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Archives >> 2006 News Talkbacks

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cieldumort
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Re: nothing active but stuff on the table [Re: dem05]
      #69580 - Sun Aug 06 2006 12:42 AM

I take a different look at the GOM feature - for one, a potent mid-level low within an MCS moving into the GOM tends to be one of the somewhat favorable ways for tropical cyclogenesis to occur pre-peak season (of course now we look to tropical waves more and more).

Simply because NHC has not made a public mention of a feature has never been entirely important to me. Consider all of the times they have seemingly overlooked things, only to have it "surprise" us all. I value the services put out by all levels of the National Weather Service, but there are limitations to the usefulness of relying on them.


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allan
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Re: nothing active but stuff on the table [Re: cieldumort]
      #69581 - Sun Aug 06 2006 12:52 AM

I see your meaning on that low in GOM. Looks like it could turn out to be a large cyclonic storm or even a hybrid storm. The way X-Chris looks... it's already absorbing it nw.
http://www.ssd.noaa.gov/goes/east/watl/loop-wv.html
You can't tell me it's moving west anymore... Looks like the process is starting with the final dissipation of whats left of Chris which is starting to get absorbed in this huge Low in the GOM. It's pretty amazing to see a large low in the GOM like this. WOW... Hybrid system?

--------------------
Allan Reed - 18,9,5


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dem05
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Re: nothing active but stuff on the table [Re: cieldumort]
      #69582 - Sun Aug 06 2006 12:53 AM

The mid level circulation is a function of an MCS. Just likke this one made it into the Gulf, They have been noted for moving into the Gulf from Mexico, and well as into the Carribean from Central America and South America. Last Summer, I also saw a better looking one that this move from Florida into the Atlantic...and it did cross the Gulf Stream. The mid level vortex becomes most evident and most impressive on satellite when the thunderstorms decay and this circulation becomes easier to see...However, their bark is significantly worse than its bite...Once the thunderstorms that created this mid level circulation are gone...there is nothing left to support/sustain it and it fade away (generally in about 6-12 hours...sometimes 24 max). This one will do the same. I'd say this is gonna be a non factor...if it still had good t-storms after being over water for this long...my conversation with you may have been different....but this system is a dead stick.

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danielwAdministrator
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FL Straits [Re: dem05]
      #69583 - Sun Aug 06 2006 01:01 AM

First of all I'm not a MET. And this post is based on a quick, multi product check of the Key West Radar, from various web sites.

Using the link below. There is a defined, circular area of "No Echoes" rotating through the FL Straits, Just East of Key West Radar. ( 60nm Range Ring currently bisects the "hole".)
The "hole" shows up at all of the levels that I've checked, and on the loops too.
http://weather.cod.edu/analysis/paulradar.pl?BYX
http://www.aprsfl.net/radar/index.php?site=KBYX&mode=N1P&animated=yes12

Key West VAD wind profiler is indicating "backing" of wind direction over the last hour...which is almost always indicative of a LOW passing from East to West, South of the observing Station.

Winds are rather light. With maximum detected wind speed near the 3000ft level. ESE near 23 knots.
http://weather.cod.edu/cgi-bin/radarhtml.pl?station=BYX&product=VAD

Edited by danielw (Sun Aug 06 2006 01:02 AM)


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dem05
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Re: nothing active but stuff on the table [Re: cieldumort]
      #69584 - Sun Aug 06 2006 01:02 AM

***Bulk of body on this post deleted by author***did not show on first post attempt...but it did post above afterall. Here's another interesting tidbit I'd like to share.
In reference to Danny (Mentioned Earlier) when it dropped off Louisinanna and developed in '97...this was not an MCS, but it's evolution was interesting. Here's the history on it if you'd like to have a look: http://www.nhc.noaa.gov/1997danny.html

Edited by dem05 (Sun Aug 06 2006 01:12 AM)


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dem05
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Re: FL Straits [Re: danielw]
      #69585 - Sun Aug 06 2006 01:18 AM

In looking at the latest IR loop....

http://www.ssd.noaa.gov/goes/flt/t1/loop-avn.html

It apperas that x-Chris finally found the COL region (Moreso a very narrow ridge)...which is only about 100 or so miles wide. Notice the clouds are ripping from NW to SE of the NE side and from SE to NW on the SW side...With that said, radar seems to continue to indicate decreasing showers and warming cloudtops...While that diurnal period is still forth coming...the history of these thunderstorms is through afternoon t-storm activity over Cuba...it can't be ruled out that the new surface low in the FL Straits won't meet it's own fate by morning of t-storms fail to refire during this period.

Edited by dem05 (Sun Aug 06 2006 01:20 AM)


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cieldumort
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Re: nothing active but stuff on the table [Re: dem05]
      #69586 - Sun Aug 06 2006 01:20 AM

Yes, I've read that, too. However, I respectfully disagree. If the description of Danny's evolution doesn't describe an MCS moving south and into the northern GOM that resulted in tropical cyclogenesis, I don't know what does.

"On 13 July, a broad upper-tropospheric trough over the southeastern United States triggered a cluster of thunderstorms over the lower Mississippi River valley. This area of convection drifted southward over the north-central Gulf of Mexico coastal waters, and appears to have contributed to the formation of a small, weak surface low near the coast of Louisiana on the 14th.

Over the next couple of days, the cyclonic circulation expanded somewhat over the northern Gulf. However, surface winds remained quite weak and the associated deep convection was not persistent or well-organized. By 1200 UTC on 16 July, deep convection became a little better organized near the center and the system began to resemble a tropical cyclone"


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dem05
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Re: nothing active but stuff on the table [Re: cieldumort]
      #69587 - Sun Aug 06 2006 01:31 AM

Had Danny evolved from an MCS feature, it would have definately been called that in the report. Long lasting t-storm complexes can for from several unique features, but the MCS is a very special one with it's own designation...I remeber tracking Danny, and if I remeber correctly, there was a surface trough involved in that interaction that formed the surface circulation. In this case, surface circulation is key...If the area over the Gulf truely is an MCS, and the t-storms are crankin downward with no evidence of a surface feature (i.e. 5:30 NHC TWO pressure statements) then it lacks the ability to comeback, which is sometimes seen with mid level features in the deep tropics...Also, while t-storms are not dead in the Northern Gulf...it is apparent that they are part of a larger. more complex weather system right now...and the primary energy is not just over the northern Gulf either (Take a look N of Houston on the Satellite). If anything were to happen...it's gonna take more time than it probably has available.

Edited by dem05 (Sun Aug 06 2006 01:35 AM)


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HanKFranK
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crowd control [Re: dem05]
      #69588 - Sun Aug 06 2006 02:04 AM

dang... lot of stuff going on.
three areas of interest are showing on u.s. radar right now.
chris's remnant low had an impressive burst of convection on it this evening, but it has since died. the low is apparent on the north coast of cuba, about 150-200 miles southeast of the keys. it should be clear of cuba later tomorrow and over the gulf... the system has already cleared the shear from the upper low backing to its east (it stopped hounding former chris finally)... it has a shot at redevelopment.
just off the houma, la area is another weak low from the mesoscale system that moved off friday night. the low persists and is over very warm water.. and has some upper support. convection isn't really concentrated near the low, and the circulation is sort of broad. it has a long way to go.
off the carolina coastline is a weakening front with a convective flare. there isn't a real low pressure area here, but anticyclonic flow aloft may aid the continued convection and work pressures down. like the previous two, surface pressures are fairly high and it isn't much of a development threat at the moment.
out in the atlantic... three more areas.
cut off low with surface reflection ~500 miles southwest of the azores.. over marginal waters, decent convection. globals indicate that this low will work to the surface... but don't show a robust tropical development. given time this may hybridize, or it might just remain an upper low. should meander for the next few days.
two waves east of the islands.. one near 50w with a mediocre signature and little convection... losing its identity to a wind surge possibly tomorrow. further east is a developing tropical cyclone. there is a convective region with the strongest turning, just separate from the ITCZ... NHC calls it a 1010mb low. this will likely slowly develop into a tropical cyclone by monday and begin moving wnw. u/a pattern should support further development. not much of an idea on the long term motion.. waiting for more models to recognize it (and for other features to evolve, i.e. the u/a low near the azores) to decide what its chances of making it into the western atlantic are. climatologically speaking it's developing far to the east, and its chances of making it across are by default reduced.
there's too much going on to not expect a storm or two over the next few days.
HF 0602z06august


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cieldumort
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Re: nothing active but stuff on the table [Re: dem05]
      #69589 - Sun Aug 06 2006 02:05 AM

http://www.cpc.noaa.gov/products/predictions/experimental/bulletin/Dec97/a48.html

..."The 1997 season reversed the trend of the much above activity from the previous two years, especially in regard to tropical-only hurricanes (Kimberlain and Elsner 1998). It should be mentioned that our models indicated that this very active period would end with the 1997 season. In particular, only one of the three hurricanes of 1997 was tropical-only (Erika). Both hurricanes Bill and Danny were baroclinically-initiated. Bill originated from a tropical upper-tropospheric trough (TUTT), and Danny from a middle latitude mesoscale convective system (MCS). "

My point is simply this. I do not believe that you are applying the term "MCS" appropriately to tropical cyclogenesis - as in your take of Danny. And then again today, clearly, there was a mid-level low that came down with the MCS today.. and through interactions with the upper-level anticyclone over it's southern half, an upper-level low to it's east, and probably some local factors, it has managed to create a surface low this evening that bears watching.


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dem05
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Re: nothing active but stuff on the table [Re: dem05]
      #69590 - Sun Aug 06 2006 02:05 AM

Well, in a case of you said toamto...I said tom-ato...I think I've reached my weather knowledge limit with technical respect to MCS. I just did a little research via google to provide proof of what an MCS was. I guess the meteorologists I know are pretty picky in what they call an MCS, but not all folks in the community are...In fact, a tropical cyclone in itself is defined as an MCS by some...At this point, I'll post some definitions, but will have to leave the rest up to the meteorologists on the board to better explain...Fun talkin' tropics, and development huh? We all learn something here!

Here are 3 definitions via google searches of MCS, there are more though...hope this helps somewhat in ralation to understanding the northern gulf feature (in some way):

1.) American Meteorological Society ( http://amsglossary.allenpress.com/glossary/browse?s=m&p=27 ): mesoscale convective complex°™(Abbreviated MCC.) A subset of mesoscale convective systems (MCS) that exhibit a large, circular (as observed by satellite), long-lived, cold cloud shield.
The cold cloud shield must exhibit the following physical characteristics.
Size: A - Cloud shield with continuously low infrared (IR) temperature °‹ −32°„C must have an area °› 105 km2; and B - Interior cold cloud region with temperature °‹ −52°„C must have an area °› 0.5 X 105 km2.

Initiate: Size definitions A and B are first satisfied

Duration: Size definitions A and B must be met for a period °› 6 h.

Maximum extent: Contiguous cold cloud shield (IR temperature °‹ −33°„C) reaches maximum size.

Shape: Eccentricity (minor axis/major axis) °› 0.7 at time of maximum extent.

Terminate: Size definitions A and B no longer satisfied.

Alternatively, a dynamical definition of an MCC requires that the system have a Rossby number of order 1 and exhibit a horizontal scale comparable to the Rossby radius of deformation. In midlatitude MCS environments, the Rossby radius of deformation is about 300 km.


Definition 2.) k12.ocs.ou.edu/teachers/glossary/m.html : (Mesoscale Convective System) - a complex of thunderstorms which becomes organized on a scale larger than the individual thunderstorms, and normally persists for several hours or more. MCSs may be round or linear in shape, and include systems such as tropical cyclones, squall lines, and MCCs (among others). MCS often is used to describe a cluster of thunderstorms that does not satisfy the size, shape, or duration criteria of an MCC.

Definition 3.) http://www.kfor.com/Global/story.asp?S=254598: Mesoscale Convective Complex (MCC): A large area of thunderstorms (larger than an MCS), usually round or oval shaped, that is about the size of Ohio or Iowa state... lasting for 6 hours or more. They normally form in the afternoon or evening, typically reaching their peak intensity at night. At this time, flooding becomes the main threat. Severe weather (damaging wind, large hail, tornadoes) may occur at any time.

Edited by dem05 (Sun Aug 06 2006 02:18 AM)


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cieldumort
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Re: nothing active but stuff on the table [Re: dem05]
      #69591 - Sun Aug 06 2006 02:29 AM

I'm picky about MCC vs. MCS as well. I thought we were discussing MCS and not MCC ;P

I think we can agree to agree to a point on this one - and watch it either do nothing (most likely) or pull a fast one on the guys at NHC. I remain of the opinion that it would be prudent for them to begin mentioning this feature and track it as a formal Invest. But alas, I am but one observer in the greater sea of opinions

Essentially, what I look for in a season that so far is tending to have a number of systems try to form from non-tropical means, are some good stalled fronts over very warm water, a decent MCS with a substantial mid-level low pushing into the GOM, a potent ULL that is drilling down to the surface, and similar features conducive to further development. Well, the MCS that rolled into the GOM today just fits that bill nicely.


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HanKFranK
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Re: nothing active but stuff on the table [Re: cieldumort]
      #69592 - Sun Aug 06 2006 02:44 AM

geez you guys... vaguely relevant to the topic, but this is some pedantic stuff. its a mesoscale convective doohickey, case closed. haven't seen one generate a tropical system in a few years, so it would be interesting if it could.
would be even more interesting if chris redeveloped. two systems in the gulf at the same time? not an everyday occurence.
HF 0644z06august


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cieldumort
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Re: nothing active but stuff on the table [Re: HanKFranK]
      #69593 - Sun Aug 06 2006 03:19 AM

I have to say, I'm starting to take some interest in the feature off the Carolinas, as well. Not that any of these stand out as some sort of shining example of imminent tropical cycloburstation, of course

However, I think we can honestly say that all is not quiet - things are percolating - and of the four or so that are on at least some degree of radar, odds are that at least one could pop this week.


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cieldumort
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Re: nothing active but stuff on the table [Re: HanKFranK]
      #69594 - Sun Aug 06 2006 06:09 AM

Aw gee, folks. You're all making me out to be the biggest weather geek this early Sunday morning

We do now have Invest 91L - and she looks fairly healthy this morning.

91L over at NRL


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Hugh
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Re: nothing active but stuff on the table [Re: cieldumort]
      #69596 - Sun Aug 06 2006 08:38 AM

Interesting that the pressure in 91L is 3 MB lower than the pressure was in Chris at its next-to-last advisory.
It's probably going to be a fish spinner, at least for the forseeable future. The one computer model up on Skeetobite, GFDL, has the system moving west, than west-southwest, then northwest. The others are up on WU, though, and they have it taking a southern route through the islands for the most part. Definately has a spin on the image loop, but the convection seems to me to be well west of the apparent LLC. Based upon the criteria the NHC used for Chris, we could have TD Four later today.

--------------------
Hugh

Eloise (1975) - Elena and several other near misses (1985) - Erin & Opal (1995) - Ivan (2004)


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FreeportGary
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Re: nothing active but stuff on the table [Re: HanKFranK]
      #69608 - Sun Aug 06 2006 10:31 AM

Quote:

geez you guys... vaguely relevant to the topic, but this is some pedantic stuff. its a mesoscale convective doohickey, case closed. haven't seen one generate a tropical system in a few years, so it would be interesting if it could.
would be even more interesting if chris redeveloped. two systems in the gulf at the same time? not an everyday occurence.
HF 0644z06august




Maybe even three systems at the same time? Look down at southern Bay of Campeche.


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