"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".

Wednesday, June 15, 2011

Hazy/Hot, Followed by Strong to Severe Thunderstorms Mostly South-Central

EXTREMELY UNSTABLE atmosphere over North and Central Florida this morning per the Convective Available Potential Energy (CAPE) and Lifted Indices (LIs). Steering so far today is generally from the NNW-NW but could become more due north toward evening.  East Coast sea breeze will not get much further west than I-95 in some locations.

TODAY: Hot and hazy will sum it up for most everyone early today. Most sounding are showing a respectable very low level inversion. This, coupled with higher ground moisture and strong insolation is trapping much of this moisture in the lower levels, yet otherwise, there is little to no cap in place aloft.  The most unstable (extremely so) is over North and Central Florida with some 'spin' to the air (helicity) near JAX associated with the back-side of the weak surface low circulation noted in the above image. Temperatures inland could again reach the upper 90s to near 100F, especially along I-10. Very hazy, and even smokey around far NE Florida toward western Daytona Beach. Smoke from SE Georgia is being pulled into the circulation of the low offshore and being drawn southward.

DIFFERENCES BETWEEN TODAY AND YESTERDAY: Much more unstable atmosphere and lower lifting condensation levels (LCLs) and  level of free convection (LFC). Additionally, spots that received more rain yesterday, namely East Central, could add some initial fuel to the fire (don't say that word) for storms over South Central later this afternoon.  As long as this weak inversion holds the greater the instability will mount. Low level lapse rates are steep and mid-level lapse rates (decrease of temperature with height) aren't so shabby either.  There was some severe category wind reports yesterday and very small pea sized hail, but from what I could find, those wind reports came in at about 5 stories (50ft) or more above the ground. Do not believe that will be the case today because of the lower LCLs and LFC today.  It was also very hot yesterday, with MLB reacing 100F and my place, for the first time ever, reaching 101F.

SPECIAL ATTENTION -  once a storm can initiate it could go up fairly rapidly. BE PREPARED FOR RAPIDLY CHANGING WEATHER CONDITIONS TODAY. Additionally, given that many areas did not receive rain yesterday there are still plenty of dry spots for rampant 'born free' lightning bolts to play with on the dry tinder. Bolts can fly well outside of any yet to form rain. Often, the first bolts are generated before the first rains barely reach the ground. This is caused by updrafts in the storm suspending small hail/rain from reaching the ground, but in turn is theorized as being a mechanism for lightning creation. It is a bit hazy today too, so as storms form nearby it might be hard to tell just exactly where they are unless very close...or if one has a watchful eye.

FORECAST: Firstly, none of the models seem to be agreeing today with the eventual outcome of what will occur with the weather today...only the RUC model picked up on the circulation off the coast of JAX as well as how unstable the atmosphere is today. Today's forecast is based on that model combined with actual analysis from the Storm Prediction Center's Mesoscale Analysis values (and trends since early morning), and latest morning well as looking through the trends in the Local Data Information System (LDIS) plots which are available on Melbourne's NWS web page..

SOUTH FLORIDA: Storms should ignite first in this area due to earlier onset of the Lake shadow affect meeting either the East and/or West coast sea breeze.  Storm motions should be toward the SE...but for the most part steering currents (mid-upper level wins) overall are weaker over South Florida. So the most likely net affect will be for storms to ride along boundaries created by earlier outflows combined with sea breeze boundaries as well as the Lake Breeze. Also believe the threat in this area for Severe Level storms is a  bit less, but not completely out of the question. Especially when considering that high moisture may work south with time later today.  It might never completely reach far South Florida..but storms could initiate to the north and roll into the Southern Tier. Looking especially toward the East side of Lake Okeechobee. Any storms to ignite will be capable of strong winds in and near activity. First storms of the day will likely create the strongest winds, especially any to go up after 2:30-3pm (during peak heating).

CENTRAL/SOUTH CENTRAL FLORIDA: It is currently in this area that the most  unstable atmosphere either lies at this time...or is being advected into from further North toward Jacksonville. Believe the east coast sea-breeze will be later in manifesting further north if at all north of St. Augustine.  Due to the high heat content, extreme instability, combined with the overall depth of the lower level moisture, the greatest threat will be what is referred to as "wet microbursts". In essence, very strong winds in excessive of 58mph, especially as storms pulse to their strongest and collapse. Wet, because they are. Some storms today may actually become a bit organized and 'pulse-up' more than once before collapsing on themselves. Jet stream level winds are stronger today as are mid-level winds...these will enabled storms to evacuate unstable air upward for longer amounts of time due to a bit of a tilt. Additionally, anvil level winds will spread toward the east...with the energy fueling the storms coming from the NNW..the energy supplying the storms will arrive from north to south and be unadulterated by storm anvil shadows which will be stretched away from incoming energy.

NORTH CENTRAL/NORTH: Strong storms also possible from Ocala/Gainesville area and into the Panhandle...very late to after dark.

Storms could continue sort of like the last kernels in a kettle of popcorn to 'pop' randomly in isolated pockets until 10pm just about anywhere.

Of most interest, as noted in the graphic...will be what could occur if timing is JUST PERFECT to allow a storm to form near Ormond Beach/Daytona as the sea breeze sets up.  Any storm that can latch on to the sea-breeze breeze boundary and be forced southward east of I-95 could rotate, especially at the lowest levels toward Southern Volusia late where the sea breeze 'could' become more Southerly very late in the afternoon due to the Coriolis Affect.  This is not expected to occur today, but then again, is it ever?! This is just a heads up for boater concerns more than anything else, as if the lightning threat is not bad enough. At time, do not see this as being any more that a casual note in passing.

Elsewhere, expecting the strongest storms into South/ Central and parts of Central Florida just north of the Beachline after 6pm, under the assumption they hold off until then. At this time of day the sea breezes will be at their prime strength, adding to low-level convergence which in turn leads to faster rising air currents with deeper overall moisture content through the lowest levels. Storm to initiate for whatever reason after 6pm have the most likelihood of being full bore 'Severe'. Some storms could produce nickel sized hail and wind gusts above 65mph - 75mph perhaps (very isolated).

Greatest coverage expected to be over Eastern Polk/Osceola Counties.

THURSDAY: Beginning to look more like a "isolated, becoming scattered thunderstorms in the interior" type day. But not completely sold just yet.

GREAT BEYOND: Continuing to watch the long term for both tropical development as well as the full-bore moisture levels across Florida to arrive. This year is turning out to be much like 1998, which had one the latest onsets of the Wet Season on record, as well as the hot temperatures, and brush-fires. This year is not at all far behind 1998 in many ways. Thankfully, Central Florida received some rain in the early spring/late winter with those squall lines that came through. Otherwise, it could be much worse.

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