"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".

Wednesday, April 27, 2011

Strong/Marginally Severe Storm or Two Possible East Central/South Florida Late Today

IMAGE: The Outlook area for General Thunderstorm Activity today issued by the Storm Prediction Center  (SPC) for late this afternoon through early evening.  Please consult the SPC website at for all official information. Note: you can also click on the title of this post to go to the NWS MLB latest forecast update and graphic:

RECAP: A strong storm materialized late afternoon through early evening along a moisture/wind convergence boundary that had materialized along the Lake Okeechobee "Shadow"/East Coast Sea Breeze boundary.  Hail to nickel size and a funnel cloud were photographed and submitted to a local news channel out of West Palm Beach of the funnel near Ft. Pierce in St. Lucie County. Details are sketchy as to whether it actually reached the surface, but either way, the storm was well structured / organized and visible even as far north as North Brevard County with a bit of a back-sheared anvil look and solid updraft. Other photographs were taken by others closer to the activity  of the hail/funnel/storm structure...but you know the drill, "All Rights Reserved".

These images show the storm as it appeared
from Cape Canaveral which was well
to the South over St. Lucie County, Fl. The
backshearing of the anvil (against the upper level winds) is seen behind the telephone pole in this first photograph captured from my camcorder. Rain showers and some thunder had also occurred from Mims/Titusville/ KSC/Cape Canaveral earlier in the afternoon.

TODAY: The first image shows the area most likely to get a thunderstorm (s) outlined by the Storm Prediction Center based in  Norman, Oklahoma. This area is not annotated (yet) with a "See Text" refrain for strong storms, likely because any strong activity will be very isolated, if it can manifest at all. I've generated an image from the OFFICIAL latest post from the NWS in Melbourne, which will likely be updated later in the day after this post is complete. I'll check it before posting today. Otherwise, expecting a strong/marginally severe storm is POSSIBLE in one of three areas as annotated and numbered below. Each area is squared off, then circled for a better location/chance per only the morning model guidance (which will change with every hour!), with annotations. They are also numbered, but the number does not necessarily reflect a greater likelihood of a strong storm, or even rain at all for that matter in any of these locations. The purple text of my own doing highlights the main reason for the green circled areas (based on morning guidance).

EXPLANATION OF EACH AREA FOLLOWS: Firstly, strong day time heating will occur today as noted by the NWS.  There is a big glitch here though, and that is upper level, thin high cirrus clouds. This could put a big damper on late day activity anywhere over the North half of the state.

Highs appear will reach the low 90Fs inland otherwise, with perhaps a few near mid-90Fs. Breezy all locations, especially over the causeways where the wind will run right up the intracoastal. A bit cooler beach-sides.  Some showers could occur in the absence of the sea breeze from North of Daytona and down the coast to Broward County, with the first activity south and working north with time, but currently the cirrus clouds are putting the big snuff on this possiblity. Some lightning could occur with this activity almost in any location...but I'm favoring far SE Florida primarily for the early afternoon activity. Showers further north will be generated purely through horizontally stretched moisture convergence rather than not expecting much thunder further north. Further south the geography alone combined with the gradient flow will add in better but not great convergence there. Later today: 

(1) East Central Florida - Local geography could play a role this late afternoon/early evening as was the case yesterday. Expecting a late afternoon sea breeze close to the coast. The past hour or so winds have been between South and SSE. This is forecast to change to a solid SE-ESE after 4:30pm (but just noticed that MLB is now ESE) as is a local station from Weather Underground in Cocoa Beach. Meanwhile, winds just above the surface will remain from the SSW at 15-20mph.  The 200-300mb jet stream will be nosing into North Central Florida late afternoon about the same time the sea breeze 'could' set up (appears it already has begun). Moisture convergence would be the main initiating factor late in the day aided by stronger winds aloft late, and a possible cool mid-level "pool" within a dry mid layer. Thus, stronger wind gusts and small hail are possible. Any sustained updraft near devoid of rain or nearby rain-cooled air could generate a funnel cloud as was the case yesterday over St. Lucie County. 

This occurs most likely when the sea breeze/gradient flow converges with the moisture/thermal gradient all in delicate unison over the Intracoastal or near shore Atlantic waters as the storm is about to peak or just peaks in height. Again, this is assuming there even IS a storm here. I have annoted this as #1 based on the notion that the NAM and GFS have targeted this area with higher precipitation between 5-9pm. Interestingly, the NAM even shows a light precipitation 'backwards hook' field going across the Mims/Titusville area with a pin prick precip core to the SW near Cocoa. This could be a flanking updraft field, but such a notion is purely conjecture/day dreaming on my part. This model, nor any really, can pick up on such storm development. Big con for this area is early afternoon cirrus clouds which will be in place through mid-afternoon, at least. Model guidance is also showing a lowering of the lifted condensation level east Central over Eastern Central Brevard after 6-7pm time frame in the absence of a precipitation field. This would aid in storms becoming fully surface based.  This is sketchy/questionable. Should this be where the model should be showing the rain in reality as opposed to further to the W-NW over the Mims area south to Cocoa? Will anything form here at all due to the current presence of cirrus clouds? They seem to be on the verge of thinning out.

(2) Further north from near Daytona/Ormond Beach to St. Augustine. This area is being watched for stronger synoptic scale winds and the tip of better moisture convergence from the South. This area does not seem as likely to generate a strong storm due to lack of convergence or a trigger, but it gets more iffy the further south one goes in that area going toward Daytona/New Smyrna. Con for this area is also cirrus clouds. The West Coast Sea Breeze does not play in today and the cirrus here also appears to be thinning as of 1:30pm.

(3) South Brevard/St. Lucie/Martin/North 1/2 of Palm Beach County: Very sketchy. Only one model shows a precip bullseye down there. One which later took that chance out. But I'm looking to differ. The best onshore/sea breeze flow should be down in SE /South Central Florida (coastal) beginning after 4:30pm and maximized after 6:30pm (as is the case in the other locations). Dew-points inland will be allowed to rise after peak heating has subsided, thus moisture convergence will increase in all areas. This area could get an additional boost from the Lake Okeechobee "Shadow Affect"  from South Brevard to Martin County. Oddly, one model showed that something to generate down there would latch on to upper level jet stream winds and take a deviant right turn down the sea breeze boundary toward SE Palm Beach County before exiting off shore and dying. VERY odd ball, but 'odd events' have occurred in the past in all 3 of these locations, even on a normal summer day. They are normally lmited though to when the gradient flow winds are much weaker than they are today. Less cirrus clouds in this least for now, favors this area.

All activity, assuming it can be generated, will be on the East Side of the state, with initiation contingent upon how far inland the Sea Breeze can penetrate...but it's hard to imagine that despite that fact I'm sitting here typing with an ESE wind to my back. that not far away to the west toward I-95 there is likely no sea breeze. So far, it seems to be not much further than I-95...additionally, the Big Lake Shadow is showing up with a vector toward North East Brevard along I-95 near Titusville along its Eastern Flank. Far South Florida seems to getting scoured out by the combined gradient flow with the Sea breeze so the Miami Metro area/ Dade and most of Broward can likely be tagged' out' for storms today.

*As of 12:45pm the Hazard outlook from the MLB NWS has not changed. See this link for the latest update or click on the title of this post to be steered there:

THURSDAY: Different type of day and much to cumbersome to go into detail with. Best chance of strong/severe storms is over North and far North Central Florida with a secondary area over Eastern Portions of North Central to Dead Central (near the Beach line to Eau Gallie Cswy corridor) late afternoon as noted yesterday.  All activity will occur along a pre-frontal boundary over North Central to Central rather than on the front proper. South Florida may also see another round of thunder/showers in the afternoon due to different circumstances altogether, favoring SE Florida.

FRIDAY: South Florida and portions of South Central will be favored during the noon time to Early Evening as the front moves further south and goes stationary over the Keys area by late Friday through Sunday. Over the weekend the Keys and extreme South Florida might have a chance of showers and thunder, especially far SW Florida over the weekend.

MONDAY-TUESDAY: Moisture inches back northward into Central and then all of the peninsula, by late Tuesday in response/ advance of another approaching frontal boundary. This boundary might not penetrate as far south and could get hooked up across North Central or North Florida beyond next later next week week is still up for grabs over the peninsula as to whether rain chances COULD remain for much of the second half of next week. It appears that if this does occur that showers would be caused by a long fetched/duration onshore moisture/flow component, with thunder favoring SW to West Central Florida. Way too soon to say.

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