Clark
Meteorologist
Reged: Wed
Posts: 1710
Loc: 45.95N 84.55W
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Couple of interesting things to watch for out there in the near-future...but I don't think anything out there right now is all that threatening. The feature near the Bahamas has a lot of deep convection, but it is fairly disorganized at the moment and largely driven by upper diffluence. I think once the shortwave trough it is associated with either lifts out or hooks up with a feature projected to cut-off along the east coast, this area will look a lot less favorable. (Having said that, somehow you get the feeling that if this were 2005, it might've popped out here already...)
That cut-off low referenced above and the non-tropical low says may form out of the mess by the Bahamas are the two areas of primary concern in the week ahead, I think. It's not all that often that you see cut-off lows at upper levels dive south along the Atlantic coastline like is widely projected by the model guidance for the next 3-5 days -- it's more of a west coast thing -- but this feature could be a prime candidate for tropical transition in the 5 day time period. As it cuts off, if it can get out over the Gulf Stream, the upper level feature should gradually erode, perhaps leaving behind an incipient low pressure area at the surface under favorable conditions for development. It needs to get reasonably far south (probably SC/GA border) to not be caught by an amplifying trough in the east at later times, though, and have enough time to develop. None of the models are showing any more than a weakness at low levels plus an interesting evolution at upper levels right now, but it bears watching -- it's an ideal, if oft-seen, scenario for tropical transition.
The second one has a bit more model support, but in an odd location. The and (both 00Z runs) show a low pressure system gradually forming out of the mess by the Bahamas, but not for a few days and initially of a cold-core (baroclinic) structure. After accelerating to the east into the open waters of the N. Central Atlantic, however, both of these models show the system trending toward a deep warm core structure at the end of the period (~5 days) per the cyclone phase space. Looking at the output grids, it shows a vertically stacked area of low pressure somewhat cut off from the predominant steering flow. The cold temperatures aloft with the upper level low feature plus the ~23-24C SSTs in the region could potentially lead to a tropical-type of development not unlike last year's features in the north Atlantic, but I wouldn't put heavy odds on it right now. Note that the 06Z showed purely cold-core development out of this one, while the 00Z UKMET didn't really capture anything out there. Still, potentially interesting to watch.
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cieldumort
Moderator
Reged: Mon
Posts: 1643
Loc: Austin, Tx 30.40N 97.80W
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I have to say, I am - a little bit surprised - that we do not have Invest tags up in the vicinities of 21N 96W and also 27N 67W. Both locations now have multiple disorganized LLCs. Admittedly not very impressive at this time, but certainly every bit as impressive as those seen with many other Invests.
Take a look:
SW GOM Disturbance
Bahamas - Bermuda area Disturbance
Suffice it to say, if these features persist overnight, and especially if they also organize just a little bit further, I will *really* be surprised not to see them tagged.
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Hootowl
Weather Hobbyist
Reged: Thu
Posts: 77
Loc: New Port Richey, Fl 28.27N 82.65W
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99L is up.
http://www.nrlmry.navy.mil/tc_pages/tc_home.html
Another one for the fish!
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cieldumort
Moderator
Reged: Mon
Posts: 1643
Loc: Austin, Tx 30.40N 97.80W
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Looks like all it needs is a little more and somewhat *deeper* convection to hold close to and/or over the center to be classified STD, IMHO. Scatterometer really shows off the primary LLC tonight(can be seen here).
Pressures do seem to be dropping (99L was most recently analyzed as 1007MB).
Nearby ship just reported 29.75" at 00Z
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HanKFranK
User
Reged: Mon
Posts: 1841
Loc: Graniteville, SC 33.56N 81.82W
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that thing (99L) is under too much shear and already headed out. the globals show the intense upper cutoff low dropping south and then opening into a shortwave trough and whipping east as the flow becomes progressive again early next week. it doesn't look like the sort of thing that would persist enough to transition.
there are some sharp troughs and cold air outbreaks coming down into the eastern u.s. later this month, but none have the staying power or blocky tendencies that tend to force pressure falls in the tropics. harder to say how things will look later in the month, with the predicted to come east. the look of the pattern is one of an el nino-carved autumn, with strong westerlies and an active storm track from the plains into the northeast. things will have to relapse back towards summer briefly to squeeze another storm out of the basin... hard to see much happening with the current pattern.
HF 2010z07october
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