Atlantic Tropical Action 2011 - Part IV

[k***]

weenie revolt

[HurricaneJosh]

My dear little children-- I'd like for you all to settle down, stop throwing food, and play nice!

No more fighting. Thank you.

[A-L-E-X]

My dear little children-- I'd like for you all to settle down, stop throwing food, and play nice!

No more fighting. Thank you.

I see you've had a hard day's work, Josh.... looks like you've been putting out fires in multiple threads

[dtk]

They have five slots total, but there are other things that can be run if NHC doesn't use their allotment. And that's only one possibility. This thing isn't going to develop for at least 3 days, and maybe as much as 5, so there is not a whole lot of need for GFDL/HWRF to be run on them at this time. Certainly, if the exact same system was sitting in the Bahamas, it would be an invest right now, but since it is out in the middle of the Atlantic, there is no urgency.

They do have five slots, but most of the time there isn't a need to run GFDL/HWRF simulations on five different storms (obviously). Unused slots from hurricane model simulations are designated to be filled with the HiresWindow runs (NMM/ARW); I believe (in other words, if there are enough hurricane runs, the HiresW runs don't get completed for that given cycle).

[MJW155]

Man this board needs a hurricane pronto like a 40 year old virgin needs to get laid.

[Ian]

If we can just kill that high over my head late in the period I'm getting a lame-o-cane IMBY.

[LakeEffectKing]

Quick thoughts on our lemon....I'd watch for the potential for this to be a rare LF TC in South America. Some of the guidance leaves this weak enough (along with a slight southward push of the massive ridge to the north) to raise the potential for at least a scrape or direct impact on extreme northern Guyana or Venezuela, as "some farily weak tropical entity", IMO.

[phil882]

...but nothing like 2010...

Ahh there is Danielle and Earl... note also that both of these systems were developing a good 5 days after today's date, so there is still plenty of time to start worrying about huge TW.

[Srain]

If we can just kill that high over my head late in the period I'm getting a lame-o-cane IMBY.

Pffft. I'll take 'your' high over mine any day...

[CUmet]

The Central Atlantic wave is considerably ahead of 93L in terms of its vorticity and convective structure at the same location, leading me to believe that it will develop somewhat more quickly. Another potential contributing factor is the interaction between this wave and an upcoming Kelvin wave passage across the Atlantic basin. On August 15, a Kelvin wave (green outlines) was diagnosed near 180W in the Pacific, while another was around 80-90W and possibly assisted in the current attempt at TC genesis by 93L:

This KW currently over the Pacific is also diagnosed by Roundy's updated methodology. Given typical Kelvin wave propagation speeds, this should cross the easterly wave's longitude somewhere around August 20-22, resulting in enhanced TC genesis probabilities around and for a couple days after this time frame. This occurs just as the wave is entering warmer SSTs west of 50W, and the influence of the environmental dry air should gradually wane as well. To sum up, I think this has a pretty high chance of developing sometime between August 20-23. I think the GFS right now somewhat too quick with genesis in its latest runs, but I don't think it'll perform as horribly as it did with 92L and 93L given the boost by this KW.

Given the delayed genesis and the strength of the ridging to its north over the next 4-5 days, I think this has a high chance of impacting the Lesser Antilles. The ridge does weaken somewhat after next Monday, which will allow for this to gain some latitude. I do not think this has any chance of crashing into South America, as the ridging is not strong enough and the initial starting point is too far north for that to happen.

[HurricaneJosh]

Given the delayed genesis and the strength of the ridging to its north over the next 4-5 days, I think this has a high chance of impacting the Lesser Antilles. The ridge does weaken somewhat after next Monday, which will allow for this to gain some latitude. I do not think this has any chance of crashing into South America, as the ridging is not strong enough and the initial starting point is too far north for that to happen.

Great to hear your thoughts-- I was looking forward to them.

What's your general hunch Re: long-term track-- 1) Caribbean Cruiser, 2) Yucatan Channel/Gulf, 3) Greater Antilles/SE USA, or 4) Bermuda/fish?

[CUmet]

Great to hear your thoughts-- I was looking forward to them.

What's your general hunch Re: long-term track-- 1) Caribbean Cruiser, 2) Yucatan Channel/Gulf, 3) Greater Antilles/SE USA, or 4) Bermuda/fish?

One of the first three.

[HurricaneJosh]

One of the first three.

You won't be pinned down tonight, I see. Fair enough. Thanks.

[phil882]

The Central Atlantic wave is considerably ahead of 93L in terms of its vorticity and convective structure at the same location, leading me to believe that it will develop somewhat more quickly. Another potential contributing factor is the interaction between this wave and an upcoming Kelvin wave passage across the Atlantic basin. On August 15, a Kelvin wave (green outlines) was diagnosed near 180W in the Pacific, while another was around 80-90W and possibly assisted in the current attempt at TC genesis by 93L:

This KW currently over the Pacific is also diagnosed by Roundy's updated methodology. Given typical Kelvin wave propagation speeds, this should cross the easterly wave's longitude somewhere around August 20-22, resulting in enhanced TC genesis probabilities around and for a couple days after this time frame. This occurs just as the wave is entering warmer SSTs west of 50W, and the influence of the environmental dry air should gradually wane as well. To sum up, I think this has a pretty high chance of developing sometime between August 20-23. I think the GFS right now somewhat too quick with genesis in its latest runs, but I don't think it'll perform as horribly as it did with 92L and 93L given the boost by this KW.

Given the delayed genesis and the strength of the ridging to its north over the next 4-5 days, I think this has a high chance of impacting the Lesser Antilles. The ridge does weaken somewhat after next Monday, which will allow for this to gain some latitude. I do not think this has any chance of crashing into South America, as the ridging is not strong enough and the initial starting point is too far north for that to happen.

Excellent post... I actually much prefer the image you posted above for detecting kelvin waves to the ones I've been pulling off from Roundy's home page. In any event, I couldn't agree more with your assessment of the olr environment from what happened with 92L and 93L compared to this current disturbance. The daily paneled plots show a strong subsident phase of the kelvin wave affecting the Atlantic invests this weekend (August 13th and 14th) which acted to speed up the low level flow while also producing a large area of subsidence that combined with the dry air induced by SAL led to a rather unfavorable environment for TCG. If the forecast panels are correct, a much more favorable low olr environment should greet the current disturbance in the Atlantic over the next few days.

[Radius]

lol...

Alternative profile name = FatherJosh

Mods, toggle as required.

My dear little children-- I'd like for you all to settle down, stop throwing food, and play nice!

No more fighting. Thank you.

[CUmet]

There was a post asking for an explanation on KW waves and TC genesis which is no longer here. But to answer the question as simply as I can:

Atmospheric Kelvin waves are eastward moving waves of alternating suppressed and enhanced convection in the tropics. They are comprised of zonal wind anomalies, with converging wind anomalies near and to the east of the convection. The phase of the KW that has westerly low-level wind anomaly also has upper-level easterly anomalies, and vice versa.

KWs can influence TC genesis by affecting the large-scale environment through several mechanisms: 1) shear anomalies, 2) low-level vorticity due to zonal wind anomalies, 3) moisture anomalies, 4) large-scale subsidence or ascent. In the Atlantic, recent research has suggested that TC genesis is about twice likely to occur during to a few days after a Kelvin wave passage. By no means are Kelvin waves the only influence on TC genesis, but they can be important at times.

Here's a relevant poster on the topic (large file): http://grip.nsstc.nasa.gov/presentations/7Jun11_Sciteam_Ventrice_Thorncroft.pdf

[Ed Lizard]

Through 102 hours, GFS is deja vu.

if only Tombo where here, this would be just like a model snowstorm thread.

[GaWx]

0Z THU GFS hits the upper Keys on 8/25 and then far SW FL/Ft. Myers on 8/26. This makes 12 U.S. hits in a row! Wouldn't it be cool if the next 35 or so runs hit the US, making it nearly 50 straight hits?

[hurricaneman]

The consistancy of the GFS is just uncanney, its basically staying within 100 miles of all its other runs

[negative-nao]

Since I might be Ground Zero for this next weekend. I want to give you guys updates. WHere can I get the Best Deal on a Wind Meter Anemometer ? What is the best brand out there ?

[GaWx]

Note that this is the earliest U.S. hit (by ~ 12 hours) of the 12 gfs runs in a row showing a hit: late on 8/25 for the upper Keys to early on 8/26 for the SW tip of FL.

[Anduril]

Through 102 hours, GFS is deja vu.

if only Tombo where here, this would be just like a model snowstorm thread.

Snow storm in August?!?!? SWEEEEEEEEEET

[tmagan]

I wonder when is the last hurricane to go through the Florida Straits east-west? Labor Day 1935?

[DopplerWx]

Since I might be Ground Zero for this next weekend. I want to give you guys updates. WHere can I get the Best Deal on a Wind Meter Anemometer ? What is the best brand out there ?

Licking your index finger and holding it high in the wind should do the trick. But in all seriousness I wouldn't worry about buying an anemometer until we get closer to the possible event.

[negative-nao]

Licking your index finger and holding it high in the wind should do the trick.

Is that like Hillbilly Handfishin ??

[GaWx]

I wonder when is the last hurricane to go through the Florida Straits east-west? Labor Day 1935?

It appears to be Rita of 2005.

[cdawgga1]

There was a post asking for an explanation on KW waves and TC genesis which is no longer here. But to answer the question as simply as I can:

Atmospheric Kelvin waves are eastward moving waves of alternating suppressed and enhanced convection in the tropics. They are comprised of zonal wind anomalies, with converging wind anomalies near and to the east of the convection. The phase of the KW that has westerly low-level wind anomaly also has upper-level easterly anomalies, and vice versa.

KWs can influence TC genesis by affecting the large-scale environment through several mechanisms: 1) shear anomalies, 2) low-level vorticity due to zonal wind anomalies, 3) moisture anomalies, 4) large-scale subsidence or ascent. In the Atlantic, recent research has suggested that TC genesis is about twice likely to occur during to a few days after a Kelvin wave passage. By no means are Kelvin waves the only influence on TC genesis, but they can be important at times.

Here's a relevant poster on the topic (large file): http://grip.nsstc.na..._Thorncroft.pdf

Thank you for the explanation. I didn't mean to delete my post. New here and was playing around with all the features and accidentally deleted it. The link really helped me understand.

[U_Thant]

To me, the increasing concern now is that the globals take the 850 MB vortex through the same general track, no matter it's strength at the surface. When this occurs, what this tells me is that the deep layer flow is going to be well-aligned, so if it can overcome dry air and spin up, the atmospheric shear profile would favor significant strengthening.

With each successive run, IMO it's becoming less of a question of where this system will track (along or near N Leewards-PR/Shredderola-Bahamas-FL) and more of a question of what it will become.

[hurricaneman]

I love tracking these systems, but this one has me slightly on edge, this could be a system that is talked about for ages if the GFS run happens to come true, and bacause of the consistancy of the runs, it may happen

[Marion_NC_WX]

0Z THU GFS hits the upper Keys on 8/25 and then far SW FL/Ft. Myers on 8/26. This makes 12 U.S. hits in a row! Wouldn't it be cool if the next 35 or so runs hit the US, making it nearly 50 straight hits?

One trend I have noticed from the 12z to 0z runs is the lack of good blocking ridge over the Northeast US once this storm cuts across Florida.

Compare these maps...

12z run @ 264...excellent NE blocking, deep inland pentration, faster moving storm resulting in massive rains, possible wind threat across inland SE.

0z @ 252...less blocking ridge, strorm has slowed and begins to turn up the coastline

Looks like a trough tries to squeeze down between the ridges and picks up this feature...therefor instead of a storm with deep penetration across the Southeast, it's now making a more sharp right turn and trying to go up the Georgia/Carolina costal plain.

That may be just a brief relapse in the model or is this the start of a new trend...as many of us would agree, the pattern that favors an East Coast (non-Florida) hit would need to include a decent block over the Northeast...what happens if this Bermuda Ridge becomes weaker with each successive model run?