"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".

Thursday, June 23, 2011

Isolated Early Afternoon Showers, Increasing Scattered Strong Evening Thunderstorms

***SPECIAL NOTE: GRAPHIC IS STRICTLY PRELIMINARY - conditions can and will likely change during the course of the afternoon with a large deviation from the above image. Official information for Florida is available through the NWS for each reader's area of responsibility (Melbourne, Tallahassee, Jacksonville, Miami, Key West, or Tampa NWS Offices)

SYNOPSIS: Mainly a late afternoon, sea breeze driven convective type cycle is in store for today...activity almost completely driven by low level wind fields and moisture convergence. There is no strong 'storm system' on the way. On the contrary, if it wasnt  for Florida being how and where it is located could be a completely sunny day. 

Areas today to be affected by showers and storms (either as they are forming or decaying) will receive  rain from either inland progressing sea- breezes, the sea-breeze/Lake Okeechobee (and other inland lakes) boundaries, and finally the west coast/east coast sea breeze boundary handshake...or as they approach to embrace.  The sea breeze collision will occur first over North Florida, possible working south toward Flagler County very late this afternoon into the early evening, whereas other large lake boundaries could meet up with either sea breeze and create showers/storms. The west and east coast sea breeze might not actually ever meet south of Lake Okeechobee due to prevailing southerly winds, whereas the east coast sea breeze north toward St. Augustine will hardly make any progress, if any, away from the coast.

Hot inland well as humid. It is going to REALLY feel like summer today. Just on schedule.

NOW: The lake breeze boundary at 10AM is already becoming apparent with a SSW flow prior to onset of the east coast sea-breeze. Showers along the Lake Shadow could form along the interiors of any county on the east coast by or shortly before 1pm and/or around the big Lake.  

EARLY AFTERNOON: Showers can continue to form along the inland progressing east coast sea breeze along and west of I-95 almost anywhere, vicinity of Lake "O" in South Florida (as noted within the green)...Some of these showers can become brief thunderstorms after 1:30pm and beyond.

LATE AFTERNOON: Expecting the east coast sea breeze to become strong from primarily Central Brevard toward Southern Volusia County as well as across NW Florida.  This sea breeze will be stronger than the winds aloft which normally would steer storms toward the coast, especially south of Daytona Beach. Therefore, storms will have a hard time crossing I-95 or US1 south of Daytona, at least at first because the winds steering the storms will not be stronger than the sea-breeze where it is at its strongest (the barrier islands and along and east of US1).

 During this time frame coastal 'wind spirals (horizontally and vertically) will be able to form...more technically, helicity and low level vorticity, as seen below, will develop. These factors add boost to storm strength. Note how the colored areas are lined up on the leading edge and just behind the east coast sea breeze primarily for Brevard County and north in this image below:

THIS IMAGE IS FOR THE LOWEST 5000ft of the atmosphere, forecast by the North American Model (NAM). Also note how, per this model guidance, there is broader expanses left behind by the west coast sea breeze over Central and North Florida. in the aqua shading..there is also some near Palm Beach County. This area may need to be monitored closely later, but believe the SE winds there will take that disturbed area to the northwest into Okeechobee County.

On the other hand, note what is happening in the upper regions of the atmosphere. It is this region that the more 'synoptic scale' , and trickiest part of the forecast comes in to play. I am providing this image to show why this forecast is so difficult today in regard to just exactly where it will rain today. Specifically, note  the lack of 'disturbances or boundaries. In the winter and early spring, it works the other way around, but in the summer months lack of an ORGANIZED focus is what makes 'where' storms will happen more concisely most difficult to determine.

At 20,000 ft there is nearly nothing to see. Today's weather will all be dictated where boundaries develop and meet closer to the ground. In winter, just the opposite is true.

TODAY'S STORM CHARACTERISTICS: Precipitation will begin as showers, possibly evolving into thunderstorms with just a few lightning strikes after 1pm - 3pm South and interior Central Florida, but will be isolated in coverage. Storm coverage will increase toward NE Florida by later in the afternoon and  around Lake Okeechobee in the area outlined in the image at the top. Note, this is  preliminary information (for purposes of this post) and not official. Official information comes through the National Weather Service. 

Expect that the big change today will occur after 5pm and become most noticeable over North Central Florida and NE Florida  heading into 6:00pm and peaking from 7:00pm - 9:00pm. The biggest hazard today I'd think will be excessive lightning strikes and heavy rainfall in metro-areas along and near I-4 and close to I-95 in Volusia and Flagler Counties and working into the Orlando Metro/near Sanford/Altamonte Springs, Deltona, Oviedo, and Deland for example. The Deland/Sanford area might really live up to some of its infamous lightning fame early this evening...time will tell.

Believe there could be some severe thunderstorm warnings or SWS

Frightening and scary as excessive lightning can be, it does not characterize a storm as 'technically severe'; thus, just because a warning is not issued does not make a storm any less deadly. Realize that any winds and/or hail is highly unlikely to be 'deadly' today. The most deadly weather related factor to occur today will be driving in an unsafe fashion on wet roads. In which case, even a heavy rain shower can be deadly.  Unless one choose to pull a Ben Franklin on a Lake, Golf Course, Lake, or Beach.

MID-EVENING: As the strong east coast sea breeze which will nearly parallel the coast and run up the intracoastal and over the barrier islands begins to relax, the steering currents will now be nearly equal to the sea breeze strength. This could permit storm activity to 'break the barrier' created by the sea breeze and either move or build toward the coast. If storms can reach the beach later (but with more difficulty)..this would occur in extreme Southern Volusia County into North Brevard, perhaps even parts of Central Brevard  after 8:30pm through 10:00pm sometime. For now, thinking worst case will be cloudiness and very light rain.

LATE EVENING: Strongest activity will continue to wane after 9:45pm or so, with perhaps a few stragglers over inland areas or near the coast in a much weakened state.

*** The very latest NAM model I have just seen prior to this writing indicates no rain today south of Daytona Beach, if even there...yet does show those disturbed areas in the second image. This seems a bit suspect, but the chance is there that most of the rain shown in the above image will not occur at all into Central Florida. Hmmm.

FRIDAY: Similar scenario, only the same type of set up is forecast to occur further south. As stated in the post of two days ago, only far Southeast Florida might avoid the bad storms as well as the immediate West Side of the state. But rains should be coming their way working into the weekend.

BEYOND: I'm seeing the forecast on The Weather Channel for storms nearly everyday, but do not believe it just yet. It appears a deformation zone, a zone where a frontal boundary is being shredded apart by opposing/non-complimentary wind fields, is forecast to approach Florida in an otherwise moist environment. This could mean that a lot of cloudiness could be in the cards with only random showers and weaker thundershowers being  in the cards...of isolated nature...or even only primarily cloudy skies rather than storms. On the other hand, depending on how either 1) a mid level ridge builds eastward across the Deep South and North Florida; or 2) the surface ridge axis remains over South Central to South Florida will be a deciding factor. However, the trend of most agreement I can find is that the ridge axis could shift way to the north of the state by Sunday, which opens up a more SSE-SE flow across the state which could start an onshore moving showers regime across Central and South Florida...evolving into thunderstorms toward the central and west side of the state going into next week.

TROPICS: As noted in a previous post a few days ago, it still appears that a disturbance could be in the making toward Honduras and into the Bay of Campeche and/or the Bay of Honduras. Expect we will be hearing a lot about that area in days ahead. One model has this area evolving into a MASSIVE low pressure area with a moisture trough appendage extending the whole way to Florida, making for continued shower chances. Time will looks a bit over done.

DISCLAIMER REMINDER: All of the images and words written in this post are of my own choosing; made neither to make/meet/nor break official outlets. Posts are strictly an avenue to express other potential possibilities with the weather on any given day and days ahead. Posts are not for planning purposes; In other words, I'm writing this just for fun..and hope you read just for fun as well. Thanks!

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