"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, April 4, 2013

Threat Thursday - Strong Severe Storm Risk Involved

Complicated Looking Graphic Explained Below

CURRENT: As of 7:30AM a developing warm front is lifting north across Central Florida. This boundary is expected to lift into extreme South Georgia by  the mid-afternoon hours. Otherwise, increase multi-layered bulk shear down to the lowest atmospheric levels is not expected to be in place across South and Central Florida (specifically) until tonight. Cold temperatures aloft are a 'go' as is the forecast Convective Available Potential Energy (CAPE) around 1700 J2/Kg2 (which is not overly impressive at all) coupled with helical spiraling wind flow streamers (helicity) in the surface to the 3KM levels to be in place by noontime spreading west to east across the state. Moisture is a non-issue, especially along the warm front today and along a pref-frontal trough tonight. Low level helicity could be magnified along the entire east coast.

OVERALL OUTLOOK: Refer mainly to the region bound by the DARK blue lines and the white squares for daylight hours. This is mainly the north half of the state.  Skies should clear some by late morning as one of (at least) two impulses approaches the west coast. By virtue of the warm frontal boundary alone, there is the potential for rotating thunderstorm / supercells near this boundary as it lifts toward JAX. Elsewhere south of this boundary, all of the guidance indicates at least a somewhat 'side shore - up the coast' low level surface wind component to come into place as daytime heating commences prior to approach of the first major impulse from the west. Therefore, per this post, I'd consider those white squares to be MDT RISK areas (moderate) as opposed to the SLIGHT RISK area the entire state is currently under and bound by the purple lines.
            High Speed Dirt's 
             "Sky Sanctums" Makes No Claims  
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”

Note, there are TWO squares along the east side. One is for daylight hours, the latter for late overnight to very early Friday morning (the southern one). Also note Brevard County/Indian River/ S. Volusia in general fall in both regions for both daylight and overnight.

In General, some discussions I've read are stating it is the GFS model all along that seems to have the best grasp on today's overall situation as best can be determined this early in the day.

DAYLIGHT: Warm front lifts north and convective instability (CAPE) increases. Wind profiles would support some rotating storms along miso-scale boundaries amid meso-scale parameters     (namely, the warm front), the secondary miso/meso boundary being along any sea breeze that might happen to form. These 'could' be enhanced up river ways as storms move from West to East. Thus..special attention to the regions along and east of I-95 for RAPID CHANGES in storm structures as they penetrate the sea breeze at the lowest atmospheric levels. Note that this is not to count out regions further south during daylight nor anywhere inland.

TONIGHT: Here is the shift of another sort. By night instability decreases but upper level divergence as the South Half of the state mainly falls increasingly under the left exit region of the upper level 120 kt, 250mb jet stream as it lifts out in side- swiping  fashion. The down player for rotation though at this point is winds start to become more unidirectional with height at lower levels. 

Again though, any activity that might be strong and move offshore could result in outflow back to the coast as they move offshore (in theory only) once again magnifying locally low level helicals (helicity values). Tilted horizontal corkscrewing winds pulled up vertically by upper level divergence could again tilt those spiral into the vertical result in rotating updrafts within embedded thunderstorm structures with little notice.

Current as of blog post with highlighted areas to watch. Again,
along the east coast 'could' in my mind be considered a MDT RISK
area  if the side shore wind and/or sea breeze develops along the east coast

In Summary, best be advised to take responsibility and accountability to monitor Local Television Networks in order to remain abreast of this ongoing and actually yet to actually develop potential weather situation. As always, tornadoes can develop with little or no warning (a tried but true reality).

THREATS: Do note that the SPC is a bit of at the mercy of whatever will or will not occur today and tonight  more so than usual as opposed to larger scale potential severe weather events that normally occur in the more tornado prone areas. This is not usual for Florida. There are times when a threat is in place and not much of anything happens. That is why it is called a Slight RISK area. There is a RISK. In a Moderate RISK, the risk appears to be higher under conditional situations like this one. In short, today's weather situation is highly conditional although looks at the same time fairly certain that somebody somewhere will get socked with a nasty storm, if not more than one over the same location.  If the situation develops as expected a tornado watch or more than one could be issued during the course of events for the more certain areas. And, if storms develop that are within those watch areas, warnings would be issued for specific storms.

Threats include quick spin up tornadoes, perhaps a bone-fide few  from longer tracking (lasting) rotating thunderstorms (supercells), wind gusts to 80mph, and golf ball sized hail (although it has been my personal observation that hail larger than peas does not occur too often in such set ups over Florida).

The risk quickly ends from north to south tonight and over night with North Central in the clear just after sunrise and working south with time. 

BEYOND: Pleasant weather with a chance of rain re-emerging perhaps around Thursday or Wednesday. The GFS is hinting at a QLCS Squall line in about just over a week from now already.  

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