"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".

Thursday, June 9, 2011

Lightning Storms Toward the Western Interior/West Coast Today

Color coded regions of possible showers and thunderstorms, with increasing chances in both categories from the interior and toward the west coast of the state. South Florida region less certain due to persistent high cloudiness.

CURRENT & SYNOPSIS/MODEL(S) REVIEW: Broad area of low pressure over the Caribbean and into the Gulf well analyzed this morning by model 'guidance'. Jet stream level winds around the base of the upper level area of low pressure across portions of South and South Central Florida combined with ample upper level moisture is resulting in high clouds over the region. Slow moistening of the atmosphere at all levels from south to north in the next few days. Nearly all the models are in consensus that a surface/mid-level low will form SE of Florida which will move northward east of the state.  The majority of the models are now in agreement with the GFS (which has been favored in these posts for several days), which would place this low pressure circulation well east of the state, however, there is still some debate. Either way though, the only impact if it  were to be closer to the Florida East Coast will be stronger east to northeast  winds for a 12-24 hour period and some near to onshore showers which, as of late this morning,  would occur on Saturday just about anytime. This will not be of fully ( or nearly 'any') tropical nature.

TODAY: East coast sea-breeze getting a mid-morning start in the easterly gradient flow. Line of some moderately towering cumulus clouds offshore the Cape area initiated some very light showers and a funnel cloud offshore the Cape which approached shore (whether  this funnel cloud touched water remains UNK (unknown). Otherwise, due to the lighter gradient flow toward the west side of the state, a west coast sea-breeze is expected to be able to form today, which could press as far east as the Western Interior.  Mid-Late afternoon thunderstorms are expected to form where  the West Coast sea-breeze and easterly gradient flow enhanced by the east coast sea breeze converge, mainly in the red area, although the region as far south as Naples could hear thunder as well based on latest visible satellite trends which show that  cirrus clouds are thinning.  Some storms could be briefly 'pulse strong' (as almost any thunderstorm can) due to some dry air entrainment  in the mid-levels. Storms would be strongest in the Tampa Bay area due to the  squirrely/swirly nature of the Bay Wind convergences  late this afternoon.

LATE AFTERNOON/MID-EVENING: Storms should (could) form along the West side of the state as noted above. Elsewhere, East Coastal showers could move onshore from South Volusia toward Ft Pierce by early evening, although this looks questionably admitted;  the signs are there with forecast models indicating  atmospheric instability to increase a bit during the day into the early evening  in the  tropical like air mass moving northward throughout the day today. Therefore, have thrown in some 'green' to the east central coast for early afternoon showers west of I-95 which will move west into the mid-late afternoon as well as for onshore moving showers at the coast after 5 or 6pm (the latter just to cover the bases).

FRIDAY: A lot depends on what and where finally develops regarding a low pressure area in the SW Atlantic near Eastern Cuba and the Bahamas. For now, though, will rely on the previous post that this entity will be too far offshore to directly impact the state. Cannot discount the chance of east coast showers though with any vorticity ('energy') lobe rotating around the backside of the low to pass over or near the coast as well as with convergence along the developing east coast sea breeze as it moves onshore and over the inland lagoons.

BEYOND: Guidance portrayed by the NOGAPS/ECMWF/GFS  (as well as two others not normally referred to in these posts) are all showing that a frontal boundary now over Eastern PA/NY into the upper Midwest will move east the next few days and merge with a trough running down the spine of the Appalachians (storms in Western North Carolina the next few days as a result).  This boundary is forecast to be forced east and south with time...and will become entrenched over Central or Southern Georgia sometime Saturday or Sunday.  Convergence along this boundary will increase thunderstorm chances over North Florida/Panhandle regions.  

Additionally, a surface ridge of high pressure following northward passage of the low pressure disturbance forecast to pass east of Florida (as noted above) will work north (aligned west to east) and be situated either along the Florida Straits or South Florida.  This will place almost all of the state in a west to east steering flow, with the east coast sea-breeze being suppressed from reaching any further west than the spine of the state and even more toward the east side with time as it forms solely based on diurnal heating of the 'landmass heating' mechanism.  

With the increased  atmospheric moisture by this time now in place from previous days, a delayed morning east coast sea breeze  could make late morning to noon time temperatures warmer than past days along the east coast. With little in Convective Inhibition (CIN), ample moisture, and little capping warm air aloft in place...mid afternoon showers and thunderstorms should have no problem being initiated which will move eastward and offshore by early evening if not sooner in the day.  This general pattern is expected to begin either on Sunday or Monday...timing of which can be refined / ascertained with greater confidence in the next two/three days.

The future forecast beyond NEXT Friday becomes less certain, with the GFS pressing the front entirely through the state with easterly flow (like that of recent days) resuming.  Generously, this model leaves that portion of the  forecast set up to be of relatively short duration by once again creating a very summer-like ridge of high pressure across South Central Florida and again placing favorable thunderstorm chances back into the forecast for mostly northern portions of South Central Florida and all of North Florida well out in time. Meaning, early day showers/thunder along the west coast and mid-afternoon to early evening showers/thunder Central to East side.

TROPICS: No tropical entities at time appear to be of an immediate or mid-range threat.

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