"But seeing they could not See; hearing they could not Hear"
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"From its chamber comes the whirlwind, and cold from the scattering winds." - Job 37:9.

"The wind blows to the south and turns to the north; round and round it goes, ever returning on its course".

Friday, May 13, 2011

Low Confidence (Location/Chances) Of Late Afternoon/Early Evening Storms In Florida Today

ALL CONDITIONAL STORM CHANCE AREAS: Chance of rain showers or thunderstorms within the green bounds, most likely area is within the light blue and lavender, with the peak conditional chance along the east coast in the yellow highlight/dark green areas (see below). Another area not shown is along the West Coast from near Brooksville and south toward Naples. Also not seen here is an area extending toward Miami in SE Florida.

OBLIGATORY DISCLAIMER: As is always the case and as printed on the web page at  all thoughts are of the author's own. Please refer to local official outlets (my most preferred is the National Weather Service until an 'event' (storm) develops), then your local televised news channel,  for the latest officially released information for where storms are located and expected to move toward.

TODAY: First of most importance there are three items to consider: 

(1) Nearly every forecast model is in disagreement with where rain/thunderstorms will develop today. It does appear that there will be an isolated  very strong storm or two or 3 today within the 'green' today, which is almost the entire state. The most likely area appears to be in the center of the state.  Even timing is an issue. One chain of thought calls for early afternoon activity which I had dismissed since sunrise, yet they are still showing the possibility. As of now it is supposed to be raining where I sit (for example) based on the short term local WRF model. Yet there is not a storm building anywhere in the state, with some cumulus along/over SE Florida and some that tried around the Big Bend but were snuffed out by high cirrus clouds.

 Note the two areas along the east coast: Those are outliers, but important. Important because if storms do develop and/or move into those locations, they could be severe, along I-95 toward US-1 late today after 6pm if conditions exist for such at that time. How/why? Temperatures aloft at 700mb are expected by one model to drop by several degrees after 4 or 5pm. Will that happen? Time will tell. But at least we have been forewarned of this possibility.

(2) Will there be many storms at all today in fact?  The atmosphere looked very unstable since sunrise, observed by the cloud types (did not need a model to see that).  However, the approaching disturbance to affect the state tomorrow is shielding cirrus clouds across the state, limiting  the atmosphere's instability, and in some model portrayals, by a big margin..significantly so.  I do believe that even still,at least sea breeze storms will form in the interior after 5pm.

The reason for the bigger threat along the East Side is caused by coastal low level helicity (sort of like little whirl pools or eddies that form along the sea breeze, which is closely paralleling the coast today. It is the near parallel motion that sets the eddies going. When a storm approaches them..they tend to 'jack up'..especially just east of I-95. If this situation does develop, it would not be until after 5:30 or even 6:30pm...and in full force east of I-95 around 6-7pm.   

(3) Lastly, there is a chance that mid-evening post thunderstorms could develop (or continue) in the favored inland location  as well as closer to the coast in South Central Florida (toward South Brevard/Indian River Counties). This is very remote but still possible. This storm would for after the sea breeze has relaxed.

(4) There is a big change to occur sometime after 4pm with wind fields as well as some lowering in mid-level temperatures. This might be throwing a lot of models of, and will affect (if this is real)..where the heaviest activity will occur).  It may also be why the weather is so benign this early afternoon. Nothing to happen until that time it occurs (if it does).  Since that time has not arrived's a waiting game. Waiting to see how long the high clouds stick around (which looks almost certain)....and if those mid-level wind fields indeed to change so quickly.

LASTLY: In Looking at the latest hourly information availabe which included (the mental analysis/picture) a vast variety of parameters, the most likely area as of 1pm for activity today is toward the center of the state, with a slight lean toward the east coast in  Volusia/North Brevard (South Florida is a different story altogether, and beyond the scope for one post). It is down there though that the first signs of an approaching rain chance are manifesting this hour.  Should the high clouds persist or thicken with time, the chance of rain diminishes significantly everywhere, other than perhaps toward South Florida, with maybe just some showers and a thunderstorm or two inland of non-strong character. Note though. No model shows a 'dead late day'...yet.

SATURDAY: The Storm Prediction Center already has the Panhandle and North Florida in a "Slight Risk" for severe weather tomorrow. In Florida, that would be mainly for hail. There is uncertainty though even there since persistent cloud cover would limit instability if it is there from early morning toward noon. It may be that Central and South Florida will end up with the stronger weather when all is said and done. I'm inclined to lean in that direction.

SUNDAY-TUESDAY: More chances for showers and some strong to severe storms will exist on 1, 2, or all days, depending where in the state one is located. After tomorrow, the Panhandle is 'out' since that area will be behind a cold front in more stable air.  The most favored area on Sunday appears to be for a portion of South Central to South Florida. But that too may change. Earlier guidance indicated the showers would begin over night into Sunday morning, and could be 'in the area' all day. Along and South of the BeachLine to Miami. 

That, plus we might not have a sea-breeze. If this indeed is the case, Sunday could just be mostly cloudy with showers ...and some thunderstorms from early afternoon to evening possible (perhaps). A lot of what occurs Sunday - Early Tuesday is contingent upon a combination of the surface winds and timing/passage of embedded disturbances aloft. All wet chances abate by late Tuesday in South Florida.

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