Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Tampa Bay Ruskin Florida
300 PM EST Friday Nov 21 2014
..gusty day across much of west central and southwest Florida...
Short term /today-Saturday/...
weak surface high pressure continues to hold over northern and
central Florida this afternoon. Over southern Florida...a remnant
frontal boundary lingers with available moisture for light rain
showers. Aloft...a 500 mb trough is exiting the East Coast of the
United States with another amplifying trough/potential cut off low
entering the Desert Southwest. This feature will be a large player
in area weather for the weekend into early next week.
For the rest of today...the showers should stay limited to southwest
Florida in the areas closest to the frontal boundary. Isentropic
lift continues to fuel the shower activity...captured well in the
310k surface of the 12z GFS. Activity could linger
overnight...though it should shift south closer to the front.
Overnight temperatures will continue to moderate as the flow shifts
easterly...providing warmer moist air from the Atlantic.
For Saturday...the cut off low out west will progress eastward
through Texas...aiding a new Gulf frontal system to develop. This
new frontal system will push the stalled frontal boundary in
southern Florida back north and place much of the peninsula of
Florida in the warm sector by the end of Saturday. Temperatures in
the warm sector will be reaching into the 80s...though some portions
of the Nature Coast may stay on the cooler side of the boundary and
only reach the middle 70s. Rain chances will be on the rise with the
warm front and thunderstorm chances return with the afternoon peak
heating. Enough instability is available along the front and in the
warm sector on Saturday afternoon to at least mention a slight
chance of thunderstorms in the forecast at this time.
Long term /Saturday night-Friday/...
model solutions are in fairly good agreement through the long term
period. During Saturday night and Sunday a middle/upper level trough
will be moving across the lower Mississippi Valley and into the
Tennessee and Ohio valleys with some shortwave energy trailing south
into the Gulf of Mexico. This will drive the developing warm front
northward through the region Saturday night...while a weakening cold
front moves into the southeast states. The warm front will then
remain just north of the forecast area on Sunday. The best rain
chances will remain over the Nature Coast where the deepest moisture
and best forcing for ascent will reside. Quite a warm and moist
airmass will be moving into the region Saturday night and
Sunday...so will mention both showers and thunderstorms in the
forecast. Additionally...the Storm Prediction Center has Nature
Coast locations outlooked for a slight risk of severe thunderstorms
Saturday night and Sunday. At this point it appears that the main
threat will be isolated tornadoes and damaging winds Saturday night
and then damaging wind potential on Sunday.
Early next week a deepening trough will develop over the central
U.S. And move eastward into the eastern states during midweek.
This will help to drive the cold front over the southeast states
into the region during Tuesday and exiting the area by Wednesday.
For Monday and Monday night south to southwest winds will continue to
bring moisture northward with a chance of showers and
thunderstorms...especially across the Nature Coast closest to the
slow moving cold front/trough. During Tuesday and Tuesday night the
front will move southward through the region and with plenty of
moisture in place we should see scattered to numerous showers and a
few thunderstorms. A few showers may linger Wednesday as the
middle/upper level trough axis swings across area...otherwise some
cooler and drier air will return.
Temperatures through Monday night will generally be above normal
with daytime highs climbing into the upper 70s to middle 80s and lows
in the 60s to lower 70s. Along with the above normal temperatures
will come increased humidity with dew points climbing back into the
60s and lower 70s. For Tuesday and Tuesday temperatures will be near
to a few degrees below normal with highs in the upper 60s to near 80
degrees and lows in the upper 40s to around 60. For Wednesday
through Friday expect below normal temperatures to return with
highs mainly in the 60s and lows mostly in the 40s.
VFR through much of the period with gusty easterly winds this
afternoon and again on Saturday. Winds should lighten a tad this
evening. Rain chances increase in swfl in the morning and spread
northward throughout the day on Saturday.
a tight pressure gradient between strong surface high pressure to
the north and a stalled frontal boundary over southern Florida
continues to produce gusty east northeast winds across the coastal
waters. Conditions will reach Small Craft Advisory level over the
outer waters through midnight tonight. Winds will remain gusty with
small craft exercise caution conditions across all coastal waters
through the weekend. The winds will veer to the south southeast and
rain chances will increase on Saturday and Sunday as an area of low
pressure moves north of the area. The cold front associated with
this low is expected to move through the coastal waters late Monday
no fire weather concerns through the weekend as abundant moisture
will prevent any durations of critical relative humidities.
Overnight and early morning ground fog is possible Saturday night
into Sunday morning.
Preliminary point temps/pops...
tpa 62 79 68 81 / 10 30 50 30
fmy 65 82 71 85 / 20 30 30 30
gif 62 77 67 83 / 10 40 50 40
srq 62 82 70 82 / 10 30 40 30
bkv 57 77 70 82 / 10 30 60 50
spg 63 77 69 80 / 10 30 40 30
Gulf waters...Small Craft Advisory until 1 am EST Saturday for Bonita
Beach to Englewood out 20 to 60 nm-Englewood to
Tarpon Springs out 20 to 60 nm-Tarpon Springs to
Suwannee River out 20 to 60 nm.
Short term/aviation/fire weather...02/Garcia
long term/decision support services...21/jelsema