MikeC
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It appears the quiet end of week may be ending, as mid August starts to roll in, the activity hinted at earlier for this week is already starting to show up in the form of two waves in the central and eastern Atlantic. Now starts the time of year where the models can be used a bit more, and many show strong development later in the week.
One of the waves already has the invest designation (92L) the other not yet (But may soon)., and these both are worth watching over the next few days, and indeed it is possible to have one or more named systems in the Atlantic sometimes this week.
More to come as it happens... Those in the Lesser Antilles, especially the Leewards, will want to keep a close eye on 92L. Longer range models suggest it may be something the mainland US has to watch later on as well.
What do you think this system will do? Take a guess in the 92L Lounge.
- Mike C
There are some intriguing changes suggested by the balance of the Global numerical models, regarding the orientation of the long wave features from the Pacific, across north America, and into the western-central Atlantic at mid latitudes.
Currently, the North Atlantic Oscillation is rising very fast; it has recovered nearly 1 Standard Deviation in just less than a week, and continues to rise. The 7 and 7-10 day outlooks regarding this index suggests that it will rise to approximately +.5 SD, or a total recovery of nearly 1.5! Normally in the summer time, subtle changes in this index will have less correlation to patterns at middle latitudes, do to a typically more nebular flow (short wave lengths among a weaker gradient field). However, we have been running along with anomalously strong gradients this summer, which has kept both the wave lengths a bit longer than usual, but also has provided for steeper gradients in the overall geopotential medium. If you understand the NAO (read primer above if you do not), a positive NAO correlates to a strengthening of the subtropical ridge in the western/central Atlantic Basin.
In simpler terms, the flow thus far this season has been more amplified than normal, and that opens the suggestion to being more sensitive to changes in the NAO. That said, a 1.5 modality in the index is fairly significant during any time so one would expect a flow morphology away from the recent eastern N/A trough plague, to take place at middle latitudes. What we are seeing is, thus, a retrograde in the trough axis longitude, to roughly the Great Lakes and Mississippi Valley areas, for the middle and extended range - again, a pleasing fit for a rising NAO. This opens a lot of questions and concerns regarding longer term steering fields, to put it conservatively.
This is important because as we head into what appears more and more likely to be an active period in the 2008 hurricane season, we would like to have some intuitive idea on what that may mean, and for whom. The strengthening plausibility in the subtropical ridge nearing mid month is physically being modeled by most operational Global numerical models, but also in their ensemble means (which makes sense in the latter for the , considering that the NAO index is computed off the ensemble mean). That is why seeing these waves develop and push mightily in to the Puerto Rican archipelago and/or Caribbean and Bahamas should be raising eyebrows.
Another clue as to the potentially active interval nearing in this season is the related 200mb level vertical velocity anomalies. We can see that the entire Basin has lost the DVM (Downward Vertical Motion) anomalies, and has replaced the region by neutral to UVM (Upward Vertical Motion) potential. This upward motion is a reflection of strengthening anticyclonic motions in the upper levels, and the restoring force for outward motion at those levels is upwelling as a mean tendency - hence the UVM anomaly potential.
What all this means in totality is that, yes...INDEED, things should be getting active in a hurry. It would not shock this Meteorologist to see several concurrent cyclones generated during the next 2 week interval of time. And, it wouldn't be too absurd to at least consider threats to the Islands and Mainland of the U.S., given the fairly obvious paradigm shift in the pattern as discussed above.
John (TT)
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typhoon_tip
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...Moved to Main Page...
John (TT)
Edited by typhoon_tip (Sun Aug 10 2008 01:59 PM)
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craigm
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Very interesting post TT. I'll have to read it a few more times to understand some of it but that is what this site is all about. Any info on T #'s for 92L. It seems to me that it is evolving rapidly. Conditions must be perfect. I think this could be another invest thst skips TD stage. Sorry if that last line belongs in the forecast lounge.
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Edited by craigm (Sun Aug 10 2008 12:38 PM)
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typhoon_tip
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If you have any specific questions/comments, feel free to PM me and I will explain things (hopefully) in a way native to your understanding.
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HanKFranK
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Odds pretty good that 92L is going to be Fay.. maybe late tomorrow or Tuesday. The Pacific-Atlantic response seems to be wasting no time. Tip just covered all of the gory details of the (spectacularly) bad omens in the tea leaves . All I'll add is what my take is on the current invest, the one in the on deck circle, and/or the guy in the hole.
92L--reckoning best bet of a Monday depression, Tuesday storm. System is sprawling and not totally detached from the active section of .. should consolidate slowly at first. Maybe a good burst of intensification on Wednesday, but the u/a environment (read, ) looks like a rusty old barbed wire fence up ahead. System gets to the Lesser Antilles Thursday, probably as a mid/high-grade tropical storm, and probably has a close encounter with the larger islands after that. I'm maybe eighty percent on it developing, fifty percent on it surviving past this point. In spite of the hugh upper trough over the east, a fairly strong western extension of the ridge from the Bahamas east should hold it down from recurvature. If I had to make a long range bet on where it ends up... Gulf of Mexico, week after the one we're starting. At that point the trough over the east is fragmenting and filling, and ridging is nosing into the western Atlantic, so it's hard to say exactly what environment it is in or what is driving it.
Next guy/Last guy--I don' t know exactly how the system will emerge or what it will look like exactly. If I had to bet on the second area the has highlighted, would guess that it's almost part of a monsoon trough feature on the , and that the larger wave to the east will overtake it. Regardless something should consolidate out of that area, and develop like one of those huge-sprawling, slow-revving systems. I'd expect this one to be a large, long-track hurricane. Should track more to the north, but still come grazing the Lesser Antilles around the start of the following week... and have a huge, swelling ridge to the north. It isn't set in stone yet, but there's a good probability that cut-off troughiness in the Mississippi/Lower Ohio Valley, with u/a ridging consolidating over the Northeast/Mid-Atlantic, could drive this system into the East Coast late that week. Mind, I'm talking about just beyond ten days from now... this is speculative and will require a couple days more of model runs to really take seriously.
In the shorter term, something that will affect the timing is whether this feature comes out of the feature or the wave further east. The tropical Atlantic is crowded with the waves stacked close together. Expect some interaction/destructive interference if more than one system tries to develop. Also expect the stronger waves that emerge to also try to develop. We should have at least 3, maybe as many as five or six more storms develop before August is out.
HF 1720z10august
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Mike V
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Quote:
Next guy/Last guy--I don' t know exactly how the system will emerge or what it will look like exactly. If I had to bet on the second area the has highlighted, would guess that it's almost part of a monsoon trough feature on the , and that the larger wave to the east will overtake it. Regardless something should consolidate out of that area, and develop like one of those huge-sprawling, slow-revving systems. I'd expect this one to be a large, long-track hurricane. Should track more to the north, but still come grazing the Lesser Antilles around the start of the following week... and have a huge, swelling ridge to the north. It isn't set in stone yet, but there's a good probability that cut-off troughiness in the Mississippi/Lower Ohio Valley, with u/a ridging consolidating over the Northeast/Mid-Atlantic, could drive this system into the East Coast late that week. Mind, I'm talking about just beyond ten days from now... this is speculative and will require a couple days more of model runs to really take seriously.
sorry to quote the entire thing, but looking at the run, it bears this scenario out exactly.
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typhoon_tip
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Quote:
sorry to quote the entire thing, but looking at the run, it bears this scenario out exactly.
The 12Z Canadian model is very ominous for Florida and much of the SE Coast! By D6, it has the appearance of a Cat 1/2 hurricane entering the SE Bahamas, moving WNW in a favorable deep layer environment. This is an evolution of 92L into a mean looking system with potential to become powerful if taken verbatim - which of course is something we should never do!
However, although not as intense, the 12Z UKMET run has virtually identical TC system placement with both 92L and the trailing developing system, as the Canadian. Interestingly, the does not like 92L much...It instead develops the trailing system mightily into similarities to Hank's discussion regarding the particular system. They did not apparently run the for 92L on the 12Z run, which is disappointing and actually odd that it was not.
Edited by typhoon_tip (Sun Aug 10 2008 03:05 PM)
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rmbjoe1954
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I hope this doesn't bear out like August-Sep 2004, but I believe that 92L (and the follwo-up 93L) may repeat history. I understand that the Bermuda High will become dominant thus increasing chances for a hit on . By wednesday the models should bear watching.
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ltpat228
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Quote:
I hope this doesn't bear out like August-Sep 2004, but I believe that 92L (and the follwo-up 93L) may repeat history. I understand that the Bermuda High will become dominant thus increasing chances for a hit on . By wednesday the models should bear watching.
93L?
It is now 4:21PM EST as I post this, and no where do I see any information regarding a 93L.
Would you please provide that link so we can all see what you are viewing?
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Hugh
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93L?
It is now 4:21PM EST as I post this and no where do I see any information regarding a 93L.
Would you please provide that link?
The 8am and 2pm s mentioned two systems with an "orange" status... the one furtherest to the west is currently designated as 92L. The one further east is the one that will likely be 93L.
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Hugh
Eloise (1975) - Elena and several other near misses (1985) - Erin & Opal (1995) - Ivan (2004)
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craigm
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I just pulled this off of the site --
TROPICAL STORM DEVELOPED IN THE MODEL ANALYSIS AT POSITION :
10.5N 43.4W
VERIFYING TIME POSITION STRENGTH TENDENCY
-------------- -------- -------- --------
12UTC 10.08.2008 10.5N 43.4W WEAK
00UTC 11.08.2008 11.2N 44.4W WEAK LITTLE CHANGE
12UTC 11.08.2008 11.5N 46.9W WEAK LITTLE CHANGE
00UTC 12.08.2008 12.1N 48.9W WEAK INTENSIFYING SLIGHTLY
12UTC 12.08.2008 12.8N 51.3W WEAK LITTLE CHANGE
00UTC 13.08.2008 13.0N 54.2W WEAK LITTLE CHANGE
12UTC 13.08.2008 14.7N 56.5W WEAK LITTLE CHANGE
00UTC 14.08.2008 15.4N 58.2W WEAK INTENSIFYING SLIGHTLY
12UTC 14.08.2008 17.7N 60.5W WEAK LITTLE CHANGE
00UTC 15.08.2008 18.6N 62.3W WEAK LITTLE CHANGE
12UTC 15.08.2008 19.4N 66.5W MODERATE INTENSIFYING SLIGHTLY
00UTC 16.08.2008 21.2N 68.0W MODERATE INTENSIFYING SLIGHTLY
12UTC 16.08.2008 23.6N 71.4W MODERATE INTENSIFYING SLIGHTLY
If I'm not mistaken 92L has already been upgraded
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cieldumort
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92L has not been upgraded. The above post of plots and intensities are merely forecast points, and may use an initialization that is more than a bit bullish.
Invest 92L has quite a ways to go before it can qualify as a Tropical Depression.
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danielw
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Those plots look like the EURO or UKMET tropical output. It's the only model I know of that classifies the intensity of the system. So that should be the 12Z or 18Z model output from today.
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Storm Hunter
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well the 8pm got a little more aggressive. 3 areas of weather to mention.. the first one is now red... greater then a 50% chance of development in the coming days... i not sure about all three.. i say two out of the three areas could develope... (1 and 3). I expect will have a busy week coming up... and 92L should flare up late monday/tuesday... curious to see how the dust is doing out there?
http://www.nhc.noaa.gov/gtwo_atl.shtml
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spinup
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three areas of interest so close together . . . whew!
can someone tell me please; in general, within what dimensional proximity can 3 healthy systems co-exist and potentially thrive?
http://www.nhc.noaa.gov/gtwo_atl.shtml
Edited by spinup (Sun Aug 10 2008 10:05 PM)
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typhoon_tip
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three areas of interest so close together . . . whew!
can someone tell me please; in general, within what dimensional proximity can 3 healthy systems co-exist and potentially thrive?
http://www.nhc.noaa.gov/gtwo_atl.shtml
Those highlighted regions are to bring notice to the potentials, respectively, for each one to develop, not so much whether or not we will have 3 systems at the same time. I do think it is possible that we will have multiple systems to track ...heck, that already the case with these waves in an overall favorable arena. If any one of these develops over the next week is of higher probability; whether or not there are 3 in such proximity to one another, that's an entirely different probability. There are plenty of years in the data set where we have seen train-style TC spin ups, though. It is not impossible to get that again at some time or another.
Edited by typhoon_tip (Sun Aug 10 2008 11:18 PM)
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LoisCane
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Dust is spotty. There but no different than the way it's been.
http://cimss.ssec.wisc.edu/tropic/real-time/wavetrak/winds/m8g10split.html
You can toggle back and forth and see how it changes over 3 hours and amazingly you can see a lot of changes in just 3 hours.
As for the lead wave/invest.. it's spinning but not carrying a lot of convection.
http://www.ssd.noaa.gov/goes/flt/t1/sloop-avn.html
If it weren't for the models jumping on it I would think it will just break up the dust and the dry air and the waves behind it will develop but looks like the has confidence in it's abilities. Keep watching.
Either way these set of waves guarantee that our part of the world is going to have to worry on the tropics a week or so down the line. Might only be worry but they aren't curving out to sea so fast.
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cieldumort
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It seems to me that an appreciable ramp-up in Atlantic tropical cyclone activity is looking more and more plausible. Looking over loops from around the globe this weekend it could actually be said that to some degree all of the major northern hemispheric basins are firing almost in concert, with the Atlantic still possibly being held back primarily by continued intrusions of very dry, stable, dust-laden air coming off of the northwesternmost parts of Africa and maybe the southwesternmost portions of Europe.
The well-developed tropical wave (Invest 92L) already has very solid cyclonic flow in the lowest layers of the atmosphere (including the surface).. Dust surrounds the system, and it might end up being the wave that "takes one for the team," as several more waves are ready to march on through the same general area during the upcoming week. However, given that it has another two or so days, at the very least, in which to travel across very warm ocean waters and within in a lower shear regime, it could easily pop. Even allowing for still unforeseeable interactions with a nearby wave, 92L should have a somewhat favorable window for further development.
When it comes to track, as well as intensity, I have already tossed Sunday's model runs out, for now. Using them, one might be placing 92L well north of the Northern Leewards as a potent cyclone, and/or washing out completely by mid-week. Neither of these two scenarios looks solid enough to base any conclusions off of, as 92L has been held in check, and steered mostly along with the low level flows out of the east throughout the day Sunday. Probably best to hold out on buying much into any of the runs until - if - we get some convection actually sticking on its bones and/or a couple of recon flights into the puppy.
Other interesting features: Southern Caribbean - Disturbance which had originally been bubbling up primarily on the other side of Panama has been pulled a bit northward tonight, and with the aid of some diffluent airflow aloft, deep convection looks to be forming on along and maybe north of a weak surface trof in the area. Never something I take my eyes off of, but there is some hostile upper level wind to its north to contend with, if it continues on that way. And then, two disturbances right behind 92L - either one might find the atmo much more to its liking in the wake of 92L.
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scottsvb
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I'll be kinda brief on this, but I have seen this year the models after 72hrs been off on strength of a system this year, especially the . Tracks have done well, but time after time again we see a hurricane in 96-144hrs and it doesnt happen or its delayed. Eduardo was a exception but also home grown and the models probably had a better idea on something forming closer to home.
Until we get a TD, I wouldnt say or think how strong a system will be. After 72hrs module runs seem to change dramatically in strength a system might get, they might of shown a hurriane in 96 hrs but almost nothing 2 runs later.
Right now with 92L, it may never develop into more than a weak TS if at all due to dry air! Same with 93 L as dry air gets between the 2 systems. I think 92ls chance is better after 5 days in the S.E Bahamas., but dont believe the models strength after 72hrs.
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