AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
920 AM EST Tue Jan 15 2013

.NEAR TERM [Through this afternoon]…
Latest surface analysis shows the quasi-stationary front still
just to the west of our CWA. Weak waves will translate along the
boundary today bringing a chance of rain mainly to our western
zones. Max temps will be held down a bit over the extreme
northwest portion of our CWA with the thicker cloud cover and rain
chances. Otherwise, look for high temps to max out around 80 degrees
expect lower to mid 70s along the immediate coast.

&&

.SHORT TERM [Tonight through Thursday]…
The mid-week weather will largely depend on the exact evolution of
the upper-level low that is projected to close off at the base of
a more amplified trough, and then eject east along the Gulf coast
states by Thursday. At start of the period (Tonight & Wednesday),
the mid-upper level flow pattern will feature a highly amplified
longwave trough with an axis extending from Michigan to central
Texas. Meanwhile, an upper level anticyclone will remain anchored
just to the east of the Bahamas – setting up broad and deep SW
flow across much of the Southeast US. As the “near term” portion
of the discussion alludes to, this means that the surface front
will be slow-moving. After a generally dry night tonight, the
front will gradually push into the area on Wednesday, allowing
chances for showers to spread east. Any rain showers through 06z
Thursday should be scattered and relatively light – PoPs mostly
40% or less in that time frame.

The mid-upper level low is expected to close off over Texas on
Wednesday, and eject east Wednesday Night and Thursday – at which
point more substantial height falls should commence across our
area. In response to the ejecting wave, the models are in good
agreement that surface cyclogenesis will occur somewhere in our
vicinity, with the resulting low moving well E/NE by Thursday
evening. However, there is still disagreement about the location
of the cyclogenesis, as well as the trajectory of the ejecting
upper level low. These details will make an impact on the
forecast, so there remains some uncertainty. However, the strength
of the ejecting wave and associated QG convergence fields ahead of
it argue for fairly widespread precipitation. Therefore, in
collaboration with surrounding WFOs, PoPs were raised to “likely”
category (60-70%) over the northwest half of our area from 06z
Thursday to 00z Friday. With widespread rain and cloud cover on
Thursday, it should be a cool breezy day with highs in the 50s in
many locations.

&&

.LONG TERM [Thursday night through Monday]…
LAST UPDATED: 235 am EST Monday Jan 14

A cooler airmass will move into the region in the wake of the
cold front. However, temperatures are only expected to fall back
to near seasonal norms. The cool surface high is expected to
become stretched east-west and centered just north of the region
moving into next weekend. This will result in a pretty healthy
easterly flow across the region, which will bring some modest
moisture return, and possibly some isolated showers for the
eastern half of the forecast area.

&&

.AVIATION [Through 12Z Wednesday]…
IFR cigs this morning should transition to VFR/MVFR conditions by
mid to late morning. Low cigs will return tonight for all
terminals, with conditions possibly reaching airport mins at KTLH
and KVLD.

&&

.MARINE…
South winds of 10-15 knots will continue in advance of the
developing low pressure system through Wednesday Night. As a cold
front sweeps through the coastal waters on Thursday, winds should
veer to the northwest and increase to advisory levels (20+ knots).
Elevated winds and seas should continue into Friday.

&&

.FIRE WEATHER…
Low level moisture will remain elevated across the region through
the end of the week, keeping fire weather concerns to a minimum.

&&

.HYDROLOGY…
After several days of very light and scattered rain showers with
limited rainfall, more widespread rainfall is expected on
Thursday. However, total average QPF through that time is expected
to range from around 0.20″ in the eastern Florida Big Bend to
1.00″ over southeast Alabama. This should not be sufficient to
produce significant rises on area rivers.