ATL: TROPICAL STORM BILL (03L)

[tolakram]

So who's copying my posts here and posting them as his/her own at Jeff's site?

I reported the ones I saw. They really need a special button to report plagiarism since that seems to be most common in a forum where expert opinion matters.

[hurricanefloyd5]

To close for comfort from 06z GFDL.



06z HWRF is a little more south than GFDL.

do you have this model loop I can look at please??

[tgenius]

I don't mean to be a rat but it just looked WAY too similar and when I compared.. verbatim.

[gtalum]

Here's a link to several model loops including GFDL.

[wxman57]

Here's a sat pic but not many sfc plots yet. Should get some reports out there at 15Z. Note that the LLC is well east of the convection (a sign of easterly wind shear) - and I have it a little west of the NHC location.

[cycloneye]

I am looking at a loop and it looks like its moving a bit more fast.

[hurricanefloyd5]

Posted by: JeffMasters, 2:02 PM GMT on August 14, 2009

A strong tropical wave (90L), with a large circulation and a moderate amount of heavy thunderstorm activity, is a few hundred miles southwest of the Cape Verdes Islands, off the coast of Africa. This morning's QuikSCAT pass shows that 90L has a large circulation, but this circulation is not yet well-formed, as it is elongated along an east-west axis. Satellite imagery from the European METEOSAT satellite show that the heavy thunderstorms associated with 90L are gradually becoming better organized, with some spiral banding evident on the south side of the storm. Satellite intensity estimates from NOAA already put 90L at tropical depression strength with 30 mph winds, but the storm does not yet have a well enough formed circulation to be classified as a depression. Water vapor imagery shows that since 90L is forming several hundred miles south of the dry air of the Saharan Air Layer (SAL), the storm should not be affected by dry air and dust as much as Tropical Depression Two was. However, there is some dry air from the SAL being sucked into the circulation of 90L, and this is retarding its development.

Wind shear is moderate, about 10 - 15 knots, but is forecast to fall to the low range, 5 - 10 knots, later today. Shear is then forecast to remain low for the next five days. Sea Surface Temperatures are about 28°C, and will remain in the 27 - 28°C range the next five days. The combination of low wind shear and sufficiently warm SSTs should allow 90L to develop into a tropical depression by Saturday, and potentially reach hurricane strength by Wednesday. Most of our reliable models strengthen 90L into a hurricane by Wednesday, when the storm is expected to be near the northern Lesser Antilles Islands. One important outlier is the ECMWF model, which has 90L passing to the north of the islands, and eventually recurving out to sea east of Bermuda. The ECMWF was by far the most reliable model for forecasting hurricane tracks last year. However, all of our models are pretty unreliable going out 5 days in advance for systems that have yet to reach tropical depression strength. Once 90L becomes a tropical depression and develops a well-formed circulation, the models will have a better handle on forecasting where it will go.

[shortwave]

After looking at the GFS loop, it seems to ignore the high being fairly weak and displaced to the east...

That's the problem with models beyond 3 days or more - the cone of error is too wide for them to be of any real use (other than making the public nervous)...

P.S. To my surprise, the NHC has backed off just a bit and changed their wording to "gradually better organized" for this disturbance, so, we'll see what happens - perhaps they are not convinced that the dry air will not be a factor, as it was for TD2...

Noticed that too...any system strong enough would take advantage of the shallowe ridgeing and tend to head poleward... hoping at least

[cycloneye]

That is posted already on page 14.

[KWT]

Wow thats getting sheared pretty badly Wxman57, no way is that a code red anymore in that case. Convection is still blowing up but quite a big way to the east.

Still ex-TD2 (which is looking better) is flaring again so it does show that get to about 40W and conditions do improve somewhat it appears.

[wxman57]

Wow thats getting sheared pretty badly Wxman57, no way is that a code red anymore in that case. Convection is still blowing up but quite a big way to the east.

Still ex-TD2 (which is looking better) is flaring again so it does show that get to about 40W and conditions do improve somewhat it appears.

No, it qualifies as "Red". That only means it has a better than 50-50 shot at being a TD within 48 hours. Once the shear diminishes, and it will, it should develop.

Meanwhile, TD 2 looks better than when it was TD 2.

[hurricanefloyd5]

:uarrow: That is posted already on page 14.

wasn't this some updated info on this system cycloneye???????

[tgenius]

So Bill AND Ana this weekend? Who would of thunk it?

[KWT]

Very true Wxman57, in that the shear is only likely a short term feature (though with TD2 its been an issue for a good 36hrs and only now easing off) but I suppose what I think is this won't be forming in the first 24hrs of that 48hrs period, I suppose if the shear does ease down after that then its got a reasonable, if elongated circulation to work with.

Still I don't think this will really get going till 40W myself. By that I mean get upgraded.

[Sanibel]

The current delayed formation sets up the scenario where the storm waits until it gets closer to land and more favorable conditions to do its peak intensification run.

Plus a weaker, shallower disturbance might remain in a lower track slot.

[Sanibel]

That looks like a recurve synoptic with the east centered Bermuda High at the end of the model runs. But it's still too early.

06z GFDL makes it look like, unless another High fills in quickly, a recurve east of Florida is certain.

[KWT]

Yep Sanibel, history shows us also that the longer this system takes to develop the more likely it is that we see a storm that may threaten the Caribbean, its something to watch very closely indeed.

[NEXRAD]

Some 90L Model Notes

Good Friday, all.

For the forecast models, the GFS is not handling troughing to develop from the Central US through East Coast late next week too well. This particular model is assuming too shallow a trough, which contrasts with most other guidance. The ECMWF being so far right in comparison to most other guidance initially seems suspect, but there are reasons to not discredit its present (00Z/06Z) solution as much as the GFS. Foremost, the ECMWF seems to maintain a bit more energy with TD-2's remnant. This, in-turn, could give a slight aid to any ridge weakness NW of 90L. Also, with the developing El-Nino, climatology favors recurving storm tracks. Yes, there are storms that defy such, but with an upcoming moderate to strong El-Nino, odds favor deep Atlantic storms that eventually recurve.

What this means for the U.S. and even the Greater and Lesser Antilles is uncertain, as we're talking about a system that's not yet been named and is still a good 4 to 5 days away from any direct land impacts.

What I would watch for over the next few days, though is: 1) TD-2's remnant. If this system dissipates into a weak wave, then I'd anticipate 90L leaning more left (though probably not as much as the GFS). 2) model handling of the mid/late week Eastern US troughing. Do models start to deepen this further? Does the GFS do such? Or do the models start to back-off and weaken or delay the troughing? 3) The Atlantic ridge itself. There seems to be a large spread in how the models handle the ridge's western peripheries with some (e.g. GFS) keeping an extended, more narrow ridge far towards the west and near or over the US East Coast; meanwhile, other models blunt the ridge's western extent (e.g. CMC and the FSU MM5).

- Jay

[Derek Ortt]

Ah yes Chris now that was a MAJOR bust.

Chris was NOT a major bust from the models. The human forecasts also only had that as a low end cat 1 hurricane. It was a relatively minor bust. Global models never did much with Chris

Derek do you tkink that 90L could pose a threat for the Wind or Leewars island? What are your recents thoughts about this feature? Tkanks a lot my friend us in the Carib continue to monitor closely the evolution of this feature.

of course it is a threat to the islands. That remains the most likely evolution

[Gustywind]

Tkanks Derek , we will continue to monitor closely the situation during the next couple of days...