Scientific Forecaster Discussion
fxus62 ktbw 201120
Area forecast discussion
National Weather Service Tampa Bay Ruskin Florida
720 am EDT Wed Sep 20 2017
20/12z tafs. VFR conditions will prevail at all terminals through
the next 24 hours. Very few clouds this morning, then slightly
increasing to a scattered cumulus deck this afternoon. Northern terminals
will stay dry while pgd/fmy/rsw may see a stray shower this
afternoon, so will cover that with vcsh after 18z. Winds
will remain light less than 10 knots. No other aviation
Prev discussion... /issued 347 am EDT Wed Sep 20 2017/
Short term (today - thursday)...
aloft - ridging across the Gulf of Mexico and Florida slips west as a trough
initially from the Ohio Valley to the deep south slides to the eastern
Seaboard...and down into North Florida and adjacent waters. Surface - broad
high pressure sprawling across the southeastern U.S. And into the Gulf
continues as a weak trough eases across the southern half of the state.
Northeasterly flow continues to prevail...light enough to allow afternoon
sea breezes to shift winds to onshore along the coast...with some lower
level moisture streaming across. Much of Hillsborough and Polk counties
and northward stay fairly dry with precipitable water values of 1.3 to 1.5 inches.
South of those counties the precipitable water ranges from 1.5 to 1.8 inches.
The higher moisture along with the trough will support lower rain
chances for the southeast and southern counties in the afternoons.
Anticipate mainly showers but there could be isolated
thunderstorms...with activity ending early evening. Temperatures
continue to run above normal...a couple of degrees for the lows
and 2 to 3 degrees for the highs.
Middle term/long term (thursday night-tuesday)...
deeper moisture will overspread the entire region for Friday
Saturday with an increasing east to northeast flow setting up. This
combined with daytime heating and the sea breezes will lead to
scattered to numerous mainly afternoon and evening showers and
thunderstorms both days. Sunday into early next week the global
models are continuing to move Hurricane Maria northward well east of
the Florida Peninsula with the northeast flow shifting to a more
northerly direction bringing some drier air back southward into the
area Sunday through Tuesday which will lower rain chances to 20
percent or less on these days.
Daytime high temperatures will be near to a couple of degrees above
normal through the period with overnight remaining near normal.
20/06z tafs. VFR prevails with few-scattered clouds although lal may see
limited br around sunrise. Increasing moisture in the south could
support isolated shra/tsra...will keep pgd/fmy/rsw just vcsh for now.
Light NE winds increase slightly in the morning...with some of the
coastal terminals shifting during the afternoon to onshore.
high pressure with a relaxed gradient will dominate the waters
through the end of the week with benign conditions...except for
higher winds and seas near thunderstorms. During the weekend
Hurricane Maria moving across the southern waters of the Atlantic
will tighten the gradient with an increase in wind speeds.
Mariners should monitor the progress of Hurricane Maria...detailed
information on Maria may be found on advisories from the National
while slightly drier air continues across parts of the area for the
next couple of days the minimum relative humidity remain above critical values.
Increasing moisture and rain chances toward the end of the week will
help maintain higher relative humidity.
flooding continues on many rivers and creeks...most have crested
and are on a downward trend. Although the Withlacoochee River at both
Croom and Trilby are expected crest in the next couple of days.
While water levels will continue to slowly decrease residents near
rivers and creeks should monitor levels and use caution in
around any residual flooded areas.
Preliminary point temps/pops...
tpa 92 75 91 75 / 10 0 10 20
fmy 91 75 92 74 / 30 20 30 20
gif 92 72 91 73 / 10 0 10 10
srq 90 75 91 74 / 20 10 20 20
bkv 92 71 91 71 / 10 0 10 10
spg 90 76 89 75 / 10 10 10 20