Area Forecast Discussion
Issued by NWS Miami, FL

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FXUS62 KMFL 180545
AFDMFL

Area Forecast Discussion
National Weather Service Miami FL
1245 AM EST Wed Jan 18 2017

.AVIATION...
VFR conditions should prevail during the TAF period. Cant
completely rule out some brief fog restrictions at Naples late
tonight, so placed 6SM group during this time. Generally calm
winds overnight will become SE at 5-10 KT during the day, then
become calm again tonight. Naples likely to have a SWly Gulf
breeze during peak heating.

&&

.PREV DISCUSSION... /issued 804 PM EST Tue Jan 17 2017/

UPDATE...
IR satellite imagery shows scattered high clouds streaming from
northwest to southeast over South Florida this evening. Surface
winds continue light and from the southeast. Still expect
portions of the interior to develop patches of fog late tonight as
the boundary layer decouples, winds become calm, and temperatures
drop. Tomorrow, the surface pressure gradient will be weaker,
thus weaker surface winds are anticipated. Otherwise, the
forecast looks on track.

PREV DISCUSSION... /issued 454 PM EST Tue Jan 17 2017/

DISCUSSION...
The 17/1200Z sounding from this morning indicated moisture in the
boundary layer, from the surface to 850 mb, with dry air aloft.
Large scale subsidence today, along with a lack of any appreciable
moisture, has kept conditions dry and the radar quiet. Visible
satellite imagery showed scattered fair weather strato-cu
streaming in from the southeast with wispy high clouds dropping
down from the northwest. High temperatures had topped out in the
low 80s along the east coast with mid-80s inland, values around 5
degrees above normal for this time of year.

Surface high pressure, currently located north of the Bahamas, will
begin to weaken and slide westward tonight. Light flow over the
peninsula, along with mostly clear skies, may allow for patchy
fog development over the interior. Wednesday into Thursday, expect
more of the same with upper level high pressure ridging in place.
Skies will be mainly clear with maximum temperatures in the low
to mid 80s, 5 to 7 degrees above normal. Friday into the early
early Saturday, surface high pressure will again fall back to the
east. This will help to gradually turn the flow southerly.

This weekend, both the 12Z GFS and 12Z ECMWF eject a deep trough of
low pressure into the southern plains. As this feature approaches
the eastern CONUS, a vigorous cold front will likely push
southeast towards southern Florida. As the front approaches,
south/southwest winds are forecast to increase and become gusty
at times. This southerly component to the flow will help to
increase moisture in a deep column of the atmosphere with PWAT
values forecast to rise to above 1.75 inches. Sunday night, a
north to south line of strong positive vorticity advection should
approach the Florida Gulf coast. With both moisture and
instability in place, showers are likely, along with a slight
chance for thunder. Some of this activity could be heavy at times,
due to the high available atmospheric moisture content. Models
show this activity pushing east, off the Florida Atlantic coast by
late Monday. However, confidence of timing is only moderate, as
the event is more than 5 days out. Expect cool weather on Monday,
as the front passes, with maximum temperatures only forecast to
reach the mid 70s. Long range models build a ridge of high
pressure over South Florida by mid next week, bringing a return
to dry conditions.

MARINE...
Southeasterly winds of 10 to 15 knots can be expected through
Friday, then increase and turn southerly over the weekend. Seas
will remain below 4 feet into Sunday. A cold front is forecast to
move across the waters Sunday night and Monday, and this will
likely lead to hazardous winds and seas, along with a risk for
thunderstorms.
&&

.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach  81  62  81  64 /   0   0   0   0
Fort Lauderdale  82  66  80  67 /   0   0   0   0
Miami            81  66  80  67 /   0   0   0   0
Naples           81  61  80  63 /   0   0   0  10

&&

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

UPDATE...27/JT
DISCUSSION...27/JT
MARINE...27/JT
AVIATION...23/SK







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