Area Forecast Discussion
Issued by NWS Miami, FL

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FXUS62 KMFL 180554
AFDMFL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
154 AM EDT THU SEP 18 2014

.AVIATION...
SCATTERED SHOWERS REMAIN ACROSS THE AREA EARLY THIS MORNING
RESULTING FROM A WEAK SURFACE TROUGH. MOST OF THE ACTIVITY REMAINS
ACROSS THE AREA WATERS AND SHOULD NOT IMPACT ANY OF THE EAST COAST
SITES THIS MORNING. KAPF ON THE OTHER HAND SHOULD CONTINUE TO SEE
INTERMITTENT SHRAS FOR THE NEXT HOUR OR SO WITH RESULTANT CIGS
BRIEFLY DOWN IN THE MVFR TO IFR RANGE. OTHERWISE...WEAK NORTHERLY
FLOW WILL TURN MORE EASTERLY INTO THE AFTERNOON WITH A GULF BREEZE
AT KAPF.

&&

.PREV DISCUSSION... /ISSUED 922 PM EDT WED SEP 17 2014/

UPDATE...

UPPER LEVEL DISTURBANCE SINKING THROUGH CENTRAL FL, AND THEN
ACROSS EXTREME SE FL AND OFF THE WATERS OVERNIGHT, SHOULD KEEP
SOME SHOWERS ACROSS THE GULF AND ATLANTIC WATERS INTO DAWN. ALL
GUIDANCE, INCLUDING THE HRRR, HAS DECENT QPF IN THE 6Z-12Z TIME
FRAME TONIGHT. SLICE OF MID LEVEL DRY AIR PER WATER VAPOR SHOULD
HELP TO QUELL SHOWERS ACROSS THE NORTHERN LAND PORTION OF THE
FORECAST AREA LATER TONIGHT.

PREV DISCUSSION... /ISSUED 218 PM EDT WED SEP 17 2014/

SHORT TERM...
AN AREA OF HIGH PRESSURE WILL CONTINUE TO WEAKEN OVER THE GULF OF
MEXICO AS A TROUGH CONTINUES TO DIG SOUTHWARD ACROSS THE EASTERN
PORTION OF THE UNITED STATES. AT THE SAME TIME, A BROAD AREA OF LOW
PRESSURE LOCATED OFF THE SOUTH CAROLINA COAST WILL CONTINUE TO
DEEPEN AND SLOWLY MOVE NORTHEASTWARD. THIS DEVELOPING LOW WILL
CONTINUE TO KEEP A SOUTHWESTERLY FLOW ACROSS SOUTH FLORIDA THROUGH
TOMORROW. THIS WILL CAUSE THE SHOWER AND THUNDERSTORM DEVELOPMENT
THIS AFTERNOON TO BE CONCENTRATED ACROSS THE INTERIOR AND EAST COAST
METRO AREAS. STABILITY INDICES FAVOR MAINLY GARDEN VARIETY
THUNDERSTORMS TODAY. HOWEVER, A FEW STRONG STORMS CANNOT BE RULED
OUT ESPECIALLY LATER THIS AFTERNOON ACROSS THE EAST COAST METRO
AREAS.

MORE MOISTURE BEGINS TO MOVE INTO THE REGION TOMORROW AS GFS
FORECAST SOUNDINGS ARE INDICATING THE PWATS GO ABOVE TWO INCHES
AGAIN. AT THE SAME TIME, WINDS WILL BEGIN TO SHIFT FROM A
SOUTHWESTERLY DIRECTION TO MORE OF A SOUTHERLY DIRECTION AND A COLD
FRONT WILL BEGIN TO APPROACH THE REGION FROM THE NORTH. FORECAST
MODELS SHOW THE FRONT TRYING TO MOVE INTO THE REGION, WHICH WOULD
ENHANCE THUNDERSTORM ACTIVITY ESPECIALLY AROUND THE LAKE OKEECHOBEE
AREA WHICH WOULD BE THE CLOSEST AREA TO THE COLD FRONT. THIS FRONT
IS THEN FORECASTED TO STALL OUT ACROSS SOUTH FLORIDA ON FRIDAY
KEEPING PLENTY OF MOISTURE IN PLACE ALLOWING FOR AN INCREASED CHANCE
OF MORE SHOWERS AND THUNDERSTORMS. THE SHOWERS AND STORMS COULD
BRING HEAVY RAIN AND POSSIBLY SOME MINOR URBAN FLOODING FRIDAY
AFTERNOON TO THE SOUTH FLORIDA ATLANTIC COAST METRO AREAS.

LONG TERM...
AS SATURDAY APPROACHES, THE GFS AND THE ECMWF INDICATED
A STRONGER UPPER LEVEL LOW MOVING INTO THE REGION. THIS WOULD
REINFORCE THE INCREASED CHANCE OF SHOWERS AND THUNDERSTORMS. THESE
MODELS CONTINUE TO DIFFER ON HOW FAST THE UPPER LEVEL LOW MOVES OUT
OF THE REGION. THE GFS CONTINUES TO MOVE IT AWAY BY SUNDAY WHILE THE
ECMWF STALLS IT OVER THE REGION. IN ANY CASE IT WILL STILL BE CLOSE
ENOUGH TO ALLOW FOR INCREASED CHANCES OF SHOWERS AND THUNDERSTORMS
THROUGHOUT THE DAY ON SUNDAY. EARLY NEXT WEEK THE TROUGH WILL BEGIN
TO LIFT OUT OF THE REGION ALLOWING FOR DECREASING POPS BY TUESDAY
INTO WEDNESDAY.

MARINE...
HIGH PRESSURE OVER THE GULF WILL CONTINUE TO WEAKEN
TONIGHT AS A WEAK COLD FRONT SLOWLY PROGRESSES TOWARDS THE REGION.
THIS WILL ALLOW FOR CONTINUED CHANCES OF SHOWERS AND THUNDERSTORMS
THROUGH AT LEAST THE WEEKEND, ALSO, A LONG PERIOD SWELL WILL
CONTINUE IN THE ATLANTIC WATERS FOR AT LEAST THE NEXT COUPLE OF
DAYS. THE HIGHEST SWELL, OF AROUND 3 FEET, WILL BE OFF THE PALM
BEACH COUNTY COAST.

&&

.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH  86  74  84  74 /  60  20  80  40
FORT LAUDERDALE  87  77  86  75 /  60  20  70  30
MIAMI            88  76  86  75 /  60  20  70  30
NAPLES           86  76  85  74 /  60  30  70  40

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...HIGH RIP CURRENT RISK UNTIL 6 AM EDT EARLY THIS MORNING FOR
     FLZ168.

AM...NONE.
GM...NONE.
&&

$$



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