Area Forecast Discussion
Issued by NWS
FXUS62 KTAE 170906
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
506 AM EDT Mon Jun 17 2013
...UPDATED FOR AVIATION DISCUSSION...
.NEAR TERM [Today]...
The large scale longwave pattern is highlighted by an elongated
ridge over the Nrn Gulf of Mex with high centered over W/Cntrl Gulf.
North of this ridge axis, exists moist quasi-zonal flow across SE
region and into the Wrn Atlc. However, a series of embedded short-
waves will continue to ride Ewd in this flow. During the predawn
hours, latest satellite imagery shows lead impulse over NW GA thru
S/Cntrl AL and into Gulf of Mex. At surface, Atlc high well east of
Carolinas with ridge axis WSW across Nrn Gulf region. Approaching
impulse continues to shunt surface ridge SEWD resulting in a
moistening up of deep layer moisture underneath the zonal flow
including a veering of low level flow. All this reflected in area
model soundings. i.e. GFS TAE with PWATS increasing from 1.38 to
1.92 inches from 12z Mon to 00z Tues, also 24 hr comparisons show
dew points running 4 to 9 degrees higher than same time yesterday
with models showing a return to inland aftn dewpoints around 70
degrees. With moist near surface conditions from recent rains,
patchy light fog or stratus may persist past sunrise.
RAP shows that shortwave will move ewd across FL/AL then FL/GA
border area during the late morning into the aftn. At surface, deep
WSW steering flow will drive Gulf seabreeze inland into late aftn
and to I-10 and beyond during eve. So models to show that the
juxtaposition of passing shortwave and lifting seabreeze plus any
convection that develops along mesoscale boundaries will generate a
good chance of storms today. HI RES guidance like WRF and NM4 imply
that focus should be across SE AL and Nrn tier GA counties in the
late aftn into eve when closest to seabreeze and when impulse
providing best lift. Strong to isold severe storms possible but any
severe threat should remain isolated and brief pulsy as is typical
for summer. i.e. RAP 21z Mon for SE AL with good cape 3200 J/KG but
0-6km shear only 20kts, BRN shear only 20 m/s and 700-500mb lapse
rate of 6c/km. Will go with sharp 60-10% NW-SE pop gradient. Expect
inland highs in the low 90s.
.SHORT TERM [Tonight Through Tuesday Night]...
A broad low amplitude upper level trough over the eastern CONUS
will gradually deepen as a series of impulses eject out of the
Plains. Deep layer moisture will be on increase and a cold front
will drop down into northern AL/GA by 00z Wednesday. The deepest
moisture and best upper level support will be over the northern
portions of the forecast area. PoPs on Tuesday will be tapered from
good chance/likely for our AL and most Georgia zones with chances
PoPs for all Florida zones (30-40%) except the southeast Big Bend
(20%). Expect slight to chance PoPs for the nighttime periods. Max
and min temps will remain near seasonal averages.
.LONG TERM [Wednesday through Sunday]...
A fairly seasonal period is expected with scattered afternoon and
evening convection each day. Some days will likely have slightly
higher PoPs than others depending on the timing of individual weak
shortwaves, which is hard to forecast in the long term. No major
synoptic scale system are expected to impact the area during the
period. Temperatures are expected to remain near their seasonal
.AVIATION [Through 12z Tuesday]...
Expect MVFR ceilings/vsbys in fog to settle in briefly rest of
predawn hoUrs. Brief IFR possible around sunrise especially at TLH
and also at DHN and VLD. Conditions should improve to VFR after 14z.
Showers and thunderstorms starting in the late morning/early
afternoon and all sites will include VCTS with prob30 TSRA at DHN
and ABY 20Z-24Z. Winds will be from the southeast around 5-10 kts
becoming light southwest after sundown. After 08z, expect MVFR CIGS
and possibly VSBYS to redevelop especially across VLD and TLH.
IFR CIGS remain possible exepcially at VLD near sunrise.
The subtropical ridge will be the dominant feature across the
northern Gulf of Mexico this week, yielding mainly light southwest
to west flow and low seas.
Red Flag conditions are not expected thru the work week as RH values
remain above critical levels. The combination of deep mixing and
somewhat stronger winds aloft will help dispersion values climb
above 75 Tues afternoon.]
River gauges are expected to remain below flood stage for at least
the next several days.
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 91 72 92 72 92 / 30 20 40 20 40
Panama City 87 75 90 75 87 / 40 20 30 20 40
Dothan 91 72 91 73 91 / 50 40 60 30 40
Albany 92 73 91 72 92 / 50 40 60 30 50
Valdosta 91 71 92 72 92 / 40 30 40 30 40
Cross City 92 69 92 71 91 / 10 20 20 20 20
Apalachicola 86 75 88 76 86 / 20 10 20 10 40
NEAR TERM/AVIATION/FIRE WEATHER...Block