AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
436 AM EDT Mon Oct 22 2012

.NEAR TERM [Through Tonight]…
Despite some SCATTERED MID-HIGH level clouds on IR satellite early
this morning, we should see another mostly SUNNY day with light
ENE FLOW on the southern periphery of the LOW-level ANTICYCLONE
that is currently centered over the southern Appalachians. The
highs should be fairly similar to yesterday with the consensus
model forecast 850mb temperatures roughly identical to the
observed value (+15C) on the 22.00z TAE SOUNDING – implying very
little low-level TEMPERATURE ADVECTION. This should result in
highs mostly 80-82 degrees.

&&

.SHORT TERM [Tuesday Through Wednesday]…
Continued sunny and dry weather is expected through Wednesday AS
the low-level anticyclone gradually migrates eastward to coastal
North Carolina, leaving our area in continued low-level easterly
flow with minimal temperature advection. Temperatures should
mostly be within a FEW degrees of normals. A few of the global
models do hint at some very light QPF (0.01-0.02″) affecting the
Atlantic coast of Florida and portions of the Gulf of Mexico late
Tuesday and into Wednesday as low-level MOISTURE gradually
increases in the easterly flow regime. While this can`t be
completely discounted, MOS POPS are too low at this time to
warrant mentioning any ISOLATED showers in the offshore waters.

&&

.LONG TERM [Wednesday NIGHT through Sunday]…
The large scale longwave pattern commences highlighted by a slowly
DEEPENING and expanding TROUGH over WRN states, a low-AMPLITUDE
upper level RIDGE over ERN states with axis that will extend from
CNTRL Gulf of MEX NEWD into the Southeast and up the Appalachian
Mountains into Canada, and a TUTT over Cuba. At surface, high off
Carolina coast with ridge axis WSW across NRN Gulf region. Low
over WI with cold FRONT SSW to TX/OK border and tropical low under
TUTT. Forecast confidence not high for latter period in part
dependent on exact TRACK of low and whether it intensifies to a
tropical or subtropical system. Models also differ on trough and
frontal timing and strength THRU period (see below).

During the rest of the period, aloft, UPSTREAM trough continues to
broaden and deepen shunting DOWNSTREAM ridge progressively EWD with
axis along ERN seaboard by early Fri. By that time, TUTT has lifted
NWWD to over S FL. This combination will progressively weaken the
ERN ridge. By SAT, EWD shifting trough and TUTT advance N then NE to
off NE FL coast combine to shunt ridge further NEWD into Atlc. By
Sun AFTN, trough axis from Wrn Great Lakes to Wrn Gulf with remnant
of TUTT low along NC coast placing a weak ridge in between and over
local area. On Mon, trough axis along ERN seaboard with low moving
NWWD into TN Valley. At surface, EWD movement of upper trough drags
cold front progressively SEWD shunting coastal high into Atlc and
allowing Cuba low to lift NWD. By Sat aftn, front has reached Wrn AL
becoming quasi-STNRY with Cuba low now just off FL NE coast with
strengthening NE flow and keeping local area on dry side of system.
Front LIKELY moves thru local region Sat night into early Sun
albeit in a noticeably weakened form while low now off Carolinas. In
WAKE of front, local flow shifts to NW. By late Sun, low in mid-Atlc
and front to our SE with noticeably colder and drier deep layer AIR
overspreading local region rest of period. But all this dependent on
which model verifies. 00z GFS appears to be the outlier and shows a
far less amplified trough keeping Atlc low farther out to sea than
00z EURO or GFS ENSEMBLE. GFS would means slower frontal progression
and more noticeably moderate TEMPS in its wake. So until I see more
model consistency, forecast based on more on EURO.

The net result for our forecast is that there will be plenty of sun
and dry weather thru Saturday then a slight CHANCE of precip
Saturday Night and early Sunday, then dry again. The potential for
heavy RAIN is not high due to lack of Gulf return flow. Temps are a
tough forecast particularly from Sun to Mon since timing of front
and amplification of trough creates very different solutions. i.e.
GFS operational is warm outlier compared to the GFS ensemble and
EURO. For now, MIN temps will commence 7 to 10 degrees above CLIMO
dropping to around climo Sun night. MAX temps will commence around 5
degrees above climo dropping to near climo Sun and 3 to 5 degrees
below climo Mon with the majority of models showing that real cold
air not impacting local area until sometime Sun night or more likely
Mon or Mon night. (AVG inland lows/highs are 51/77 degrees).

&&

.AVIATION [through 06z Tuesday]…
VFR conditions under clear skies and generally light
northeasterly winds are expected through the TAF cycle.

&&

.MARINE…
Not much has changed with respect to the expectations for the
marine weather over the upcoming work week. We are still expecting
a ridge of surface high PRESSURE to remain anchored over the
Southeast and along the Atlantic seaboard, with gradual pressure
falls over the northern Caribbean and Bahamas. This will SET up
persistent E-NE flow with occasional SCEC conditions, particularly
from about 03-15z each night. SCEC for this morning is for all but
the far eastern legs through late morning hours.

&&

.FIRE WEATHER…
Minimum RH values will modestly increase this afternoon over the
Florida Panhandle and Big Bend. Although lowest inland RH will hover
near 35 percent, afternoon dispersions values and likely ERC values
will remain below red flag levels so no WARNING has been issued. In
Georgia and Alabama, neither minimum RH values nor winds will REACH” onClick=”return popup(this, ‘notes’)”>REACH
red flag levels. The airmass will begin to moisten up on Tuesday
with no red flag conditions expected through the work week.