Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 231855

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
255 PM EDT Wed Aug 23 2017

.SHORT TERM (Today and Thursday)...
A potent upper level trough continues across the Great
Lakes and New England with strong surface high pressure
building southeastward from Canada in the wake of a fast
moving cold front. Meanwhile, robust mid level ridging
extends across the Southern Rockies into the Southern Plains
and Gulf Coast. Weak surface high pressure extends across
the Gulf of Mexico and western Atlantic on the norther
periphery of two tropical features of note; tropical
depression Harvey, and a weak tropical wave located
somewhere between the Florida Straits and west of the
Florida Keys. Harvey will remain well west of the region,
bring the potential for extensive life threatening flooding
to portions of Texas and Louisiana. The tropical wave near
south Florida will be the primary feature of concern over
the next two days.

Scattered showers and an isolated thunderstorm or two are
in progress across mainly south Florida. This activity is
expected to persist and eventually become more widespread as
daytime heating continues and the seabreezes eventually
merge over southwest Florida. Given deepening tropical
airmass as depicted by precipitable water values in excess
of 2 inches, locally heavy rainfall may occur, especially
over areas south of I-4. As the tropical low lingers over
the area into tonight, showers and storms may be slow to
dissipate, but an eventual weakening of activity is forecast
by midnight with more activity developing offshore.

For tomorrow, as the low lifts northward across the
southern and central Florida peninsula, even more widespread
shower and thunderstorm activity is expected. The
combination of deep tropical moisture with the usual
afternoon seabreezes and weak lift associated with low
pressure should yield widespread rainfall coverage. Areas
that receive prolonged rains may experience localized
flooding, but widespread flooding is not currently expected.
With increased cloud cover and moisture, we should catch a
slight break from the heat as well, with upper 80s to lower
90s over the mid 90s highs we have seen of late.

.Long Term (Thursday Night-Wednesday)...
A weak surface trough will be lingering over the area
through Monday, and then start to lift out to the NE with
weak ridging in place at the upper levels. Plenty of
uncertainty at the end of the period with respect to what
will evolve with Harvey currently forecast to move into the
northern Gulf coast region. Deep moisture will remain in
place across the area with the trough, and expect scattered
to numerous showers and thunderstorms each day across the
area. Temperatures near normal through the period. All
interests should monitor the tropics for the next few days
as conditions evolve.


.AVIATION (18z TAFs)...
Scattered showers and storms continue to develop south of
I-4 this afternoon. Will maintain VCTS all terminals and
send tempos as needed with passing showers/storms. Greater
chances will mainly be confined to KPGD/KFMY/KRSW. VFR
conditions to return by 03z to all terminals with light east


An area of low pressure will linger near southern Florida
into tomorrow night, generating scattered to numerous
showers and thunderstorms over the Gulf waters. This feature
will lift to the northeast Friday into Saturday, imparting
drier conditions. Light winds and seas will persist through
the weekend, but winds may increase slightly over the
northern waters as this area of low pressure interacts with
a weak cold front over the southeastern U.S. early next
week. This could lead to increasing winds over the northern
waters Monday into Tuesday, but winds generally look to
remain below 15 knots. All eyes will remain on Harvey as
well early next week, though it looks to remain well to the
west at this time.


As a tropical wave lingers over the area, deep tropical moisture and
increased chances for rain will prevent any fire weather concerns
through the weekend. A drier weather pattern may take shape early
next week, but humidities still look to remain well above critical
levels through next week.


.Preliminary Point Temps/PoPs...
TPA  78  91  78  89 /  30  60  30  60
FMY  76  89  77  87 /  40  80  50  70
GIF  75  91  75  90 /  20  60  30  70
SRQ  77  89  78  89 /  40  60  40  60
BKV  75  92  75  90 /  20  50  30  60
SPG  79  91  79  89 /  30  50  40  60


Gulf waters...None.


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