882  
FXUS62 KMFL 280004  
AFDMFL  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MIAMI FL  
804 PM EDT TUE JUN 27 2017  
   
UPDATE
 
 
IR SATELLITE IMAGERY SHOWS CONVECTION DWINDLING ACROSS THE CWA  
WITH CLOUD TOPS SLOWLY WARMING. HOWEVER, LEFTOVER BOUNDARIES FROM  
THIS EVENINGS STORMS MAY TRIGGER A FEW SHOWERS AND STORMS DURING  
THE NEXT SEVERAL HOURS. ANOTHER FEATURE OF INTEREST IS THE LINE OF  
THUNDERSTORMS PUSHING NORTHWARD OFF OF THE CUBAN COAST. SHORT  
TERM MODELS SHOW OUTFLOW FROM THIS ACTIVITY POSSIBLY INTERACTING  
WITH BOUNDARIES NEAR OUR COAST EARLY WEDNESDAY MORNING. IF THIS  
OCCURS, ADDITIONAL THUNDERSTORMS MAY DEVELOP OVER THE ATLANTIC  
WATERS. WILL CONTINUE TO MONITOR THROUGH THE NIGHT. PREVIOUS  
FORECAST PACKAGE APPEARED ON TRACK, SO BESIDES LOADING IN THE  
LATEST WIND AND SKY GUIDANCE, DID NOT HAVE TO TEAK OTHER FORECAST  
PARAMETERS.  
 

 
   
PREV DISCUSSION
 
/ISSUED 723 PM EDT TUE JUN 27 2017/  
 
AVIATION...LINGERING CONVECTION THIS EVENING INLAND OF TERMINALS,  
BUT WILL HAVE TO MONITOR OUTFLOW BOUNDARIES FOR ADDITIONAL ISOLATED  
DEVELOPMENT IN THE VICINITY OF BOTH KAPF AND EAST COAST TERMINALS  
THROUGH 02Z. FOR NOW, BEST POTENTIAL WILL BE AT KAPF WHERE VCSH  
WILL START THE FORECAST. LIGHT/CALM WINDS OVERNIGHT WITH DRY  
FORECAST EXPECTED. TOMORROW LOOKS SIMILAR TO TODAY WITH VCTS AT  
ALL SITES BEGINNING 14Z-16Z AS SEABREEZES DEVELOP AND MOVE INLAND.  
TEMPO GROUPS WILL LIKELY BE NEEDED WITH LATER TAF PACKAGES AS  
TIMING OF TSRA CAN BE BETTER PINNED DOWN.  
 
PREV DISCUSSION... /ISSUED 358 PM EDT TUE JUN 27 2017/  
 
DISCUSSION...  
LATEST WATER VAPOR IMAGERY LOOP SHOWS A CYCLONIC SPINNING LOW  
OVER NEW YORK STATE WITH A LONGWAVE TROUGH DRAPED ALONG THE  
THE MID-ATLANTIC. SURFACE ANALYSIS INDICATES A EAST- WEST  
ORIENTED STATIONARY BOUNDARY SITTING STAGNANT ACROSS NORTH-  
CENTRAL FLORIDA. THIS FEATURE HAS MANAGED TO PUSH THE BERMUDA HIGH  
EASTWARD, AWAY FROM OUR REGION, RESULTING IN NEAR NATURAL FLOW.  
THUS, WELL ESTABLISHED SEA BREEZES HAVE ALREADY DEVELOPED AND  
CONTINUE TO PUSH INLAND, TOWARDS THE INTERIOR. SATELLITE DERIVED  
PWAT VALUES RANGE FROM 1.7 INCHES IN THE SOUTHERN PENINSULA TO  
NEAR 2.0 INCHES FURTHER NORTH. THESE VALUES ARE SLIGHTLY HIGHER  
THAN CLIMO AND MORE THAN SUFFICIENT FOR HEAVY, SLOW MOVING STORMS.  
WITH A MODIFIED DCAPE OF 1,400 J/KG, WET MICROBURSTS PRODUCING  
STRONG WIND GUSTS ARE ALSO A POSSIBILITY. SHORT TERM MODEL  
GUIDANCE PROGS CONVECTION TO PROPAGATING ACROSS THE INTERIOR  
THROUGH THE EARLY EVENING. AFTER DIURNAL HEATING CEASES, ACTIVITY  
SHOULD BEGIN TO WANE. SPC HAS PLACED A MARGINAL RISK OF SEVERE  
WEATHER FROM WEST PALM BEACH TO LAKE OKEECHOBEE, SO WILL CONTINUE  
TO MONITOR FOR THE REMAINDER OF THE DAY. TOMORROW SHOULD BE A  
SIMILAR SET UP, WITH NOT MUCH CHANGING SYNOPTICALLY. LIGHT FLOW  
WILL AGAIN LEAD TO SEA BREEZE CONVERGENCE INLAND FROM THE COASTS.  
AS THE DAY PROGRESSES, OUTFLOW BOUNDARIES WILL SHIFT MOST OF THE  
CONVECTION TOWARDS THE INTERIOR. MAXIMUM TEMPERATURES TOMORROW  
ARE FORECAST TO HOVER IN THE UPPER 80S ALONG THE COASTS, WITH  
LOWER 90S INLAND. THESE VALUES ARE AROUND NORMAL TO SLIGHTLY ABOVE  
NORMAL FOR THIS TIME OF YEAR.  
 
LATE NEXT WEEK INTO THE WEEKEND: BY THURSDAY, BOTH THE GFS AND  
ECMWF PROG THE AFOREMENTIONED FRONT TO WASH OUT AND RETREAT  
NORTHWARD. THIS WILL ALLOW SURFACE HIGH NEAR BERMUDA TO ONCE AGAIN  
INCREASE IN STRENGTH. STRONGER SOUTHEAST FLOW WILL BEGIN TO  
CONCENTRATE AFTERNOON CONVECTION BACK TOWARDS THE WESTERN  
INTERIOR, AS SEA BREEZE COLLISION SHIFTS WEST. FRIDAY INTO THIS  
WEEKEND, A MORE TYPICAL SUMMERTIME REGIME REESTABLISHES ITSELF.  
LONG RANGE MODELS SHOW AN ELONGATED HIGH BUILDING ALOFT OVER THE  
PENINSULA WITH SURFACE HIGH BUILDING NEAR BERMUDA. THIS PATTERN  
TYPICALLY BRINGS PERSISTENT SOUTHEAST FLOW. AFTERNOON CONVECTION  
WILL MOST LIKELY OCCUR IN THE WESTERN INTERIOR AND GULF COAST WITH  
NIGHT SHOWERS AFFECTING THE EAST COAST METRO REGION. PWATS  
DECREASE SLIGHTLY BELOW CLIMO DURING THIS TIME FRAME, SO NOT  
ANTICIPATING MUCH IN THE WAY OF SIGNIFICANT HEAVY RAIN EVENTS.  
 
MARINE...WINDS AND SEAS SHOULD REMAIN BELOW SMALL CRAFT ADVISORY  
CRITERIA ACROSS THE LOCAL WATERS THROUGH THE FORECAST PERIOD WITH  
MAINLY LIGHT SOUTHEASTERLY FLOW PREVAILING. SEA BREEZES MAY  
ENHANCE WINDS NEAR THE COAST TO 10-15 KNOTS AT TIMES EACH  
AFTERNOON. ONLY EXCEPTION WILL BE WITH ANY THUNDERSTORM THAT  
FORMS, WHICH WILL BRING BRIEF PERIODS OF STRONG GUSTY WINDS AND  
ROUGH SEAS. WATERSPOUTS ARE ALSO POSSIBLE, ESPECIALLY IN THE  
MORNING HOURS, MAINLY OVER THE ATLANTIC WATERS. SEAS WILL BE 3  
FEET OR LESS HEADING INTO THE WEEKEND.  

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
WEST PALM BEACH 76 91 78 91 / 40 50 30 50  
FORT LAUDERDALE 78 90 79 91 / 30 50 30 40  
MIAMI 78 92 79 91 / 30 50 30 40  
NAPLES 76 91 76 91 / 20 40 20 50  
 

 
   
MFL WATCHES/WARNINGS/ADVISORIES
 
 
FL...NONE.  
AM...NONE.  
GM...NONE.  

 
 
UPDATE...27/JT  
DISCUSSION...27/JT  
MARINE...27/JT  
AVIATION...88/ALM  
 
 
 
 
 
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