NEAR TERM [Thru TODAY]...
We continue in a very wet and unsettled pattern. During the overnight hours, shortwave energy moving from the Cntrl/Srn Gulf of Mex has energized another band of deep tropical moisture (PWATS 2.1-2.2 inches) with training cells and interacted with a stalled front producing moderate to locally heavy rains across portions
of the local area, especially the Panhandle.
This aggravated the flooding situation which necessitated the issuance of a flood warning for Jackson and Washington counties.
RAP soundings imply that low level steering flow was switching from SW to more sly feeding more of this moisture Nwd into our AL/GA counties near the front yielding rain rates of up to 2-3 inches per hour. By 3 AM EDT, strong storms developed across the nearshore waters and this will soon move over coastal counties. All this reflected well in HRRR.
The large scale pattern continues to amplify with little change in last 12 hrs providing all the ingredients necessary today for a continued widespread heavy rain event further aggravating the flooding situation.
Aloft, ridge over Wrn 1/3d and deep trough over Ern 2/3rd of Conus with axis down MS Valley. A deep 580DM low will centered over MO/TN border with a trough axis extending into the northwestern Gulf of Mex. A potent vortmax over AR/TN border with 90kt upper jet round the base of the trough placing the area in the favorable right entrance region. Several small shortwaves riding down base of trough nudging it ewd. All this increasing upper lift/diffluence over mainly WRN CWA. At the same time, weal upper ridging exists over Srn FL and a low/tropical wave was located in the SW Gulf on Mex (NW of Campeche). The combination of these features has allowed for sfc-H4 SW unidirectional flow providing a deep conveyor belt of tropical moisture spreading Newd across our local area.
At the surface, front remains largely stalled from Srn Walton county NNE to along I-10 into SE GA yielding SWLY flow. However the combination of diurnal heating plus building H5 ridging across the Wrn Atlc and FL Peninsula should lift front Nwd thru the day placing more of area in warm sector. Convergence along this boundary should continue to serve as the focus for low level lift and where
heaviest rains should occur (AL/GA). Model soundings show area
PWATS in excess of 2 inches.
Flash flooding will remain a serious concern as activity continues
to train over areas which have already received significant rainfall.
As the Gulf system moves further Wwd, guidance places the highest QPF and highest PoPs over the NW third of our forecast area.
With many of these areas already saturated from a very wet summer,
flash flooding will continue to be closely monitored.
Thus the flash flood watch remains in effect for the entire area but Ern sections should be dropped this aftn.
Will have categorical PoPs for most of the area with temperatures well below normal. See the hydrology section of this product for more details on the potential.
As far as strong to severe storms, the existence of a very moist boundary layer and weak lapse rates argue against these storms, however with upper trough/jet/vort, cant discount wet microbursts with
gusty to damaging winds best bet. SPC keeps us in 5% severe prob.
Will go with CAT POPS west half and likely POPS east half with heavy
rain in grids.
Under cloudy and rain conditions, Max temps to remain well below normal, from around 80 SE AL to mid to upper 80s SE Big Bend.
SHORT TERM [Tonight Through Monday]...
As the Gulf system continues to shift Wwd into Wrn Gulf, expect
corridor of heaviest rain progressively sliding west and out of our forecast area as Atlc ridge progressively builds NWWD thru period.
However, the continued influence of the trough along the MS Valley (even thought its deamplifying) and now SW-NE oriented quasi-stnry front should combine for sct-likely POPs thru the period.
For tonight, the deep layer conveyor belt will diminish as dry air spreads into Srn periphery of upper low but FL Panhandle and SE AL will remain in a favorable position to receive additional rain, possibly moderate to heavy, and thus lingering flooding concerns.
By Sun, the upper low will lift Newd towards OH River Valley but trough and front will linger while the Gulf system should be far enough west (S TX or Mex) for little impact.
However, latest guidance indicates that a piece of this feature will shear Nwd strengthening H85 flow and keeping moisture in at least our Wrn CWA even with the Atlc subtropical ridge building Nwwd into our area.
By Mon, upper ridge over Wrn Atlc will expand into local area while front has moved further Nwd and weakened. We will return to a more seasonal pattern of mainly aftn/eve sct seabreeze driven convection as max temps return to near climo.
Will go with 60-40% NW-SE POPs tonight, 60-50% on Sun and 50-30% N-S on Mon.
Lows tonight around 70. Highs Sun Mid 80s NW to around 90 SE
rising on Mon to upper 80s NW to lower 90s SE.
LONG TERM [Monday Night through Friday]...
Upper trough over the Lower Mississippi Valley is forecast to linger through the first half of next week keeping a moist and unstable airmass in place over the tri-state area. This will keep PoPs relatively high through at least Tuesday.
By later in the week, there is more uncertainty in the guidance as to how much ridging will build back over the region, with the ECMWF keeping the upper trough in tact and the GFS indicating a stronger ridge. Will keep conditions close to climo as a compromise.
Low cigs and showers with embedded convection will prevail with MVFR to IFR conditions expected.
Winds and seas will be on the increase through the weekend,
especially around any convection and especially over the western
waters, as a trough of low pressure lingers to the north and west.
However conditions should remain below exercise caution levels
Winds and seas will diminish early next week.
Abundant moisture and rainfall will prevent red flag conditions from
being met well into next week.
Up until this morning, except for the FL Panhandle, showers have been progressive enough and not training which has kept the flood threat low.
However, this should change today as the heaviest rains of this wet period are expected with widespread average rainfall amounts of 3 to 5 inches still anticipated mainly Wrn areas.
Isolated higher totals are expected, possibly upward of 5 to 8 inches in some locations.
River flooding will become an increasing concern by late today
and into next week, especially depending on where the heaviest
rainfall ends up occurring.
The current thinking is that much of the heaviest rains will occur in the lower half of the basins.
Thus, if the latest forecast holds, the Choctawhatchee Basin from
Geneva through Bruce would easily return to minor flood stage late
in the weekend with the potential for moderate flooding from
Caryville southward to Bruce early next week.
The Chipola has some capacity for heavy rainfall, but if rainfall amounts trend higher than expected, minor flooding would be a possibility at Marianna and Altha early next week.
Into Southeast Alabama, soils are especially saturated and area
creeks and stream will quickly respond to any significant rainfall. Minor flooding along the Choctawhatchee and Pea Rivers could occur quickly in this scenario late this weekend.
In Southern Georgia and the Florida Big Bend, current projections
move the Apalachicola, Flint, and Ochlockonee River systems to near flood stage with anticipated rainfall, though heavier amounts would easily lead to minor flooding, especially in the lower portions of these basins where heavier rains were received in July.
Lighter rainfall amounts are anticipated further east into the
Withlacoochee and Suwannee River basins and the current
anticipation is for these rivers to remain below flood stage into
PRELIMINARY POINT TEMPS/POPS...
Tallahassee 84 71 91 74 91 / 80 60 60 50 50
Panama City 83 75 88 77 86 / 90 60 60 50 50
Dothan 81 70 86 71 88 / 90 60 60 40 50
Albany 82 71 88 73 90 / 90 60 60 30 50
Valdosta 85 70 91 73 91 / 70 60 50 40 50
Cross City 88 73 91 72 91 / 50 40 50 40 50
Apalachicola 85 78 87 79 87 / 80 60 60 50 50
FLASH FLOOD WATCH through this evening for Coastal Dixie-
Coastal Franklin-Coastal Jefferson-Coastal Taylor-Coastal
Wakulla-Gadsden-Inland Dixie-Inland Franklin-Inland
Jefferson-Inland Taylor-Inland Wakulla-Lafayette-Leon-
FLASH FLOOD WATCH through Sunday evening for Calhoun-Central
Walton-Coastal Bay-Coastal Gulf-Holmes-Inland Bay-Inland
Gulf-Inland Walton-Jackson-South Walton-Washington.
FLASH FLOOD WATCH through this evening for Baker-Ben Hill-
FLASH FLOOD WATCH through Sunday evening for Coffee-Dale-
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