Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Tampa Bay Ruskin Florida
256 am EDT Friday Aug 26 2016
Short term (today - saturday)...
not too much to talk about between now and Saturday. The GFS
initialized well over the region and shows the very dry air over
the Florida Panhandle and the deep tropical moisture over South
Florida. The large deep-layered ridge to our north will gradually
lift northeast and reach the mid-Atlantic coast on Saturday. The
tropical wave/invest area 99l will be moving into the central
Bahamas on Saturday, and may still have a weak low pressure area
associated with it. Any impacts from this system should hold off
until after Saturday.
After a rather dry day for the Tampa Bay area northward yesterday,
we should see a return to scattered afternoon showers and storms.
Deepest moisture will again reside south of the Tampa Bay area
where scattered to numerous afternoon storms are expected.
Slightly drier air will again try to work its way southward into
Levy, Citrus and Sumter counties on Saturday, but areas south of
there will continue to see higher rain chances with precipitable
water values at or above 2 inches.
Sea breezes will continue to remain pinned near the coast as we
remain in enhanced easterly flow through Saturday.
Middle/long term (saturday night through next friday)...
the beginning of the medium range period will feature a fairly
noticeable change in sensible weather across much of the central and
southern Florida Peninsula. Broad upper ridging will extend across
much of the eastern Continental U.S. With troughing across the northern plains
and upper Midwest. The primary feature of concern will be a tropical
wave near Cuba, set to slowly approach South Florida over the
Somewhat seasonal conditions will persist much of the night Saturday
night with low level easterly flow and humid conditions. This looks
to gradually change from Sunday into next week though, as the
tropical disturbance, invest 99l slowly approaches the southern
Bahamas and Florida Straits.
99l is currently struggling mightily with some dry air in the
vicinity and modest wind shear. This will likely prevent the system
from developing further over the next couple of days, however some
gradually strengthening may occur over the weekend, as conditions
become slightly more conducive to intensification. Medium range
guidance is in generally good agreement, bringing the feature along
cuba's northern coast and into the southern Bahamas and Florida
Straits sometime Sunday. What is not clear, however, is the
potential intensity of the system. The most recent guidance suggests
99l will have a very hard time strengthening through at least
Saturday, and a few models even depict the system may move over
Cuba, which would make its ultimate fate uncertain. Regardless of
its intensity, the general track of this system into the weekend
would certainly favor a dramatic increase in rain chances across
much of central and especially southern Florida. Given the deep
tropical moisture associated with 99l, you can bet some of the rain
will be heavy, and we may be dealing with at least a threat of
localized flooding over the coming weekend. Breezy east winds may
also overspread South Florida, which will generally remain fairly
harmless inland, but could pose a problem for boaters offshore.
As we head into early next week, the picture becomes even less
clear. Most long range models move 99l into the eastern Gulf of
Mexico. Climatologically, this would be a favored area for tropical
cyclone development/intensification, but several models show less-
than-optimal conditions through at least the first few days of next
week, leading to very low confidence on the ultimate intensity of
this disturbance. However, history tells US we should keep a very
close eye on this feature if it does eventually move into the Gulf
of Mexico, and all interests from Florida to Texas should do so. At
the very least, the potential for heavy rain and flooding is likely
to exist as the system looks to be a slow mover.
mainly VFR next 24 hours. There could be some MVFR ceilings between
09z and 15z, but confidence not high enough to include in tafs at
this time. Typical Summer-time storms expected this afternoon with
brief IFR/LIFR possible 18z to 24z.
easterly winds continue between 15 and 20 knots early this morning
with seas around 3 feet. Winds should diminish a bit today as the
evening surge continues to move away and weak sea breeze
circulations attempt to develop. The same will be true overnight
with another easterly surge followed by a lull on Saturday.
Afternoon storms over land will likely push quickly westward into
the waters late each afternoon and continue into the evening.
The forecast from Sunday through Tuesday continues to hinge on what
becomes of the tropical wave approaching the Bahamas. This system
has failed to get any better organized, and is unlikely to develop
significantly within the next couple of days. It could however
develop as it moves near the Florida Straits and into the Gulf of
Mexico. Impacts to our coastal waters could include increased
coverage of showers and thunderstorms along with gusty winds,
building seas, and a risk for waterspouts. Overall the risk is lower
than it was 24 hours ago, but mariners are still urged to keep tabs
on the latest forecasts through the weekend.
no humidity issues. Enhanced easterly flow will continue for a
couple more days. This should keep any wind shifts associated with
the sea breeze from getting much farther east than the immediate
Preliminary point temps/pops...
tpa 92 77 92 78 / 40 10 50 10
fmy 92 77 91 77 / 60 30 60 20
gif 92 76 91 76 / 40 10 50 10
srq 92 77 92 78 / 50 30 50 10
bkv 92 75 92 75 / 40 10 40 10
spg 92 79 91 79 / 40 20 50 10
Short term/aviation/marine/fire weather...jillson
middle term/long term/decision support...Austin