Area Forecast Discussion
Issued by NWS Miami, FL

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FXUS62 KMFL 231930

Area Forecast Discussion
National Weather Service Miami FL
330 PM EDT Sun Jul 23 2017



As of 330 PM EDT...A relatively tranquil afternoon for late July
continues across South Florida, as deep subtropical ridging
continues to build across the region. In addition to the ridging in
place, a remnant SAL layer continues to move across the southern
half of the area, with a noted warming and drying trend in the
midlevels on the 12z observed KMFL sounding. Further north across
northern Florida, a weak upper-level low has spawned more numerous
showers and storms north of Lake Okeechobee.

For the rest of this afternoon and into the evening, sea breeze
convergence will help to spawn some scattered showers and storms
mainly over interior areas, with the best coverage being north near
the lake and into Palm Beach county where the least amount of
midlevel dry air exists. An occasional isolated shower/storm may
affect the far southern tip of the peninsula towards the Keys as
well along the southern periphery of the subtropical ridge axis.

Garden variety storms are mainly expected today, as enough dry air
in the midlevels should inhibit any more impressive convective
development. Frequent lightning will be the main threat. Any
lingering activity over the mainland will rapidly fizzle this
evening leaving dry overnight conditions. Isolated showers and
perhaps a few storms will be possible overnight mainly over the
local Gulf and Atlantic waters.

After high temperatures topping out in the 90s this afternoon, low
temperatures will settle towards their normal values of mid to upper
70s over much of the area, with a few readings near 80 along the
east coast.


The remnant SAL layer will continue to drift off into the Gulf of
Mexico Monday as deep subtropical ridging remains locked in place
across the region. With east/southeast flow in place, moisture
levels will return back to normal levels by Tuesday with PWATs
approaching 2 inches, but enough lingering dry air in the midlevels
looks to keep rain chances more in the scattered range. Best chances
for showers/storms will be across the interior and portions of the
Gulf Coast. During the nighttime hours, isolated activity will be
favored over the Atlantic and Gulf waters and portions of the east
coast at times. Most storms will be garden variety, although cannot
rule out a rogue strong storm or two Monday and Tuesday afternoon
with some gusty winds where sea breeze convergence is strongest.

With only scattered convective coverage expected during the day,
temperatures during the short term period will be a little above
normal, with highs well into the 90s for most areas. With increasing
low-level moisture during the early week, heat indices will easily
exceed 100 degrees everywhere, with most areas exceeding 105 degrees
during peak heating. Will need to monitor trends for Tuesday, as a
few locations may flirt with heat advisory criteria. Low
temperatures will be in the mid to upper 70s for most, with readings
in the lower 80s along the east coast.


The long term period will feature the subtropical ridge breaking
down slightly as a deep longwave trough pattern sets up over the
eastern third of the CONUS. This will allow the flow to gradually
become more southerly with time, advecting in deeper tropical
moisture. With this pattern in place, coverage of showers and
thunderstorms looks to be greater, with the east coast seeing better
chances especially towards the end of the work week.

Temperatures will be near to slightly above normal during the long
term period.


Generally good boating conditions will prevail across the local
waters through midweek under a light east/southeast flow. Winds may
briefly near 15 knots at times over the offshore Atlantic waters,
but expected to remain around 10 knots or less near the coasts. Seas
will be 2 feet or less through midweek. Isolated to scattered
showers and storms will be possible.


Gulf and Atlc seabreezes have moved inland of most sites this
afternoon, but remain close enough to KPBI and KTMB to keep VCTS
through 20Z. Sct TSRA over interior through 24/02Z, will have to
monitor for potential for a few to drift back towards terminals
later this aftn. Isold Gulf/Atlc convection again overnight, which
may brush Atlc terminals towards daybreak but threat is too low
to mention at this time. Seabreezes diminish after 00Z becoming
light/vrb with similar winds for Mon.


West Palm Beach  78  93  80  94 /  20  20  20  30
Fort Lauderdale  80  91  80  92 /  20  20  30  30
Miami            79  92  80  92 /  20  30  30  40
Naples           76  93  78  93 /  10  20  10  30



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