"The Chainsaw Massacre" Begins Irene's Downgrade - "Florida Antics Part Deux"?

TROPICAL STORM IRENE NOT LOOKING SO "TROPICAL"
- DRAINED HER PURSE IN MANHATTAN 

SYNOPSIS/SCOPE/GENERAL OVERVIEW:  "Synopsis" is the meteorologically preferred term for "here's what's happening around a big area at many levels of the atmosphere"... Synopsis takes up less key strokes. 


Tropical Storm Irene is looking very extratropical this morning as it continues to get absorbed into the troughs/front along the eastern seaboard. The 'Storm' continues to move NNE-NE and should clear NYC shortly. Irene likely encoutered the 30-50kts of shear I was seeing yesterday along the PA/NY border. Clean up time begins where electricity as gas supplies allow. Rev'n up the chain saws and generators while rainfall in what I'd guess varies from 6 "-16" soak already moisture laden soil,  flooding streets, swelling rivers, and turning basements into swimming pools ..awful stuff to mess with. But don't forget, it still has New England to reign...but Irene is handing over the crown..(see Tropics). Folks well up in New England will have their fair share of high rainfall totals, flooding, beach erosion, and downed trees (power outages).

LOCALLY:  Tough forecast. It would be very easy to write for all intensive purposes that there is a very low chance of rain today.  The atmosphere in the mid-levels is quite dry, winds are unidirectional, possibly no sea breeze. How could it rain today!!? 


Yet, there has been persistent showers and storms well out west in the Gulf along an axis of sorts that has been regenerating heavy showers near the Tampa Area to just offshore. There is some big ones way out in the Gulf along this axis.  Thus, we present DOOR NUMBER !.


DOOR #1: Mostly dry, hot with highs in the mid-upper 90Fs (mainly NE Florida/I 10)...fast moving isolated , small showers maybe becoming thunder after moving off shore from St. Augustine to Miami, but the best chance of rain being South Florida in Broward, Dade, Martin, and Southern Palm Beach County later far East Central IBrevard). 


Could leave it at that, and perhaps should. But being curious as a cat:


DOOR #2:  Then again...some pictures might help in vying for another option. Using some current conditions and extrapolating these conditions with future projections of the trough associated with Irene...there is a bit of a hypothetical/conditional chance of a much broader expanse of showers and some thunder with the help of a little pro-active imagination....

700MB (Roughly 10,000 feet above):

700 mb (10,000ft) Analysis reveals best moisture far South Florida (green line and south). Note  several weak troughs (blue) embedded in the mean flow...these are all part of a MUCH larger trough extending down the East Coast from Irene...and on into the NW Caribbean.

The mean (main) trough is shown by the one black solid line (above). This could buckle as Irene moves away...allowing that moisture over far South Florida (Green Line)..to work northward. Vorticity (energy) is also associated with these troughs.

INSTABILITY:

Moderate instability exists way out in the GULF (orange, note values in the 4000 range)...for comparison, we never see much more than 500 in the winter, even with severe weather . And the higher the better (for active weather).  These values are constantly being transported over the peninsula south of the mid-level mean trough axis and jet level axis as well.

So, there is possible mid-level moisture transport northward as Irene also lifts north as shown in the first image (remember, they are both to be within the same broader scheme trough up and down the east coast). There is also some moderate instability on a train track from the Gulf across the state...but the mid-level is still going to be a bit dry even if it can work north to I-4 by late today.  

THEN THERE IS THE JET STREAM:

See captions:  Blue is the jet stream level trough. The troughs aloft are in roughly the same location. Winds of 35 kts on the jet which for summer is not shabby in Florida.  As the trough approaches just a bit more today, forecasts show the winds increasing another 10 kts..especially over  Central Florida, but divergence (purple lines)..also increases. No divergence was analyzed at the time I saved the image other than west of the Keys. Watching the area between the two (three) purple arrows) cartooned in...where divergence could form , aiding in upward lift from the mid-levels. Note the black arrow along the east coast.

DOOR #2
1. Possible mid-level northward transport of moisture from South Florida as Irene lifts North
2. Continuous stream of moderate instability, advected by prevailing WSW winds at nearly all levels
3. Divergent jet stream aloft;
4. And, just maybe..a side shore/river upwind component at the surface along the east coast as the pressure gradient just above the surface decreases (which allows the sea breeze to try to develop). However, I do not believe this will be a sea breeze (but could be in part, especially far SE Florida), rather a moniker.


 When added, the vectors of a SE Sea-breeze with the decreasing 2000ft wind vector magnitude...which should weaken today...the sum of the vectors..which are indicated by an arrow of direction AND strength..adds up to a South to SSE winds..see black arrow in image above. 

DOOR #2  - "Sum Total of all the Parts" Visualization:

See Captions: Note the blue area up and down the west coast...I added the brighter blue one. This is low level moisture convergence which means little now. But as the day wears on..the mass convergence ..like water backing up against a dam..could climb the wall and become DEEP moisture convergence...and when or IF the damn breaks..abetted by the assumption that moisture will work up from the south...the result would be showers. Add that vector in (shown in black again)...with divergent flow aloft, PLUS the instability...we have showers and thunder..mainly East of I-95 north of Ft. Pierce to near South Volusia.  If this does occur, outflows could extend showers near the coast up to at least St. Augustine..with thunder as well (not shown here) to DAB.

REALIZING: The Above extrapolation into the future, if even one of the fictional factors does not fall into place, much of what is depicted in the image will not transpire. On the other hand, if they come together, along with some upper level energy which will be a given considering that something is driving those showers with some thunder to form near Tampa (they can be seen in this image..it has a radar over lay in it)...rain fall chances could go from 20-30 percent to 50-60 percent. with thunder in orange as well as shown.

IN SUMMARY:  "A word of the wises; Be prepared for Surprises"

TROPICS: Enough already. Moving on.  No way, Jose! Yes, Tropical Storm Jose was crowned heir to Irene..or rather..they share. Irene 's not going down easy! (just ask someone in New England today).... Queen?,  New 'England'?..Hmm, ...  The storm is not all so far from Bermuda actually, but it does not appear it will do all that much. Not a US (U.S.) threat.  Watching two big areas:


1. The western and central Caribbean into the Southern Gulf and the Bay of Campeche
2. A newer area that has emerged off the coast of Africa.


Neither area poses a threat, but both hold potential. Recall, the Gulf has been capped and heated since early spring. The problem therein though lies, is that that was likely the onset of the High Pressure over Texas. Thus, any development into the SW Gulf would head toward Brownsville or South..unless it can form south and east of the Mississippi River. Jamaica could be under the gun from several tropical waves though..and maybe a depression could emerge off the western tip of Cuba in the next week.


The next name storm is eerily, KATIA. (hmm...they really should have thought that one through).

SAL (Saharan Air Layer) shows much LESS reds and oranges than 10 days ago. Note that big white area coming off Africa..with little to zero dry air ahead of its westward motion. Also note, I'm detecting a weakly cyclonic circulation in the makings in the Bay of Campeche toward Jamaica...additionally, the base of the previously mentioned trough extending from Irene bottoms out SOUTH of the Florida Panhandle. You can see the thunder activity out there in this image. Central Florida lies along that same mid-level sector today (Sunday)...could that act as an impetus for showers and storms today and especially Monday/Tuesday time frame?