Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Tallahassee Florida
332 am EDT Tuesday may 26 2015
Near term [through today]...
A broad long wave trough continues to dominate the central and
western U.S with a ridge axis just off the East Coast. While there
are several lows and/or vorticity centers of note within the trough, the
nearest feature has the best chance of influencing weather across
the southeast as it crosses the Mississippi River. Surface analysis
continues to show high pressure centered off the middle Atlantic coast
ridging southwestward into Dixie. This feature continues to bring
moist southeast flow into the region at lower levels. Regional
radars shows a squall line moving eastward across Louisiana. Most
wrfs maintain this features as it moves eastward with some weakening
as it reaches our far western zones late in the day. Even if the
feature does not make it this far east, its remnant outflow will
help enhance convective development across our western zones. This
will also be the region that gets the most contribution to lift from
DPVA. Therefore, similar to yesterday, probability of precipitation are highest across our
southeast Alabama zones (80%) and taper off to the southeast (40-50%
across the Florida big bend). Storm Prediction Center has the northwestern half of the
forecast area outlooked for a marginal risk for severe storms. The
primary threat would be damaging straight-line winds, although most
storms are expected to remain below severe limits. Rainfall totals
should be insufficient to produce flooding concerns, although
isolated spots in southeast Alabama and the inland Florida Panhandle could get
1-2 inches. Maximum temperatures will range from the upper 80s northwest to the
lower 90s southeast with the sea breeze keeping coastal communities
in the middle 80s.
Short term [tonight through thursday]...
An elongated area of +pv is forecast to stretch essentially the
entire length of the Mississippi River by tonight. This will
result in broad southwesterly flow across the southeast on the
leading edge of a shortwave trough centered over the upper
Mississippi Valley. The southern half of the +pv anomaly is
forecast to weaken as it reaches the southeast Wednesday
afternoon, though should still yield widespread showers and
thunderstorms, especially west of a line from Albany through
Tallahassee. Slightly above average precipitable water values, coupled with
relatively light steering flow may set up some heavy rain in spots
west of the Apalachicola and Chattahoochee rivers, though
widespread flooding is not expected. On Thursday, a weaker
southern stream anomaly will move into the tri-state area and once
again focus the bulk of convection west of the aforementioned line
while drier air moves in across the eastern half of the region.
Afternoon highs are expected to run near seasonal averages.
Long term [thursday night through tuesday]...
While there is some agreement between the global models in weak
ridging leading up to the weekend, their solutions begin to
diverge by Saturday. While they tend to agree that another
shortwave trough will move through the Central Plains and Midwest
this weekend, the GFS breaks off a wave and subsequently spreads
weak troughing over the southeast both Saturday and Sunday. This
would result in a rather wet weekend. For now will trend towards
the previous forecast and the European model (ecmwf) which would suggest more
climatological pops, scattered along the afternoon seabreeze. By
early next week, there remains agreement that the aforementioned
shortwave will reach the eastern third of the country and result
in higher than normal rain chances.
[through 06z wednesday]
Once again, we expect a round of MVFR ceilings to set in during
the predawn hours, with IFR possible at vld. The ceilings will
lift to VFR by middle morning. Decent coverage of showers and storms
are expected once again today with greater chances northwest vs
southeast. Therefore, ts is included with greater certainty at dhn
East or southeasterly flow will prevail through the weekend. Each
night, expect enhancements in winds and seas; though the surges
should remain mostly below headline levels.
Relative humidity will remain above critical thresholds this week with wetting
rains expected across portions of the forecast area each day.
The next few days will be rather wet for the western half of the
region. Expect average rainfall amounts of 1-3 inches across
southeast Alabama and the Florida Panhandle, with generally an
inch or less east of a line from Albany to Tallahassee. Training
cells, or just general slow storm motion will yield isolated
amounts that could be double the average. Generally speaking,
rivers are well poised to handle the aforementioned amounts,
though sensitive basins that get the isolated higher amounts may
reach action stage.
Preliminary point temps/pops...
Tallahassee 89 72 85 70 87 / 50 30 50 20 30
Panama City 84 74 84 73 83 / 50 40 70 20 50
Dothan 87 69 85 68 84 / 80 40 70 40 70
Albany 90 70 86 68 86 / 70 40 70 40 30
Valdosta 91 69 88 66 88 / 50 40 40 10 20
Cross City 92 70 88 67 87 / 50 40 30 10 10
Apalachicola 86 75 83 73 82 / 30 40 60 20 40
Florida...high rip current risk until 5 am EDT /4 am CDT/ tomorrow for
coastal Bay-coastal Franklin-south Walton.