Tornado and Damaging Wind in Florida, September 29, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
756 AM EDT TUE SEP 29 2015

.AVIATION...

WITH A WEAKENED PRESSURE GRADIENT ACROSS THE REGION...REGIONAL
WINDS ARE CURRENTLY LIGHT AND VARIABLE. HOWEVER AS THE MORNING
PROGRESSES SOUTHWESTERLY TO WESTERLY WINDS ARE FORECAST TO BUILD ACROSS
THE REGION. THIS COMBINED WITH EXTENSIVE CLOUDINESS ACROSS THE
REGION WILL LIKELY INHIBIT THE EAST COAST SEA BREEZE TODAY...WITH
SOUTHWESTERLY TO WESTERLY WINDS FORECAST FOR THE ATLANTIC COAST
TERMINALS AFTER 14Z. THE COMBINATION OF WARM MID- LEVEL
TEMPERATURES AND THE AFOREMENTIONED CLOUDINESS WILL LIKELY INHIBIT
THUNDERSTORM POTENTIAL TODAY...WITH VCSH ASSIGNED ALL TERMINALS
THROUGH MOST OF THE DAY. THERE COULD BE VERY BRIEF PERIODS OF NEAR
MVFR CONDITIONS WITH PASSING SHOWERS. WILL AMEND AS NECESSARY IF
ANY ISOLATED THUNDERSTORMS SHOULD OCCUR.

60

&&

.PREV DISCUSSION... /ISSUED 437 AM EDT TUE SEP 29 2015/

..TIDAL FLOODING AROUND HIGH TIDE CYCLES CONTINUES...
..HIGH RISK OF RIP CURRENTS NORTHERN PALM BEACH COAST...

DISCUSSION...
BIG CHANGES IN THE WEATHER WILL TAKE PLACE THIS WEEK. SOUTH FL
WILL REMAIN IN A VERY MOIST AIR MASS THROUGH TOMORROW (WITH PW
AROUND 2.25 INCHES) AHEAD OF A BROAD TROUGH OVER THE GULF OF
MEXICO. A LONGWAVE TROUGH WILL BE MOVING TO THE U.S. EAST COAST.
BOTH GFS AND ECMWF DEVELOPED A CLOSED LOW OVER THE SOUTHEAST
STATES. THIS TROUGH WILL ACT TO KEEP T.S. JOAQUIN TO OUR EAST.
RECENT RUNS OF THE ECMWF DEVELOP JOAQUIN INTO A HURRICANE WHILE
MOVING SLOWLY WEST-SOUTHWESTWARD OVER THE NEXT FEW DAYS AND
TOWARDS THE EASTERN BAHAMAS BEFORE THE TROUGH DRIVES JOAQUIN AWAY.
GFS IS NOT AS FAR SOUTHWEST AT THE ECMWF AND WEAKER. EITHER
WAY...FLORIDA WILL BE UNDER THE TROUGH'S INFLUENCE WHICH IS GOOD
NEWS.

AS THIS TROUGH MOVES SLOWLY EAST MID-LATE WEEK...MUCH DRIER
AIR WILL MOVE INTO FLORIDA. PW VALUES DROP SIGNIFICANTLY
ESPECIALLY THU NIGHT-FRIDAY AND CONTINUE TO FALL THIS
WEEKEND...WITH FORECAST SOUNDINGS OFF BOTH THE GFS AND ECMWF
SHOWING PW DOWN TO AN INCH OR LESS BY SATURDAY. DEWPOINTS LOWER
AS WELL...WITH IT BECOMING NOTICEABLY LESS HUMID THIS UPCOMING
WEEKEND AS THE SULTRY MID 70F-DEGREE DEWPOINTS ARE REPLACED BY
MID-UPPER 60F-DEGREE DEWPOINTS. THE FIRST TASTE OF FALL...SOUTH
FLORIDA STYLE!

AS THE DRIER AIR POURS IN, RAIN AND TSTORM CHANCES WILL BE ON THE
DECLINE MID- LATE WEEK. IN FACT...NO TSTORMS ARE FORECAST FRIDAY
THROUGH EARLY NEXT WEEK AS A DRY, STABLE AIR MASS ENTERS FLORIDA.
FORECAST SOUNDINGS SHOW A SIGNIFICANT CAPPING INVERSION...HARD TO
SEE TSTORMS WITH THAT ALONG WITH THE SLIGHTLY COOLER AND
SIGNIFICANTLY DRIER AIR ACROSS THE AREA THEN. SO MOSTLY DRY
WEATHER IS FORECAST WITH JUST A SLIGHT CHANCE OF SHOWERS.

ABOVE NORMAL TIDES CONTINUE...SO WE CONTINUE TO EXPECT MINOR TIDAL
FLOODING AT THE HIGH TIDE CYCLES...VERY SIMILAR TO WHAT OCCURRED
YESTERDAY. HIGH TIDES FOR THE EAST COAST WILL BE MID MORNING AND
MID EVENING AND FOR THE GULF COAST AT MID AFTERNOON. SHARE ANY
FLOOD REPORTS OR PICS TO US @NWSMIAMI. TIDES WILL BE GRADUALLY
LOWERING...BUT TIDAL FLOODING COULD CONTINUE, THOUGH MORE MINOR,
OVER THE NEXT FEW DAYS...SO THE STATEMENTS AND/OR ADVISORIES MAY
NEED TO BE EXTENDED IN TIME.

A NORTHEAST 2-3 FT SWELL LEAD TO RIP CURRENTS (WHICH WERE CLEARLY
VISIBLE ON THE JUPITER INLET WEB CAM) ALONG AT LEAST THE NORTHERN
PALM BEACH COAST YESTERDAY AND THIS SWELL WILL CONTINUE TODAY
BEFORE GRADUALLY FADING. SO WE WILL HIGHLIGHT A HIGH RISK OF RIP
CURRENTS FOR THE NORTHERN HALF OF THE PALM BEACH COAST...TAPERING
TO MODERATE DOWN TO ABOUT FT. LAUDERDALE...AND SLIGHT RISK POINTS
SOUTH. /GREGORIA

AVIATION...
SIMILAR CONSTRAINTS TO WIDESPREAD CONVECTION ON TUESDAY,
AS THERE WAS MONDAY. MID LEVEL TEMPS WILL REMAIN WELL ABOVE
NORMAL RESULTING IN WEAK MID LEVEL LAPSE RATES. DESPITE THE MORE
FAVORABLE WIND PROFILES FOR CONVECTION IMPACTING EAST COAST, THICK
HIGH CLOUDS AGAIN COULD LIMIT COVERAGE. CONSENSUS OF SHORT RANGE
MODELS INDICATE AREAS OF MOSTLY LIGHT TO MODERATE RAIN IMPACTING
WEST COAST MORNING AND SHIFTING FOCUS TO THE EAST COAST BY
AFTERNOON AND EVENING. DUE TO LIMITED INSTABILITY, VFR CONDITIONS
SHOULD PREVAIL FOR THE MOST PART. SHOULD ANY SHOWER OR TSTM
AFFECT A SITE MVFR CEILINGS/VIS ARE THE MAIN CONCERN BUT ONLY FOR
BRIEF PERIODS OF TIME. WE WILL HANDLE THAT WITH AMENDMENTS AS
NEEDED. LIGHT AND VARIABLE WINDS THIS MORNING WILL GIVE WAY TO
SWLY WINDS OF 5 TO 10 KNOTS AT ALL SITES FROM MID MORNING ON
BECOMING LIGHT AND VARIABLE ONCE AGAIN IN THE EVENING. /PS

MARINE...
A SMALL NORTHEAST SWELL IN THE ATLANTIC WILL FADE OVER THE NEXT
COUPLE OF DAYS. SOUTHWEST WINDS TODAY WILL BECOME WEST-NORTHWEST
BY TOMORROW. A BRIEF INCREASE IN WINDS TONIGHT OF NEAR 15 KT.
OTHERWISE, SPEEDS ARE FORECAST TO BE LESS THAN 15 KT THROUGH
WEEK'S END ON A PREVAILING W-NW DIRECTION. /GREGORIA

&&

.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH  89  76  91  77 /  50  20  40  20
FORT LAUDERDALE  88  78  91  77 /  50  20  50  20
MIAMI            89  78  92  77 /  50  20  50  20
NAPLES           87  79  89  78 /  50  20  40  20

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...COASTAL FLOOD ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR FLZ168-172-
     173.

     HIGH RIP CURRENT RISK THROUGH THIS EVENING FOR FLZ168.

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

SHORT TERM...60/BD
LONG TERM....60/BD
AVIATION...60/BD

HAZARDOUS WEATHER OUTLOOK FOR SOUTH FLORIDA
NATIONAL WEATHER SERVICE MIAMI FL
947 AM EDT TUE SEP 29 2015

AMZ610-630-650-651-670-671-FLZ063-066>075-168-172>174-GMZ656-657-676-
300200-
LAKE OKEECHOBEE-BISCAYNE BAY-
COASTAL WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL OUT 20 NM-
COASTAL WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL OUT 20 NM-
WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL EXTENDING FROM
20 NM TO 60 NM-
WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL EXTENDING FROM 20 NM
TO THE TERRITORIAL WATERS OF THE BAHAMAS-GLADES-HENDRY-
INLAND PALM BEACH-METRO PALM BEACH-COASTAL COLLIER-INLAND COLLIER-
INLAND BROWARD-METRO BROWARD-INLAND MIAMI DADE-METRO MIAMI DADE-
MAINLAND MONROE-COASTAL PALM BEACH-COASTAL BROWARD-
COASTAL MIAMI DADE-FAR SOUTH MIAMI DADE-
COASTAL WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL OUT 20 NM-
COASTAL WATERS FROM EAST CAPE SABLE TO CHOKOLOSKEE, FL OUT 20 NM-
GULF WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL EXTENDING FROM
20 TO 60 NM-
947 AM EDT TUE SEP 29 2015

...COASTAL FLOOD ADVISORY SOUTHEAST FLORIDA COAST...
...MINOR COASTAL FLOODING POSSIBLE NEAR TIME OF HIGH TIDES...
...HIGH RISK RIP CURRENTS NORTHERN PALM BEACH BEACHES...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH FLORIDA.

.DAY ONE...TODAY AND TONIGHT

RIP CURRENTS: A RETREATING 1 TO 3 FEET SWELL OFF THE COAST OF PALM
BEACH WILL RESULT IN A HIGH RISK OF RIP CURRENTS. THE RISK IS HIGHEST
ALONG THE NORTHERN BEACHES OF THE COUNTY AND DURING LOW TIDE IN THE
MID AFTERNOON HOURS. HEED THE ADVICE OF LIFEGUARDS, BEACH PATROL
FLAGS AND SIGNS.

THUNDERSTORMS: SCATTERED SHOWERS WITH ISOLATED THUNDERSTORMS WILL
IMPACT PORTIONS OF SOUTH FLORIDA TODAY. THEY WILL GENERALLY MOVE
FROM THE SOUTHWEST SLOWLY AND THEREFORE THE MAIN CONCERN WITH ANY
ACTIVITY TODAY WILL BE LOCALLY HEAVY RAINFALL ALONG WITH
OCCASIONAL LIGHTNING STRIKES.

FLOODING: COASTAL FLOODING IS POSSIBLE ALONG THE ATLANTIC, GULF,
AND BISCAYNE BAY SHORES NEAR TIMES OF HIGH TIDE. THIS MAY LEAD TO
PONDING OF WATER ON ROADWAYS AND URBAN FLOODING ESPECIALLY IN
VULNERABLE LOCATIONS. THIS COULD ALSO BE EXACERBATED BY ANY HEAVY
SHOWERS IMPACTING THOSE LOCATIONS PARTICULARLY AROUND THE TIME OF
HIGH TIDE. HIGH TIDES ARE AROUND 10 AM AND 10 PM ALONG THE
SOUTHEAST FLORIDA COAST AND MID AFTERNOON/EARLY MORNING AFTER
MIDNIGHT IN THE SOUTHWEST FLORIDA COAST.

WATERSPOUTS: THERE IS A SLIGHT CHANCE OF WATERSPOUTS ACROSS THE
REGIONAL WATERS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

SCATTERED AFTERNOON AND EVENING STORMS ARE POSSIBLE THROUGH FRIDAY
WITH ONLY A SLIGHT CHANCE OF SHOWERS CURRENTLY FORECAST FOR THE
WEEKEND.

MINOR COASTAL FLOODING IS LIKELY ALONG SOUTH FLORIDA COASTLINES NEAR
TIMES OF HIGH TIDE THROUGH THE MIDDLE OF THE WEEK. TIDES WILL
CONTINUE TO GRADUALLY SUBSIDE THROUGH THE END OF THE WEEK WITH
VERY MINOR COASTAL FLOODING STILL POSSIBLE ALONG MOST VULNERABLE
SPOTS.

CHANCES OF RIP CURRENTS WILL CONTINUE TO BE MODERATE OR HIGH FOR PORTIONS
OF THE SOUTHEAST FLORIDA COAST THROUGH THE MIDDLE OF THE WEEK WITH
THE RISK DIMINISHING TOWARDS THE LATTER PART OF THE WEEK.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED.

FOR MORE INFORMATION...VISIT THE NATIONAL WEATHER SERVICE IN
MIAMI WEBSITE AT WWW.WEATHER.GOV/MIAMI.