"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, July 27, 2011

There Lies a POTENTIAL for Scattered Thunderstorms, Some Strong, East Central Florida Today

As anticipated, the upper level low remains in place east of Florida as noted above. NNE winds on the backside of this low  are advecting dense cirrus clouds southward, along with being created by the winds and moist air aloft stand-alone. I expect these clouds to persist in various degrees all day today, with filtered sunshine. More breaks over South Florida. This low is expected to move across the state late today, tonight, and begin to wash out by Friday over the Gulf.

SYNOPSIS AND SET-UP/FORECAST REASONING:  Upper level low remains off the East Florida Coast. Circulation well aloft at jet airplane flying levels is from the NNE, and is pulling high cirrus clouds SSW across Florida. Both the moisture and the winds alone are reason for the clouds, as well as thunderstorm tops off South Carolina, like yesterday, being sheared off and picked off by this wind aloft. There might be some thin breaks off and on over Central and North Florida...but not truly significantly so.

On the other-hand, the clouds are much thinner over the southern 1/3 of the state. The surface ridge has lifted to North Central Florida, and will probably work further north during the day. But, the mid-level ridge axis', which help determine storm steering (direction storms will move IF PRESENT), are located near Lake Okeechobee. What this equates to is a storm motion in the direction shown by the blue arrows.  Moisture is still ample for storm generation without question over most of South Central through North Florida, but there is considerable drying in the mid-levels over Southeast Florida, so rain there seems unlikely other than in  the vicinity of Lake Okeechobee.
In fact, it is the Lake that might be the necessary ingredient to set the wheels in motion today, combined with the sea breeze. Granted, winds over South Florida are already a bit Southeasterly, but that is gradient flow. The true sea breeze might be delayed until around 1pm from Vero toward the Cape area, while in the meantime the Lake Breeze will also be at play on both shores..spreading a shadow toward the NNW. Showers and storms could form on either side of the shadow, and begin to interact with the East Coast Sea-breeze.

ASSUMPTIONS: First and foremost, one HUGE assumption was made today. That being, that despite the high clouds being present, heating alone which is not being hindered too much combined with these breezes will help generate storms. If that is NOT going to be the case today...then the chance of rain goes very very low except right close to wind boundaries.  Mid-level instability though seems very good today, and the KSC sounding came in this morning with cooler mid-level temperatures than it has for several days near 7.5C rather than 10C. This should aid in mid-level lift. This combined with lower level lift provided by breeze collisions could lift moist parcels via FORCING at the low levels and thermodynamically through the mid-levels, which could overcome any hindering factors (i.e., high level cloud cover).

With the above said, I'm drawn to the latest mesoscale analysis page depicting the low level vorticity building up along the SE Florida coast due to primarily stronger SE winds advecting up the coast and interacting with the landmass. This vorticity should work into the Cape area by mid-afternoon as the sea breeze develops, and provide ample fuel for further lift at the low levels.

The light blue lines show vorticity. Forecasts show this to increase further and work inland toward all  of South Central and Central Florida by late afternoon with the sea breeze conflicting with the SSW to NNE steering flow just above the ground. This will occur over the larger inland lakes such as Lake Kissimmee and Lake Harney in Seminole county.
TODAY: Thus, with the above stated...and do not forget that BIG ASSUMPTION...believe that thunderstorms could form first mostly over South Central Florida near the east coast and combine with the lake affect: showers/and storms, and spreading NNE into Central Florida and increase in number during the mid-afternoon, primarily after 3pm. These should be able to work into North Central Portions, where there could also be a merger of the East and West Coast sea-breeze toward Flagler County.  

Believe that far North Florida might be in for more of a one shot deal, whereas storms further south might be able to regenerate, at least for a while and affect mainly the eastern 1/2 of Central and North Central Florida ..waning in deliberation headed toward 8pm as the sun sets. Showers and storms could linger until around 9pm though either  over the interior or as they exit the east coast north of Brevard County.

Storms will be capable of frequent lightning and wind gusts as would be expected in stronger thunderstorms up to 45-50mph in very isolated cases..although even stronger is not entirely inconceivable in a remote, random chance if conditions come together just right. I'm toying with watching for the possibility of waterspouts as well along the near-shore and intracoastal waters of Brevard and Volusia Counties, although this is currently not being considered by the NWS. Just something to consider today, especially after 4:30pm as the sea breeze could become more unidirectional with those waterways...or what I've fondly started to refer to as 'upwind the intracoastal' or 'upwind' for short. That is not an official term, if not possibly illegitimate, but it sounds good.

THURSDAY: Done with the fun -n-games as winds start to become more unidirectional for the ESE-SE. There could be enough moisture, for late morning toward noon time showers to form along and west of the intracoastal of Brevard and Volusia. These would readily move to the west by early afternoon, after which point, rain chances look non-existent for most of Florida except perhaps north of I-10 and toward SW Florida and maybe up toward Tampa on Saturday/Sunday.

FIRST WEEK OF AUGUST: Instant replay as stated yesterday of the on-going trend this Summer of 2011. Another trough to dig down into the SE States...Monday looks to be a good day for SW and NE Florida with a ridge axis over Central Florida..with less coverage but still some storms favoring more toward the East north of Brevard but mostly just west of I-95 most everywhere. 

NEXT TUESDAY/WEDNESDAY: Ridges drop toward Lake Okeechobee if not further south on Wednesday, for greater state wide rain chances. This variation of ridge placement to the south has been emphasized to continue into the second week of August.

TROPICS: In the long range, although this 'troughing' is expected to persist into the second week of August, the tropics might also be starting to become a bit more active, with already a tropical wave being outlooked in the long range by the GFS weather forecast model to approach the Lesser Antilles are already proven to exist via satellite imagery. 

The tropics could play into the equation and either increase or significantly decrease rain chances heading toward next Thursday/Friday time frame. Otherwise, there is the Invest  area (very active) approaching the Yucatan Peninsula today. The jury is out in regard to where it will go and how strong it will be when it gets there. So far, I've seen anything from an open wave to a tropical storm. From what I can tell, on average it seems to be going to impact the Houston area or just south of there..although guidance diverges to anywhere toward Louisiana (which I'm discounting at this time)...toward Brownsville as a much weaker system.

In the rough cut for today..again..on the assumption storms can form by early afternoon:

FINAL CONCLUSION: Based on the assumption that storms can form, the heaviest rainfall totals due to heavier stand alone storms combined with some training should occur in the lavender area. Stronger Storms could occur in the red area, and thunder in the orange as noted on the annotated captioning of this hand drawn best guess in a worst case scenario for rain haters.

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