Scientific Forecaster Discussion

Return to Local Conditions & Forecast
Area forecast discussion 
National Weather Service Tampa Bay Ruskin Florida
423 am EDT Sat Apr 19 2014

..showers and thunderstorms developing in interior central and
southwest Florida this morning...

Short term (today - tonight)...
a vigorous frontal system is beginning to push across the
peninsula of Florida this morning. The surface low pressure is
tracking across The Big Bend of Florida towards northeast Florida.
Ahead of the cold front...showers and thunderstorms have developed
across a large portion of the peninsula south of Interstate 4.
Some of this morning/S storms have been strong enough to present a
wind and hail concern...though the higher severe potential remains
across southern and east central Florida this morning.

At 12z...model guidance depicts the arrival of a vorticity
maximum...a healthy low level jet of nearly 40 knots...and the
presence of the upper level jet above much of central and southern
Florida. With the front advancing into west central and southwest
Florida this morning...expect rain and severe storm chances to
generally decrease after sunrise. The best shear appears to be
along the Interstate 95 corridor this morning...with most guidance
placing 0-1km helicity values of 100 m2/s2 or greater along the
East Coast. These factors led to a Tornado Watch until 10 am this
morning for much of east central and southern Florida.

There could be a secondary surge of shower activity...and possibly
elevated convection...later today as the upper level low...with
500mb temperatures of -10 degree c as far south as Tampa Bay...moves
across northern and north central Florida. The biggest question
will be whether enough moisture remains to allow any rain to
materialize. Currently believe best chances are over the Gulf
waters and along the immediate coast.

Winds will pick up this afternoon behind the front...though
sustained winds should remain below 20 knots. Temperatures will be
cooler behind the front tonight...though not unseasonable with
temperatures generally settling into the 60s.

Middle term (sunday - monday)...
upper ridging will build in from the west in the wake of the
departing closed middle level and surface lows moving northeast
over the Atlantic as surface high pressure from New England
noses south to the northern Gulf. A drier subsident airmass
associated with the ridging will support pleasant dry weather
across the forecast area on Easter Sunday and on Monday as
well with near seasonal level temperatures expected.

Long term (monday night - friday)...
a progressive amplified split flow pattern will continue over
the Continental U.S. During the long term period. Both the GFS/European model (ecmwf) are
in agreement with synoptic scale features so will a blend.
Nearly zonal flow aloft and surface high pressure over the region
at the start of the period will provide pleasant dry weather
across the region Monday night and Tuesday with a continuation
of seasonal level temperatures.

During Tuesday night and Wednesday the tail end of short wave
trough an attendant cold front will move southeast through the
region. Limited moisture return via model cross-sections should
result in a dry frontal passage. In the wake of these features
high pressure surface and aloft will maintain pleasant dry weather
on Thursday and Friday. Seasonal level temperatures Monday night
through Wednesday will rise to slightly above normal during Thursday
and Friday.


low ceilings are creating conditions ranging from VFR to brief patches
of IFR this morning. Showers and thunderstorms have developed near
the swfl terminals and lal...though activity should decrease this
morning. Some showers are possible this afternoon...though
confidence is too low to include in the taf at the moment.


as the frontal system moves across Florida today...gusty winds and
elevated seas will be the story. Conditions will improve into
Sunday as high pressure builds back in to start the work week.


Fire weather...
recent wetting rains should mitigate most fire weather concerns.
Gusty winds are expected today and tomorrow...which will produce
elevated dispersion index values.


Preliminary point temps/pops...
tpa 75 62 80 63 / 20 20 0 0
fmy 80 63 82 63 / 10 10 0 0
gif 76 60 81 62 / 20 10 0 0
srq 74 62 78 63 / 10 10 0 0
bkv 75 57 80 57 / 20 20 0 0
spg 73 65 78 65 / 20 20 0 0


Tbw watches/warnings/advisories...
Gulf waters...Small Craft Advisory until 10 PM EDT this evening for
Englewood to Tarpon Springs out 20 to 60 nm-Tarpon
Springs to Suwannee River out 20 to 60 nm.



Short term/aviation/marine/fire weather...02/Garcia
middle term/long term/decision support services...57/McMichael