Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Tampa Bay Ruskin Florida
358 PM EDT Tuesday Mar 11 2014
..strong cold front to pass through the area Wednesday night...
..Cooler and drier weather expected on Thursday...
Short term (today-Thursday morning)...
The main player weather wise in the short term remains the
developing system in the north central Gulf. Visible satellite
imagery shows the eastern extent of the cloud cover currently
approaching the western Panhandle. As the afternoon/evening
progresses this cloud cover will eventually overspread across
northern portions of the County Warning Area. Introduced rain chances along the
Nature Coast starting at 00z this evening. Included the mention of
a few thunderstorms for the area by daybreak but overall thunderstorm activity
should be minimal. The coastal waters appear to have the best
chance for thunderstorm activity as greater instability will be present
over that area.
By daybreak...a few localized areas of patchy fog may be possible
overnight and into Wednesday morning but coverage will likely be
too sparse to include in the grids as cloud cover and precipitation
should limit overall fog potential. As far as rain is
concerned...most areas will likely see some light to moderate
showers over the course of the day on Thursday. That being said
overall quantitative precipitation forecast will likely be less than a quarter inch. Instability
is not overly impressive nor are Li values...despite temperatures warming
into the lower to middle 80s across portions of the County Warning Area. Not out of the
question we may see a thunderstorm or two but expect mostly showers for
west central and SW Florida tomorrow. Wind wise...gusty southwest
winds are expected to develop ahead of the cold front tomorrow
afternoon and a lake Wind Advisory may need to be issued by the
middle shift tonight.
Once the front pushes through the peninsula...winds will shift
out of the north and we will see strong cold air advection over the area. This
should keep high temperatures Thursday limited to the lower 60s
north...with lower 70s expected in far SW Florida.
Long term (thursday-monday)... models are in fairly good
agreement through Friday night or Saturday...then significant
differences develop for the remainder of the extended forecast.
The cold airmass will be sliding off to the northeast on Friday...
but not before giving US a chilly morning. Have kept temperatures
above freezing for now...but there is at least some chance that we
will see temperatures at or below freezing over Levy County.
Elsewhere...middle 30s to lower 40s will be common from north to
south...with temperatures holding near 50 right along the coast.
On Saturday...models begin to struggle with pieces of energy
ejecting eastward from a cut-off low that is forecast to be over
or near Southern California on Thursday. The GFS moves a slightly
better defined short-wave trough across the northern Gulf states
on Saturday whereas other models are weaker/flatter. The more
defined GFS solution would bring more clouds and perhaps even some
shower chances north of the Tampa Bay area while the European model (ecmwf) and
Canadian would favor dry weather with fewer clouds. 00z wpc
forecast also favors the drier scenario...so will optimistically
keep one of the weekend days dry.
On Sunday...a stronger short-wave in the northern stream digs
southward toward Texas...but what happens after that point depends
on the orientation of the polar low near Hudson Bay. The GFS has a
north-south orientation which begins to phase with the southern
stream. The European model (ecmwf) has more of an east-west orientation and does
not phase. This leads to timing differences throughout the
remainder of the extended period resulting in a rather low
Not going to try to get too detailed with all these differences...
but suffice to say that with a rather robust trough to our west
and a frontal boundary nearby...we will see our share of clouds
and rather high rain chances for March. The best rain chances
should be centered on Sunday and Monday with some improvement by
brief periods of MVFR visibility from patchy fog may affect
kpgd...kfmy...and krsw terminals after 09z otherwise VFR will
be the rule at all sites with an increase in middle and high level
clouds at or above 100 expected. Increasing moisture ahead of a cold
front will bring increasing rain chances from ksrq north to
ktpa and kpie and klal after 06z and have included vcsh with
prevailing p6sm -ra likely after 14z. Southwest winds around 10
knots will diminish to 5 knots or less after 02z before
increasing to 12 to 16 knots with gusts up to 26 knots possible
after 14z on Wednesday.
a cold front will move across the waters during the
day on Wednesday with winds and seas increasing to Small Craft
Advisory levels behind the boundary very late Wednesday night into
Thursday morning. High pressure will then dominate into the weekend
with winds and seas diminishing during the day on Friday.
a cold front will approach the region on Wednesday and
move through the region Wednesday night. Showers and a few thunderstorms
are expected very late tonight and into Wednesday with breezy conditions
and elevated dispersion indices expected Wednesday afternoon. High pressure
and a much drier airmass will move back into the region for the end of the
week...with critical humidity levels expected Thursday afternoon...with
near critical winds possible on Thursday.
Preliminary point temps/pops...
tpa 64 79 52 64 / 40 60 20 0
fmy 66 83 62 71 / 20 40 30 0
gif 64 82 53 65 / 40 60 20 0
srq 64 76 58 63 / 40 60 30 0
bkv 60 80 48 63 / 50 60 10 0
spg 66 77 57 63 / 40 60 20 0
Short term/marine/fire weather...11/mckaughan