001  
FXUS62 KTBW 230513  
AFDTBW  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL  
113 AM EDT WED AUG 23 2017  
   
AVIATION
 
 
23/06Z TAFS. PREVAILING VFR EXPECTED THROUGH THE TAF PERIOD...  
HOWEVER VCTS WITH FEW-SCT CB BTWN 18Z-03Z MAY PROVIDE BRIEF  
MVFR/LCL IFR LATE IN THE PERIOD. LIGHT AND VARIABLE/EASTERLY  
WINDS REST OF TONIGHT PICK UP SOME FROM THE E OR SE IN THE  
MORNING AND CONTINUE. ALTHOUGH TPA/PIE/SRQ MAY BAY-SEA BREEZE.  
 

 
   
PREV DISCUSSION
 
/ISSUED 521 PM EDT TUE AUG 22 2017/  
 
UPDATE...  
ALTHOUGH SOME MOISTURE RETURN IS EVIDENT IN WV IMAGERY  
ALOFT OVER THE SOUTHERN HALF OF THE FORECAST AREA, THE  
EXTENT OF INFLUX HAS BEEN MINIMAL. IN ADDITION...IT IS QUITE  
EVIDENT VIA SATELLITE TRENDS (AND LOOKING OUT THE  
WINDOW)...THE WE ARE STILL DEALING WITH EFFICIENT  
SUPPRESSION IN THE ATMOSPHERE...KEEPING THE CU FIELDS  
GENERALLY SHALLOW. ANOTHER BIG FACTOR WE ARE SEEING AS OF  
5PM IS THE WE STILL HAVE FAIRLY HEALTHY OFFSHORE FLOW ALONG  
THE SUNCOAST...MAKING THE LIKELIHOOD OF DEFINED SEA-BREEZE  
FORMATION INCREASINGLY LESS LIKELY WITHIN THE NEXT HOUR OR  
TWO. WITH ALL THIS IN MIND...HAVE MADE A FAIRLY LARGE  
DECREASE IN THE OVERALL RAIN CHANCES FOR OUR FAR SOUTHERN  
ZONES FROM HIGHLANDS TO CHARLOTTE/LEE COUNTIES. FURTHER  
NORTH THAN THAT, NOT NEEDING MUCH IN THE WAY OF CHANGE AS  
CHANCES WERE ALREADY SLIGHT CHANCE/ISOLATED AT BEST UP TO  
THE I-4 CORRIDOR...AND LESS THAN 10% FURTHER NORTH.  
 
WILL NOT REMOVE POPS ALTOGETHER THIS EVENING FOR THE  
SOUTHERN ZONES, AS STILL ANTICIPATE A FEW WIDELY SCATTERED  
CELLS TO GET ESTABLISHED BETWEEN 22Z AND 00Z...MAINLY SOUTH  
OF A LINE FROM SARASOTA TO SEBRING...WITH BETTER CHANCES  
THE FURTHER SOUTH. HOWEVER, AT THIS POINT...ALL THE FACTORS  
ABOVE MAKE IT DIFFICULT TO EXPECT MORE THAN ABOUT A 30%  
CHANCE AT ANY ONE LOCATION. WILL REMOVE ALL POPS OVER THE  
LANDMASS AFTER 02Z...WITH A DRY REST OF THE OVERNIGHT  
REGION-WIDE.  
 
THE MOISTURE WILL CONTINUE A SLOW RECOVERY ALOFT DURING THE  
DAY WEDNESDAY...AND BE BACK ABOVE NORMAL FOR ALL AREAS BY  
THURSDAY. THE COMBINATION OF THIS INCREASE IN AVAILABLE  
MOISTURE, AND THE ARRIVAL OF A WEAK SURFACE TROUGH FROM THE  
EAST (AND RESULTING ENHANCED SURFACE FOCUS)...THE CHANCES  
FOR DIURNAL SHOWERS AND STORMS WILL SLOWLY RAMP UP THROUGH  
THE MIDDLE OF THE WEEK.  
 
PREV DISCUSSION... /ISSUED 303 PM EDT TUE AUG 22 2017/  
 
SHORT TERM (TONIGHT-WEDNESDAY)...  
A TROPICAL WAVE JUST TO THE EAST OF THE SOUTHEAST FL COAST  
WILL GRADUALLY SHIFT WEST OVER SOUTH FL AND WEAKEN ACROSS  
THE AREA THROUGH WEDNESDAY. DEEP MOISTURE WILL MOVE INTO THE  
AREA AND ALLOW FOR SCATTERED TO NUMEROUS SHOWERS AND  
THUNDERSTORMS, WITH THE HIGHEST CHANCES WEDNESDAY AFTERNOON  
AND ACROSS THE SOUTH. GENERALLY EAST TO NE WINDS WILL BE IN  
PLACE THROUGH THE PERIOD, BECOMING LIGHT OVERNIGHT, AND A  
WEAK SEA BREEZE WEDNESDAY AFTERNOON TURNING WINDS ONSHORE.  
LOWS TONIGHT WILL BE IN THE LOWER TO MID 70S NORTH AND  
INLAND, AND IN THE UPPER 70S TO LOWER 80S ALONG THE COAST.  
HIGHS WEDNESDAY IN THE LOWER TO MID 90S.  
 
LONG TERM (WEDNESDAY NIGHT THROUGH NEXT TUESDAY)...  
AT THE BEGINNING OF THE LONG RANGE PERIOD, A POTENT UPPER  
TROUGH WILL EXTEND FROM THE NORTHERN PLAINS INTO NEW  
ENGLAND. HIGH PRESSURE WILL DOMINATE THE REMAINDER OF THE  
COUNTRY WITH A COUPLE OF NOTED WEAKNESSES IN THE TROPICS. AT  
THE SURFACE, HIGH PRESSURE WILL EXTEND ACROSS THE WESTERN  
ATLANTIC OCEAN AND THE GULF OF MEXICO WITH A WEAK TROPICAL  
LOW NEAR THE SOUTHERN TIP OF FLORIDA, AND A STRENGTHENING  
LOW PRESSURE SYSTEM OVER THE WESTERN GULF OF MEXICO.  
 
WE AGAIN FACE AN UNCERTAIN FORECAST AS MODELS CONTINUE TO  
HANDLE THE EVOLUTION OF A WEAK SURFACE LOW QUITE POORLY.  
THIS TROPICAL DISTURBANCE IS CURRENTLY SITUATED OVER THE  
BAHAMAS AND WILL DRIFT SLOWLY WEST TO NORTHWEST TO A  
POSITION EITHER OVER THE SOUTHERN FLORIDA PENINSULA OR JUST  
OFFSHORE IN THE FAR EASTERN GULF BY LATE WEDNESDAY. AS IS  
COMMON WITH WEAK AREAS OF LOW PRESSURE, MEDIUM RANGE  
GUIDANCE CAN HARDLY RESOLVE THE SYSTEM, WHICH IS MAKING THE  
EXACT TRACK OF THE FEATURE VERY DIFFICULT TO DISCERN. THE  
MORE RELIABLE MID/LONG RANGE SOLUTIONS ARE BEGINNING TO  
CONVERGE SOMEWHAT, BUT WE HAVE A LONG WAY TO GO BEFORE  
CONSENSUS IS OBTAINED. TO COMPLICATE THINGS, THE REMNANTS OF  
HARVEY LOOK TO MOVE OUT INTO THE WESTERN GULF, EVENTUALLY  
STRENGTHENING INTO AT LEAST A TROPICAL DEPRESSION OR  
TROPICAL STORM. BOTH OF THESE FEATURES, ALONG WITH A  
DEEPENING OF THE UPPER TROUGH AND A SOUTHWARD MOVING COLD  
FRONT WILL LEAD TO A COMPLICATED FORECAST AND ERROR IS  
CERTAIN TO BE QUITE HIGH AS WE MOVE BEYOND THIS WEEKEND.  
 
WHAT WE DO KNOW IS THAT THE WEAK TROPICAL DISTURBANCE IS  
LIKELY TO AT LEAST AFFECT AREAS OF SOUTHERN AND PERHAPS  
CENTRAL FLORIDA WEDNESDAY INTO THE WEEKEND, AS A PLUME OF  
DEEP TROPICAL MOISTURE JOINS THE DAILY SEABREEZE  
CIRCULATIONS AND DAYTIME HEATING. THIS SHOULD PROMOTE FAIRLY  
WIDESPREAD SHOWERS AND THUNDERSTORMS THURSDAY THROUGH  
SATURDAY AFTERNOON, ESPECIALLY SOUTH OF THE I-4 CORRIDOR.  
LOCALIZED FLOODING MAY OCCUR IN AREAS THAT RECEIVE TRAINING  
ROUNDS OF HEAVY RAIN, THOUGH WIDESPREAD FLOODING DOESN'T  
APPEAR LIKELY AT THIS TIME. FURTHER NORTH, OVER NORTH  
CENTRAL FLORIDA AND ALONG THE NATURE COAST, LESSER CHANCES  
OF RAIN WILL EXIST DUE IN PART TO THE PRESENCE OF SOME  
SLIGHTLY DRIER AIR ALOFT.  
 
BEYOND THE WEEKEND, EVEN GREATER UNCERTAINTY EXISTS AS  
MODELS ATTEMPT TO SPIN UP TWO TROPICAL CYCLONES ALONG THE  
STALLED FRONTAL BOUNDARY. RIGHT NOW, WE LOOK TO REMAIN  
BETWEEN THESE TWO SYSTEMS, WHICH WOULD GENERALLY FAVOR DRIER  
AND HOTTER CONDITIONS THAT NORMAL, BUT A SMALL DEVIATION  
COULD RESULT IN GREATER IMPACTS TO THE AREA, AND WILL WILL  
HAVE TO MONITOR THE SITUATION CLOSELY.  
 
MARINE...  
WEAK PRESSURES WILL BE IN PLACE ACROSS THE WATERS WITH WEAK  
RIDGING IN PLACE AND A TROPICAL WAVE ALONG THE SE FL COAST.  
INCREASING MOISTURE WILL ALLOW FOR SCATTERED TO NUMEROUS  
SHOWERS AND THUNDERSTORMS THROUGH THE WEEKEND AS GENERALLY  
EASTERLY FLOW CONTINUES, TURNING ONSHORE ALONG THE COAST  
EACH AFTERNOON. NO HEADLINES CURRENTLY EXPECTED THROUGH THE  
PERIOD.  
 
FIRE WEATHER...  
NO CONCERNS.  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
TPA 94 79 91 78 / 40 30 60 30  
FMY 92 76 89 77 / 70 40 80 40  
GIF 94 76 92 75 / 50 20 70 30  
SRQ 94 78 90 78 / 40 30 60 40  
BKV 95 75 93 75 / 30 20 60 30  
SPG 94 79 90 79 / 30 30 60 30  
 

 
   
TBW WATCHES/WARNINGS/ADVISORIES
 
 
FL...NONE.  
GULF WATERS...NONE.  

 
 

 
 
AVIATION...RUDE  
UPDATE...MROCZKA  
PREVIOUS DISCUSSION...HUBBARD/AUSTIN  
 
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