TODAY: Just looked at the morning sample taken by a weather balloon (in essence) of the atmosphere from the Kennedy Space Center. It is showing an increase in atmospheric moisture, but most of this is either at the lowest levels or highest. A dry layer remains above cumulus cloud level as has been the case for a while now, and little change is expected from that through today into tonight. The most instability is just near and off both coasts which developed relative to the cooler air above the land mass over night. There was much more there this morning then in the past, and even more is expected to be there tomorrow morning. Daytime heating will dry out the interior, whereas afternoon sea breezes will create sinking motion near the coast to clear out any remaining cumulus clouds near the coast before noon...although they might linger longer toward coastal SE Florida. Highs will be in the low 90s inland and closer to the mid-80s at the beach. Not expecting any showers today, although a shower could pop up on the western portion of Tampa Bay late this afternoon into the early evening. Maybe they will eke out thunder due to low level forcing of local bay boundaries, but at this time it does not look like the moisture will be deep enough, nor will any 'forcing' be strong enough, in the absence of any upper level energy, to generate thunder there later today as of this hour.
FURTHER NORTH: A disturbance will drop SE and across the area above noted in RED much later today (in general)...and create strong to marginally severe thunder later this afternoon into early evening. Another impulse may very well make a repeat performance in the same area early Wednesday morning. Those could lay the frame work for some stronger storms over the Jacksonville area later on Wednesday if they manifest. However, it does look likely that they will.
WEDNESDAY: Chance of storms toward Jacksonville and over the St. John River Valley Basin in general. These, if they can form in the still somewhat questionable situation at hand, could end up being rather strong as a result of the cold air aloft combined with boundaries created by that activity moving off the South Carolina Coast. There was some unstable air near the coasts of Central Florida this morning, and there is expected to be even more of it there tomorrow morning. Additional atmospheric moisture combined with strong winds aloft should work in tomorrow to support a chance of an isolated shower early in the morning near the Cape and further south toward Ft. Pierce, with redevelopment of a possible thunderstorm from near Sebastian to just south of Vero Beach/Ft Pierce in the afternoon, to possible into a portion of Osceola County later in the afternoon . An additional storm or two could form later in the afternoon around convergence of the sea breeze/lake breeze frontal boundaries off the Gulf/East Coast, and and Lake O '. Most likely on the NW-W side of the lake.
Any showers to form will be very isolated, with the best chance near Lake O.
THURSDAY: Isolated late afternoon sea -breeze front convergence thunder storms are possible down the spine of the state. See image below for these two days (Wednesday/Thursday). This is a first order 'best guess' based on what was available early this morning and will very likely have changed by later this afternoon or tonight. Just to serve as a heads up that there could be some thunder around the state Wednesday/Thursday. The GFS and now NAM are supporting the activity for Wednesday in a various forms though. The GFS for 36 hours now. Last night, in fact, the NAM was showing the potential for bombastic storms from JAX-N. Brevard late afternoon to mid-evening, but completely dismissed this chance only 6 hours later. Just to make a point how things can change fairly rapidly when using a model as a basis for where rain will occur.
BEYOND: The chance for isolated showers and thunderstorms will continue into Friday and Saturday, with a possible up tick toward Sunday or Monday. Models are varying in timing and strength of what could be one or two afternoons of strong thunderstorms from Jacksonville to Miami beginning Friday or Saturday...isolated. The bigger increase in coverage arrives on Sunday or Monday. Theres days favor the East Side of the state. There has been indications this activity will be quite potent; however, given the time of day (earlier than normal), and lack of a weak cap indicated, it could end up that these days will end up with general, wide spread thunder rather than stronger and more isolated activity.
Chances of afternoon thunderstorms outside of an inherent pre-noon time coastal shower activity could continue off and on for another week if the current longer range forecasts verify. However, I have very little faith in them at this point. But a pretty big change for most of North America is in the works heading toward next Monday and beyond once that low off the Mid-Atlantic Coast is out of the picture.
AND FINALLY: Way out in time the GFS is showing the first signs of a Summer Like Wet Season Pattern Developing going into the last week of May with much higher moisture content air in the tropics and a low level ridge axis across the state. This will change though, and more than likely be pushed further out in time rather than sooner. The GFS seems to have a built in clock, perhaps 'climatology' as a part of its inheritance from the model developers/scientists/climatologists/meteorologists. Interesting to see this appear though.
See the deep moisture down in the Caribbean approaching the Gulf by the lavender and deep red heading toward the last week in May? This would lay the foundation for more typical South/Central Plains Severe Weather, and eventually that for the Florida Wet /Thunderstorm Season. Also note all of the moisture over much of the Eastern and Southeastern States. This would be the indicator of continued thunderstorm chances in the Southeast and Deep South even as far out as May 25th. However, both of these depictions cannot be relied upon truth as much as in theory.