Area Forecast Discussion
Issued by NWS Miami, FL

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000
FXUS62 KMFL 201135
AFDMFL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
735 AM EDT WED AUG 20 2014

.AVIATION...
VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE BULK OF THE
PERIOD AS HIGH PRESSURE REMAINS IN CONTROL. THE LATEST MODEL RUN
SHOWED ISLTD/SCT SHRAS/TSTMS DEVELOPING ALONG THE EAST COAST SEA
BREEZE BOUNDARY AROUND 16-17Z JUST INLAND OF THE EAST COAST TAF
SITES WITH THE LOW-LEVEL FLOW PROJECTED TO BE MORE ORIENTED OUT OF
THE ENE. WILL INCLUDE VCTS FOR THE EAST COAST SITES TO CORRESPOND
WITH THIS TIMING FOR NOW AND UPDATE AS CONDITIONS EVOLVE TODAY.
THIS ACTIVITY SHOULD CONTINUE INLAND THROUGH THE MID-LATE
AFTERNOON AND SETUP ACROSS THE INTERIOR AREAS THROUGH THE EARLY
EVENING HOURS BEFORE DIMINISHING TONIGHT. WINDS WILL BECOME CALM
AND SHIFT TO OFFSHORE ALONG EACH COAST THROUGH THE LATE NIGHT
HOURS. 85/AG

&&

.PREV DISCUSSION... /ISSUED 238 AM EDT WED AUG 20 2014/

DISCUSSION...

SOUTH FLORIDA IS UNDER AN AREA OF HIGH PRESSURE LOCATED OVER THE
FLORIDA STRAITS. THE FORECAST CALLS FOR THIS AREA OF HIGH PRESSURE
TO MOVE TO THE NORTHWEST INTO THE SOUTHEASTERN US. THE 00Z AUG 20
SOUNDING SHOWS THAT THE SAHARAN DUST THAT HAS BEEN AFFECTING SOUTH
FLORIDA SINCE THE WEEKEND IS ERODING BETWEEN 600 AND 700 MB (OR 3-4
KM ABOVE THE SURFACE). THIS IS ALSO DEPICTED BY THE LIDAR LOCATED
AT THE UNIVERSITY OF MIAMI. THE LIDAR ALSO SHOWS THAT THE SAHARAN
LAYER IS BEING ERODED FROM BELOW. AS THE HIGH PRESSURE CONTINUES
TO MOVE TO THE NORTHWEST, AN INFLUX OF ATLANTIC AIR ASSOCIATED
WITH A WEAK FRONTAL BOUNDARY OVER THE ATLANTIC (BACK DOOR COLD
FRONT) WILL CONTINUE TO PROVIDE A SOURCE OF CLEANER AIR. THE LOW
LEVEL VISIBILITY WILL CONTINUE TO IMPROVE AS THE WEEK PROGRESSES.

THE CIMMS WATER VAPOR IMAGERY SHOWS INCREASING MOISTURE OVER THE
BAHAMAS MOVING OVER SOUTH FLORIDA FOR WEDNESDAY EVENING BEHIND THE
DRIER AIR THAT HAS BEEN AFFECTING SOUTH FLORIDA SINCE SATURDAY. THE
FORECAST SOUNDINGS ALSO SHOW THIS INCREASE IN PW FOR WEDNESDAY
AFTERNOON. THE PW DECREASE AGAIN ON THURSDAY DUE TO THE
SUBSIDENCE ASSOCIATED WITH THE HIGH PRESSURE MOVING INTO THE SE
US.

THE FLOW OF EASTERLY WINDS WILL FAVOR LOWER POPS FOR THE IMMEDIATE EAST
COAST WITH THE BEST CHANCES FOR AFTERNOON AND EVENING THUNDERSTORMS
OVER THE INTERIOR AND WESTERN PORTIONS OF THE COASTAL COUNTIES.
THE WEEKEND SEEMS TO BE THE DRIEST PERIOD WITH DRIER AIR FROM THE
ATLANTIC AFFECTING SOUTH FLORIDA. CONDITIONS ARE FORECAST TO
CHANGE FOR MONDAY AND TUESDAY AS MOISTURE ASSOCIATED WITH THE
TROPICAL WAVES OVER THE CENTRAL ATLANTIC IS EXPECTED TO AFFECT
SOUTH FLORIDA. AT THE PRESENT TIME IT IS NOT POSSIBLE TO PREDICT IF
A TROPICAL SYSTEM COULD AFFECT SOUTH FLORIDA NEXT WEEK, BUT AT
LEAST WE CAN BE SOMEWHAT CONFIDENT THAT AN INCREASE IN MOISTURE
AND LOW LEVEL FLOW FROM THE SE IS FORECAST FOR THE BEGINNING OF
NEXT WEEK ASSOCIATED WITH THESE WAVES. THE CURRENT FORECAST FROM
THE NATIONAL HURRICANE CENTER INCLUDES A MEDIUM CHANCE FOR
DEVELOPMENT FOR THE NEXT FIVE DAYS.

MARINE... WINDS ARE FORECAST TO REMAIN SOUTHEASTERLY TO EASTERLY
ACROSS THE ATLANTIC WATERS AROUND OR BELOW 10 KNOTS AND PERSISTING
THROUGH WEDNESDAY. AS A RESULT, SEAS ARE FORECAST TO BE 2 FEET OR
LESS THROUGH THIS TIME FRAME. SURFACE WINDS ARE THEN FORECAST TO
INCREASE SLIGHTLY FOR THE LATTER HALF OF THE WEEK WHILE REMAINING
GENERALLY EASTERLY AS HIGH PRESSURE BUILDS NORTH OF THE REGION.

PREV DISCUSSION... /ISSUED 126 AM EDT WED AUG 20 2014/

AVIATION...

WINDS WILL REMAIN EASTERLY FOR THE EAST COAST TERMINALS WHICH WILL
FAVOR THE BEST CHANCE FOR THUNDERSTORMS IN THE INTERIOR. AT THE
PRESENT TIME WE ARE NOT INCLUDING VCTS FOR THE EAST COAST
TERMINALS SINCE THE CONVECTION IS FORECAST TO DEVELOP WEST OF THE
EAST COAST TERMINALS. HOWEVER, INCLUDED VCSH FOR ALL TERMINALS
AFTER 15Z EXCEPT PBI. APF HAS THE GREATEST CHANCE OF PRECIPITATION,
AS THE EASTERLY FLOW FAVORS THUNDERSTORM DEVELOPMENT OVER THE
INTERIOR, AND SOMETIMES IT COULD AFFECT THE NAPLES AREA.

&&

.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH  92  78  91  78 /  40  10  30  10
FORT LAUDERDALE  92  81  91  80 /  30  10  30  10
MIAMI            91  80  91  80 /  30  10  30  10
NAPLES           91  78  92  78 /  40  10  50  20

&&

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

$$

SHORT TERM...71/JE
LONG TERM....71/JE
AVIATION...71/JE


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