AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
532 AM EST Mon Jan 7 2013
.NEAR TERM [Today]…
The 03 UTC regional surface analysis showed a weak frontal wave
propagating eastward across the southeast Gulf of Mexico, and a
1030 mb high over southern IN. Local radars showed patches of light
rain over our Gulf coastal waters, but any moderate rain was well
south and east of our forecast area. Vapor imagery and upper air
data showed split flow over the CONUS, with a closed southern stream
low over southern CA, a ridge over the southern Plains, and a trough
translating eastward over the mid Atlantic states.
Any sprinkles early this morning over north FL will end shortly
after sunrise as large scale subsidence (and mid tropospheric
drying) develop over our region. Skies will partially clear over
most of the forecast area, but high level clouds are likely to
remain over the Cross City area. With limited mixing and fairly low
sun angle, highs will only reach the lower 60s (except mid 60s Cross
City), which is near average for this time of the year.
.SHORT TERM [Tonight Through Wednesday]…
500 mb heights are forecast rise about 100 meters over much of our
forecast area between now and Wednesday. At the surface, the high
pressure system currently centered over southern IN will move east
off the mid Atlantic coast by Wednesday, providing our region with
east winds Tuesday and Wednesday. There is good agreement among the
global models in warm frontogenesis over the Gulf Coast states
Tuesday night and Wednesday, but it appears that most of the Q-G
forcing, instability, and deep layer moisture will be a bit to our
west and northwest. This is where the higher rain chances will be.
Our current PoP is only in the 20-30% range for our northwest zones.
With the rising heights comes warmer temperatures, as we expect high
temperatures in the mid 60s (FL Panhandle, GA, & AL) to mid 70s (FL
Big Bend) Tuesday, and in the lower 70s (GA & AL) to mid to upper
70s (FL) on Wednesday. Lows will be in the 40s Tuesday, and well
into the 50s Wednesday. Wednesday`s temperatures will generally be
10 to 20 degrees above average (low and high
.LONG TERM [Wednesday Night through Sunday]…
The long term period begins with a large mid level ridge in place
just off the Florida East Coast and a strong upper low across the
Rio Grande Valley. This upper low will eject northeastward into the
western Great Lakes by Friday as the ridge strengthens its position
across Southern Florida. This results in a stalling frontal boundary
to our west early in the period with minimal rain chances. The next
substantive system approaches on Sunday and may indeed get into our
western zones before stalling as it approaches the strong ridge
across Southern Florida. Overall, rain chances throughout the long
term period will remain on the low side.
With such a strong ridge and prolonged period of southerly flow in
place, the long term period is expected to feature temperatures well
above climatology. Max temperatures could possibly flirt with 80
degrees late in the period with lows in the mid and upper 50s being
common. This is effectively 10 to 15 degrees above climatology for
Mid January. Even though this will be quite warm, this won`t be
record warmth as record highs for mid January at Tallahassee range
from 81 to 83 degrees.
.AVIATION [Through 12z Monday]…
VFR conditions are expected to prevail through this evening.
Southerly flow will return low level moisture quickly tonight with
MVFR ceilings developing after midnight and spreading inland,
particularly at ECP/DHN. Ceilings could potentially be in the IFR
range toward the end of the TAF cycle at these sites as well.
The winds well offshore were nearing advisory levels as of
06 UTC, and the latest NWP guidance consensus suggests advisory
conditions are likely for our outer coastal waters until about mid
morning. We added the eastern portion of our outer coastal waters to
the advisory issued on Sunday, but cancelled the nearshore portion.
Winds and seas will gradually subside later today through
Dry conditions will continue today, but relative humidity values
will stay above critical levels. Expect a moistening trend to begin
on Tuesday and continue through the week as low level southerly flow
The recent rain “events” (which featured good area coverage but
relatively low amounts) have had no significant impacts on local
river stages. Given the low PoP over the next few days, rivers are
expected to remain below action stage.