"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".

Sunday, June 12, 2011

Changing of the Guard Today As Pattern Transitions/Some Strong Storms Possible Late

Showers and thunderstorms (some  isolated strong storms conditionally possible late as noted below). 

TODAY: As the title of today's post implies and as noted yesterday, we will have a changing of the 'guard' today in the wind surface and upper level wind fields as the nuisance/non-eventful filled pattern which harbored a high false alert rate for rain potential has moved on.  However, there still remains the upper level low which is forecast to move over the north half of the state today and exit off the NE Coast by early evening.

CON in forecasting today:  Weak wind fields and warmer air in the mid-levels, adding to indecisiveness. Change in the pattern. Affect of potential subsidence/timing of unfavorable jet stream level winds until late today. Will they move on in time? Additionally, at this hour about the most stable (non-convection conducive) area is in and near that highlight for strong storms later today (East Central)...EEK.

FORECAST: Expecting 'relatively' strong sea breeze along the East Coast after 4pm. Due to prevailing upper level winds from the WNW-NNW (albeit light), the west coast sea breeze would theoretically be the dominant, most evasive boundary to push east of I-75 and toward the Orlando area ( the spine of the state)  by 5pm. Convergence along this boundary combined with PERHAPS a magnified east coast sea breeze wind surge could induce stronger storms East Central after 5pm.  

Believe ' near collisions' will start out further north and work south with time toward the early well as over South Florida.  Moisture is greatest this morning over South Florida; however, that could be rationalized as being because that area has been under cloud cover until this might be misleading to this forecaster.

It must be noted the atmosphere on the generalized synoptic scale this morning probably will not resemble that which will exist later today due to the pattern change, making this forecast a bit more difficult than usual.  Additionally, although there is some moderate instability in place, most of the afternoon convection (rain) will be induced by near sea breeze and lake breeze collisions.  If some of the latest guidance I've seen this morning is remotely close, then vertical velocities (upward motion) along the strongest boundary collision will occur west of I-95 over  western Volusia, Seminole,  Orange, and Osceola Counties. Thus, the stronger storm chance there as noted above.

Additionally, strong storms could form earlier (due to earlier collisions) over South Florida. A Lake Breeze could be an additional factor here, although I'm a bit more skeptical about this area at time. But given that instability is greatest there right cannot be counted out. 

Otherwise, given the above, areas along the East Coast could become cloudy after 6-7pm due to debris clouds/anvil level clouds UNDER THE ASSUMPTION that storms and showers  form as outlined.

Overall \, atmospheric moisture and instability isn't quite up to seasonal norms, but there does appear to be a trigger or two embedded within the mid-upper level flow from the NNW, one of which might have based over Central Alabama earlier in the morning per satellite animation as well as another over Central Georgia. The latter is no longer apparent, presumably because it entered some drying air or it simply was the perfectly wrong time of day for it to manifest in the cloud signature.

WORST CASE SCENARIO: Very strong storms with active lightning west of I-95 and near the turnpike from West Volusia/Seminole/Central-East Orange/Central-East Osceola County during the time noted in the provided self, hand-painted graphic. This would be due to, if it occurs, a secondary 'surge' in the East Coast Sea-breeze combined with a dominant west coast sea breeze late (essentially about 2-3 hours after peak heating). During this time of day, dew point /ambient air temperatures come closer together (humidity increases). In the absence of gradient flow, the east coast sea breeze can take on a more southerly component due to the Coriolis affect which in turn increases low level helicity along the leading edge of, and within, the sea breeze front.

OTHERWISE: Without an East Coast sea-breeze surge...more generic type showers and thunderstorms will be possible of lesser coverage and strength. Either way, it could get cloudy along the east coast communities by early evening unless of course storm initiation falls to materialize as hypothesized to the degree being depicted by model guidance. (one model initiates nothing more than some sprinkles today). 

MONDAY: Although atmospheric moisture will continue to be below seasonable norms, isolated thunderstorms will remain a possibility along and west of I-95 Monday, but at time it does not appear coverage on Monday will be as high (nor strength as great) based on guidance.

TUESDAY: Still holding firm for now that some strong to severe storms will be possible over a portion of North Central and North Florida. South Florida might begin to have less of a chance of rain on Tuesday, if only on this day.

WEDNESDAY: Westerly mid-upper level wind component increases just a bit. Some coastal communities from JAX to MIA might actually get some rain or a thunderstorm. Most activity would form late (other than near JAX) and be glued very close toward the east side of the state, possibly only forming along I-95 then moving offshore by late afternoon.

THROUGH THE WEEKEND: So far, the GFS is holding firm to its forecast reasoning of the past 6 days now. That being, a low level ridge axis located near the Florida Straits works north with time toward Central Florida by the weekend. If so, this will favor storms over the interior (under the climatological assumption that there would be at least some minimal atmospheric moisture and a non-capping (air not too warm aloft) environment in place. Could be some days will be much drier than others contingent on 'booster shots'   by disturbances migrating down from the more northern border states.


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