"But seeing they could not See; hearing they could not Hear"
“The views expressed herein are those of the author and do not necessarily represent those of the National Weather Service or affiliate/related organizations. Please consult .gov sites for official information”

"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".

Tuesday, December 11, 2012

Strong/Severe Storms Possible Today Mainly Along/South of I-4

Chance of Isolated Strong To Severe Mainly In Red Zone. Best tornado threat, albeit minimal, appears to be in the purple zones of Central and Far East Central down the coast toward Ft. Pierce. Further South, Wet Downburst winds are possible, with a much smaller tornado threat.
TODAY: Potential for a round two of active weather today. The difference today number one is that it is no mystery, per official outlets that there is a chance of isolated severe storms, some of which may acquire rotation.  

The largest threat area as of early afternoon appears will set up in the coming hours between 2:30pm - 7pm along the Central Dividing Line zone from Tampa Bay toward Cape Canaveral. This is oft the favored zone when the most buoyant and unstable atmosphere resides over the South Half of the state, and the strongest wind shear resides over the North half of the state, with the intersect of both conditions favorable for strong storms residing where they overlap.  

Here is a depiction of the jet stream winds today.

Additionally, the Bulk Richardson Shear values (BRN) noted on the Storm Prediction Center's mesoscale analysis page indicates that conditions for rotating thunderstorms (supercells) could occur in the red area, but most likely in the purple zone. Thus, the higher tornado risk, especially in areas where larger cloud breaks and heating occur near the east coast where either a light sea breeze or 'river breeze' could occur from north to south underneath deep westerly shear aloft, most noted near Central Florida. It is that area under the jet where the BRN shear and Effective Shear is in place which abets in severe storms being realized. Only one thing will be needed. An actual storm to go up.  

The greatest instability is being noted in SE Florida however, an area infamous for throwing curve balls.  There is also a chance of hail in Central. The final clincher for Central is a sharp moisture gradient at 10,000 ft aloft, where 700mb moisture drops off significantly north of the Beach Line toward I-4. 

This mid level boundary (gradient) could act as an impetus for storm initiation in advance of the approaching upper level impulse later this afternoon. Any storm that either manifests along the boundary or rolls off to the right or left and crosses it could have unpredictable results. Point blank, if nothing else, today could be a day summed up with "expect the unexpected, especially after 4pm through 7pm time frame." That could mean nothing happens, or a few tricks could be up this pattern's sleeve, such as 'left movers' as opposed to the usual deviate right moving storms in severe weather situations in Florida. Time, as always, will tell.

There are, however, several 'flies in the ointment' at the current time if the Analysis Page which pulls off the RAP model is correct. That is to say, Lifted Parcel Levels as well as the level of free convection are quite high at this time  (which is unfavorable for tornadoes, per se). A factor playing  for isolated activity is the amount of Convective Inhibition working against the updraft instability in those same areas. Any storm that can manifest and punch through could see rapid growth into a strong storm with very little warning or notice.  For all purposes, that would hold off storm formation early on, but this 'could' quickly change later today. But if not, perhaps it will be a dud over South Florida altogether and much of Central.

Further south, there's bound to be some remnant boundaries laying around down there after early morning activity has now cleared the area setting up all sorts of gradient boundaries. 

In the long run though, any strong to severe storms that manifest will likely be a result of small (mesoscale) boundaries combining from early day to day activity that has since moved out.

Further north of I-4,the mid levels appear to dry for storms to manifest, above an environment of lower dewpoints, and thus less buoyant air near the ground,  ( lower convective available potential energy (CAPE)). Not to say conditions could not change later on today though.  It is noted that some discussions are referring to a boundary lying around far South Central, but that appears to possibly have lifted further north ahead of an approaching upper level 'impulse". The effect of that impulse can be seen in the above image with storms out over the SE Gulf of Mexico...moving toward the ENE.  Not unlike yesterday, high clouds could move in more abundantly in advance of approaching rain showers.

WEDNESDAY: The shows not over until it's over, and the frontal boundary will not be passing through Central into South Florida until after sunset Wednesday (the actual temperatures in the panhandle this hour are in the lows 50Fs  whereas the dew-points alone across the south half of the state are now near and above 70F!)

 As such, rain chances could manifest, with some heavier rainfall totals still remaining up through sunset Wednesday, particularly on a synoptic scale level across Central Florida just about anywhere, not so much it seems across South Florida (yet).

BEYOND: Temperate drops behind this front are not expected to be significant, with a quick shift of wind to the north and NE on Thursday afternoon. Low topped showers and flat topped alto-cumulus clouds, especially across the coast could work in especially later Thursday through Saturday.

OTHERWISE: There has been a trend for a potentially very windy day coming up this time next week behind the next system yet to form. There has been some consistency in the GFS for wind advisory conditions not associated with storms. The trend so far for much cooler to colder air keeps popping up as well after the 18th, but has shifted from one extreme to the other heading to the great beyond of Christmas Day. Hold fast, it could be a cool to cold week preceding Christmas yet still.

No comments: