Area Forecast Discussion
Issued by NWS Miami, FL

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FXUS62 KMFL 232345

Area Forecast Discussion
National Weather Service Miami FL
745 PM EDT Wed Aug 23 2017

Most of the convection from earlier this afternoon has diminished
across S FL with VFR cigs at this time. A few iso SHRA starting
to initiate over the coastal waters will gradually move inland
closer to midnight. Expect scattered showers brief MVFR cigs/vis
with passing SHRA. Current light winds increase again to near 10
kts out of the east late this morning and afternoon.


Robust convection of this afternoon has for the most part
diminished and exited the region, and near-term models suggest
evening will be relatively quiet across South Florida. Thereafter,
expected increasing coverage of showers and thunderstorms along
the east coast. Have adjusted POPs to reflect this thinking.
Temperatures are already rain cooled in the upper 70s to low
80s, and will fall very little overnight.


.PREV DISCUSSION... /issued 414 PM EDT Wed Aug 23 2017/


SHORT TERM (Tonight through Friday night)
Numerous showers and a few thunderstorms have impacted South
Florida today and this activity is likely to continue into
tonight. Very heavy downpours does bring mainly urban flood
concern in the near term. Culprit for the abundant precipitation
is tropical disturbance, generally centered just south and west of
South Florida, will remain nearly in place through at least Thursday
night. Plume of moisture (PWATs 2.1-2.4 inches) will remain over
South Florida through the period, thus numerous showers and
thunderstorms will persist. Locally heavy rainfall is possible,
and as the prolonged rainfall continues, more and more locations
will see saturated ground. See HYDRO section below for details on
flood potential. By Friday, a weak cold front will enter north
Florida, and will draw up the tropical disturbance to the
northeast. Development of this system is not expected in the short
term, with NHC only calling for a 10 percent chance of tropical
cyclone formation through the end of the work-week.

Generally overcast conditions and widespread rainfall will curb
diurnal heating, but do expect the few peaks in clouds to allow
maxima to still rise well into the 80s, with some low 90s, each
afternoon. West Palm Beach set a daily record warm minimum
yesterday (Tuesday), only falling to 82F. The old record was 81
degrees from 2000. With most areas seeing rain cooled air over the
next few days, additional heat records are not anticipated.

LONG TERM (Saturday through Monday)
Front will stall over Central Florida into early next week, and
the tropical disturbance will only slowly move northeast into the
Atlantic and out to sea (when chances for development increase
slightly). Across South Florida, abundant tropical moisture and
deep southwesterly flow will provide ample conditions for numerous
showers and thunderstorms, with potential for heavy rainfall

Tropical disturbance in the vicinity of South Florida is not
expected to develop into a Tropical Depression or Storm, but will
bring scattered to numerous thunderstorms to regional waters into
the weekend. Southerly wind of 10 to 15 knots is expected away
from these thunderstorms, with the potential for some higher
southwesterly wind Friday and Saturday. Speeds will closely be
monitored for the potential need for a Small Craft Advisory.

Some scattered showers have developed over the Atlantic waters
during the overnight hours and moved inland, with tempos for -ra
in place for MIA and TMB. Brief MVFR cigs/vis are possible with
the heavier showers. TS has not been an issue so far, but VCTS
will be introduced after 15Z at all terminals. Current light winds
increase again to near 10 knots out of the east late this morning
and afternoon.

Overall, PWATs of 2 to 2.5 inches will dominate South Florida into
early next week. A tropical disturbance over the region will bring
plenty of lift to induce numerous showers and thunderstorms during
this period. The system will remain nearly stationary until
Friday, when a cold front moves into Central Florida and stalls.
This front will lift the disturbance northeastward, only gradually
away from South Florida over the weekend. Still, deep, moist
southwesterly flow will continue the likelihood of showers and
thunderstorms over the region. Locally heavy rainfall is expected
throughout this period, with WPC suggesting widespread 2 to 5
inch amounts. However, the flood problems will be most likely
where localized much higher rainfall amounts occur. At this point,
models suggest the heaviest rain and highest flood potential will
not onset until later Thursday. Thus, no Flood Watch will be
issued this evening. One could be issued as early as early
Thursday morning.

West Palm Beach  79  90  77  90 /  50  70  50  60
Fort Lauderdale  78  88  78  88 /  60  60  50  50
Miami            77  89  77  88 /  60  60  50  50
Naples           77  90  79  86 /  50  60  60  70




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