Special Weather Statement, NWS Miami, FL

Area Forecast Discussion
National Weather Service Miami FL
817 AM EDT Tue Sep 20 2016

.AVIATION...
The weather over South Florida will continue to be influenced by a
weak low sitting well to the north northeast. As it meanders
around, the wind will continue to be on the light side, although
it will have a more north to northwest component to it today. This
should keep APF with a dry forecast, and bring another round of
showers and storms to the Atlantic coast this afternoon. There is
still high uncertainty as to exact timing and location, so have
kept the VCTS for most of the afternoon hours. Convection should
begin to quiet down as the sun sets, with dry conditions forecast
overnight, into tomorrow morning.

&&

.UPDATE...
made some changes to the PoP forecast for today, mainly to
increase temporal resolution for the convective activity. A blend
of synoptic and hi-res models is indicating somewhat lower chances
of convection than previously forecast, but still likely in the
interior, just west of Miami. However, there is still uncertainty
in this, and the metro areas may see convection more widespread
than the models are producing this morning. One of the biggest
players will be the Atlantic sea breeze, and if it is able to
develop better today than yesterday. However, with a somewhat
stronger northerly component today, the southern half of the CWA
would make sense to see the highest chances. Otherwise, only minor
tweaks to account for current conditions.

&&

.PREV DISCUSSION... /issued 404 AM EDT Tue Sep 20 2016/

DISCUSSION...
Short Term (Today-Thursday)...sfc high pressure remains in
control of the area, with a mid level ridge also remaining aloft
over the state and most of the region. Meanwhile, both GFS and
ECMWF depict a deepening mid level trough moving eastward across
the eastern seaboard and producing a cut-off low by Wednesday.
This mid level low seems to linger over the eastern seaboard and
is not anticipated to push further southward during the next
several days. However, the low may help in bringing slightly
cooler temps aloft over the Florida peninsula, which could enhance
the overall instability and thunderstorm activity.

Latest MFL sounding depicts plenty of deep moisture available across
the area with PWAT values over 2 inches, temps around -6 C. But
with a prevailing light easterly flow pattern in place, expect
most of the significant convective activity to develop along
seabreeze boundaries. For today, expect a generally quiet morning
weatherwise followed by a fairly active afternoon and early
evening. POPS have been adjusted to increase the likely coverage
across most of the interior portions of South Florida, and high-
end scattered elsewhere. A similar weather pattern should continue
through the short term, although thunderstorm activity will
decrease a little by Thursday as the aforementioned low gradually
weakens and allows for a warming trend in temps aloft. Best
chances for thunderstorms will be during the afternoon and early
evening hours.

Long term (Friday-Monday)...models remain in fair agreement for
the long range forecast, keeping a generally light easterly flow
across the area through early next week, and with daytime
heating/sea seabreeze boundaries providing the main driving
mechanism for afternoon/early evening convection. Best chances of
rain and thunderstorms will remain over interior and Gulf coast
areas. However, a few strong cells are possible over the Atlantic
metro areas during the early afternoon hours as sea breezes push
inland. Temperatures will remain near seasonal normals.

MARINE...winds over the coastal waters are expected to remain
mainly from the east southeast at 10 knots or less over the next
several days with seas 3 feet or less. Only exception will be around
any thunderstorm that forms, which will generate brief periods of
rough seas and gusty winds.

&&

.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach  90  75  91  77 /  50  50  40  30
Fort Lauderdale  90  77  90  78 /  50  40  40  40
Miami            91  77  91  78 /  50  40  40  30
Naples           90  77  90  76 /  20  10  40  20

&&

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

AVIATION...13
UPDATE...13

HAZARDOUS WEATHER OUTLOOK FOR SOUTH FLORIDA
NATIONAL WEATHER SERVICE MIAMI FL
853 AM EDT TUE SEP 20 2016

AMZ610-630-650-651-670-671-FLZ063-066>075-168-172>174-GMZ656-657-676-
210100-
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 FROM 20 TO 60 NM-
WATERS FROM DEERFIELD BEACH TO OCEAN REEF FL FROM 20 TO 60 NM
EXCLUDING THE TERRITORIAL WATERS OF 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-
WATERS FROM CHOKOLOSKEE TO BONITA BEACH FL FROM 20 TO 60 NM-
853 AM EDT TUE SEP 20 2016

...THUNDERSTORMS POSSIBLE FOR SOUTH FLORIDA THIS AFTERNOON...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH FLORIDA.

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS: SCATTERED THUNDERSTORMS ARE FORECAST DURING THE
AFTERNOON AND EARLY EVENING HOURS, WITH THE BEST COVERAGE OVER THE
INTERIOR AND ATLANTIC COASTAL AREAS. THE PRIMARY THREAT WILL BE
LIGHTNING.

WIND: THUNDERSTORM WIND GUSTS OF UP TO 50 MPH ARE POSSIBLE THIS
AFTERNOON AND EVENING.

FLOODING: HEAVY RAIN COULD PRODUCE URBAN STREET FLOODING,
ESPECIALLY IN LOW LYING AND POORLY DRAINED AREAS.

WATERSPOUTS: THERE IS A SLIGHT CHANCE OF WATERSPOUTS ACROSS ALL
SOUTH FLORIDA WATERS TODAY.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

SCATTERED THUNDERSTORMS ARE POSSIBLE EACH AFTERNOON AND EVENING,
ESPECIALLY OVER INTERIOR AND WEST COAST METRO AREAS OF SOUTH
FLORIDA.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED.

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

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MIAMI FL
113 PM EDT TUE SEP 20 2016

FLZ072-074-172-173-201800-
COASTAL MIAMI DADE COUNTY FL-COASTAL BROWARD COUNTY FL-
METRO BROWARD COUNTY FL-METROPOLITAN MIAMI DADE FL-
113 PM EDT TUE SEP 20 2016

...SIGNIFICANT WEATHER ADVISORY FOR FREQUENT TO EXCESSIVE
LIGHTNING...UP TO NICKEL SIZED HAIL AND 45 TO 55 MPH WINDS FOR
SOUTHEASTERN BROWARD COUNTY UNTIL 200 PM EDT...

* AT 113 PM EDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM
  OVER OJUS...OR OVER HALLANDALE. THIS STORM WAS NEARLY STATIONARY.

* FREQUENT TO EXCESSIVE LIGHTNING...GUSTY WINDS FROM 45 TO 55 MPH...
  UP TO NICKEL-SIZED HAIL...TORRENTIAL DOWNPOURS...OR A COMBINATION
  OF THESE ARE POSSIBLE. LIGHTNING IS THE NUMBER ONE WEATHER RELATED
  KILLER IN FLORIDA. TREES AND OPEN SHELTERS OFFER NO PROTECTION.
  THESE WINDS CAN DOWN SMALL TREE LIMBS AND BRANCHES...AND BLOW
  AROUND UNSECURED SMALL OBJECTS. SEEK SHELTER IN A SAFE BUILDING
  UNTIL THE STORM PASSES.

* LOCATIONS IMPACTED INCLUDE...
  PEMBROKE PINES...HOLLYWOOD...MIRAMAR...MIAMI GARDENS...
  HALLANDALE...NORTH MIAMI...NORTH MIAMI BEACH...AVENTURA...DANIA
  BEACH...SUNNY ISLES BEACH...WEST PARK...SUN LIFE STADIUM...OJUS...
  GOLDEN GLADES...PEMBROKE PARK...GOLDEN BEACH...IVES ESTATES AND
  HOLLYWOOD DOWNTOWN.

LAT...LON 2604 8022 2604 8011 2591 8010 2592 8024
TIME...MOT...LOC 1713Z 319DEG 1KT 2598 8016

SI