Scientific Forecaster Discussion
fxus62 ktae 152349
Area forecast discussion
National Weather Service Tallahassee Florida
649 PM EST Fri Dec 15 2017
Near term [through tonight]...
Local radar imagery shows patchy light drizzle across the
northwestern half of our County Warning Area this evening and model analysis shows
moderate isentropic ascent along the 300-305k surface will allow
this patchy drizzle to continue through around 2 am, but tapering
off through the evening as the forcing shifts eastward. Otherwise,
expect a cloudy night with low temperatures in the 30s north of a
line from De Funiak Springs, Florida to Fitzgerald, Georgia and lows in the
low to mid 40s south of that line.
Previous discussion [621 PM est]...
Short term [saturday through Sunday night]...
On Saturday, zonal flow aloft will amplify into deep layer
ridging, with no rain forecast and mid/high clouds gradually
dissipating. Sunday, while ridging will prevail over the immediate
tri-state region, a shortwave moving through the Mississippi
Valley will result in increased rain chances from the central Gulf
Coast through the Tennessee Valley. Though the shortwave will
quickly lift northeast and the associated cold front won't quite
reach our area by Sunday night, it will open up a strong low-level
warm air advection regime as the surface ridge slides eastward, with isentropic
ascent focused primarily in the 295-305k window. Thus, shower and
isolated thunderstorm chances will increase dramatically overnight
Sunday, especially along and west of a line from Albany through
Panama City. After Saturday, temperatures both day and night will
likely be 10+ degrees above normal.
Long term [monday through friday]...
The unstable warm air advection regime under low amplitude ridging will continue
through Tuesday when a shortwave is forecast to move through the
southeast and possibly clear out the wet pattern by Wednesday
afternoon. However, there remains disagreement as to just how
fast this is going to happen, with the European model (ecmwf) being the slower
solution and not really pushing the shortwave through until
Thursday afternoon. Further, the GFS and the European model (ecmwf) are in decent
agreement timing another late week cold front into the region. So,
with the slower ecwmf solution regarding the initial wave, the
entire extended period remains wet while the GFS gives US a couple
dry days to end the week. Fwiw, the Canadian favors the more
progressive GFS and so the forecast closer reflects the GFS though
holds slight chance pops through the period. Either way, expect
two frontal systems next week with their exact timing still a bit
uncertain. Highs and lows will generally be above average,
especially in the European model (ecmwf) solution.
Aviation [through 00z sunday]...
Expect a broken to overcast upper level cloud deck with surface
winds veering to the north then northeast through the period as
a low level ridge of high pressure shifts eastward. Low to mid
level isentropic ascent across 305k surface is allowing patchy
drizzle across the region this evening, which may continue on and
off through around 06z, but is not expected to reduce vsbys at
Winds will generally be in the 10 to 15 knot range through the
weekend with slightly elevated seas (especially offshore).
Conditions will calm a bit to start next week before becoming a
bit more unsettled by mid-week depending on the timing of a cold
front. Showers and thunderstorm chances increase Sunday night
through much of next week.
Much drier air will be in place tomorrow and relative humidity
values will dip into the low 30s. Transport winds will be low,
which will mean no red flag conditions, but will also mean low
dispersions in the southeast Big Bend.
Rain is not expected through Sunday. Starting Sunday night we'll
transition to a wetter pattern with the potential for widespread
average rain amounts from 1-3" through next week. These amounts
will be most common along and west of a line from Albany through
Panama City, with isolated higher amounts possible. At this time,
the forecast rain amounts are not expected to cause any flooding
Spotter information statement...
Spotter activation is not requested. However, spotters are always
encouraged to safely report significant weather conditions when they
occur by calling the office or tweeting US @nwstallahassee.
Preliminary point temps/pops...
Tallahassee 42 63 44 73 59 / 10 0 10 10 20
Panama City 42 61 50 70 64 / 10 0 10 20 40
Dothan 34 58 40 69 60 / 10 0 0 20 50
Albany 34 58 39 68 58 / 10 0 0 10 40
Valdosta 41 61 42 72 57 / 10 0 0 0 20
Cross City 45 67 46 75 60 / 10 0 0 0 10
Apalachicola 45 62 52 70 65 / 10 0 10 20 30
Florida...high rip current risk until 4 am EST /3 am CST/ Saturday for