"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, May 9, 2012

Strong Storms "Possible" East of I95 Later This Afternoon

Today's lead off image shows the upper level low over the Desert SW noted yesterday has dropped further south than expected. Meanwhile, in red is shown where the leading edge of upper level winds are estimated to be located earlier today, and in purple where that leading edge is expected to be by late afternoon moving in across the North 1/2 of the state.

TODAY: A front boundary will be entering the NW Panhandle by tonight. Meanwhile, SW flow is expected to increase toward sunset at the surface, but before that time (and here is the clincher of clinchers), the pressure gradient might not be strong enough to offset an east coast sea breeze which would end up pinned close to, if not east of, US 1.  for many locations along the entire east coast before the gradient increases toward sunset. 

Considering also, good surface heating toward the east coast and inland could provide for the added boost of a temperature (thermal) gradient from the cooler near shore waters to provide for a shallow sea breeze to form or upwind river breeze at least along the Brevard barrier islands. Further South, lake shadow wind effect could enhance storms either side (north of south) of the shadow into Palm Beach County or Martin/St Lucie County.  Further north toward JAX, there could also be a sea breeze south toward Northern Ormond Beach. So far, guidance is painting that the area just along or north of I-4 might become 'capped' due to a surge of warmer 850mb air temperatures, although this cannot ever be for certain. For now, the next graphic has made that 'assumption'. Also assumed is "the clincher of clinchers", a sea breeze or side shore component. If this does not form, chances are much lower of anything beyond some storms of generic quality except toward Lake Okeechobee and NE Florida.

Otherwise, although 500mb temperatures are not as cold as two days ago, that aren't far off from yesterday with still cool  at 700mbs. Good surface heating, instability (light -mdt), and some upper level energy to trigger showers and storms, especially after 4pm or so. Whether or not this will be of in the form of rain showers over the interior is difficult to pin point, but the best chance of thunder seems to be within 20 miles of the coast except toward NW Florida and the Panhandle as the front moves in. Conditions appear most favorable for any strong to marginal severe storms that might occur to be after 4:45pm today closest to the coast from the Cape and South due to local affects, and near Jax due to the proximity of the approaching frontal boundary, except near Palm Beach County will it looks like more of a low level wind field boundary happen-chance situation.  Showers and some thunder could continue in very isolated fashion anywhere along the east coast as late as 11pm in random fashion due to remnant out flow boundaries and residual convective instability.

This image shows a guesstimate for showers (green) to stronger storms (lavender) , although the area near JAX/St. Augustine and in the Panhandle could have easily been included for some 'purpling'. Stronger storms near the coast could contain small hail and wind gusts in excess of 50mph, especially after 4:30pm in a few spots under the premise a sea-breeze or side shore wind can form. 

THURSDAY: The Front will glide slowly south over night toward Dead Central by noon time Thursday. At this point, it is becoming just a bit flaky as to how far south and how fast the boundary will continue southward during the first half at least of the afternoon during peak heating. Winds aloft will be paralleling the front, and that factor combined with surfacing heating could slow it down. There is minute indications a weak surface low could try to form near Tampa Bay as well, which would further impede southward progress until after or near sunset. With this in mind, a pre-ump agreement (despite a few model runs showing otherwise) could call for showers or thunder to occur from the Cape south along the east coast on Thursday. Some could be strong as well with colder air aloft, but a seabreeze and thus lack of low level convergence would be a mitigating factor in that regard. Where ever the boundary is stalled or slowly moving will more than likely be the additive factor for stronger activity tomorrow, wherever that might happen to be.

Possible storms on Thursday if low develops. Otherwise, any storms will be relegated a bit further south toward Vero Beach. Some consistency indicates at least showers or something looking like showers no matter
what from the Cape and South
FRIDAY/SATURDAY: The boundary will remain toward far South Florida into the Straits Area but the 700mb trough never really clears Central. This COULD end up acting as a future source of storms by early Next Week, surprise surprise...otherwise, shallow depth easterlies could become a bit gusty on Saturday at 18-25mph, especially due the mid afternoon and into the evening.

 As such, showers could re-emerge toward SW Florida on either day, with possibly some light rains South Florida, but clouds seems to be the more prevalent mode south of the mid-level boundary except toward the SW Coast.

SUNDAY/ MONDAY: Upper low shown previously toward the SW U.S. never really clears the SE States but lingers across the Northern Gulf and parts of Florida as anticipated in yesterday's post. 

As noted before  (yesterday) another upper low fills the void from the Northern Plains states which drops SSE into the 'gap', re-enforcing that trough, while a surface low forms toward Coastal Louisiana and lifts another boundary northward, a part of the old surface front and mid-level boundary. Net affect, we could be seeing more thunderstorm chances as soon as overnight Sunday or early Monday near the East Coast south of the Cape, and much more widespread Monday afternoon and potentially for much of next week. After this point, it gets messier and messier in model inconsistency , at least in regard to climatology.
OVER GULF is what WAS the Desert SW Low. Note the trough
swinging southward from the Plain to fall into the same trough and re-enforce it.
Better YET! Look what is forecast then to approach from the west. Do note though,
this could all change by the next model run.
At this point, this is all a tough call. The  extended outlook'd 'pattern' is highly unusual for this time of year. The GFS and another model take it so far as to produce a tropical system over the western Caribbean which drifts north across Cuba in the next 12 days or so, which would be a first in QUITE a number of years this early in the season. If nothing more, the fact that a model (s) is even hinting at the possibility is worth noting at this stage.

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