AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
405 AM EDT Mon Oct 29 2012

.NEAR TERM [Today]…
The 02 UTC regional surface analysis showed a cold FRONT southeast
of our forecast area, and an unusually tight PRESSURE GRADIENT (with
above-NORMAL WIND speeds) owing to the steep pressure difference
between HURRICANE “Sandy” (off the MID Atlantic Coast) and a rather
strong ANTICYCLONE over the Central Plains. Vapor imagery and upper
AIR data showed a broad longwave TROUGH over the Southeast U.S.,
including a short wave over our region and Hurricane Sandy, which
will essentially merge with this cold core system over the next day
or two. With a deep, dry airmass in place, sinking air, and cold air
ADVECTION, we expect a SUNNY (but relatively cool) day. Highs will
only REACH” onClick=”return popup(this, ‘notes’)”>REACH the mid 60s (about 10 degrees below CLIMATOLOGY). The
consensus of the latest local WRF, 4km inner next NAM, GFS, and
“normal” adjustments to the sustained wind speeds indicate the
potential for wind gusts of 30 KT or more this afternoon, especially
in south GA & AL where we have a Wind ADVISORY.

&&

.SHORT TERM [Tonight through Wednesday]…
The large, deep layer CYCLONE (which will include the remnants of
“Sandy”) will move little Tuesday and Wednesday, but will gradually
begin to fill. Tuesday promises to be nearly a carbon copy (or “copy
& paste” in today`s parlance) of today, with unusually strong
northwest winds and relatively cool temperatures. The latest
GFS/NAM/ECMWF MOS are all quite cold for Tuesday morning, with lows
just above freezing at our normally coldest inland sites. However,
the HIGH resolution NWP guidance is about 10 degrees warmer. While
that is normally the case in the cool season, the high-res guidance
has shown some skill when forecasting LOW temperatures on mornings
when the boundary layer winds remain elevated, AS we expect in this
case. We blended the MOS with the high-res NWP to get lows that are
in the upper 30s. With the elevated wind speeds and dry air, FROST
appears unlikely at this time. Highs on Tuesday will once again only
reach the mid 60s. Wind gusts may once again approach local wind
advisory criteria for portions of our forecast area.

After another relatively cool morning Wednesday (with lows in the
upper 30s to lower 40s inland), a warming trend will begin as
500 MB heights rise about 10 dm between Tuesday and Wednesday. Highs
will return to near average (lower 70s), and winds will be
considerably weaker. For our first “guess” at Trick-or-treat time,
we expect FAIR skies, West wind 5 MPH or less, and temperatures
falling from the mid 60s to upper 50s- which would be a fairly
accommodating evening for most costumes.

&&

.LONG TERM [Wednesday NIGHT through next Monday]…
A rather uneventful period is expected from the end of the week
through the weekend. The pattern will become more progressive with
the large east coast trough moving eastward and an upper level RIDGE
building into the area for the weekend. Dry conditions are expected
with gradually moderating temperatures.

&&

.AVIATION [Through 06z Tuesday]…
VFR conditions are expected to prevail through the period. WINDY
conditions are LIKELY with northwest winds gusting to between 25 and
30 knots through the day before diminishing after SUNSET. The
strongest winds are expected to be at KDHN and KABY.

&&

.MARINE…
Advisory conditions continue, with even a FEW gusts approaching
GALE force. The various MOS, global, and high-res NWP guidance are
in good agreement in forecasting advisory conditions persisting
until about 18 UTC Tuesday, which is about the time the waves will
drop below 7 FT in the offshore waters.

&&

.FIRE WEATHER…
The combination of gusty winds and very dry air overspreading the
region will create red flag conditions over all of our northwest
Florida and southeast Alabama areas this afternoon and likely again
on Tuesday afternoon. Red flag conditions are also possible on
Wednesday before the airmass begins to slowly moisten while winds
decrease. The southwest Georgia zones do not have their 6 percent
fuel MOISTURE requirement for red flag warnings, although it will be
dry and windy there as well.

&&

.HYDROLOGY
Since there has been no heavy RAIN in our region for several
weeks, and since rain is unlikely for the next several days, river
stages will remain below action levels.