Area Forecast Discussion
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FXUS62 KTAE 121032 AAA
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TALLAHASSEE FL
532 AM EST Thu Dec 12 2013
Updated Aviation Discussion.
.NEAR TERM [Through Today]...
Although overnight low temps will not be especially cold tonight,
a secondary dry cold front is making steady progress
southeastward towards our region. This has caused a fairly
significant drop in expected afternoon high temperatures in much
of the numerical guidance, and for the second day in a row,
decided to follow our CAM ensemble very closely. This gives us
high temps below climo levels, ranging from the lower to middle
50s to the NW to the upper 50s and lower 60s to the SE.
Interestingly, these values are closer to, but not quite as low as
the Raw Model data, which continues to drop even further. The new
00 UTC run of the ECMWF has raw 2m temps ranging from the mid 40s
to the lower 50s in fact, so the day shift may still need some
slight downward adjustments.
.SHORT TERM [Tonight through Saturday night]...
The short term will start off dry with cool high pressure the
dominant feature. Overnight lows tonight may dip to near freezing
in a few of the normally colder locations, but a widespread freeze
is still not expected. This is mainly due to the expectation
that winds may not go completely calm with high pressure centered
north of the area, and MOS has had a tendency to be a few degrees
too cold so far this cool season. The official forecast went on
the warmer side of the guidance spread for tonight.
Friday will be a transition day as surface ridging moves to the
east and the flow turns more southeasterly. The next system will
still be too far away to give us any chance of precip on Friday
though. Highs will be near the seasonal average.
Guidance is in agreement that Saturday will be a wet day as the
next system affects the area. Moisture return looks fairly
substantial with this system, and the eastern Gulf of Mexico SSTs
are currently above average for this time of year due to the lack
of very many cold air intrusions so far this cool season. There
remains a non-zero chance of isolated severe storms on Saturday
and/or Saturday night with this system, but it currently looks
like a lower end threat as the dynamics are not overwhelming and
the instability still looks a bit marginal despite the strong
moisture return. One additional thing to watch out for may be the
threat of heavy rain due to training convection. Both the GFS and
NAM forecast precipitable water values to rise to over 1.75 inches
on Saturday evening, which is near the 99th percentile for
December. (The December record is 2.00 inches.) As this occurs,
guidance shows the front temporarily slowing down, and training
convection would become a possibility with several inches of rain
occurring in a short amount of time over localized areas.
.LONG TERM [Sunday through Wednesday]...
A decreasing trend in the rain is expected during the day Sunday
as the front clears the area. Then, a seasonably cool, dry
airmass will be in place across the forecast area Monday through
Wednesday, with near-average temperatures.
.AVIATION [Beginning 12Z Thursday]...
-- Changed Discussion --The threat for any period of MVFR Cigs has now passed, so nearly
unlimited VFR conditions should rule the skies for the next 24
hours. The only expected aviation hazard will be gusty winds out
of the N and NW during the daylight hours.
-- End Changed Discussion --
Winds and seas will increase today as a strong area of high
pressure moves over the Tennessee Valley and increases the
pressure gradient. Low end advisory conditions are expected across
the offshore zones with exercise caution conditions across the
nearshore zones. Winds may briefly reach advisory levels this
evening nearshore, but confidence is not yet high enough to go
with an advisory there. Conditions will improve slightly on
Friday, but stronger winds and higher seas are likely once again
on Saturday as a cold front approaches from the west.
Relative humidity values will be quite a bit lower across the
region this afternoon, but it still appears that the other
necessary criteria for Red Flag conditions for each of our 3
states will not be met. However, as we gradually get into a drier
pattern, conditions will have to be monitored more closely as time
goes on, especially if ERCs begin to increase in FL and Fuel
Moisture levels start to drop in GA.
Average rainfall totals of 1 to 3 inches are expected this weekend,
but localized amounts around 5 inches are possible if training
convection occurs on Saturday. These rainfall totals will result in
rises along area rivers.
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 59 33 66 51 73 / 0 0 0 10 70
Panama City 59 40 64 56 73 / 0 0 0 20 70
Dothan 54 32 61 49 71 / 0 0 0 20 70
Albany 55 32 62 48 70 / 0 0 0 10 80
Valdosta 58 34 65 49 73 / 0 0 0 10 70
Cross City 63 35 70 51 75 / 0 0 0 10 50
Apalachicola 61 41 64 57 72 / 0 0 0 20 70
GM...SMALL CRAFT ADVISORY until 4 AM EST Friday for Waters from
Suwannee River to Apalachicola FL from 20 to 60 NM-Waters
from Apalachicola to Destin FL from 20 to 60 NM.
Near Term/Aviation/Fire Weather...Gould