AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
630 AM EST Mon Nov 26 2012

.NEAR TERM [through this afternoon]…
The upper FLOW along the northern Gulf coast will remain
primarily zonal today, with the nearest amplified SHORTWAVE
digging into the central plains. At the surface, HIGH PRESSURE
centered over south Georgia this morning, will slide east during
the day, allowing for some weak return flow west to develop by
this afternoon. MOISTURE will not be sufficient for any
PRECIPITATION today.

After a chilly start, with temperatures near freezing away from
the coast, the airmass should modify noticably this afternoon.
Expect to see high temperatures 5-7 degrees warmer than Sunday
afternoon.

&&

.SHORT TERM [Tonight Through Wednesday]…
By tonight, the aforementioned central plains shortwave is
forecast to dig southeastward and interact with a fast moving
shortwave embedded in the subtropical JET. A cold FRONT associated
with these features will push southeastward towards the region AS
well. The left-exit region of the subtropical jet and the right-
entrance region of the polar jet are forecast to align late Monday
NIGHT into Tuesday across the tri-state area, providing a boost in
upward velocities across the region.

Despite anemic LOW-level forcing with this system, the upper
forcing is expected to be strong enough to generate a broad area
of showers starting late Monday night across the western zones,
and spreading eastward into Tuesday afteroon. By late Tuesday
afternoon, the subtropical jet will push east of the forecast
area, rapidly diminishing the upper forcing, and bring the precip
to an end. The progressive nature of the pattern will limit
RAINFALL totals, with amounts of a quarter to half an inch.

The ensuing frontal passage will be rather meager, given the
rapid return to zonal upper flow. Therefore, temperatures on
Wednesday will be very close to seasonal norms.

&&

.LONG TERM [Wednesday Night through Sunday]…
The extended forecast will feature a predominately zonal flow
across the continental US. The 500mb HEIGHT trend over the time
frame in question is approximately +50m, and the subtly building
RIDGE will favor warming temperatures. However, the low-level
ANTICYCLONE over the Southeast is LIKELY to anchor a cooler AIR
mass in place a bit longer, so the warming trend should be
gradual. By Monday, the GEFS ENSEMBLE MEAN 2m TEMPERATURE
departures over most of the CONUS are above NORMAL, including all
of the ensemble members over our area. With normal highs Monday
(Dec 3rd) in Tallahassee around 68 – this likely spells a stretch
of days with highs in the 70s at the end of the extended RANGE
forecast. Despite some sporadic light QPF from a FEW of the global
models, there is little continuity on timing or spatial extent
(plus an overall lack of forcing). Therefore, POPS were capped at
a silent 14% to produce a dry forecast.

&&

.AVIATION [Through 12Z Tuesday]…
Updated at: 630 am
Light winds and VFR conditions will prevail at the terminals through
the duration of the TAF period. BKN-OVC skies are likely to develop
around SUNSET today, and ceilings should gradually lower from
10-15kft through 4-6kft by 12z Tuesday. Showers and the possibility
of some MVFR ceilings should mostly hold off until after 12z Tuesday.

&&

.MARINE…
Winds and SEAS will remain minimal through Tuesday as the
pressure GRADIENT remains weak. A cold front will cross the waters
late Tuesday night followed by an increase in offshore winds.
Winds will then shift to the northeast and east by the end of the
workweek. At this time, winds are forecast to remain below
headline criteria throughout the week.

&&

.FIRE WEATHER…
The driest air mass, and thus lowest afternoon minimum RH, today
will be found over the eastern half of the area. Winds will be
light and dispersions low, so the only areas that will likely see
red flag criteria MET would be Florida zones where the ERC is
forecast to be at least 35. This only appears to affect Leon and
Wakulla counties, where long durations of low relative HUMIDITY
are also expected. The existing Fire Weather WATCH for Bay and
Washington counties will be cancelled, as forecast RH is higher
than 35% now. Increasing moisture thereafter should limit fire
weather concerns for the remainder of the week.

&&

.HYDROLOGY
Rainfall expected with this week`s frontal system will not be
sufficient to produce significant river rises.