Area forecast discussion
National Weather Service Tallahassee Florida
1121 am EDT Wed Jun 19 2013
Near term [today]...
broad cyclonic flow continues across the southeast U.S. A short wave
trough remnant of yesterday's Texas mesoscale convective vortex is working its way eastward
across MS and Alabama. A cold front to our north continues to make very
slow southward progress and currently stretches east to west across
central Georgia and Alabama. The subtropical ridge axis remains suppressed to
our south across the Florida Peninsula and central Gulf of Mexico. The
ktae 12 UTC sounding was modified to reveal an afternoon cape of
around 2400 j/kg. Precipitable water has inched up to 1.62 inches
and additional moisture is expected to pool ahead of the slowly
advancing frontal boundary this afternoon. The sounding also shows
that we remain in a type 5 sea breeze regime with strong west-southwest flow
through 700 mb. With contributions from the synoptic scale and
mesoscale lifting mechanisms such as the sea breeze and outflow
boundaries, we expect higher than normal coverage of showers and
storms today. Most of the area now has a likely pop (60%).
Concerning the severe weather threat, deep layer shear will hold
near 30 kt in some areas as the upper short wave moves over the
area. Delta Theta-E values are forecast to be around 32-34 today
indicating a wet microburst potential. Storm Prediction Center has the area outlooked in
a 5% risk area for damaging convective wind gusts, which looks
reasonable.
&&
Short term [tonight through saturday]...
the large scale long wave pattern commences with a trough over wrn
states, ridge over cntrl into ern Continental U.S. And a trough over ern
Seaboard with srn end over nrn Florida ewd into wrn Atlc. Several
shortwaves will continue to ride down ridge into backside of
trough. At surface low over ern Canada with quasi-stnry front south-southwest
across S/cntrl GA/al. High pressure remains over Gulf of mex.
This places local area in the warm sector with moist onshore flow
and lingering convection of this afternoon's rain will yield
20-40% pops mainly 00z-06z.
During the rest of the period, westerlies will gradually lift into
nrn tier states on Fri holding ern trough in place. The front will
likely stall generally east-west across far srn Georgia/nrn Florida on thurs as a
surface wave develops along it and aided by digging impulse provide
a focus for convection and higher pops. Area precipitable waters along frontal
axis will remain in the 1.7 to 1.9 inch range. A moderate west to
southwest steering flow along West Coast sea breeze will push
assocd convection east-northeast each day so highest pops likely to be near
I-75 each aftn/eve. Weakening front will inch towards coast on
Fri with some model differences I.E. NAM furthest south into
coastal FL, conversely, GFS showing little swd movement thru Fri
keeping almost of our area in warm sector. European model (ecmwf) in between. Thus
GFS probability of precipitation noticeably higher than NAM thurs and Fri. Expect an
unsettled weather pattern with increasing marine convection
especially with impact of nocturnal land breeze. By Sat, upper
trough axis will have shifted ewd with drying influence of
upstream ridge moving into ern states while front begins to wash
out with weak high pressure building over the region. However very
light winds will support active sea breeze and sct aftn convection.
Heavy rain and gusty winds are possible especially near frontal axis
and during time of passing impulse. Will lean towards wetter solution
and go with 40-50% west-east probability of precipitation thurs and Fri into eve and 30% on
Sat. However, overall severe threat will remain low with little or
no shear and weak lapse rates, however with cool temps aloft (-9c)
an isolated microburst could not be ruled especially on thurs.
Otherwise, temperatures will remain near normal with highs in the
lower 90s and lows around 70.
&&
Long term [saturday night through tuesday]...
pattern will support seasonal conditions through the early part
of next week with afternoon highs inland in the lower 90s along
with a chance of afternoon/evening showers and thunderstorms each
day. Overall, rather benign mid and upper level pattern is
expected to become established by the weekend and result in little
day to day change.
&&
Aviation...
[through 12z thursday] remaining areas of MVFR ceilings will lift to
VFR for this afternoon. However, scattered thunderstorms may bring
them briefly back down into that category. The overnight forecast
calls for a return to MVFR prevailing conditions after about 09 UTC.
&&
Marine...
the subtropical ridge of high pressure, which will extend from the
western Atlantic Ocean into the eastern Gulf of Mexico, will keep
winds light to moderate out of the southwest until tonight,
with the strongest winds over the nearshore legs with the afternoon
sea breeze. Then, a cold front approaching from the northwest will
cause a temporary shift in the winds to light offshore, before it
stalls out and weakens in our vicinity on Thursday. Thereafter, a
new ridge of high pressure will build in to our northeast, giving US
lighter winds out of the east and southeast, with a continuation of
the low seas.
&&
Fire weather...
moist conditions will continue throughout the remainder of the week.
Even though a weak frontal boundary will near the area today, drier
air is not expected to move into the region. As a result, red flag
conditions are not anticipated through the next several days.
&&
Hydrology...
no problems are anticipated in the near future.
&&
Preliminary point temps/pops...
Tallahassee 91 71 90 69 90 / 60 30 50 30 50
Panama City 88 73 89 73 86 / 50 30 40 30 40
Dothan 90 71 91 71 90 / 50 30 40 20 40
Albany 91 71 91 70 90 / 60 40 40 30 40
Valdosta 93 69 91 70 91 / 60 40 50 40 40
Cross City 91 71 90 69 91 / 60 30 40 30 40
Apalachicola 88 73 87 72 85 / 50 30 40 30 40
&&
Tae watches/warnings/advisories...
Florida...none.
Georgia...none.
Alabama...none.
GM...none.
&&
$$
Near term/aviation...wool
short term/marine...block
long term...Evans
fire weather...Godsey
hydrology...Evans/block
