NEAR TERM [Today and Tonight]...
The forecast over the next 24 hours is centered around weak but
steady cyclogenesis in the Gulf of Mexico.
An upper level low was evident in water vapor satellite loops early this morning over Texas.
As a trough digs into the northern states and mid-upper level height falls overspread much of the CONUS east of the Rockies, stronger westerlies will develop and cause the Texas low to devolve into an open wave and deamplify as it ejects east.
A surface low should develop ahead of this ejecting wave in the
central Gulf, and in the RRQ of an upper level jet.
Mass response will cause a LLJ to develop and intensify today over the Florida Panhandle and much of Alabama and Georgia.
The increasing low- level moisture flux and isentropic ascent should support fairly widespread rain, particularly NW of a Mexico Beach to Lake Seminole to Fitzgerald line (NW 1/2 of area) prior to 00z.
PoPs were increased into the 90-100% range in those areas for today.
Steady rain and dense cloud cover should keep those areas much cooler with highs expected to be in the low to mid-50s. Further southeast, there may be a few breaks of sun with only isolated light showers or sprinkles expected prior to 00z.
Overnight the surface low is projected to pass over the northwest
corner of our forecast area.
This is when Q-G forcing will be maximized and moderate-heavy rain will spread over the entire area from west to east. Categorical PoPs were utilized over basically the entire area.
Average rainfall amounts are expected to be around 1-2" over most of the area, with some locally higher amounts in the far NW - particularly SE Alabama and adjacent parts of SW Georgia and FL Panhandle.
The heavier rain should fall near the surface low track where low-level convergence and moisture flux is likely to be maximized.
Given fairly high flash flood guidance, we do not anticipate widespread flooding issues. Localized flooding, primarily of urban areas, will be possible in the aforementioned areas where locally heavy rain is expected.
Regarding thunderstorms - they would be most likely overnight when
the low tracks inland and the warm sector briefly shifts onshore.
Marginal instability is indicated on the models so isolated to
scattered thunderstorm wording was used in the forecast.
Severe weather seems unlikely given a variety of factors. Lapse rates
should be poor and instability quite marginal, and this will be
reinforced by persistent cool E-ENE flow in the boundary layer
through around 03z. Additionally, mid-upper level height falls are
quite limited across the area as the wave aloft deamplifies as it
passes by. Our local hi-res model ensemble shows updraft velocity
values limited to 10 m/s or less, which suggests that storm intensity will be greatly limited by the poor lapse rates.
SHORT TERM [Sunday Through Monday]...
Majority of the focus from Sunday into early next week will be with
departing shortwave trough and associated rain/clouds Sunday.
Models are consistent in maintaining widespread rain and scattered
thunderstorms Sunday morning from parts of central GA into the Big
Bend of FL shifting steadily eastward through the day.
Severe threat will remain quite low over the eastern Bend Sunday morning given fairly pronounced low level shear. However, expect
instability will remain quite limited and dampen overall severe
threat. The GFS is a bit faster than the ECMWF, SREF mean and local
high-res guidance in clearing the eastern counties by early Sunday
afternoon. Will lean towards a blend and keep a mention of showers
and thunderstorms into the afternoon Sunday, particularly over the
Regardless, in the wake of this departing system, area should finally see an end to the persistent cloudiness and a return to normal temps Monday and Tuesday under base of larger upper trough extending out of eastern Canada ahead of next system later next week.
LONG TERM [Monday Night Through Saturday]...
A re-enforcement of slightly cooler but much drier air will filter into the region on Tuesday behind the passage of a dry cold front Monday/ Monday night.
This dry period will be short lived as the next low pressure system will begin to develop across the Southern Plains on Wednesday in this very progressive pattern.
A sharpening upper trough will move east with it`s axis through the Lower Mississippi Valley on Thursday sending a cold front across the Tri-state region.
In contrast to it`s predecessor, deep layer moisture and plenty of upper level energy is expected to accompany this system.
For now will increase PoPs into the chance category for Thursday.
Cooler and drier air return to end the typical work week.
A complicated mixture of several cloud layers is expected today across the area.
Prior to 22-00z timeframe, this should be mostly MVFR or VFR, with the greatest likelihood of MVFR CIGS further west (DHN and ECP).
CIGS should lower somewhat overnight with the potential for some IFR.
Rain will gradually increase over the western terminals (ECP and DHN) today, and then rain and some thunderstorms will spread east tonight affecting all terminals by 12z.
Some periods of IFR visibility will be possible in +RA or +TSRA.
Confidence in timing was not high enough to have any prevailing thunderstorms, although some narrower periods with VCTS were included in each TAF.
Winds and seas will steadily increase into Sunday ahead of a fast
moving weather system ejecting across the area.
A surface low will move into the FL panhandle late tonight, with trailing cold front advancing eastward tomorrow.
Easterly winds will increase to advisory criteria today, especially over the western legs, with winds strengthening and shifting to a southerly direction tonight across all legs.
Expect winds and seas will relax some Sunday as winds shift to offshore behind the front, but conditions will still warrant caution through the day Sunday.
A return to lighter winds and lower seas can be expected for the early part of next week.
Widespread rain over the next 24 hours will limit any fire weather
Red flag conditions are not expected for the foreseeable future.
Mixing will be poor the next couple days.
The Apalachicola River at Blountstown is above flood stage and is
forecast to remain in minor flood stage through at least January 1st
with releases from Woodruff Dam.
Elsewhere, rivers and creeks are currently below flood stage, although many are elevated.
Rainfall this weekend is currently expected to average in the 1-2" range.
This should help to keep river levels elevated, but widespread river flooding is not expected.
A few river points may hit minor flood stage, particularly in the western Florida Panhandle.
Upstream tributaries of the Apalachicola River - such as the Flint
and Chattahoochee - should see widespread rainfall amounts of 1.5
inches or so in their drainage basins.
As this water is routed downstream, there may be additional rises on the Apalachicola River in the future, but that is somewhat uncertain at this time.
PRELIMINARY POINT TEMPS/POP...
Tallahassee 65 60 70 46 65 / 50 90 60 10 10
Panama City 63 58 67 47 62 / 80 80 30 10 10
Dothan 55 50 64 42 61 / 100 100 30 10 10
Albany 57 53 67 41 62 / 80 90 60 10 10
Valdosta 65 60 70 46 67 / 40 80 80 10 10
Cross City 74 64 73 53 68 / 20 70 80 10 10
Apalachicola 66 61 68 48 63 / 50 90 50 10 10
GM...Small Craft Advisory until 10 AM EST Sunday for all zones.