Rip Current in Florida, August 14, 2016

Area Forecast Discussion
National Weather Service Miami FL
141 PM EDT SUN AUG 14 2016

.AVIATION...

Easterly winds continue to increase to the 10 to 15 knot range
with higher gusts. Latest guidance and regional observations
indicate some drier air moving westward across the Atlantic
waters although some shower activity is possible for the Atlantic
coast terminals with a slight chance of thunderstorms but only
VCSH assigned at 18z with mainly VFR conditions expected to
prevail with very brief periods near MVFR conditions possible with
showers or an isolated thunderstorm. During the afternoon and
evening hours showers/thunderstorms mainly expected western
peninsula with VCTS assigned to KAPF at 19z with brief periods of
MVFR to IFR conditions possible with strong showers or
thunderstorms.

60

60

&&

.PREV DISCUSSION... /issued 1048 AM EDT SUN AUG 14 2016/

UPDATE...

The active convection early this morning across the local
Atlantic waters has subsided. But deep moisture continues across
the region with the 12z sounding indicating a PWAT of about 2.1
inches. However recent model guidance and recent satellite
analysis indicate some relatively drier air moving westward into
the western Bahamas islands and expected to continue moving
westward today. While this might help to limit additional
convection across the Atlantic waters and metro areas later today,
the forecast maintains chances of showers and thunderstorms across
these areas because of lingering outflow boundaries and the
presence of an upper level low centered over the eastern Gulf. The
latest HRRR guidance also indicates possible convection across
the Atlantic waters and Atlantic metro areas later today. But the
main bulk of convective activity is expected to be across the
interior and west peninsula after 17z and could also affect the
Gulf waters later today. Most of these features were already
indicated in the current forecast and no major changes were
required to the current forecast package. /60

PREV DISCUSSION... /issued 800 AM EDT SUN AUG 14 2016/

AVIATION...

For the short term, there are thunderstorms in the vicinity of
KFLL and KFXE, with VCTS assigned at 12z, with most likely short
term impact on KFXE with brief MVFR conditions possible.
Otherwise, very active convection earlier across the adjacent
local Atlantic waters slowly subsiding although with a few
lingering thunderstorms and outflow boundaries from earlier convection
could allow for additional thunderstorms for the next few hours
over the Atlantic waters with any of the Atlantic coast terminals
possibly assigned VCTS in amendments and might have brief impacts
as they drift westward. For the early afternoon hours relatively
drier air is forecast to move eastward into the region with
afternoon convection expected to be in the western interior with
terminal KAPF assigned VCTS at 16z.

60

PREV DISCUSSION... /issued 450 AM EDT SUN AUG 14 2016/

SYNOPSIS...
A ridge of high pressure over the western Atlantic will
continue southeasterly flow through mid next week. Expect highest
concentration of showers and storms over the inland and Gulf Coast
regions during the afternoon. Maximum temperatures will be around
average for this time of year. By the end of next week, increasing
moisture and light southernly flow may lead to a slightly higher
thunderstorm chances, especially for the interior.

DISCUSSION...
Light to moderate showers continue to move slowly
northwest over portions of the east coast metro. The activity, thus
far, has been slowly dissipating as it moves inland. Hi-res models
indicate this trend to continue through mid morning.

Today, a ridge over the western Atlantic will maintain deep
southeasterly flow across southern Florida. The vort max responsible
for the flare up of showers and thunderstorms overnight will push
north of the region by this afternoon. Behind this feature, negative
vorticity advection and relatively drier air will push into the
region. GFS forecast PWAT values drop to as low as 1.5 inches, which
is well below normal for this time of year. Only scattered
convection is expected this afternoon, with most activity over the
interior and Gulf Coast regions. Increased SSE winds over the
coastal waters will create a high rip current threat along the
Broward and and Miami-Dade County beaches through this evening. Heat
index will range between 100-105 F, with the highest values across
central Collier County. Tonight through Wednesday, models depict
various subtle disturbances moving through the predominant SE flow
pattern. This may act to increase thunderstorm activity at times,
including over the east coast metro.

Thursday through next weekend, a trough of low pressure will push
through the eastern CONUS and act to flatten the stagnant ridge of
high pressure in the western Atlantic. As this occurs, southeast
flow over Southern Florida will transition to southerly. This
pattern generally favors the interior for diurnal convection.

MARINE...
Easterly flow will prevail over the local Atlantic and Gulf
waters into next week as high pressure builds across the region.
Winds will generally be 10-15 knots, increasing to around 15
knots by tonight. Similar conditions will be possible heading
into early next week as well. Despite the gradual increase in wind
speeds, seas are expected to be 4 feet or less over the next
several days with little to no swell. There will be a chance of
showers and thunderstorms through out the period.

AVIATION...
While VFR will prevail, still a tricky forecast as models have
struggled handling the existing convection off the Atlantic Coast
into the Keys. Carried VCSH through mid morning at all Atlantic
terminals as moist airmass remains in place. More steady rain and
possibly thunder for the next couple of hours may bring MVFR
conditions to KOPF, KMIA, and KTMB as stronger cells move inland
from the Atlantic waters. Drier air mass moves into the east coast
after sunrise and focus for Sunday afternoon showers and
thunderstorms should shift west over the interior to the Gulf
Coast including KAPF.

&&

.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach  82  91  80  91 /  20  40  40  40
Fort Lauderdale  81  90  80  89 /  10  40  50  50
Miami            80  91  79  90 /  10  40  30  50
Naples           77  93  76  92 /  20  50  20  60

&&

.MFL Watches/Warnings/Advisories...
FL...High Rip Current Risk until midnight EDT tonight for FLZ172-173.

AM...None.
GM...None.
&&

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

HAZARDOUS WEATHER OUTLOOK FOR SOUTH FLORIDA
NATIONAL WEATHER SERVICE MIAMI FL
1151 AM EDT SUN AUG 14 2016

AMZ610-630-650-651-670-671-FLZ063-066>075-168-172>174-GMZ656-657-676-
150400-
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-
1151 AM EDT SUN AUG 14 2016

...HIGH RISK FOR RIP CURRENTS MIAMI-DADE AND BROWARD BEACHES...
...SCATTERED THUNDERSTORMS, ESPECIALLY WEST THIS AFTERNOON...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH FLORIDA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

RIP CURRENTS: THERE IS A HIGH RISK OF RIP CURRENTS ON MIAMI-DADE
AND BROWARD COUNTIES BEACHES. FOR PALM BEACH COUNTY BEACHES, THERE
IS A MODERATE RISK FOR RIP CURRENTS.

THUNDERSTORMS: THERE IS A CHANCE FOR THUNDERSTORMS THROUGH THIS
EVENING. THE BEST CHANCE FOR THUNDERSTORMS WILL BE OVER WESTERN
SECTIONS OF SOUTH FLORIDA THIS AFTERNOON. THE PRIMARY THREAT FROM
THESE THUNDERSTORMS WILL BE CLOUD TO GROUND LIGHTNING.

WIND: THE STRONGER THUNDERSTORMS WILL BE CAPABLE OF PRODUCING
GUSTY WINDS FROM 45 TO 55 MPH.

TEMPERATURES: HEAT INDEX VALUES OVER WESTERN PORTIONS OF INTERIOR
SOUTH FLORIDA WILL BE AROUND 105 DEGREES TODAY.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

THE RISK OF RIP CURRENTS ALONG ATLANTIC BEACHES WILL LIKELY BE AT
LEAST MODERATE THROUGH TUESDAY.

THUNDERSTORMS ARE POSSIBLE THROUGH THE WEEKEND, ESPECIALLY DURING
THE AFTERNOON HOURS. AFTER TUESDAY, THE BEST CHANCE OF
THUNDERSTORMS WILL BE OVER INTERIOR AND WESTERN SECTIONS OF SOUTH
FLORIDA. LIGHTNING WILL BE THE PRIMARY THREAT FROM THESE
THUNDERSTORMS.

.SPOTTER INFORMATION STATEMENT...

WIDESPREAD SPOTTER ACTIVATION IS NOT ANTICIPATED, HOWEVER
INDIVIDUAL SPOTTERS ARE ENCOURAGED TO REPORT HIGH WIND TO THE
NATIONAL WEATHER SERVICE FORECAST OFFICE IN MIAMI.

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