Area Forecast Discussion
Issued by NWS Miami, FL

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FXUS62 KMFL 230012

Area Forecast Discussion
National Weather Service Miami FL
812 PM EDT Wed Mar 22 2017

Winds will become light and variable tonight with VFR conditions
prevailing through Thursday morning. Patchy fog could develop
near APF early Thursday morning. A cold front passage will bring
some periods of VCSH, or even brief MVFR under showers Thursday


.PREV DISCUSSION... /issued 745 PM EDT Wed Mar 22 2017/

As of 745 PM EDT...Current forecast on track with only minor
updates made to account for the latest trends in observations.
Previous discussion highlights ongoing forecast well and is below.

PREV DISCUSSION... /issued 309 PM EDT Wed Mar 22 2017/



As of 305 PM EDT...High pressure continues to weaken across the
region as a frontal boundary approaches from the north, currently
making its way into northern Florida as of the mid-afternoon
hours. Ahead of the front, another pleasant spring day continues
with mostly clear skies and temperatures reaching into the 80s.
For the remainder of today and into tonight, fair weather is
expected to continue, with increasing cloud cover tonight from
north to south along with increasing low-level moisture. This
increasing low-level moisture will lead to another night of patchy
to areas of fog across portions of the interior and Gulf Coast,
especially in vicinity of any ongoing wildfires. Low temperatures
will range from near 60 in the interior and Gulf Coast to low and
mid 60s along the east coast.


The aforementioned frontal boundary will continue to weaken and
eventually wash out as it moves into South Florida Thursday into
early Friday. Despite the decaying frontal boundary, enough low-
level moisture will be pooled out ahead of it, along with weak
overrunning/isentropic lift, to help promote scattered showers
across much of the region, especially for the latter half of
Thursday. Model guidance does hint at some mid-level instability as
well, so have added a slight chance of thunder mainly across
portions of the lake region and Palm Beach County. Overall rainfall
amounts are expected to generally be light, but a few areas could
see a nice soaking rainfall of around a half an inch, helping the
ongoing drought situation.

Behind the front, northeasterly winds will become brisk to
occasionally breezy at times, especially along the east coast where
wind gusts of 20-30 mph will be common at times late Thursday and
continuing into the day Friday. Lingering showers along the east
coast will also continue on Friday, again light in nature.

High temperatures on Thursday will range from the upper 70s in
northeast areas to low and mid 80s in southwest areas, warmest where
significant cloud cover holds off the longest. Highs on Friday
behind the front will be slightly cooler, ranging from the mid 70s
to around 80. Low temperatures Thursday and Friday night will
generally be in the 60s, with a few upper 50s readings in the


The long term period will be characterized by upper-level ridging
aloft and brisk easterly flow as the region remains under a tight
pressure gradient from strong surface high pressure in the western
Atlantic basin. With this synoptic pattern in place, generally fair
weather will prevail, although with the flow off the Atlantic,
enough low-level moisture will be in place to allow for a periodic
isolated shower and increased clouds mainly along the east coast.

Temperatures will be near to slightly above normal for the long term

Small Craft Advisory conditions possible across portions of the
local waters as early as late Thursday...

Generally good boating conditions will continue into early Thursday
with seas 4 feet or less and north/northeast winds under 15 knots.
Beginning late Thursday, marine conditions will rapidly deteoriate
as a weak frontal boundary moves across the region with scattered
showers. In the wake of the frontal boundary, hazardous marine
conditions for small craft are likely with increasing northeast flow
and seas 7 feet or greater, especially for the Atlantic waters.
Hazardous marine conditions will also be possible for the Gulf
waters, Lake Okeechobee, and Biscayne Bay as well.

Hazardous marine conditions, especially for the Atlantic waters, are
expected to continue through much of the weekend.

A Moderate Risk of rip currents will continue for the Atlantic
beaches through most of Thursday, with the main contributor being
some northeasterly swell 2 feet or less. The threat for rip currents
for the Atlantic beaches looks to increase to a High Risk beginning
late Thursday and continuing into the weekend with increasing
onshore flow in the wake of a frontal passage.

Relative humidity values may reach critical levels across portions
of South Florida through the remainder of this afternoon. Despite
these values, sustained 20ft winds are expected to remain under 15
mph with only fair dispersion. However, conditions will continue to
be closely monitored for a heightened fire weather risk into the
evening hours as ERC values are forecast to be in the low 30s across
much of South Florida.

Fire weather concerns will diminish Thursday as an approaching
frontal boundary brings scattered showers to much of the region, and
continue to remain diminished into the weekend with relative
humidity values being above critical levels.

For the short term, for Atlantic coast terminals weak westerly to
variable winds expected to transition to an easterly sea breeze
around 19-20z. For all terminals mainly VFR conditions expected
through the afternoon and evening hours. Patchy fog could develop
interior peninsula early Thursday morning but thus far not
expected to impact South Florida terminals, although terminal KAPF
could experience brief periods of fog around 09-12z Thursday but
low confidence.

West Palm Beach  65  77  68  78 /  20  60  30  20
Fort Lauderdale  65  78  69  78 /  10  60  40  20
Miami            65  81  68  79 /   0  50  30  20
Naples           64  81  62  81 /   0  40  10  10



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