Area Forecast Discussion
Issued by NWS
FXUS62 KTAE 201417
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
917 AM EST Thu Nov 20 2014
.Near Term [Through Today]...
The 9 am EST regional surface analysis showed a high pressure
ridge centered over North FL, and we expect a continuation of fair
weather today. Highs will be a little warmer than yesterday- generally
in the mid 60s (still slightly below average).
[Through 12Z Friday] Unrestricted vis & unlimited cigs will
continue through the period, with light N to NE winds (generally less
than 8 KT).
.Prev Discussion [429 AM EST]...
.Short Term [Tonight Through Saturday]...
A gradual warming trend will continue through the short term as
the surface high pressure starts to lift out to the northeast. A
marginal light freeze remains possible tonight across the
typically colder areas of the Florida big bend with mostly clear
skies, light winds, and low dewpoints still in place there. By
Friday, low level moisture will start to increase with easterly
surface flow developing. On Saturday, this trend will continue,
and a strong upper level shortwave will move into Texas.
Increasing moisture and lift ahead of it may allow for a few
showers to develop late in the period over the Florida panhandle,
but the bulk of the heavier rain and storms is expected to hold
off until Saturday night and Sunday.
.Long Term [Saturday Night Through Thursday]...
Global models continue to be in reasonable agreement on swinging a
strong, negatively tilted upper level shortwave from the MS
Valley to the Great Lakes region Saturday through Sunday with an
associated strong surface low. As this occurs, a warm front will
lift northward from the Gulf, separating cooler and more stable
air to its north from the warmer and more unstable air to the
south. There remains some uncertainty as to how far north the most
unstable air will get, but it does appear that it will move inland
enough for some risk of severe weather to develop across the area
from late Saturday night through the day on Sunday. The greatest
risk will probably be closer to the coast where more confidence
exists in an unstable airmass, but we cannot rule out any portion
of the forecast area from the risk yet. Given the strong shear
that will be in place, damaging winds along with isolated
tornadoes would be possible.
As the system occludes over the Great Lakes on Sunday night, a
secondary shortwave will move across the southern U.S and push a
cold front through the area on Monday afternoon. Thus, a chance of
showers and thunderstorms will continue through Monday, with
lower chances by Tuesday.
Light to moderate offshore will remain in place through this
evening. Thereafter, the gradient will sharply tighten between a
high pressure to the east and a strengthening low pressure system
to the west. This will result in a prolonged period of advisory
conditions starting on Friday night and continuing through Sunday.
In fact, a strong to severe squall line may sweep across the
coastal waters Saturday night into Sunday.
The relative humidity will still be quite low today. This combined
with elevated ERC values for Leon and Wakulla counties will lead
to Red Flag conditions in those two counties only. Also, due to
relatively low mixing heights and light transport winds,
dispersion indices will be low with values as low again today,
generally in the 20s. Moisture levels will increase later in the
week with widespread rain expected over the weekend.
The storm system for Saturday night through Monday will have the
potential to produce widespread rainfall amounts of 1.5 to 3
inches, with locally heavier amounts, especially if a secondary
impulse generates another batch of heavy rainfall on Monday
afternoon. The heaviest amounts currently appear to be focused
across the Florida panhandle. However, this system still looks
progressive at this time, and given the rather dry conditions that
have prevailed through the fall, flooding does not appear to be
a significant concern outside of the urbanized areas. River levels
are currently very low, with plenty of capacity for runoff.
.Preliminary Point Temps/PoPs...
Tallahassee 64 32 68 45 73 / 0 0 0 10 10
Panama City 64 43 66 50 70 / 0 0 0 10 30
Dothan 63 37 66 42 67 / 0 0 0 0 10
Albany 63 34 66 41 69 / 0 0 0 0 10
Valdosta 63 33 66 44 72 / 0 0 0 0 10
Cross City 64 33 69 47 76 / 0 0 0 10 10
Apalachicola 63 40 66 51 70 / 0 0 0 10 30
FL...Red Flag Warning until 5 PM EST this afternoon for Coastal