NEAR TERM [Through Tonight]...
An unusual retrograding mid/upper low centered over the Midwest
is providing the Southeast and the northern Gulf with broad troughing. In fact, there may even be another (weaker) closed low over the northern Gulf based on VWP data. At the surface, similar to aloft, broad troughing covers the Gulf Coast states on into the northern Gulf.
Within the broad trough there appears to be two closed circulations, one off the southeast Louisiana coastline, and one just southwest of buoy 42039. Additionally, a notable surface trough embedded in the large area of low pressure extends from the closed circulation east to the western Florida Peninsula coastline, northeast up the eastern Georgia coastline. In this area, steady convection has been ongoing throughout the day.
Further to the west, a stationary boundary divides a very dry vs. very moist airmass essentially along the Mississippi/Alabama state line, with another weak trough extending north out of the Gulf ahead of the front. This is another area where storms have focused this afternoon. Locally, scattered convection and light rain plague the Tri-State area where convergence is maximized on the eastern edge of the main low/mid level circulation. Expect this general pattern to remain in place through the day, with the low moving slowly north and west later tonight.
Thus, expect the best chances of rain to gradually slide slightly west through the night.
SHORT TERM [Sunday Through Monday Night]...
The weak surface low in the Gulf of Mexico will be pulled
northwestward toward the Mississippi coast on Sunday by the
retrograding upper level low moving into the Southern Plains.
Deep layer tropical moisture will continue to be pulled northward into
the area with precipitable water values well over 2 inches. PoPs
will be in the high likely category.
We will also see increasing southeasterly shear. While the degree of destabilization will likely be mitigated by abundant cloud cover and convective coverage, deep layer shear will be sufficient (25-30kt) to produce isolated strong to severe storms in any areas that get a bit of sunshine. SPC has the region in a 5% risk area for severe with damaging winds and perhaps even a tornado the potential threats.
The upper low will reach the TX Panhandle by Monday. This will allow a big upper high centered over eastern PA Sunday morning to slide west to Indiana by Monday.
Beneath the ridge, a tropical wave will approach and cross FL on Monday and this will keep PoPs elevated in the likely range, despite the building ridge to the north.
Max temps will be kept below guidance and several degrees below normal due to anticipated cloud cover and the numerous showers and storms.
LONG TERM [Tuesday through Friday]...
By the start of the period, the upper low will have retrograded all
the way to eastern New Mexico with a 598-dm high centered over
Indiana. This high will lose amplitude as it drifts to the southwest toward the Great Plains.
By the end of the week, a broad trough will be in place across the Northeast and Mid Atlantic.
At the surface, a tropical wave will move west of the forecast area Tuesday and Tuesday night. After that, the subtropical ridge will reestablish itself over the Southeast with the axis slipping south of the region by Friday and Saturday.
Despite the influence of the upper ridge, PoPs will be close to climatology on Tuesday due to the passing wave. The ridge will win out on Wednesday with below normal PoPs and above normal temps (a rare thing this summer). By Friday and Saturday, temps and PoPs will be very close to normal July values as the once familiar subtropical ridge pattern sets up the more typical sea-breeze induced thunderstorms each day.
Scattered showers and thunderstorms will generally spread westward through the day as a developing low pressure in the Gulf of Mexico drifts northwest.
From latest satellite imagery, it appears MVFR ceilings, where currently present, will likely lift early in the period.
Overnight and early tomorrow morning, expect MVFR ceilings to develop and persist through most of the morning.
Although possible, we don`t have enough confidence to lower ceilings to IFR/LIFR restrictions before sunrise, so will defer to next TAF package.
Weak low pressure over the north central Gulf of Mexico will drift
northwest toward the Alabama or Mississippi coast through Sunday
Winds will generally be in the exercise caution range across the western legs.
High pressure will then become established north of the area from Monday through midweek. This will set up diurnal easterly surges over the marine area bringing winds to near cautionary levels during the overnight and morning hours.
Showers and thunderstorms will remain numerous through Monday.
Red flag conditions are not expected through the period.
Rainfall amounts today have been rather insignificant thus far, with
the exception of the Southeast Big Bend earlier this morning, where
3 to 5 inches of rain fell, mostly over Dixie and Lafayette
Although we will be in a rather wet stretch, average rainfall totals for the next couple of days should peak around 2 inches. However, locally higher amounts are certainly possible (e.g. 2 to 3 inches fell in one storm across western Walton county earlier today).
Should any of these locally higher amounts fall over any of our warned basins, it could result in some rather sharp rises. In general however, expect area rivers and streams to remain in a rather steady state over the next few days.
Please refer to our River Forecast page (below) for more detailed information.
PRELIMINARY POINT TEMPS/POPS...
Tallahassee 83 71 86 72 87 / 80 50 70 40 60
Panama City 85 74 85 75 87 / 60 60 70 40 60
Dothan 89 71 84 72 85 / 60 60 70 40 60
Albany 84 70 86 72 87 / 80 50 70 30 60
Valdosta 82 71 87 72 87 / 90 40 70 30 60
Cross City 84 72 87 71 87 / 90 40 70 40 60
Apalachicola 84 77 85 75 87 / 80 60 70 50 60