Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 09/21/23
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
731 PM EDT Wed Sep 20 2023
...New UPDATE, AVIATION...
.UPDATE...
Issued at 722 PM EDT Wed Sep 20 2023
The forecast is currently in good shape with numerous to
widespread showers/storms across the area this evening. However,
starting to see some signs of the intensity and coverage dwindling
with the loss of daytime heating. The precipitation is a bit more
synoptically driven with a weak shortwave trough moving through
the region. This trough should shift to the east throughout the
evening and into the overnight hours with dry conditions moving
into the area over the next 2-3 hours and persisting throughout
much of the overnight period. Overnight lows tonight will drop
down into the upper 60s to low 70s.
&&
.DISCUSSION...
Issued at 306 PM EDT Wed Sep 20 2023
An upper-level trough is in place across the SE CONUS with
associated shortwave energy propagating across the FL Peninsula.
In association with this shortwave, an MCS has developed across
the E Gulf and diurnal sea breeze convection is beginning to
develop along the SWFL coast.
The atmosphere is unstable. Afternoon ACARS soundings show a
saturated atmosphere, with a PW value now over 2 inches. There is
low-level veering, indicating that the atmosphere is indeed
continuing to trend more summer-like as the low-level boundary lifts
northward. The upper-level pattern is more synoptically influenced
than a true summer day, though.
Considering a favorable atmosphere, the expectation is for
widespread convection to develop this afternoon. Right now, we
are sitting in the subsidence region of the MCS offshore; the MCS
is also warming the upper-levels through latent heat release. This
will probably delay convection until closer to 4 or 5PM outside
of SWFL, but should still lead to significant coverage once storms
do start to kick off. Main concern through the rest of the day is
for heavy rainfall with the atmosphere primed for efficient
rainfall rates; but the main impact is likely to only be localized
flooding of low-lying and poor drainage areas. Frequent lightning
is also expected with colder mid-levels and some small hail is
not out of the question either.
This boundary continues to linger tomorrow as well, and we could see
a similar setup again tomorrow. Albeit, we may see everything pushed
a little farther south if the boundary also shifts south again. As a
low begins to take shape off the east coast of Florida towards the
weekend, drier and more stable air wraps over our area. This will
limit rain chances primarily to SWFL through Sunday. This is
still short-lived, though, as a more southerly flow next week
quickly brings humidity and rain chances back by early next week.
&&
.AVIATION...
(00Z TAFS)
Issued at 722 PM EDT Wed Sep 20 2023
Storms are beginning to decrease in coverage and intensity with
the loss of daytime heating. Continued with a mention of TS at
LAL, SRQ, and PGD with dry conditions or VCSH elsewhere. Any
ongoing convection should come to an end by 02-03z with dry
conditions forecast overnight. Models are in fairly good agreement
with keeping the best chances for showers/storms over the southern
half of the area tomorrow and mentioned PROB30 for TS late in the
TAF cycle at PGD, FMY, and KRSW.
&&
.MARINE...
Issued at 306 PM EDT Wed Sep 20 2023
A large area of thunderstorms remains beyond 60NM offshore, with
additional storms likely to form in coastal waters along the coast.
Hazardous waves and seas are possible in the vicinity; and that
potential will continue at least through tomorrow. Drier conditions
return towards the weekend, but at least some isolated storms may
still continue offshore. Away from storms, though, winds remain 15
knots or less with seas around 2 feet or less.
&&
.FIRE WEATHER...
Issued at 306 PM EDT Wed Sep 20 2023
Ample moisture favors widespread shower and thunderstorm activity
through tomorrow, keeping fire weather concerns low. Drier
conditions return towards the weekend, but RH values are forecast to
remain above critical thresholds.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 74 88 74 89 / 60 50 20 30
FMY 73 89 72 89 / 40 60 30 40
GIF 72 87 71 87 / 60 50 10 30
SRQ 72 89 71 89 / 50 50 30 30
BKV 69 88 68 89 / 60 40 10 20
SPG 76 87 76 87 / 60 50 20 30
&&
Sea Breeze Thunderstorm Regime For Thursday: 2
Sea Breeze Thunderstorm Regime For Friday: 3
For additional information on sea breeze regimes, go to:
https://www.weather.gov/tbw/ThunderstormClimatology
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...None.
Gulf waters...None.
&&
$$
UPDATE/AVIATION/MARINE/FIRE WEATHER...Anderson
DECISION SUPPORT...Close
UPPER AIR/CLIMATE...Zayas