Otherwise, the best instability and chances for thunderstorms will occur along and south of the stationary frontal boundary (wherever it happens to be this afternoon) and where skies are cleared enough for instability to build up. Those storms will move briskly toward the ENE so even locations upstream of their formation could get in on the act, even if mostly cloudy. Skies over South Florida are much more sunny this morning than they are closer to the frontal boundary, but bigger breaks are anticipated central by noon time..not so sure about that either if more energy moves in to early. The best instability is forecast to mount South of the surface front for storm initiation, but steering could transport this activity into the prevalent cloud covered skies just to the north of their initiation. The surface front will waiver north/south by 50 miles today and tomorrow, but should lift north as Katia progresses north as well.
In the image above is the mid-level depiction of Hurricane Katia to the east of Florida. As the storm lifts north of the latitude of Central Florida, this should also lift the surface boundary north a bit as well, especially because high pressure is expected to build in from the east across South Florida in Katia's wake. By Friday the boundary should be as far north as I-10.
In consideration of all the factors above, it appears showers or considerably cloudiness could be in store for North Florida, with showers and a very small thunder chance from near the Flagler/Volusia County line south to North Brevard. Further South toward Central Brevard to Palm Beach County (especially if a sea breeze can form), thunderstorms are more likely. Indian River/St. Lucie/Martin/Palm Beach County toward the coast seem the most likely candidates for this activity after 3pm and beyond until dark at some point. The west coast also has a chance of thunderstorms.
THURSDAY/SATURDAY: There is great uncertainty in the forecast for the follow up days, but given the expectation (and likelihood) that high pressure will build across South Florida from the Atlantic, this will place South Florida in very weak steering currents with an east coast sea breeze as far north as at least Sebastian Inlet. But, this high pressure will have drier air associated with. Hence, the greatest moisture reside across Central and North Central Florida..at least for a day or two. What happens in the Bay of Campeche in regard to a potentially strengthening tropical system is also a big player. If a storm can get wrapped up in this location, then the moisture source for Florida will be reduced and as such, the rain chances everywhere. So far, it looks like it will be a long time coming before that will occur though. Thus, thunder storm and rain shower chances prevail during this time frame..with that chance working northward toward JAX with time.
TROPICS: "Much ado about nothing or reason for greater attention in the SW Gulf ?" is the question of the day. Models are split 50/50 on whether this area will become well organized and then threaten the northern Gulf toward the Pensacola/SE Louisiana area...or...never progress into the Gulf at all. Big Difference. So word of the wises, be prepared for surprises...but not anytime soon. This system has a long way to go before becoming 'well organized'..at least as of this morning. Once the area is investigated by the Hurricane Hunters more will be revealed.
For instance, the ECMWF model implies that as Katia moves north, that storm literally drags all of the dynamics and pressure systems associated with remnant Lee along with it. That includes a profound blocking pattern the United States has entered. Blocking patterns tend to hold fast for 4 to 10 days, thus, it is more then questionable that a hurricane in passing would have such an effect on a Northern Hemisphere blocking pattern. But, that is not to say that some variant of that model's hypothesis can't be reached. Either way, all models show that Katia will become one MONSTER of a extratropical storm heading into the North Atlantic ocean in the next 3-7 days. Extratropical Katia could be a major player in many locations in the Northern Hemisphere two weeks down the line.
In regard to the ECMWF, haven drawn the blocking pattern out, the next assumption is that this willl open the gates for the system in the SW Gulf to emerge and work north and east toward the NE Gulf as a hurricane.
HISTORY OF THE BOC: Historically, the majority of storms that form in this location are pulled northward , but not all of them. In going back and looking at this history, I found that the storms that did so nearly ALL occurred early in the season and not later. This would be because cold frontal boundaries, such as what is now in place...penetrate further into the Deep South the later in the season one progresses with time preventing from working north. That is...all of them but 3 since 1900..and two of them occurred onlly 2 years apart around 1903. The only other one that was actually a hurricane at this time of year was Hurricane Opal...which incidentally followed a Gulf storm just a time prior to another one. Think Lee. The problem with such a due course of action in 2011 is the current location of the frontal boundary and the VERY dry air behind it. This will have to be greatly displaced..and for that to occur, so would the high pressure over Texas have to be displaced, which has been in place since Spring.
Another observation made this morning is that the models might be giving this system more 'pre-organization' than is realistic. This determination was realized when looking at lightning data and satellite imagery. The most lightning is occurring on the Southeast side of the Yucatan and not in the Bay of Campeche. Thus, the area of low pressure might be much broader than the tight knit depiction of the models.
Below is a two fold image..the lightning as noted above..placed side by side with the track of Opal. Note that Opal FORMED SE of the Yucatan, then crossed it..then took its course toward the Southeast U.S. Other storms that were tracked from the BOC (Bay of Campeche) toward the U.S. did not originate there..but rather further east in the Caribbean.
|To the left is lightning imagery. To the right is the track of Opal. Note where Opal Formed.|
Opal crossed the Yucatán Peninsula while still a tropical depression from September 27 then strengthened northward in the Gulf, becoming the most powerful Category 4 Atlantic hurricane before making a second landfall, October 4, in the Florida Panhandle near Pensacola as a 115-mph (185-km/h) hurricane. Opal devastated the Pensacola/Panhandle area with a 15-ft (5-m) storm surge and travelled up the entire state of Alabama, becoming a tropical storm in Tennessee. Opal also caused heavy damage in the mid-Atlantic states before dissipating. This is the track implied by the ECMWF, except it is not generating in the BOC..and it has the storm taking this course of action in fairly rapid fashion. That means, Katia needs to pull out the blocking pattern in place in the next 96 hours. The ECMWF is not the only model to show this trend as a side note. So this is not to imply the ECMWF solution is not plausible.
The other side note to consider is that 'even if' this system develops in the BOC and lifts northward, it still must contend with upwelling created by Tropical Storm Lee as well as cooler rain waters that drained into the coastal areas off the Mississippi and other tributaries. Thus, to palliate the storm's future course (in this example) perhaps a 'big storm' would be greatly weakened before a true landfall.
The final note on this system...is that other than hurricanes..there was a Tropical Storm that crossed the Big Bend area of Florida at this time of year ..this seems more likely if anything were to move north.
Outside of the BOC, there is yet another developing system approaching the Leeward Islands. This looks to be our next named storm system. Again, guidance is leading the reader in two directions. Will that system follow the course of Katia..or continue toward the Caribbean? Again, we are back to square one with what Katia does or with..or what results from..the storms interaction with the remnant blocking pattern of "Lee".
Thus, Future Forecasts are Fruitless not only in regard with Florida's Local Weather, but with regard to the tropics as well.
In closing, the more interesting system if none of these systems impacts the Deep South will be the NEXT one toward the last week of September. By that time, and under the assumption the blocking pattern does not break down early (in which case none of these shorter term systems will directly strike the U.S)..the pattern will or should be in the process of breaking down, but not before the next Atlantic system will already be in the Caribbean. As always, all thoughts are of the writer's own..images provided are actual guidance or real-time information...and future projections, especially beyond 1-2 days are as good as a blind man relying on a blind seeing eye-dog.