Area Forecast Discussion
Issued by NWS
FXUS62 KTAE 271510
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
1110 AM EDT Sun Jul 27 2014
.Near Term [Through Today]...
Morning analysis shows moderate low level westerly flow in place
across the region. An extensive area of low ceilings and fog
persisted til 1030 am in some locations delaying the warm up. The
KTAE sounding from 12 UTC shows a much drier atmosphere in place
than 24 hours ago with the precipitable water down to 1.55 in.
Much of the sounding had also warmed throughout the troposphere,
especially in the 800-700 mb layer. The combination of the drier
mid and upper level air and this mid layer warming, will greatly
limit afternoon storm coverage.
Temperatures will still likely reach into the upper 90s inland
despite the cloud cover this morning. With a ridge temporarily
building in and drier mid level air, expect the cumulus field this
afternoon to be rather flat and scattered. So while we are
running a couple of degrees below the hourly forecast now,
temperatures should get back on track by early afternoon. Heat
indices will approach 108 degrees at times this afternoon. In fact
a few sites already have heat indices in the 102 to 105 degree
range as of 11 am ET.
.Prev Discussion [446 AM EDT]...
.Short Term [Tonight through Tuesday]...
A deepening upper trough over the eastern half of the country will
push an unusually strong deep summer cold front south into the
forecast area on Monday. Ahead of the front, a very hot and humid
airmass will be in place, with temperatures rising into the upper
90s Monday afternoon. Coupled with dewpoints in the mid 70s,
expect to see heat index values exceed 105 degrees over a large
portion of the area, with values as high as 110 degrees possible
in Florida. Another heat advisory may be needed for Monday
As the front approaches the northern CWA border Monday afternoon,
expect to see a swath of southward moving thunderstorms develop.
With such a hot and juicy low-level airmass, expect to see CAPE
values approach 4000 j/kg Monday afternoon ahead of the front.
When coupled with a modest increase in mid-level northwesterly
flow, expect to see a few of these storms reach severe limits,
with damaging straight-line winds and large hail being the primary
threats. With the aid of the front, the line of convection will
likely remain active through Monday evening as it crosses
the FL/GA line.
The front will push to near a Valdosta to Panama City line by
Tuesday morning, likely slowing its southward progress through the
day. A much drier airmass will push in behind the front, with
dewpoints dropping well into the 60s. Temperatures will be
somewhat cooler as well, with highs ranging from around 90 degrees
along the northern border, to lower to mid 90s along the coast.
Showers and thunderstorms will continue south of the front, across
the central and eastern Big Bend.
.Long Term [Tuesday Night Through Sunday]...
Model guidance continues to be in excellent agreement in the
amplification of the Eastern CONUS trough through the long term
period. While there are some slight differences on timing and
magnitude of the cooler and drier air behind this frontal
boundary, there is good agreement now that the front will clear to
the south. Dry conditions should be in place across the region
from Tuesday evening into Thursday. This interval will also
feature some cool overnight lows, possibly dipping into the lower
60s in the colder spots across Southern Alabama. Even in the
Florida Big Bend, temperatures Wednesday and Thursday mornings
should drop into the upper 60s or just a bit cooler. Records for
this period at Tallahassee are as follows:
July 30 - 67 (1927)
July 31 - 63 (1896)
Aug 1 - 64 (1993)
By Thursday afternoon, moisture will begin to increase once again
across the forecast area as another upper disturbance within the
main upper trough moves into the forecast area. Unsettled
conditions look to return Friday and into next weekend with rain
chances increasing considerably. While overnight lows will return
to climatological norms for early August, daytime temperatures
will still be below normal due to plenty of convective activity.
[Through 12z Monday] Some low ceilings and patchy fog with MVFR
to IFR conditions have developed this morning with a very soupy
airmass in place. Conditions will improve rapidly to VFR after
sunrise. Although an isolated thunderstorm is possible this
afternoon, the chances for convection are well below average for
this time of year with mid-level dry air in place and appear too
low for any mention in the TAFs at this time.
The pressure gradient between the subtropical ridge to the south
and an approaching cold front to the north will tighten over the
next two days, leading to a modest increase in westerly winds
across the coastal waters. Winds will reach exercise caution
levels at times through early Tuesday. Winds will then slowly
diminish and become offshore through the middle of the week.
Red flag conditions are not expected over the next several days,
although high dispersion values are expected this afternoon across
the inland Florida big bend and across most of the area away from
the coast on Monday.
The Shoal River at Mossy Head has reached bank full stage but is
not forecast to reach flood stage. All other area rivers are below
bank full stage. Thunderstorms could bring locally heavy rainfall
the next few days but widespread impacts are not expected.
.Preliminary Point Temps/PoPs...
Tallahassee 97 78 96 75 94 / 20 10 40 40 30
Panama City 90 80 92 78 91 / 20 10 40 40 20
Dothan 97 76 97 72 91 / 10 10 50 40 10
Albany 99 77 96 72 91 / 10 10 50 40 10
Valdosta 100 76 96 73 93 / 10 10 40 40 30
Cross City 93 76 94 76 93 / 20 10 30 30 50
Apalachicola 91 79 91 79 90 / 20 10 30 30 40
FL...Heat Advisory until 7 PM EDT /6 PM CDT/ this evening for Calhoun-
Central Walton-Coastal Bay-Coastal Franklin-Coastal Gulf-
Coastal Jefferson-Coastal Taylor-Coastal Wakulla-Gadsden-
Holmes-Inland Bay-Inland Franklin-Inland Gulf-Inland
Jefferson-Inland Taylor-Inland Wakulla-Inland Walton-
GA...Heat Advisory until 7 PM EDT this evening for Baker-Ben Hill-
AL...Heat Advisory until 6 PM CDT this evening for Coffee-Dale-Geneva-