"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".

Monday, October 10, 2011

The "Storm With No Name":Scattered Showers, Isolated Thunder Mainly East Side Late

What looks like an "EYE" can be seen in this radar image from WeatherTap last
night east of Patrick AFB. This feature moved WNW-W and came ashore near the 520 CSWY in Cocoa Beach. Animation of this feature was impressive as it became visible on Melbourne's Radar when considering it wasn't supposed to exist.

ANOTHER IMAGE: Below. This is from Melbourne's Local Data Integration System (LDIS) available from their website. Shown is lines of constant barometric pressure. Note the tiny bulls-eye along the south end of Cape Canaveral. The strongest winds last night occurred north of this feature, from the north half of Cape Canaveral to the Brevard/Volusia County line. Wind gusts measured at 54Ft above ground contained several gusts between 75-81mph, and land based observations recorded winds over 50mph from near Vero Beach north. A separate post concerning the event and of days past (the weekend) should be in the works later today or tonight.. A brief YouTube video is also in the works.

Note the tiny bulls-eye just south or on the 520 Cswy in Cocoa Beach in this image from 11:45pm last night. Winds in Canaveral at my location had gone from estimated gusts near 65-70mph to only 6 mph in a matter of 15 minutes. Barometric pressure fell rapidly, and bottomed out at 29.47" (from 29.88" three hours earlier) per my weather station.

 Meanwhile, Melbourne which was south of the feature was reporting a west wind gusting over 20 mph.


In regard to last nights system, it had been outlooked by the Hurricane Center as an Invest, but I think that the ball might have been dropped on not naming the prime area a Tropical Storm and fairly high end one at that. Several problems with doing so though, other than for the sake of 'naming a system' (which in the past they've seemed to have no problems with doing so in much more questionable situations out in the middle of the Atlantic) . This might have been all coordinated behind the scenes, but I'm not getting that impression.

 It is a good thing the NWS Melbourne had issued high wind and flood warnings  in the afternoon, although those were issued for a different reason other than what eventually developed.  There is some procedural politics involved.

 The saving grace was that the highest wind and rain impacts occurred in a very lowly populated area of the Mosquito Lagoon ..with the only inhabited areas fully affected being the north end of Cape Canaveral, possibly some areas near SR3 in North Merritt Island as well. Hurricane Force gusts were measured at 54 Ft, and tropical storm force gusts were measured in a bigger area.  Further reasoning for why it could have been named is it seemed to go 'warm core' as it approached land, as surface temperatures ROSE even during heavy rain and lightning ceased (indicating warmer air aloft as well).
Radar animation overall was the most one single 'red flag' though.

TODAY: The low pressure system "that wasn't" (?) has exited the Big Bend area. A tornado watch had been issued for NE Florida, but none have been reported and it was dropped for that area. The low is wrapping into the parent mid-upper level low over the Eastern Gulf. Otherwise, models agree fairly closely on these features.

The morning surface plot:

The low circulation is now barely discernible, but appeared to be just west of Gainesville. The main feature low with upper level support is west of SW Florida extending toward Jacksonville. The red arrow on the east coast indicates the prevailing wind direction later today.
In the Mid-Levels of the Atmosphere, per LDIS:

There are two circulations noted by the red "L"s. Moisture remains, but there is some drying in far South Florida. Otherwise, steering early was from the SSW, and fairly fast at 20kts. This should decrease only slightly later today.

TODAY: The NAM has been consistent for three consecutive runs with showing scattered showers forming toward SW Florida and spreading East and north with time. Most of this activity should remain showers, with maybe some thunder toward Osceola County. 

Winds today are expected to become 'side-shore' except toward West Palm Beach due to the configuration of the coast, and along Brevard's Barrier Islands. The atmosphere will take a while to destabilize, but South Florida is getting underway right now. The two source regions for instability today will be South Florida and the near shore waters of the Atlantic. Instability should advect up the coast and  rivers during the day, with  possibly a sea breeze creating a storm, possibly strong, toward West Palm Beach along what could be a Lake Okeechobee/Sea Breeze merger variant. This should occur toward mid afternoon.

Further North, a slight sea breeze could develop, but expect winds will remain SSE nearly parallel to the shore except over the Barrier Islands of Brevard County. Instability from South Florida as well as the Atlantic Waters could arise to showers progressing from the west and southwest along an upper level trough feature rotating around the mid-level low configuration pictured above off the West Coast. As this area approaches the East coast the showers will encounter a full days worth of mounting instability and side shore winds with steering from the SW. It is possible that in this area, especially in North Brevard, that a strong storm could form during the last hour or two of daylight and move offshore . More rain showers and maybe thunder could occur further north into Volusia and Flagler, but showers so far seem to be the rule in those most northern locations. Temperatures aloft are still very cool by the summer standards of the past wet season, with 700mb and 500mb temperatures running around  +7C / -7C respectively, and perhaps a degree colder with one or the other of those. Thus, if any much stronger storm than expected occurs, tiny hail is possible, but I do not believe at time that upward forcing will be strong enough for this to occur today. Any stronger storm could have gusts to 50mph, but given the events of the past two won't seem like much. The other complication for thunderstorms, especially a stronger one, is that the days are getting shorter...and heating is decreasing for less instability. So nothing is a given today. I simply do not trust this low pressure system out in the Gulf. Its presence puts a twist on things.

Showers in Green, maybe some thunder in orange, with thunder more likely toward the coast along and east of I95 .
Some showers in North/Central Brevard to Volusia, with thunder waning, could last until 10pm or so.

TUESDAY/WEDNESDAY: Overall atmospheric moisture will be waning as the upper level low starts to open up and lift north up the east coast. It will be a slow process though, and timing of the required features becomes increasingly difficult as well as key to determining where/when and 'if' thunder will occur . It does look at time that Tuesday will be similar to today, with a slight variation due to decreasing moisture and possibly later sea breeze development. Temperatures aloft will be warming somewhat on these days, but not so much as to completely negate the thunderstorm chance.  

Eventually, as we head toward Later Wednesday, the low pressure party will lift up the east coast, with an attendant surface trough dragging behind and across the state. This could be key to some stronger storms again on Wednesday mainly along and south of the Beachline toward the Eastern Interior of South Florida.

THURSDAY: Big problem. The NAM is consistent with developing a low pressure system along the northern banks of Cuba and lifting it northward to 70-80 miles SE of Key Largo, Florida. So far, at best this could be dubbed a tropical depression...but winds do not indicate it will be strong enough. It does look fully tropical though, with no jet stream winds near by and warmer air aloft. Chances are, this would be regarded as another "Invest".

If this system does develop, the forecast for Thursday becomes a problem in regard to rainfall. So far, rain chances look very low, although any sliver of moisture that is broad enough could generate showers and maybe a thunderstorm across South Florida and Central, but very isolated if even.

BEYOND: Cold front is having a big problem getting  through the Southeast States and Florida, but the GFS remains adamant that it will plow through by Friday, the low supporting the frontal boundary weds with the low pressure  system/systems from the Southeast states. Another low may form and move up the east coast just offshore during mid-week from the Mid-Atlantic toward New England.

Temperatures will not get quite as cool once the front moves through, and onshore winds resume much more quickly as well. This front could pose as an impetus along with a disturbance from the SW Atlantic for tropical develop again later next week near the Yucatan, or even the west central Gulf of Mexico. 

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