MikeC
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Saturday (09/30) 11AM Update
Isaac now a minimal hurricane with 65 knot sustained winds - moving to the northwest at 5 knots and located over 650 miles east southeast of Bermuda. Isaac expected to turn more northerly and eventually north northeasterly in advance of a strong frontal system now off the east coast. Isaac, as a strong system, expected to head off into the north central Atlantic and may brush extreme eastern Canada with some squally weather next week.
As September comes to a close, nothing of any real concern going on in the rest of the Atlantic basin. Invest 97L has faded and another wave in the southern Caribbean Sea has weakened. One remaining large wave over Africa at 30/12Z near 12N 6E, however, it may not even make it to the African west coast - the Cape Verde environment has changed and CV activity is over for this season.
Perhaps one more baroclinically induced hybrid before this season ends - but not too much of a chance for even that type of a system to evolve as the SSTs begin to cool and the subtropical jet intensifies. The week ahead (perhaps two) looks quiet.
ED
Thursday Update - 11AM
At 11AM will upgrade TD 9 to Tropical Storm Isaac with sustained winds of 35 knots. The system has moved under a weak upper level low - and manages to survive. The position under the low has actually reduced vertical shear. Movement continues to the northwest.
Invest 97L now active as well as another area well east of the Windward Islands - see the Storm Forum for additional details.
ED
Original Post
Tropical Depression nine has formed in the Central Atlantic, yet another fish spinner.
TD#9 is forecast to move northward, gradually strengthening. Not approaching any US land areas, and staying out to sea. It has some chance to strengthen into a tropical storm, but likely not enough to reach hurricane strength.
This continues the 180 season from last year, if it keeps up we thankfully may very well get through the season without a landfalling US hurricane.
Mike
Hurricane Isaac
Animated Model Plot
Animated Model Plot
SFWMD Model Plot
More model runs on from Jonathan Vigh's page
Visible Satellite Floater
IR
Animated Floater with overlays
Edited by Ed Dunham (Sat Sep 30 2006 12:16 PM)
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Ed in Va
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The storm has two very distinct areas of convection. What bearing would having one or the other becoming the primary one do to the track...anything?
http://www.ssd.noaa.gov/goes/flt/t1/avn.jpg
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Survived Carol and Edna '54 in Maine. Guess this kind of dates me!
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Steve H1
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97L up now for real. I've been watching this since it separated from 09L. This should become a TD/TS in the next 24 - 36 hours, passing through the Leewards today and tonight. Who knows, if it avoids the shear to the NW, it may threaten the SE in the long range. Looking soewhat impressive on satellite. Ignore the old Tuesday plot that's on .....it way off. Currently the Invest is at 18N/60.2W. Definitely something to watch, particularly for Puerto Rico. Cheers!!
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LoisCane
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Hey Steve.
Hard to get excited about TD9 but the Invest by the islands shows potential.
Also, there is a lot of shear out of ahead of it and a diving sort of trough to it's west but...
think that it has pretty much reached it's low point and the set up in a day or two might be interesting.
Either way, it begs watching. It has consistency going for it too.
As for TD 9.. that forecast path is consistent too...
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http://hurricaneharbor.blogspot.com/
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Lee-Delray
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We now have TS Isaac spinning in the Atlantic, but I guess that was predicted. Though I guess 97L, if it turns into Joyce will be the big topic.
Edited by Lee-Delray (Thu Sep 28 2006 11:09 AM)
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LoisCane
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Joyce would be cool... will check out Isaac.. Could clip New Foundland ya know?
Still looks like a big Upper Level Low to me.
Thanks, really would like thoughts on the wave
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Steve H1
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Yeah Lois, Isaac looks like he's destined for the open waters. 97L looks a bit odd right now, but has held together, small as it is. With everything having such difficulty getting organized this year, we can't forget it CAN happen. Ed was also looking the the wave ESE of the Windwards. Its pretty far to the south, but has the structure a something that could develop. If this was 2005 I'd say its definitely a go. But this year i cast doubt on everything. Conditions just haven't been that favorable. But think we'll be getting into a surge of development during the next few weeks. Then bring on the cold fronts!!
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Clark
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To me, Isaac looks definitively subtropical at best, at worst, with the convection displaced to the north of the storm in sort of a "delta" shape and a well-defined feeder band/frontal structure extending to the southwest (coincidentally, 97L is flaring up at the tail end of that boundary). The QuikSCAT passover mentioned in the 11a discussion only clipped the east side of the storm, so it's tough to discern anything significant from that, but based on the current satellite appearance -- I'd have to go with subtropical. However, I've never seen them reclassify a tropical system as subtropical in the middle of the game, so it's likely tropical until they call it . The track guidance looks good and it's one for the fish.
97L is probably one for the fish as well if it gets going thanks to a rather large upper trough along the eastern seaboard. If it doesn't get going, it might sneak into the Florida peninsula and bring some moisture and a chance of rain. Wouldn't worry about it much right now.
The east Atlantic is effectively shut off with a sharp upper trough across the entire basin. Once that thing takes hold this time of year, it's hard to budge. Would bet pretty fair money that we've seen the last of the CV storms for this season.
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Ed in Va
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Clark,
What about the disturbance at 10/50, if it survives past South America?
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Survived Carol and Edna '54 in Maine. Guess this kind of dates me!
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Clark
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I would tend to say it looks like a run-of-the-mill flareup in a region of weak diffluence aloft and convergence at the surface and low levels. There's not much signature of a true wave/inverted V feature in either the 850hPa streamline analysis or QuikSCAT winds (what winds are available, at least). I don't see it gaining much latitude under ENE winds at low levels and think it'll likely head into at least the north portion of S. America. Nothing to worry about, in my estimation.
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cieldumort
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I would really take exception with calling Isaac extra-tropical in nature - certainly subtropical, yes - but, as you point out, is unlikely to go back mid-stream and reclassify it as such -- however, they repeatedly do make references to it's subtropical nature. It reminds me quite a bit of a June subtropical cyclone that went unnamed ( 06/24/2345 UTC 34.4N 51.1W ST1.5/1.5 92L ) -- and certainly if Isaac can be classified as a 40kt "tropical" storm, June's 92L really is deserving of a post-season up to 40 kt subtropical, to say the least, IMHO. They are/were nearly twins. One thing for certain, Isaac is no ULL - not by a long shot.
97L is practically DOA tonight, but I wouldn't write it off just yet, as it has been one tenacious low all along -- especially in light of it's fight with 96L Norte all of this past week. While still looking abysmal, it's weak condition may allow it to slide a little further west just yet - and you know - sometimes all these things need is one good night of relaxed shear and/or notably higher SSTs to pop.
Speaking of ULLs -- really is lots of diffluence-enhanced convection associated with that 25N 32W on it's eastern side - and, there is some reflection at the surface -- I guess personally I will be watching it over the next few days for some slightly possible chance of slow development, just in case -
Real story as of late seems to be the Pacific, once again. All's not quiet on the western front.
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Lee-Delray
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Is 97L a goner? From the 5:30 looks like the is saying so.
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Ed in Va
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Looks like it's on life support. Even if holds together, it should be swept away by the front off FL. Have noticed a little flare-up off Nicaragua(?), but it looks like it's died down some.
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Survived Carol and Edna '54 in Maine. Guess this kind of dates me!
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HanKFranK
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isaac looks like the lesser version of what we've been seeing all september, post-ernesto. the ragged, subtropical appearance it has been exhibiting much of its life has already been duly noted; will be interesting to see if it improves once it gets out of the 'wake' of the previous hurricanes.
97L probably isn't worth biting at. the synoptic environment is giving it a less favorable shot than isaac (and isaac isn't really there by much), and it hasn't been as convectively active as before. it'll probably become indistinct as it drifts westward-wnw.
probably the best shot at a next system is the deep layer low developing south of the azores. i know, why not another east atlantic fishspinner, right? the globals have it cut-off from the westerlies over marginal waters, sort of stuck under a tilted rex-block most of next week. it'll develop a surface reflection... at least isn't showing much warm-core transition, but that sort of thing isn't uncommon.
for october... in spite of some sharp amplifications in the east, the kind of deep longwave trough that needs to drop in for a few days to get the caribbean cranked up doesn't appear in the offing for the near term. there is something like that happening around next weekend, and in spite of lowered pressures the models (at least the ones i've seen) don't show much out of it. it's likely just a tad too far east, as heights will remain high centered over texas... that sort of pattern usually causes anything that were to develop to just zip westward rather than come up.
big typhoon in the south china sea that ripped through the central phillipines is driving westward towards north/central vietnam right now. the westpac is active.. until something sputters up in the eastpac, we're probably going to be under the influence of quiet unless an october cut-off or pattern-induced type storm gets going. african waves are quieting down. with the already mature autumn pattern we're in, i'm not expecting much more activity, unless things really jam up somewhere, or the subtropical ridge makes a brief summer-like resurgence.
HF 1525z29september
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Lee-Delray
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HF
Might be a stupid question, but does an "Indian Summer" warm up in October effect storms off the east coast of the US?
I also note that Dr. Masters in his blog seems to be leaning the same way for October, with not much activity.
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Clark
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Isaac is looking better now, though I would still argue it was more subtropical than tropical yesterday. It's sort of lived an odd life, with tropical origins, finally getting going with an upper-level boost, then working out of that back to more of a tropical state. Goes to show that not every storm is quite alike.
I won't disagree that yesterday's Isaac looked a lot like that early season feature along the eastern seaboard and I wouldn't be shocked to see a very short subtropical lifespan added in the post-season report, but I also wouldn't be shocked to see it not added either (more likely IMO).
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Lee-Delray
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From the :
Shower activity associated with a weak area of low pressure just north of the U.S. Virgin Islands has diminished.
Good news to start the weekend.
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cieldumort
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It does appear as of this afternoon that Isaac has just about worked out the last remnants of being essentially subtropical, and does now forecast Isaac to become a hurricane. Nova Scotia may want to pay attention just a skosh, as the track has been shifted a bit left, as well. Looks like Isaac may not be out to just spin fish, and with his mechanics being partly ULL/cooler upper-level temperature -induced, he may still surprise a little on the upside like an Epsilon-type of animal. Being that the large-scale features in the states are now very much more like mid to late Fall, this really would not surprise me.
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SebLouis12
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Unless something forms very close to U.S., I.E. Florida,or Gulf Coast States Our U.S. Hurricane Season Is Over, Never Really Began. Something like that would probably stay weak, and not even be too major of a problem. Anything else in the east or central Atalantic should hook up and out. Fronts comming down should be our real concern at this time, we'll see what the next several weeks hold. The way I see it, any other opinions?
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Ed in Va
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I think you've got it. Looks like the remnants of old 97 are showing a little life south of the DR this am. If it holds together, it could remain far enough south to avoid the EC troughs and develop.
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Survived Carol and Edna '54 in Maine. Guess this kind of dates me!
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cieldumort
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Upper level setup is brutal along the east coast and in the GOM - and looks to stay that way for a little longer. Some models keep wanting to lower pressures rather substantially in the Caribbean over the next seven days, so there might be something trying to coalesce down there. I can no longer make out the surface low which was being tracked as 97L, and all that is left is the tail of old 96L, now essentially free of Isaac, and getting chewed-up today by shear... although in the meantime the diffluence is enhancing a few of it's showers. I might not write off the wave mentioned above coming off Africa - just yet - as it is a very healthy one , and does look as if it will survive the trip all the way to the coast, afterall.. but the environment is a changing. I would be shocked if we do not see at least 2 more named systems before the end of the year, but the trend this year has indeed been to steer them well away from the states.
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Lee-Delray
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It seems that Dr. Grey's team was only off by 1 storm for September (97L took a run at it). He was also right about the intense hurricanes (2).
What will October bring? 
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HanKFranK
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two named storms, one hurricane was the earlier prediction for october given by the colostate guys. i'd expect them to hang their hats on it again.
isaac is beginning to depart rapidly... obviously feeling the advancing upper trough in a big way now. it came further west than the last two, but not florence. might nick newfoundland on the way out, though, which is more than any of the others that formed during september managed.
the deep layer low out in the eastern atlantic hasn't developed cleanly like some of the models are showing, and resembles more a typical upper trough. it's southern shear axis extends down to the region around 40w, which will probably chop up the rather impressive tropical wave just past the cape verdes. it's fairly normal for a feature like that to block/shut down the CV source region around this time. there's a frontal tail stagnating near the bahamas, but not a whole lot of mid-upper vorticity getting left behind to fester. we're probably back to an empty ocean when isaac departs.
we've had close to the long-term average season so far this year in the atlantic. the eastpac has been a little quiet and isn't terribly likely to generate more storms. a 'real' el nino signal would have enhanced things over there a bit. leaves me wondering if the reasons for our low activity in this historical period aren't due to simpler things, like longwave pattern with strong ridging over the continent/trough in the western atlantic, the stronger SAL, enhanced , and lower latitude of the subtropical ridge. SSTs sure weren't the problem (near and above normal over large expanses of the tropical atlantic).
HF 1656z01october
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Cat 5orBust
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Jeff Masters and Accuweather have both mentioned the disturbed area around the Bahamas along the old front might possibly develop later in the week or into the weekend. Dr. Masters mentioned if it did it would move NE out into the ocean, but wont the high pressure be in place still off the southeast coast and wouldnt that push it back to the west or SW or will the high be gone by then? That area has persisted for several days now.
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Ed in Va
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It does look like something is trying to take shape:
http://www.goes.noaa.gov/HURRLOOPS/huirloop.html
With the track record of this season, I think the odds are strongly against anything
but a quick recurvature.
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Survived Carol and Edna '54 in Maine. Guess this kind of dates me!
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cieldumort
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I'm not very impressed with the frontal remnants along the east coast. Lots and lots of shear. Shower activity is being deceptively enhanced by the upper-levels, without much chance, if any, of coalescing into a depression of any tropical nature at the surface. Maybe conditions become more favorable later in the week, but for now I really think it's a non-starter.
More likely in the nearer-term I think the deeply-stacked non-tropical low centered near 30W 30N looks to have a shot of becoming at least subtropical over the next 72 hours, or so. Also, models still want to bubble something in the southern Caribbean. There's also that low near 10N 33W, but for now upper-level winds are not treating it kindly.
Unless one of these pops by the end of the week, I would think Isaac might be it for a bit.
I've got to amend my comment on 30W 30N - the more I've looked at the loops this afternoon the more I believe it is already on the precipice of being a subtropical storm. Speaking of which, has the 98L tag up at 30 knots.
Edited by cieldumort (Mon Oct 02 2006 06:21 PM)
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allan
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hmm wouldnt bet on Isaac as the last storm of the year.. In fact not for sure but the has a Carribean storm on the loose in 2 weeks. Way far to tell right now. Though whats not far to tell is a Possible Kirk off the east coast by 144 hours as every Global Model is developing it. Joyce should but may not be the sub-tropical feature near the azores. Thats not looking as good as it did yesterday. had that wave off of Africa going but since Isaac is gone can't really tell. It's really been a usual Hurricane season. We did beat 1997 as they only went up to Grace. Though really start watching stuff closer to home and people for the last time...... It's not over yet so please don't say its done. " Remember " ... It could happen again. 
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Allan Reed - 18,9,5
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HanKFranK
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gray doesn't think it's done. two more, one a hurricane, is his plug. sounds about right.
the subtropical-wannabe out south of the azores isn't really developing a sound surface low. the upper trough remains too sharp for hybridization of the system, as it can't keep a convective region going. that's going up and out in a couple of days.
closer in most of the globals have an interesting feature off the southeast... basically an inverted trough responding to passing shortwaves, spitting a low up towards the mid-atlantic that gets blocked and cyclonically whipped around offshore. it'll be under a whole lot of southwesterly shear most likely, so chances of a tropical development aren't very high.
there are still tropical waves crossing the basin, and one could still develop into something if one of those autumn highs drops in and forces a 'rebound' from the tropics... but the quick transit and pacific-type airmasses that are dominating north america don't usually set such things into motion. next time the pendulum swings, it could still happen. is still cooking up caribbean mischief, but that's a model pipe dream for now.
our rather mundane hurricane season this year really illustrates how intense the run of the last two years has been.
HF 2139z03october
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cieldumort
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I would actually submit that the feature now out near 32N 31W was a subtropical cyclone yesterday - but a subtropical storm most likely not meeting the subjective requisites usually followed at . (There have been quite a good number of alternate definitions of what should and should not be included in the count when it comes to subtropical storms, and of course perhaps someday considers these and adjusts accordingly, but for now it never seemed to "have it." ) Still, in a nutshell, for the better part of 18 hours, even in the absence of especially deep convection near the center, there was some deepish convection at times - and also numerous 35-45 knot vectors *classically* between 40 and 100 miles from the coc.
With the old LLC clearly washed out as the parent upper and mid level circs drifted north over cooler waters, this afternoon a new LLC has formed much closer to 29N 34.5W, with some notable convection building in the region of this new low level center. The new low level center is clearly identifiable on the 2034Z QuikScat. Given the very unfavorable upper-level winds throughout the basin, I don't give this new 98L-related feature much chance, but it could pop, especially if the upper-levels just relax long enough to give it a fighting chance.
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dem05
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Some further Study is required of this feature on my part here...However, the Bay of Camp. is an area of reference in my mind now. Generally, there is ridging western half of the GOMex/BOC. The wave in the BOC seems to be demonstrating some slight promise and curvature is growing with and orientation that is now NNW to SSE (Link: http://www.ssd.noaa.gov/goes/east/gmex/loop-ir2.html ). As far as the models...severalon the site are showing at least some weak vorticity and slinging it westward into the Mexican Coast. Based on history, this is a true possibility. However, the amplified troughing pattern may make things interesting in the US if something pops up.
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Hurricane29
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Things could get somewhat interesting in the next week or two as the Pulse makes its way into the Gulf of Mexico and parts of the caribbean.
Here is a pic of the threw Mid- October. BLUE areas mean upward-motion which is greatly needed for tropical development.
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HanKFranK
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nice contribution H.29, i'd like to know where you snagged that image. that more or less coincides with the feature is trying to make in the western caribbean. contrary to what i was expecting this month the ensembles are keeping a persistent max on the subtropical ridge near the southeast through mid-month. in other words, steering could be such that a tropical cyclone down there would come north to the vicinity of florida. haven't been keeping track, but the 'look' of the basin makes me think we're under the positive (inhibiting) part of the wave... and that the westpac is currently under the negative part. with it forecast to go negative here later this month, that would make some sense.
last time we had an el nino (aside from the weak/overshadowed one in 2004), during the end of the 2002 season... things ended sort of early. kyle and lili persisted into october, and the last system was the season's 14th depression in the northwestern caribbean that never really got going, got munched by the shear monster.
HF 0629z04october
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stormtiger
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interestingly enough attributed drier air at the mid levels for limiting the tropical storms that formed in September. He noted that the shear monster was below normal.
He did note the unusual rapid increase in the El Nino and that was to play a major role in this October, but the way I took it was that the El Nino did not play a major role in August/Sept.
Comments welcomed.
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Steve H1
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Things could get interesting indeed. Globals showing development in/near the Bahamas in the short/medium range. Still a lot of shear, but some baroclonic forcing could allow development. , and UKMET showing a low there near the islands, with the moving it into south Florida. GOM looks like it could produce something, and a nice circulation is developing well to the SW of 98L. If the phase brings more favorable conditions, there could be a solid round of development during the next couple of weeks. Not over yet. Cheers!!
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allan
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Yes things are yet again starting to look interesting. the so called "blob" eats of Florida I think is the low the , , and UKMET is trying to get going. Accuweather calls it a nor'easter (coastal storm) Though I believe the models are right, It may not be just non tropical. Accuweather has been proved wrong alot of times this year so I really can't buy what they say much. now has the "carribean storm" in 2 weeks heading in the Gulf. Again still is a 1 out of 100% as of now for this actually happening. Though they do see the going on there. It's been an unusually quiet season but it deffinatly is'nt over yet.
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Allan Reed - 18,9,5
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cieldumort
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I guess I have to concede improving interest in the persistent batch of showers and thunderstorms to the northeast of Cuba. While upper-level winds are still rather unfriendly, they appear to have come down a bit to levels that I suspect "could" allow something to slowly take hold at the surface. Indeed, thunderstorm tops have cooled to below -60 today, and perhaps someone else with more patience than myself might want to watch the loops on zoom for a bit longer to correct me if I'm just seeing things, but I can just make out two short-lived, small, embryonic low level swirls in that whole mess. Perhaps over the next few days the environment improves further and it pops, afterall. The western GOM/BOC still strikes me as having less of a chance in the nearer-term to gel, and convection there has been far less intense, but there is at the very least an obvious surface trof in the area.
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Clark
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The models that are showing any development in that region are showing purely development, per the cyclone phase space, except for the (which has a known bias with trying to develop false warm core/tropical structures). With a shortwave trough in place now and more of one projected to develop along the east coast into the weekend, it's not likely conditions will be condusive to tropical development except in the very short term. Possible to get a circulation going, sure...but likely non-tropical in nature.
The Gulf of Mexico area is mostly just an area of diffluence aloft leading to convective development. A weak upper low in southern Texas has been the culprit for this, with some weak ridging aloft in its vicinity. It probably has a better environment in the short-term, but no models are showing any surface development and the conditions favoring its existence may well not last much longer.
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HanKFranK
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felt a little dumb about the comments on how the coastal low at the end of the week would organize. yes, there's a tropical connection, but the u/a charts i looked at later showed it originating from a vigorous low aloft moving off the continent. it gets cut off to a degree and rotates around the base of a mean trough along the east coast, so during this time it could make a brief run at hybridization. there's also a little question about what the surface trough to it's southeast does... probably just end up being a frontal trough on the low.
the 18Z is now showing a precursor to the mid-month tropical low from the western caribbean that we've been talking about. as the coastal low is making its rounds this weekend, a disturbance is shown tracking over the yucatan, festering on the tail of the frontal trough, and then zipping northeast along the baroclinic zone past southern florida. this doesn't appear to be particularly tropical in nature, and anything in that area will have some shear to contend with. but, worth noting that most systems you'll see when el nino's influence is there intensify while moving northeast. the later month system is being shown a bit further east than yesterday and if such were the case it would likely track more for eastern cuba and the bahamas, rather than take aim on florida.
H.29 sent me the link to that graphic he posted the other night. it shows the basin becoming favorable right around/after mid-month. don't really know how reliable it is, but the favorable/unfavorable dipole between the atlantic and pacific is easy to pick out, so i'd reckon it's on to something.
HF 0101z05october
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dem05
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I dunno...Looking at the 18Z ...I See a small, yet strong tropical cyclone making landfall in SW Florida (Ft.Myers-Naples) in 7 days. I'm wondering if you are looking at a different grid run version of the or something. The one I'm posting is the vesrion which covers the . Maybe yours is not this run, but I'msharing what I'm seeing. Link: http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/index_slp_l_loop.shtml
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cieldumort
Moderator
Reged: Mon
Posts: 1068
Loc: Texas 30.40N 97.80W
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My interest in the region northeast of Cuba (really in an area in and near 27N 67W) continues to percolate and percolate overnight - Yep, keeps using the "UPPER-LEVEL WINDS REMAIN NOT CONDUCIVE FOR FURTHER DEVELOPMENT" disclaimer, but shear in the immediate area had dropped to as low as 30 knots Wednesday, and now appears to me to be under 20 in spots early this predawn. More impressively, *deep* convection really exploded overnight. I won't hold my breath, but I will nonetheless be looking forward to daylight loops for any significant suggestion of a persistent and noteworthy LLC having formed overnight. This region could be closer to popping than we have given it credit for.
The < 20 knots of shear is supported by the most recent CIMSS shear analysis.
CIMSS also supports some 850 hPa vorticity in the region, as well.
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Clark
Meteorologist
Reged: Wed
Posts: 1710
Loc: Great Lakes 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.
--------------------
Current Tropical Model Output Plots
(or view them on the main page for any active Atlantic storms!)
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cieldumort
Moderator
Reged: Mon
Posts: 1068
Loc: Texas 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: 1068
Loc: Texas 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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