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Atlantic Tropical Action 2011 - Part II


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They have become helical convective vortices (HCVs), the paper is in internal review and heading for AMS review within a month. It ends up they're not really related to standard PBL rolls at all, they seem to be generated by bouyant forcing combined with the shear profile of the HBL, which leads to a DNA-esque flow structure. They may be important in understanding VHTs, since where HCVs meet the eyewall updraft and turn upwards is where you find the VHTs. Essentially, HCVs may be the mechanism by which high vorticity and low angular momentum air is injected into the eyewall, which is what VHTs are proposed to do.

That's great to hear that you guys are making the connections to hot towers. This then also ties into past ideas that wind shear and the subsequent internal dynamics (buoyancy and shear from HBL producing helical vorticies) are more important than a hot SST bubble for HT production; although, obviously, they are all important factors (SST=buoyancy). This all almost sounds a lot like tornadogenesis, when you described the upward tilting HCV as it meets the eyewall. ;)

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I am encouraged that the GFS continues to advertise a pattern change for the Western Basin. That model does suggest the MJO influence will provide for an environment conducive for possible development near the BoC.

post-32-0-34590300-1308673750.gif

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i dont think anyone would argue that an east coast landfall is promoted with a north or nw flow aloft over the east coast. clearly, the preferred pattern is a west atlantic ridge with a trough about 500 miles further west than it is now. that would steer storms into the coast, not away. there are numerous examples of this. floyd is a super example. the ridge steered in west to just off florida, then it got caught up in the southerly flow between the ridge and trough west of the appalacians. to srains point. the far greater number of US landfalls occur from close in development, including the gulf coast. close in development is near impossible with this current pattern. its far more likely with a strong high locked in over and east of new england. high pressure to the north facilitates lower pressure to the south. we have had a couple of possibilities so far this june in the west carib, but when i saw the overall pattern i felt it was unlikely.

Great post. So very true of what you speak of. You need a good pattern to get a tropical cyclone to not recurve out to sea and that pattern has not set up as of yet, but yet it could of course can change. Case in point is during the winter the east coast was cold and snowy and west was warm, but that changed, so could the pattern over the Atlantic. No season is all one pattern, so it could change later on, but some seasons can lock in like last season. That is what rainstorm is afraid of. It is all a wait and see, but rainstorm has a point.

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Great post. So very true of what you speak of. You need a good pattern to get a tropical cyclone to not recurve out to sea and that pattern has not set up as of yet, but yet it could of course can change. Case in point is during the winter the east coast was cold and snowy and west was warm, but that changed, so could the pattern over the Atlantic. No season is all one pattern, so it could change later on, but some seasons can lock in like last season. That is what rainstorm is afraid of. It is all a wait and see, but rainstorm has a point.

Fascinating stuff, spot on post. So the patten can stay the same or switch from this point on...got it.

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that shows the strong nw flow over the east coast and west atlantic that has dominated june. that has to change.

http://www.accuweather.com/us/radar/r1h/korf/radar.asp?play=true

just a radar shot, but it shows once again the powerful nw flow that shows little sign of relaxing.

Your posting privileges have little chance of relaxing before Oct 1.

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The 12z Euro shows it Ed, just suppressed very far south in the BOC

msl_uv850_z500%21Wind%20850%20and%20mslp%21168%21North%20America%21pop%21od%21oper%21public_plots%212011062112%21%21chart.gif

Yeah, I guess I can see a tiny closed isobar and a small area of ~30 knot winds at the 850 mb level, but the 500 mb height field shows little, and any TC worth its salt has a 500 mb reflection. The GFS 500 mb closed low at Hour 180 is small and unimpressive, but the GFS still has a 500 mb reflection for its forecast cyclone.

Edit to add Euro 500 mb heights...

msl_uv850_z500!Geopotential%20500%20hPa%20and%20Temperature%20at%20850%20hPa!168!North%20America!pop!od!oper!public_plots!2011062112!!chart.gif

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I'd edit to add, but post is big enough. I know Adam isn't a giant fan of the GFS ensembles, but between the GFS showing something, several other global models showing something, and the ensembles at 180 hours showing mean pressure below 1008 mb in the BoC, a less than impressive European, and not unfavorable MJO conditions based on GFS and GEFS, I'm not ruling anything out. Or in.

I'd feel better if the Euro was in, and CMC and NoGaps not my favorite models, but I'm a natural optimist, and a one quarter glass full silver lining kind of guy,

spatial_olrmap_full.gif

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I'd edit to add, but post is big enough. I know Adam isn't a giant fan of the GFS ensembles, but between the GFS showing something, several other global models showing something, and the ensembles at 180 hours showing mean pressure below 1008 mb in the BoC, a less than impressive European, and not unfavorable MJO conditions based on GFS and GEFS, I'm not ruling anything out. Or in.

I'd feel better if the Euro was in, and CMC and NoGaps not my favorite models, but I'm a natural optimist, and a one quarter glass full silver lining kind of guy,

We've got this going for us, too. Which is nice.

ECMF_phase_51m_full.gif

UKME_phase_23m_full.gif

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We've got this going for us, too. Which is nice.

ECMF_phase_51m_full.gif

UKME_phase_23m_full.gif

I agree that the period the mjo moves into the Atlantic is a much more favorable period for tropical cyclone development and is when I expect something to form on avg. It is a good tool to judge when a cyclone may form. GFS hints at lowering pressures as early as 96 hours and keeps a slow brew of "whatever" system that might take 3-5 days to slowly pull its self together. I'd say with the model support and the mjo shown within this thread that chances look good for something to develop within the next 7-9 days.

Right now it is more or less watch the trend and grow more and more conferences as more and more models join within that trend.

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ECMWF operational is an awfully unimpressive system, and with the ensemble 500 mb heights, assuming a reasonably deep system that more or less follows 500 mb steering, whatever forms wouldn't come very far North into the Gulf.

But its a week away, and since it'd be late June/early July, even if a system does form and goes straight to Mexico, I'm not worried.

post-138-0-59940900-1308695256.gif

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For entertainment purposes. 18z Nogaps is a tad aggressive with this system :P

e9dp9z.gif

It seems to bend the 500 mb ridge over North America to make its own path, I looped it as well, and it seems funky to me it would be heading NNW...

But I'm not expert.

post-138-0-91915300-1308710454.gif

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