Area Forecast Discussion
Issued by NWS Miami, FL

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FXUS62 KMFL 280815

Area Forecast Discussion
National Weather Service Miami FL
415 AM EDT Fri Apr 28 2017

Through this weekend: Latest surface analysis indicates a longwave
trough sagging along the eastern CONUS with a cold front draped
southward from upstate New York down to northern Alabama. Another
feature of interest is the elongated surface high stretching from
the Gulf of Mexico to the western Atlantic. Clockwise flow around
the high provided light southeast flow to the CWA yesterday.
Shallow low level moisture was also advected across the peninsula
from the Atlantic, allowing dew points to rise into the mid 70s.
This morning, light winds will allow moisture to pool and
temperatures to drop to their dewpoint across portions of the
western interior, from Naples to Lake Okeechobee. Thus, patchy fog
will be possible with diminished visibility at times. High
pressure will continue to build aloft today with the 00Z GFS
generating a 590 dm high pressure cell directly overhead. Strong
subsidence from the high will produce very warm, near record
breaking maximum temperatures. Look for mid 80s along the east
coast beaches and low to mid 90s along the the interior and Gulf
Coast regions. The heat index will approach 100 degrees, for
interior Collier County, due to elevated dewpoints near 70
degrees. Stronger east southeast flow today will push the sea
breeze convergence boundary westward, closer to the Gulf Coast.
Hi Res models, including both the HRRR and WRF, develop a few
showers in this region, but nothing too significant. For now, will
keep a slight chance of showers in the grids. Otherwise,
expecting dry conditions area wide. On Saturday, the
aforementioned surface high pressure will strengthen and edge
further west, closer to the Atlantic sea board. This will act to
increase southeast flow over South Florida with breezy conditions
developing from late Saturday into Sunday. Maximum temperatures
should decrease slightly from previous days, esepcailly along the
east coast metro.

Early to mid next week: By Monday, both the GFS and ECWMF indicate
a weak cold front beginning to approach from the west. Ahead of
this feature, the flow will turn more southerly and draw deeper
moisture into the region. The combination of sufficient heat and
and humidity will lead to a daily chances of shower and
thunderstorm activity. Another, stronger cold front is progged to
push through the region by mid to late next week. This is where
models differ. The GFS is more progressive, pushing the front
across by Thursday night, while the ECMWF is slower with a Friday
night passage. This far out, however, confidence on timing is
rather low.


Southeast winds will remain around 10 to 15 knots through this
evening with seas less than 4 feet. As the surface gradient
strengthens through the early weekend, southeast winds will
increase to 15 to 20 knots. By Saturday night, winds over 20 may
need the issuance of small craft advisories. Mostly dry conditions
are expected this weekend, with increasing chances of showers and
storms by early next week.


High pressure over the Atlantic will keep a moderate SE wind flow
across South Florida through the next 24 hours. Patches of
scattered clouds around 1,500 ft will affect terminals through
about 13z-14z, then lifting to 2,500 ft from 14z-00z. There could
be brief periods of broken ceilings with these clouds, but VFR
should be the prevailing condition. Only possible exception could
be KAPF/Naples where a periodic broken cloud layer at or below
1,000 ft/visibility below 5SM could develop between 08z-13z. Not
enough confidence in this occurring to mention in TAF at this
time, however. Despite the low level moisture, little in the way
of showers expected.


West Palm Beach  88  77  86  77 /  10  10  10  10
Fort Lauderdale  88  79  85  79 /  10  10  10  10
Miami            89  77  87  77 /  10  10  10  10
Naples           91  73  91  72 /  20   0   0   0



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