TODAY: There is much less over all atmospheric moisture availability today state wide as opposed to yesterday, on the other-hand, high cirrus clouds which moved in yesterday that likely capped off the rain chances to very low do not appear will be a problem today across Central Florida; however, they do appear to be encroaching into SW toward all of South Florida as of 1pm. Already, developing cumulus cloud fields over SW Florida have dissipated (for the time being) in that area, whereas showers have formed along the east coast sea breeze.
This post today is a blend of the RUC and latest 8AM GFS. The RUC has been ADAMANT at nearly scattered thunderstorms this afternoon across all of Central Florida into South Florida, this is due to vorticity at the low through upper levels that it presents. However, no such feature (s) is apparent, so will downplay to isolated activity due to low atmospheric moisture with not boundaries. A ridge axis from the North Central Gulf extend across Central Florida, whereas another ridge axis does the same from the Atlantic. Storm/shower motion should be toward the SSW/SW but be quite slow to negligible since activity should not move far from where it forms. Showers/storms should wane quickly with the setting sun, although there could be a few showers or small storms over the interior until just after sunset. The more dominant feature will be a stationary boundary along the northern Gulf Coast from Louisiana through the Florida Panhandle extending toward JAX, where a more prominent storm could from West of the St. Johns in northeast Florida, with more activity along the western Panhandle.
THURSDAY: The upper low over the Great Lakes will be on the move late today very slowly toward the East as a more powerfully progressive trough tracks across Southern Canada. As the large low moves east the boundary over North Florida will wash out into Central Florida on Thursday, with a slightly better chance of showers/thunder over the NE quadrant of the state, namely from Brevard County toward Ocala/Gainesville/Jax triad. South Florida will have a day similar to today with mainly showers along the sea breezes, and maybe an isolated thunder chance.
FRIDAY: The upper low over the Great Lakes will move east and relax into an open wave/ trough while the secondary, more powerfully progressive trough drives ESE-SE into the Great Lakes to replace where the former one had been stationary. As the two systems merge a more organized cold front will form Thursday night which will drive into the Mississippi River Valley and the Deep South Thursday night into Friday. Like on Thursday, this boundary will be located across Central Florida on Friday during peak heating, with the better chance of storms associated with it over Dead Central, favoring the east side from early afternoon through sunset. Moisture still isn't all the greatest, but colder air aloft in the mid-upper levels should help negate the lack of overall moisture, which should converge along and ahead of the boundary under the cold air aloft and continued high temperatures near 90F at the surface. Some of this activity could be quite active into Sunset Friday night mainly along central Florida from Daytona Beach toward Vero, with other showers further south along the east coast...but again, it will be isolated in nature.
SATURDAY: So far, timing has the actual frontal boundary driving through the state after sunset Friday night through mid-day Saturday, perhaps even faster after dark. Northerly winds should be in place for all of the state Saturday afternoon accompanied by near clear skies and temperatures Saturday afternoon in the low 80Fs to upper 70Fs far north Florida. Overnight Saturday night high pressure builds in quickly across the southern tier of states and winds become more NE-ENE during the day Sunday, strongest across far South Florida and the keys.
SUNDAY/TUESDAY: The only favorable location for rain showers/thunder will be across the Far Southern tip of the state from Southern Dade County and through the Keys, including Key Largo.
During the course of this first frontal passage, which coincidentally is forecast to occur on the exact same date as last year, October 1st, morning lows along the east coast will be close to 70F and highs will be in the low to mid 80Fs, with some upper 40s to mid-50Fs mostly around the Big Bend and all of the panhandle. By Tuesday east coast temperatures will essentially be equal to the ocean temperature near shore, or just a bit below that by noon time, with only about a 10F degree variation in the temperature fields between morning lows and afternoon high temperatures. So far, it does not look as likely that a major rain event, or any event, will be in the works as opposed to earlier model runs, but this will need to be watched for as the time approaches (by Wednesday), when such a set up would be more likely as winds become more due easterly.