Area Forecast Discussion
Issued by NWS Miami, FL

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000
FXUS62 KMFL 201157
AFDMFL

Area Forecast Discussion
National Weather Service Miami FL
757 AM EDT Fri Sep 20 2019

.AVIATION...
Generally VFR with gusty easterly winds and passing showers
through much of the period. Some easing in the wind speeds and
gusts are possible overnight. Brief bouts of sub-VFR are possible
with showers, particularly along the east coast terminals.

&&

.PREV DISCUSSION... /issued 317 AM EDT Fri Sep 20 2019/

DISCUSSION...

Today and Tonight...

South Florida will be located between expansive mid-upper ridging
extending from northern Mexico into the Ohio Valley and Humberto
associated troughing over the western North Atlantic Ocean.
Surface high pressure will strengthen from the lee side of the
Appalachians through the south Atlantic states while a tropical
wave advances through the western Caribbean Sea. A pronounced low-
level pressure gradient will ensue between these surface features
resulting in brisk easterly winds averaging up to 25 kt at times
along the Atlantic coastal interface. Wind profiles through 850 mb
suggest that gusts exceeding 30 kt are also possible over the
local waters and east coast metro areas as well. It still appears
that we will remain below wind advisory criteria (30+ mph
sustained winds and/or frequent gusts >35 mph over 3 hours or
more), but we will continue to monitor the latest data and
observations in case deeper mixing becomes established. The
easterly flow should advect a pocket of low-level moisture
(characterized by precipitable water values > 1.5 inches) across
our area today resulting in fast-moving scattered showers and a
few thunderstorms. Precipitation chances should be fairly uniform
across the area today given the fast flow in place, with greater
coverage focusing on the east coast metro and Atlantic waters
overnight. Given the rather strong winds aloft it shouldn`t take
much for gusty winds to accompany any of the stronger showers and
storms. Highs should average between about 85 and 90, with the
warmest readings over the western interior and Gulf coast regions.
Lows will dip into the lower to mid 70s inland, with upper 70s to
around 80 along the coasts.

Saturday and Sunday...

A low-level trough is forecast to be in the vicinity leading to an
increase in shower and thunderstorm coverage, particularly on
Saturday. By Sunday, some of the deterministic guidance shifts the
trough axis farther to our south thus decreasing rain chances for
northern portions of the area. Attempted to represent the greater
spread in model solutions during this period with widespread PoPs on
Saturday, but with a more pronounced north to south gradient across
the area on Sunday. Given strong low-level ridging across the South
and Mid Atlantic states, the strong pressure gradient will be
maintained with breezy (and at times gusty) easterly flow
persisting. Temperatures will remain seasonal with highs perhaps a
touch cooler than on Friday.

Monday through Thursday...

Mid-level ridging should strengthen from the Southeast CONUS into
the Gulf of Mexico early in the period with the ridge center
shifting towards the Carolinas by late week. This should result in
mostly dry and subsident conditions for the early portion of the
week as the low-level trough shifts farther to our south. There may
be enough moisture for a few showers to impact far southern portions
of our area however. As the mid-level ridge re-orients farther to
our north late in the period low-level moisture return should
commence with shower chances increasing by late week into the
weekend.

MARINE...

Fresh to strong ENE breezes will create hazardous conditions for
small craft operators across all South Florida waters through
this weekend. Occasional gale force gusts are also possible for
the Atlantic waters from today into Saturday, although they
appear to be too infrequent for a gale watch at this time. Steep
waves are also anticipated over the Atlantic waters due to the
residual swell and winds. A Small Craft Advisory remains in effect
for all waters (including Lake Okeechobee and Biscayne Bay), and
small craft should exercise extreme caution, especially around
jetties and inlets.

BEACH FORECAST...

A high rip current risk continues for the Atlantic beaches due to
strong onshore flow. This risk will persist through at least this
weekend, and potentially into next week as well. Surf-zone wave
heights over 7 feet are possible through this weekend for waters off
the Palm Beach County coast, possibly leading to localized beach
erosion. A High Surf Advisory remains in effect for this area
through this weekend. Swimmers and beachgoers are urged to use
extreme caution this week and follow the instructions of lifeguards
and other public safety officials.

&&

.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach  85  79  85  78 /  50  50  50  20
Fort Lauderdale  86  79  85  79 /  60  60  60  30
Miami            87  79  86  78 /  60  70  70  40
Naples           89  75  90  74 /  40  30  30  20

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk through Sunday evening for FLZ168-172-173.

     High Surf Advisory until 8 PM EDT Sunday for FLZ168.

AM...Small Craft Advisory until 8 AM EDT Sunday for AMZ610.

     Small Craft Advisory until 8 PM EDT Sunday for AMZ630-650-651-
     670-671.

GM...Small Craft Advisory until 8 AM EDT Sunday for GMZ656-657-676.

&&

AVIATION...02/RAG


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