Area Forecast Discussion
Issued by NWS
FXUS62 KTAE 020651
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
251 AM EDT Thu Oct 2 2014
...Stormy Conditions Expected on Friday with Much Drier and Cooler
Weather on Tap for the Weekend...
.Near Term [Through Today]...
An upper level shortwave trough over the four corners region is
deepening the upper level trough over the western CONUS, with weak
ridging still in place aloft over the Mississippi valley. At the
surface, high pressure is still in place over the eastern CONUS, but
will continue to slide eastward through the period as a developing
front over the Plains begins to trek eastward. Today will be dry,
with only a slight (20%) chance for showers in extreme western
portions of our area. Highs will be quite warm for October- in
the upper 80s to around 90.
.Short Term [Tonight Through Saturday]...
The 4-Corners short wave will pivot across the Southern Plains
before being absorbed by the trough currently over western Canada.
This 2nd trough will dig southeastward to a position over the
Mississippi Valley by 00Z Saturday. The trough will continue to
amplify and come to dominate eastern North America on Saturday with
its axis extending from Ontario to FL by 00Z Sunday. The associated
cold front will reach the Lower Mississippi Valley tonight and cross
AL on Friday. The front will then sweep across our forecast area
from northwest to southeast Friday night. Pre-frontal convection
will approach our western zones by daybreak Friday with likely PoPs
for most of the area Friday afternoon. The likely PoPs will linger
into the evening for South Central GA and parts of the FL Big Bend.
Shear values have increased in the models since last night`s runs,
but are still marginal for severe. We would expect to see a
weakening linear MCS approaching from the west. In our area, look
for some of the stronger storms to produce wind gusts up to about 40
mph. Friday will also be pretty humid for October with dew points in
the lower 70s. With afternoon highs in the mid to upper 80s, heat
indices will peak in the mid 90s along and south of I-10 with lower
90s to the north.
.Long Term [Saturday Night Through Thursday]...
The ridge of high pressure behind the cold front will quickly
build into the region on Saturday night and Sunday, and remain
centered in our vicinity through Monday. While there will be
significant cool air advection, the exact position of the ridge
during the overnight hours will be critical for radiational
cooling for both Sunday and Monday morning. At this time, the
model guidance is continuing to trend cooler, with lows on Sunday
expected to be in the middle to upper 40s over much of the
interior, with upper 40s to lower 50s fcst for Monday morning.
High temps will gradually moderate through the period, ranging
from the middle to upper 70s on Sunday, to the lower to middle 80s
on Wednesday. Rain chances will be very slim through the entire
period, with just a slight chance of a shower on Monday night and
Tuesday as an upper level disturbance moves through from the NW.
[Through 06Z Friday] With high pressure and high moisture in
place over the region, another morning with MVFR visbys and
possibly IFR cigs is in store for DHN, ABY, and VLD, clearing out
after sunrise. Afterward, VFR will prevail with light winds,
generally 5 knots or less, from the east-southeast.
Light winds and low seas will dominate the marine area through
tonight. Winds will be on the increase out of the southwest by
Friday afternoon ahead of our next cold front. A wind shift to the
northwest then north will occur behind the front Friday night and
Saturday with winds expected to reach cautionary to marginal
advisory levels. Offshore winds will drop off on Sunday and veer to
onshore by Monday.
Relative humidities will dip into the mid to upper 20s this weekend
west of a line from Apalachicola to Fitzgerald in the wake of a cold
front. At this time, it looks like Alabama will reach its relative
humidity duration and 20-ft wind criteria and likely its KBDI
values as well on Saturday. The Florida Panhandle and western Big
Bend counties appear to be more borderline, with most of the
Panhandle reaching duration criteria and much of both areas
reaching wind criteria, but the ERC values are more uncertain as
they will depend on how much rainfall we will accumulate. In
Georgia, relative humidities are expected to remain above 25
percent, preventing red flag criteria from being reached there.
Relative humidity will be low for long durations Sunday as well,
but winds will be lower, preventing red flag conditions in
Alabama. Depending on the ERC values, Florida may be borderline
once again Sunday.
Although some of the stronger storms on Friday could produce locally
heavy rainfall in excess of 2", most areas should receive average
totals of 1" or less due to the fast moving nature of the
approaching cold front. This amount of rainfall will have little
impact on our area rivers and streams.
.Preliminary Point Temps/PoPs...
Tallahassee 90 70 88 64 80 / 10 10 60 60 10
Panama City 86 75 86 64 79 / 10 20 70 50 0
Dothan 89 70 84 56 74 / 10 20 70 40 0
Albany 89 68 87 59 76 / 10 10 70 50 0
Valdosta 88 67 87 64 77 / 10 10 60 60 20
Cross City 88 68 87 70 82 / 10 20 40 50 30
Apalachicola 85 74 85 67 80 / 10 10 60 60 10