Near Term [Through Today]...
As of 18Z, scattered showers and thunderstorms had begun developing along and near the surface trough and convergence zone in the eastern sections of our forecast area - particularly in SC GA.
Model guidance - both global and convection-allowing - is still in good
agreement that convection will fill in across the Florida Big Bend
region between 18-00Z. Therefore, 60-70% PoPs have been maintained in that area.
Isolated-scattered showers and storms are expected elsewhere.
In general, the main threat with any storms should be heavy rainfall and lightning. Where some thunderstorms manage to train or move very slowly, localized rainfall totals up to 2-4" will be possible.
One or two strong storms with gusty winds can not be ruled out, but in general the threat of severe weather is fairly low for the rest of this afternoon and this evening.
There is also good agreement amongst the various computer models for a general westward progression of convection with time - numerous storms in the eastern parts of the area 18-22Z will begin to consolidate and move west, diminishing in the 22-02Z timeframe. The PoP forecast follows this general trend through the evening.
Short Term [Tonight Through Wednesday Night]...
The area of high 500 mb heights over much of the Southeast will
continue to be centered over the TN area.
A north-south oriented trough will translate slowly westward across the FL Peninsula Wednesday and Wednesday night.
The GFS, and to a lesser extent the ECMWF, forecast a much drier airmass over our region Tuesday and Wednesday.
The driest of the days appears to be Tuesday, when the PoP will generally be around 20% (below climo of 40%).
With increasing moisture later in the day on Wednesday, the PoP will be in the 20-30% range.
Highs will be in the mid 90s, lows in the lower 70s.
Long Term [Thursday Through Monday]...
Through Saturday there will be an east-west oriented ridge at 500 mb over the Southeast, and a broad, north-south oriented trough over the eastern Gulf of Mexico.
Both of these features will dissipate over the weekend as a broad long wave trough develops over the Upper Midwest and Northeast.
At the surface, the western periphery of the Bermuda ridge will gradually shift from our north on Thursday, to our south (over the FL Peninsula) over the weekend.
Both the GFS and ECMWF depict a larger, stronger 500 mb trough than 24 hours ago, and show more deep layer moisture as well.
While they differ on just how moist and exactly where the highest moisture will be, this new development implies slightly higher PoPs and slightly cooler high temperatures than what we were forecasting previously.
We are now forecasting near-climo PoPs (around 40%) through the
period, with highs in the mid 90s and lows in the lower 70s.
Despite the increased influence of the 500 mb trough, the PoPs will still follow the normal summer diurnal cycle.
While VFR conditions should prevail for much of the forecast period, IFR VIS is likely in heavier showers and thunderstorms this afternoon and early this evening.
+TSRA and IFR VIS would be most likely to affect TLH, VLD, and ECP and mainly between 18-00Z.
Some storms could produce some gusty winds, and for now we`ve included gusts in the TEMPO groups 20-30 knots.
A high pressure ridge will remain near, but just north of of the coastal waters through much of the work week.
Winds will be light, and mostly out of the northeast or east overnight, then veer to the southeast during the morning.
Winds will become onshore and increase slightly near the coast each afternoon from the strong heating of the land.
Waves will be 2 ft or less.
No red flag conditions are expected through the period.
Seabreeze showers and thunderstorms in the Florida Big Bend and
South Central Georgia are expected to bring widespread 0.25 to 0.5
inch of rain today with locally higher amounts of 2- 4 inches possible.
All area rivers are below flood stage so these amounts will not have a significant effect on river levels.
Preliminary Point Temps/PoPs...
Tallahassee 70 95 72 94 71 / 40 10 10 10 10
Panama City 74 90 75 89 75 / 30 20 10 20 10
Dothan 72 96 72 95 73 / 30 10 10 20 10
Albany 71 96 71 95 72 / 30 10 10 10 10
Valdosta 69 96 68 94 69 / 20 10 10 10 10
Cross City 69 93 69 92 68 / 30 20 20 30 20
Apalachicola 72 88 74 88 73 / 30 10 10 10 10