY ALONG THE I-10  
CORRIDOR). RECEIVING ANY RAIN WILL BE THE EXCEPTION RATHER THAN THE  
RULE. HEAT INDICES WILL RISE INTO THE 98-103 DEG(F) RANGE AGAIN  
TOMORROW AFTERNOON.  
/23 JMM  
 
SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...AN UPPER LEVEL  
RIDGE BUILDS OVER THE SOUTHEAST INTO THE COMING WEEK, SHIFTING A  
SURFACE RIDGE FROM OVER THE CENTRAL GULF TO OVER THE NORTHERN  
GULF COAST. DURING THE BUILDING PROCESS, BANDS OF DRIER AIR WORK  
THEIR WAY ACROSS THE FORECAST AREA, AND WITH HIGH PRESSURE IN  
CONTROL, RAIN CHANCES DECREASE. INCREASING SUBSIDENCE WITH THE  
BUILDING HIGH BRINGS TEMPS ABOVE SEASONAL. ADDING IN THE  
REMAINING LOW LEVEL MOISTURE OVER THE AREA, DAYTIME HEAT INDICES  
GENERALLY RISING TO AROUND 105 ARE LIKELY, WITH A FEW LOCALITIES  
BUMPING HEAT ADVISORY LEVELS (108+), ESPECIALLY ON MONDAY.  
 
/16  
 
LONG TERM /TUESDAY THROUGH FRIDAY/...THE UPPER HIGH OVER THE  
SOUTHEAST LASTS INTO WEDNESDAY, THEN BEGINS TO SHIFT WEST AS  
SHORTWAVE ENERGY BEGINS TO DIG AN UPPER TROUGH OVER THE NORTHEASTERN  
CONUS. AT THIS POINT IN THE FORECAST, GUIDANCE DIVERGES  
SIGNIFICANTLY IN THE UPPER PATTERN OVER THE EAST, WITH THE GFS  
DEVELOPING A SURFACE LOW CENTERED OVER TENNESSEE BY THURSDAY,  
LASTING THROUGH FRIDAY BEFORE MOVING OFF. THIS SQUEEZES THE UPPER  
LEVEL RIDGE SOUTHWARD TO OVER THE NORTHERN GULF COAST. THE ECMWF  
ON THE OTHER HAND SHIFTS THE UPPER HIGH FROM OVER THE DESERT  
SOUTHWEST TO OVER THE CENTRAL MISSISSIPPI RIVER VALLEY THROUGH THE  
WEEK BEFORE MOVING OFF THE END OF THE WEEK AS A SHALLOW UPPER  
TROUGH DEVELOPS OVER THE NORTHERN GULF COAST. THE ECMWF ADVERTISES  
A STRONGER UPPER LEVEL HIGH PRESSURE OVER THE LOWER MISSISSIPPI  
RIVER VALLEY AND WESTERN HALF OF THE SOUTHEAST. WITH THAT, WARMER  
TEMPS THROUGH THURSDAY BEFORE THE UPPER TROUGH BECOMES DOMINANT.  
LOW LEVEL FLOW REMAINS OFF THE GULF AND WITH THE WARMER TEMPS  
COMES AROUND SEASONAL CHANCE OF RAIN. THE GFS ADVERTISES A BIT  
COOLER/SIGNIFICANTLY DRIER SOLUTION. HAVE WENT WITH A BLENDED  
APPROACH IN ABOVE SEASONAL TEMPS CONTINUING THROUGH MID WEEK, THEN  
COOLING TO AROUND TO A BIT BELOW SEASONAL. THE CHANCE OF RAIN  
INCREASES TO AROUND TO A BIT ABOVE SEASONAL BY THE END THE WEEK.  
VERY HIGH HEAT INDICES LOOK TO BE A PROBLEM THROUGH WEDNESDAY  
BEFORE DECREASING A BIT WITH THE COOLER TEMPS.  
 
/16  
 
MARINE...A SURFACE RIDGE STRETCHING WEST OVER THE CENTRAL GULF  
WILL SHIFT NORTH TO THE NORTHERN GULF COAST EARLY IN THE COMING WEEK,  
SHIFTING GENERAL SOUTHWEST TO WEST WINDS TO SOUTHEASTERLY. A PASSING  
SYSTEM WILL BRING GENERALLY MODERATE FLOW INTO SUNDAY, THEN EASE TO A  
LIGHT TO AT TIMES MODERATE. INCREASED SEAS WILL EASE SUNDAY NIGHT  
INTO MONDAY.  
 
/16  
 

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

 
 

 
 
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