Area Forecast Discussion
Issued by NWS Miami, FL

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FXUS62 KMFL 281409 AAB
AFDMFL

Area Forecast Discussion...UPDATED
National Weather Service Miami FL
1009 AM EDT Wed Sep 28 2016

.UPDATE...
An upper level low over the Great Lakes region will drift
southward towards the Tennessee Valley today allowing for a cold
front over the Southeastern United States to move southward into
northern Florida. This will allow for a southwest steering flow
over South Florida today letting the west coast sea breeze push
across the area, while the east coast sea breeze remains over the
east coastal areas of South Florida. Therefore, the scattered
showers and thunderstorms are possible over the interior and east
coast metro areas this afternoon with best coverage of over Palm
Beach County. The west coast metro areas of South Florida should
only see isolated coverage this afternoon.

The showers and thunderstorms should come to an end early this
evening leaving the area dry late this evening into the overnight
hours tonight. Therefore, the pops have been removed from South
Florida mainland after midnight tonight. There could also be some
patchy fog development late tonight around the Lake Okeechobee
region, due to the low level moisture and temperatures getting
down to around 70 degrees.

Rest of the forecast looks good at this time and no other changes
are planned.

&&
.UPDATE...54/BNB


.PREV DISCUSSION... /issued 720 AM EDT Wed Sep 28 2016/

AVIATION...
The winds will be light from the southwest this morning into early
this afternoon, before going to a south/southeast direction (170
degrees) late this afternoon at most of the taf Sites. The only
exceptions are at KTMB and KAPF taf sites where they will remain
in a southwest direction. The wind speeds will be around 5 knots
at most of the taf sites today. The weather should remain dry this
morning into early this afternoon, before some thunderstorms
develop late this afternoon over the east coast taf sites.
Therefore, VCTS will be kept in for the east coast taf sites after
18/19Z time today. KAPF taf site will see some showers this
morning before thunderstorms this afternoon. Therefore, VCSH
until 17Z then VCTS after 17Z today. The ceiling and vis will
remain in VFR conditions today, but could fall down into MVFR or
even IFR conditions with any thunderstorm passage.

&&
AVIATION...54/BNB


PREV DISCUSSION... /issued 418 AM EDT Wed Sep 28 2016/

DISCUSSION...
Synopsis: Expansive trough and closed mid/upper level low pressure
centered over the Ohio Valley and extending into the northeast
Gulf of Mexico will continue to be the dominate weather feature
for the remainder of the week. This feature will weaken and lift
north as high pressure builds in from the north and east over the
weekend and into early next week. A continued warm and moist
atmosphere will provide high chances for showers and thunderstorms
through the period.

Short Term (Today through Friday):
Mid and upper level trough axis that has resided in eastern Gulf
and northward has shifted slightly closer to Florida peninsula
early this morning, but over South Florida, deep southwesterly
flow prevails, advected substantial moisture into the region.
Aside from some marine showers, CWA is dry early this morning, but
as heating destabilizes atmosphere later this morning and early
afternoon, showers and thunderstorms should develop. Gulf sea
breeze will move far inland but Atlantic breeze will struggle to
even form, thanks to SW winds at 10-15 mph. This will cause
convection to focus convection toward east coast and northern
region. Activity should wane tonight then re-invigorate Thursday
by afternoon as synoptically, conditions will remain quite
similar. Rain chances are slightly higher Thursday as guidance
depicts moisture plume moving in from the west during the day.

For Friday, deep layer wind profile shifts more southerly so both
sea breeze may be of equal magnitude with storms remaining most
prevalent over interior South Florida.

Long Term (Friday night through Tuesday):
As trough lifts out of the region and weakens, high pressure will
build in from the north and east over the weekend and into early
next week. The weak cold front that was expected to stall as far
south as central Florida now seems to at best read the Florida
panhandle before dissipated and will have no impact on South
Florida. Instead, easterly flow will establish and warm moist
conditions will persist. Rain chances will remain climatologically
high.

The National Hurricane Center is monitoring a strong tropical wave
approaching the Windward Islands this morning. This system has a
90 percent chance of developing into a tropical depression or
tropical storm later today. It is likely to move west or west-
northwest into the eastern and central Carribean Sea into the
weekend. It is too early to tell if this system will have any
impacts on South Florida, and if it does these impacts will likely
not occur until at least early next week (or beyond the extended
period).

MARINE...
Wind and seas will remain below critical thresholds through the
weekend, except locally in and around thunderstorms. Stronger
east and northeast winds are expected early next week along with
at least slightly higher seas.

AVIATION...
For the short term, an area of showers is currently affecting
terminal KAPF, with brief periods of MVFR conditions possible with
passing showers over the next couple of hours. For the Atlantic
coast terminals, mainly VFR conditions are expected to prevail
over the early morning hours. Light southwesterly winds will
prevail across the region by mid-morning, but around 18z the
Atlantic coast sea breeze could penetrate eastward to most of the
Atlantic terminals, except for maybe KTMB and KOPF. Afternoon
convection is forecast, with VCTS assigned at terminal KAPF at 16z
and at 18z for the Atlantic coast terminals.  60/BD
&&

.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach  90  72  89  75 /  50  30  50  30
Fort Lauderdale  90  74  89  76 /  40  20  50  30
Miami            91  74  90  76 /  30  20  50  30
Naples           87  74  88  75 /  20  10  40  20

&&

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

$$

DISCUSSION...60/BD
MARINE...60/BD
AVIATION...54/BNB
UPDATE...54/BNB


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