Area Forecast Discussion
Issued by NWS Miami, FL

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FXUS62 KMFL 200532

Area Forecast Discussion
National Weather Service Miami FL
1232 AM EST Fri Jan 20 2017

VFR conditions will prevail tonight for all terminals except
APF with possible fog formation. Expect fog to develop over
south west Florida Gulf coast reducing vis from 4 to 5 miles.
As winds become light and calm tonight, expect fog to develop
in the early morning hours before sunrise. Conditions will
improve quickly in the morning hours. Light winds in the morning
remain through the day under a more southerly flow in the
afternoon but with a weakening high pressure winds will remain
close to 10 knots and light in the evening.


.PREV DISCUSSION... /issued 717 PM EST Thu Jan 19 2017/

VFR conditions with light and variable winds through the night.
South winds between 6-9 KT will increase along the east coast TAF
sites around 20/17000Z, then dwindle aft 20/2300Z. A weak gulf
sea breeze may also develop along the west coast. Otherwise, expect
dry conditions with partly cloudy skies through the period.

PREV DISCUSSION... /issued 359 PM EST Thu Jan 19 2017/

High pressure is in control, and is forecast to remain so through
Saturday. This will keep the weather quiet for South Florida. With
the flow trying to turn southwest, which may allow some patchy fog
to develop tonight, mainly in the western interior. Tomorrow will
see what will seem to be a repeat of today, except the wind
turning more to the southwest. This may result in higher chances
of fog over a wider area, as well as Saturday night.

The main weather concern for the forecast package is a cold front
for Sunday afternoon and overnight hours. Models are in fairly
good agreement with a 500mb short wave developing in to a closed
low, and spawning lee side development of a surface low over the
Texas Panhandle. There is also a stalled boundary sitting over
northern gulf coast. The low will interact with the boundary,
forming a cold front. it also may form a prefrontal trough just
ahead of the main front. The front will quickly approach South
Florida on Sunday. Showers are forecast to start spreading across
the western portion Sunday morning. The GFS is indicating that the
prefrontal trough may have the majority of any convective
activity. However, there is still a large amount of uncertainty
as to how strong the convective activity will be. The GFS is
showing a strong low level jet at 850 mb, with in excess of 50kts
wind moving across the CWA Sunday night. This could help to
increase the chances for strong convection in the overnight hours.
However, the GFS is also showing signs that the front will catch
up to the trough as it passes over the east coast of South
Florida. This could allow for the strongest convection to affect
the southeast Florida metro areas Monday morning. Any which way,
there is a potential for showers and thunderstorms, with the
potential for strong thunderstorms from Sunday afternoon through
Monday morning.

Another aspect of the front is the marine impact. Models are
indicating the Gulf could see very rough seas Monday, and possibly
Tuesday. The offshore Atlantic may also see rough sees about 6 to
12 hours later. See the marine and beach sections for further

behind the front, high pressure builds back in, bringing somewhat
cooler and drier weather for the middle of the week.

Quiet weather and and calm seas today, and tomorrow, will give
way to increasing winds and seas this weekend. this is ahead of a
cold front that will move across the region Sunday afternoon
through Monday morning. The weather will start getting rough on
Sunday, with the wind increasing to 20 to 30 kts in by Sunday
afternoon. This will cause seas to build to 7 to 10 feet Sunday
afternoon, and increase to 13 to 17 feet in the Gulf by Monday
evening. The Atlantic waters will also see rough seas, although
not quite a high as the Gulf, with seas currently forecast to
reach 8 to 13 feet. Seas will begin to subside on Tuesday.

Beach conditions are forecast to quickly erode on Sunday, as the
wind ahead of a cold front quickly increase. This would bring a
high risk of rip currents to the gulf coast beaches from Sunday
through Monday evening, and possibly Tuesday morning. It will also
lead to the potential to beach erosion and even some minor coastal
flooding, especially in flood prone coastal areas.

On the Atlantic side, a west wind would not typically cause any
issues. However, if the wind reaches 25 to 30 kts, it could cause
some reflection of the waves off the Bahamas, which could lead to
some risk of rip currents for the Atlantic beaches, possibly late
Monday into Tuesday.

West Palm Beach  82  65  83  70 /   0   0   0   0
Fort Lauderdale  81  68  81  72 /   0   0   0  10
Miami            82  67  82  71 /   0   0   0  10
Naples           79  65  81  70 /   0  10  10  10



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