Area Forecast Discussion
Issued by NWS
FXUS62 KTAE 201122
Area Forecast Discussion
National Weather Service Tallahassee FL
622 AM EST Fri Jan 20 2017
.AVIATION [Through 12Z Saturday]...
Showers have diminished across the region at this hour, with
areas of patchy fog and low CIGs lingering at most TAF sites
across the region. VFR conditions expected to resume by late
morning, with chances for SCT SHRA and TSRA across the region this
afternoon. Confidence is currently low in the placement of this
activity, thus left it out of this TAF package. Low CIGS and fog
will likely affect all terminals again tonight ahead of another
round of TSRA late tonight/early Saturday.
.PREV DISCUSSION [233 AM EST]...
.NEAR TERM [Through Today]...
Line of showers and embedded thunderstorms continues to move across
the region at this hour. The current meso-scale analysis shows a
sharp gradient of instability along the Florida Panhandle coast,
with generally 500-1000 J/KG of CAPE remaining off-shore. The latest
convective trends over the past hour continue to suggest that the
strongest storms will be confined to coastal waters and along the
shoreline over the next several hours. The latest CAM guidance
continues to suggest a weakening trend with this line over the next
several hours, with dry mid-level air intruding from the west and
inhibition increasing across the eastern half of the area.
The mid-level trough responsible for these showers and storms will
continue to lift northeastward across the Tennessee and Ohio Valleys
during the late morning and afternoon hours. Scattered shower and
thunderstorm development is expected, mainly during the afternoon
hours, as a result of continued low-level and surface southerly flow
and weak isentropic lift across the region. This activity is
expected to wane during the evening hours. Despite mostly cloudy
skies today, highs will generally run in the mid to upper 70s across
.SHORT TERM [Tonight Through Sunday]...
**The main story in the short term remains the possibility of severe
weather, with all facets of severe weather threats, for Saturday
through Sunday afternoon.**
Shortwave ridging will move by and off to the east Friday night
in response to the deepening longwave trough across the central
CONUS with a shortwave trough lifting northeastward across the
upper Midwest. Low level warm air advection, along with
convergence from the strengthening low level jet and increasing
vorticity advection, will spark an increase in showers and storms
Friday night across the northern Gulf coast and spreading inland
and eastward as a warm front moves inland Saturday. Initially,
CAPE and Shear across the area are low Saturday morning but begin
to ramp up beginning late morning. This is when our window of
opportunity opens up for severe weather. Day 2 SPC convective
outlook has most of our area in a slight risk for severe weather.
Again, all facets of severe weather are possible.
Closed upper low develops Saturday night across the TX/OK panhandles
and moves eastward to northern Mississippi Sunday afternoon and into
the Carolinas Sunday night. Although instability decreases through
the evening and overnight, strong wind fields will lead to an
increase in shear and helicity values. Large scale lift will
increase as well as the closed low gets closer with diffluence
aloft. Still expecting a squall line of sorts to move across much of
the CWA with damaging winds and isolated tornadoes possible. That
threat will linger into Sunday across the eastern and southeastern
half of the CWA before dry slotting decreases rain chances from west
to east later Sunday into Sunday night. Day 3 SPC convective outlook
has our area in an enhanced area for severe weather mainly east of
Mexico Beach to Marianna FL to Albany GA. Slight risk remains west
of this line.
.LONG TERM [Sunday Night Through Friday]...
Light rain may linger into Monday on the backside of the departing
low pressure system. A cold front will swing through Monday which
will knock our temperatures down to near seasonal averages. Slightly
warmer temperatures expected Wednesday as surface high pressure
moves by but a fast moving cold front will bring another chance for
rain beginning Wednesday night.
As the next low pressure system arrives Sunday, winds ahead of this
system will increase in response. Cautionary winds will develop
tonight with advisory winds by early Saturday. As the cold front
moves through the coastal waters Sunday, a further increase in winds
are possible. Gale force gusts are possible late Sunday through
Monday. Seas will climb to near 15 feet in response to these strong
winds across the far offshore waters. Winds will fall below advisory
level by Tuesday morning.
On average, 2-4 inches of rainfall is expected through Sunday night
across the area with isolated amounts approaching 6 inches. These
amounts will most likely fall over a long enough period that flash
flooding wont be a concern. Across area rivers, with these expected
rainfall amounts, rivers are expected to stay below flood stage.
There are a few rivers to keep an eye on however, such as the
Kinchafoonee Creek or Choctawhatchee River.
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 77 64 74 64 75 / 40 50 80 80 70
Panama City 73 67 73 66 71 / 40 60 80 80 70
Dothan 76 63 74 61 71 / 40 60 90 80 70
Albany 77 63 74 62 73 / 50 50 90 80 80
Valdosta 77 63 75 64 75 / 30 40 80 80 80
Cross City 77 63 76 65 75 / 20 30 80 80 80
Apalachicola 73 67 73 67 73 / 30 50 80 80 70