Area Forecast Discussion
Issued by NWS Miami, FL

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FXUS62 KMFL 252348
AFDMFL

Area Forecast Discussion
National Weather Service Miami FL
748 PM EDT Tue Apr 25 2017

.AVIATION...
Light to calm winds will prevail tonight across all sites with
a few clouds through the period with mainly VFR conditions. The
winds will begin to veer southerly into Wed after 15z increasing
to no more than 10 knots with the exception of MIA and TMB which
could see a few gusts in the afternoon hours. Expect lighter wind
to return in the early evening hours. No precipitation is expected
through the period.

&&

.UPDATE...
Forecast remains on track with small update to reflect current
obs conditions across the forecast area. Expect light to calm
winds tonight with mostly clear conditions across the region.

&&

.PREV DISCUSSION... /issued 347 PM EDT Tue Apr 25 2017/

DISCUSSION...

A dry air mass is in place over Florida this afternoon in the
wake of Monday`s cold front. Water vapor satellite imagery
indicates the closed/vertically stacked low over North Carolina is
slowly moving northeast. A stronger low is developing over
Wyoming with a strong digging jet over the west coast.

Near term (tonight into Wednesday evening)...The dry air mass will
remain in place tonight. Winds will be very light as the pressure
gradient slackens with the mid-Atlantic low moving away. Good
radiational cooling potential will allow temperatures to fall into
the upper 50s in the interior again tonight, ranging to the upper
60s at the Atlantic beaches. Cannot rule out some late night
patchy ground fog in the interior but not expecting widespread
coverage.

Strong pressure falls in the middle of the CONUS will bring about
a more southerly component to the low level winds tomorrow.
Precipitable water values currently near 0.6 inches will rise to
about 1.25 inches by afternoon. A weak shortwave trough embedded
in the sub-tropical jet and associated patch of cooler air in the
mid levels are currently entering the north-central Gulf, and this
will move into south Florida tomorrow coincident with modest low
level confluence and increasing moisture. Although global models
and MOS guidance are mostly dry, the suite of convection-allowing
models is consistent showing isolated to scattered showers
developing just inland from the east coast during the early
afternoon hours. So have inserted some low POPs to cover for this
possibility.

Short term (Wednesday night into Friday night)...Warmer and more
humid air mass will take hold with dewpoints returning to near 70
and high temperatures in the upper 80s near the coasts to lower
90s interior. No large scale forcing expected for organized
showers, but would not be surprised to see an isolated shower or
two along the sea breezes each afternoon. POPs have been kept
below 20 for now as coverage is expected to remain isolated.

Medium range (Weekend into Tuesday)...A couple of strong shortwave
troughs and associated surface lows are likely to evolve out of the
mean central CONUS trough. The first will move out of the Plains
into the Great Lakes Wed-Thu, driving a surface front toward the
northern Gulf Coast. But this will likely wash out before reaching
South Florida as a stronger shortwave trough develops over the
Southern Great Plains this weekend. With a stacked ridge
developing over the western Atlantic this setup will favor deep
southeasterly flow over the region and very warm/humid conditions.
With sufficient instability and moisture in place, the western
side of the Peninsula would be favored for a few afternoon showers
as the Atlantic sea breeze pushes well west and collides with the
Gulf breeze held up near the west coast. However, PW values
holding generally below 1.5 inches and a mid level inversion in
place suggest any showers will be isolated and low-topped.

A powerful shortwave trough is likely to rotate through the
Plains into the Great Lakes early next week driving the next front
closer to South Florida, but this is near the end of the 7 day
forecast so for now the forecast only indicates chance POPs with
a slight chance of thunder.

MARINE...
Light to moderate winds and seas generally 3 feet or less through
Friday. Winds and seas both gradually increase over the weekend as
a strong low pressure develops over the middle of the US and high
pressure strengthens over the western Atlantic.

AVIATION...
Other than some early morning patchy fog possible mainly at KFXE
and KTMB, VFR flying conditions with dry weather will prevail
through the TAF period. Winds will be westerly at 10-15 knots
through around 00z before trending under 10 knots overnight. Winds
will shift to the southeast at 5-10 knots for the east coast sites
late in the TAF period.

FIRE WEATHER...
Relative humidity values across the interior have fallen into the
mid-upper 30s as expected this afternoon, with 20 foot winds
around 10 mph. A red flag warning remains in effect for the rest
of the afternoon and early evening. Tomorrow, expecting minimum
afternoon RH values to be similar in the mid to upper 30s interior
sections, but the 20 foot winds should weaken, with guidance
consistent in speeds being 8 mph or less across the interior. So
for now there are no fire weather headlines issued for tomorrow.
&&

.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach  64  83  71  89 /   0  20  10  10
Fort Lauderdale  68  84  76  89 /   0  20  10  10
Miami            68  84  75  90 /   0  20  10  10
Naples           63  85  71  88 /   0   0   0   0

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...Red Flag Warning until 8 PM EDT this evening for FLZ063-066.

AM...None.
GM...None.
&&

UPDATE...67/MT
AVIATION...67/MT







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