Area Forecast Discussion
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FXUS62 KTAE 301039
AFDTAE

Area Forecast Discussion
National Weather Service Tallahassee FL
639 AM EDT Tue May 30 2017

.AVIATION [Through 12Z Wednesday]...

Patchy fog/low clouds are currently impacting ECP with LIFR
conditions and VLD with IFR cigs, with VFR conditions elsewhere. A
few light showers are occurring at DHN, but these will not cause
significant visibility reductions. Patchy fog and low clouds
should dissipate within the next couple of hours, and after this
occurs VFR conditions should generally prevail across our area
through the remainder of the period. However, a few showers and
thunderstorms cannot be ruled out, especially at TLH later this
afternoon through the early evening as the sea breeze moves
inland. Brief visibility reductions to MVFR/IFR are possible in
any showers or storms that develop.

&&

.PREV DISCUSSION [331 AM EDT]...

.NEAR TERM [Through Today]...

As of 2 AM EDT, a cluster of strong thunderstorms has developed
along the Gulf Coast and is located near Pensacola. An upper level
shortwave over MS/LA and ample instability, along with 20-30 kts of
effective bulk shear are likely helping to maintain this feature.
The strongest thunderstorms are currently just offshore, but the
line segment has a potent bowing signature and an embedded cell
likely producing small hail. Most of the latest CAMs are not
initializing this feature well (some don`t show any development in
this area, others just show a few showers) but the environmental
conditions are favorable for these storms to remain strong as they
move toward our western areas. Therefore, chances of showers and
thunderstorms have been increased across the FL Panhandle and SE
Alabama during the early morning hours.

This feature could also affect chances of showers and thunderstorms
later today. Leftover outflow boundaries could serve as the focus
for development during the afternoon and early evening. However,
ample cloud cover from the morning convection will likely suppress
instability, mid-level lapse rates will be low and PWAT values
should remain around 1.5", near average for this time of year. This
does not inspire confidence for widespread convection across our
area, though a few showers and thunderstorms cannot be ruled out
both during the morning (leftover from the aforementioned
thunderstorm complex) and with redevelopment during peak heating
hours of the afternoon and early evening. I will go with PoPs around
30% across most inland areas as a result. Due to the ample cloud
cover, highs should remain in the 80s across most of our area today,
although lower 90s are possible in south central GA and the eastern
FL Big Bend where less cloud cover is anticipated.


.SHORT TERM [Tonight Through Thursday]...

In the upper levels, our forecast area will be under west-southwest
winds aloft, in between a region of higher heights east of the
Bahamas and lower heights centered just north of the Great Lakes.
The Precip Water values in our region will be around 1.50 inches,
which is near average. With little Q-G forcing, thunderstorm
initiation will have to come from mesoscale boundary interactions-
primarily the sea breeze circulation and convective outflow
boundaries. However, the NWP models, especially the GFS, forecast
marginal MLCAPE (generally less than 1000 J/kg) for our forecast
area Wednesday and Thursday afternoons, due to modest PBL moisture
and poor mid-layer lapse rates. Based on these questionable
thermodynamics we`ve gone a little lower than the numerical
guidance consensus for PoPs (20-30% instead of 30-50%). Temperatures
will be near normal.


.LONG TERM [Thursday Night Through Tuesday]...

There continues to be agreement in the medium range NWP guidance in
developing a weak upper-level trough in the western Gulf of Mexico
by the weekend. This synoptic pattern would favor above-average rain
chances as southwest winds ahead of this trough advect
significant deep-layer moisture from the Tropics and promote
large scale ascent. Typically such a weather pattern allows rain
to occur even outside the favored diurnal cycle (i.e. afternoon
and evening hours), but PoPs will generally be maximized during
the daytime. The expected increase in clouds and rain chances will
likely keep high temperatures from reaching 90.


.MARINE...

With a high pressure ridge across the coastal waters this week,
winds will be rather variable at 10 knots or less, and seas
generally 2 feet or less through Friday. There will be an onshore
sea breeze near the coast each afternoon at 10 to occasionally 15
knots.


.FIRE WEATHER...

No fire weather concerns are expected due to light winds and
minimum RH values much higher than critical thresholds.


.HYDROLOGY...

Organized heavy rain is unlikely through the work week, but isolated
heavy rain is possible each afternoon. Area rivers were below their
local action stages. There may be some potential for more
widespread, heavier rain this weekend and into early next week.

&&

.PRELIMINARY POINT TEMPS/POPS...

Tallahassee   88  69  89  69  90 /  30  10  20  20  30
Panama City   82  72  83  73  84 /  30  10  20  10  10
Dothan        87  68  88  69  88 /  40  20  30  20  30
Albany        88  69  89  69  89 /  30  20  30  20  30
Valdosta      90  69  90  69  90 /  30  20  30  20  30
Cross City    91  70  92  69  91 /  20  10  20  10  20
Apalachicola  85  71  86  71  86 /  20  10  10  10  20

&&

.TAE WATCHES/WARNINGS/ADVISORIES...

FL...None.
GA...None.
AL...None.
GM...None.

&&

$$

NEAR TERM...Lahr
SHORT TERM...Fournier
LONG TERM...Fournier
AVIATION...Lahr
MARINE...Fournier
FIRE WEATHER...Lahr
HYDROLOGY...Fournier



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