AREA FORECAST DISCUSSION…UPDATED
NATIONAL WEATHER SERVICE TALLAHASSEE FL
625 AM EST Wed Nov 28 2012

.NEAR TERM [Today and Tonight]…
Updated at: 515 am EST

The Dense FOG ADVISORY that was previously in effect for portions
of the area has been cancelled. Between 04z and 08z there were a
FAIR number of observations in SW Georgia that had visibilities
at 1/4SM or 1/2SM, but a recent increase in winds has caused
VISIBILITY to improve areawide. Despite a small CHANCE that a couple
of the observations could see visibility dip briefly in patchy fog
early this morning, the PROBABILITY no longer seems HIGH enough to
warrant an advisory.

A frontal INVERSION should keep the mixed layer relatively shallow
today, which will keep temperatures cooler than the +10 to +11C
850mb temperatures would suggest. In shallow CAA regimes just
after a cold FRONT passage, the morning temperatures tend to be
slower to increase than the typical DIURNAL curve. The TEMPERATURE
curve was nudged down in the morning to account for this. However,
with breaks of sun LIKELY to develop by afternoon we are still
expecting highs to get into the 60s just about everywhere.

For tonight, some MOS guidance is still indicating lows close to
freezing in our SE Alabama zones. However, it would take a very
strong inversion to produce lows of those values given the
temperature profile in the 925-850mb layer. That is not expected
to be the case, and so despite clear skies and lighter winds the
lows should mainly stay in the 37-42 degree RANGE. These types of
lows would also prevent FROST in most spots.

&&

.SHORT TERM [Thursday Through Friday]…
A lingering LOW-level RIDGE of high PRESSURE along the Atlantic
seaboard will keep east to northeast FLOW in place across much of
the east coast. This pattern should prevent rapid modification of
the cooler AIR mass that will be in place. However, highs should
increase a couple degrees each day at the end of the work week
with mostly SUNNY skies and a deeper mixed layer each afternoon.

&&

.LONG TERM [Friday NIGHT through next Wednesday]…
Guidance is in good agreement that the flow across the CONUS will
continue to be fast and primarily zonal through early next week. The
primary JET and any associated disturbances are forecast to remain
well north of the forecast area through next Tuesday, before digging
southward by midweek and driving a cold front towards the Gulf
Coast. Before this TROUGH digs southward, expect an upper ridge to
develop over the gulf and nose northeast across the area.

The impact of this upper pattern will be for warmer than NORMAL
temperatures into early next week, with minimal RAIN chances. Expect
highs in the MID 70s with lows generally in the lower 50s. Rain
chances will be introduced for late Tuesday into Wednesday ahead of
the approaching cold front.

&&

.AVIATION [through 12z Thursday]…
Low CIGS & fog currently dominate the region with IFR conditions
ongoing at all terminals. Expect conditions to improve after
SUNRISE, with the fog burning off before cigs lift. VFR conditions
are anticipated by afternoon and will continue through tonight with
light north to northeast winds.

&&

.MARINE…
With the 4am CWF issuance, we plan to maintain the SCEC headline
across all but the far eastern nearshore zones (Apalachee Bay and
along Taylor and Dixie Counties) through mid-morning. The latest
buoy and tower observations continue to indicate winds around
15-16 knots over the bulk of the coastal waters, with a FEW gusts
to around 20 knots. A 0315z ASCAT pass also showed a sizable swath
of 15-20 KNOT winds, which matched well with RAP and local WRF
(which were used AS the basis for the updated WIND forecast in the
first 12 hours). Winds quickly veer to the east by tonight as high
pressure settles into the Southeast, setting up the typical surges
of easterly winds at night over the next few days.

&&

.FIRE WEATHER…
A slightly drier airmass will filter into the region today in the
WAKE of a cold front. However, HUMIDITY values are not forecast to
REACH” onClick=”return popup(this, ‘notes’)”>REACH critical levels, and ERC values should remain below thresholds
following Tuesdays RAINFALL. By Thursday into the weekend, easterly
flow is forecast to bring in enough Atlantic MOISTURE to keep RH
values above critical levels. No Red Flag conditions are expected
through the end of the work week.

&&

.HYDROLOGY
Rainfall totals over the past 24 hours ranged from NIL or TRACE
amounts near the Suwannee River in the eastern Florida Big Bend,
to around an inch in southeast Alabama. These rain amounts are not
expected to cause any notable changes in the area rivers.