Invest 90L:East Atlantic,Discussions,Analysis and Sat Pics

[Sanibel]

I asked the high tops exposure question last night and got no answer. I thought if it bursted in intensity it would trend slightly more poleward due to higher steering influence. But remember Ivan. It was revving through category 3 while jogging WSW and towards Grenada. All depends on the type of ridge I guess. GFS is insisting W again tonight in a flat-track west.

[vbhoutex]

If 90L develops into a powerful system wouldn't it cause it to move more poleward due to the upper levels of the atmosphere.

According to the Pro Mets, it won't recurve.

Actually I meant to say a more WNW track rather than the west track that the GFS has been showing.

A stronger TC will try to move more poleward. However, with the ridging that is in place and expected to be in place as this system develops it does not appear that that is a good bet, at least not until it gets further West towards what could be the Western edge of the ridging. Of course if a really strong trough comes in it could produce a weakness that a really strong TC could take advantage of. But right now that does not appear to be what is going to happen. First concern is our friends in the islands and how strong this system becomes before it gets to the islands.

[btangy]

If 90L develops into a powerful system wouldn't it cause it to move more poleward due to the upper levels of the atmosphere.

According to the Pro Mets, it won't recurve.

Generally, yes, stronger systems tend to move more poleward because of stronger beta gyres and also the flow at upper levels tends to be more meridional (vs. zonal). You see this often in the E Pacific as storms weaken and then tend to bend more toward the west more in line with the flow at lower levels.

At this time, the models indicate a pretty broad ridge (>588dm) staying firm in the subtropical N Atlantic, but as I stated in a post in the model thread, timing the individual shortwaves around the broad longwave through over the E coast is almost impossible to do with this much lead time. If one of those shortwave troughs is sharp enough, it may cause our eventual TC (assuming it develops) to turn northward, but I'm not saying this will or will not occur because at this point in time there's no skill in making such a forecast. But the overall pattern of a sharp trough off the W coast, weak ridging or zonal flow across the C US and a broad longwave trough over the E coast in 5-7 days is a good bet.

[wxmann_91]

I went out on a limb there but I felt that that heat content was something
that was certainly remarkable...and of course there are other conditions. So
based on the shear, moisture content, etc. we will see what happens.
I hope this does not intensify because it poses a threat to the islands...
But I am still very concerned about the heat content...rarely is it that
high across the central atlantic.

And this is very important for those in the islands...the heat
content factor. Shear, moisture, and organization will play
roles. Also, if feedback from the system enhances the high
to the north and that enhances conditions for the system that would
be of concern.

I've always believed that OHC was more important to maintain major hurricanes, but was a non-factor in their maturation and development.

[boca]

The way the pattern of the east coast trough still has me concerned ,but I know patterns change and lets see if this has a Gilbert track written on it.

[Tampa Bay Hurricane]

I'm not sure...OCH may be for maintenance of intensity.
But that is reasonable given that condtions must be
optimal for initial development. I think you're right wxman91.

This system really looks like at least a tropical depression:
Notice the intense convection and its focus about a circular
region indicative of a center, these are the characteristics
necessary for classification...but I think the NHC will
wait to see the information and the data that will come
in tomorrow morning:
http://cimss.ssec.wisc.edu/tropic/real- ... xirg8n.GIF

And as far as track goes, the high to the north shows no signs
of breaking down and there are no troughs.

The system may try to get close to the caribbean.

[Blown Away]

On the visible yesterday @2pm there was a nice blob of convection, but it was on the W side of the mostly exposed LLC. Is the LLC now near the center of the convection or are we still looking at nice convection on the W side of a east sheared LLC?

[Tampa Bay Hurricane]

http://cimss.ssec.wisc.edu/tropic/real- ... xirg8n.GIF
From the infrared appears that the system is fairly circular...the
LLC is likely embedded within the blob of heavy convection, not
exposed I do not think.

[cheezyWXguy]

http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/images/xxirg8n.GIF
From the infrared appears that the system is fairly circular...the
LLC is likely embedded within the blob of heavy convection, not
exposed I do not think.

I agree. Shear appears to have decreased over the system, even though it is moving fairly fast. Based on IR imagery, it appears a little fanning or anticyclonic outflow has developed on the east side:

http://www.ssd.noaa.gov/goes/east/catl/loop-avn.html

[Extremeweatherguy]

It looks nice tonight. I am thinking TD tomorrow at 5am or 11am if this trend continues.

[Blown Away]

http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/images/xxirg8n.GIF
From the infrared appears that the system is fairly circular...the
LLC is likely embedded within the blob of heavy convection, not
exposed I do not think.

I agree. The models have 90L moving nearly 60 degrees longitude and gaining only 8 degrees latitude, that's a long way to go west w/o finding a weakness. If Dean develops soon I think it's going to be close for us in FL when this is all done, IMO.
BTW, TWC tropical update gave 90L about 5 seconds of discussion.

[crazycajuncane]

I would worry about a weakness father down the road that may draw the storm more WNW. I saw a local forecast track that pinned the storm up the N TX coast on Aug 23rd (no not my birthday!)

but it's way to early to tell. I don't think this will take a direct W track all the way. Looks more like a WNW track through the carribean, but a lot of factors can change between now and 5 - 7 days.

TS Dean on Monday?

[RL3AO]

...SPECIAL FEATURE...

A 1006 MB LOW...ASSOCIATED WITH A TROPICAL WAVE ALONG 26W/27W S
OF 18N...IS LOCATED SW OF THE CAPE VERDE ISLANDS NEAR 12N MOVING
W 15 KT. THE LAST VISIBLE SATELLITE IMAGERY SHOWED A LOW LEVEL
CIRCULATION PARTIALLY EXPOSED TO THE E OF THE CONVECTION.
SCATTERED MODERATE/STRONG CONVECTION IS FROM 10N-14N BETWEEN
29W-33W.

They mention a 7 hour old sat image and not much else.

[Scorpion]

There is something going on here... the Euro and now the GFDL lose this system. Sounds to me like it will dissipate soon. This has happened many times before, particularly last year.

[RL3AO]

Convection is starting to develop on the north side of the LLC.

[Extremeweatherguy]

JB is now saying that his original ideas of this going to FL may have to be tweaked. He is thinking this may have a better chance of coming through the caribbean and into the GOM now. He has not made an official prediction yet though, as there is still time to watch this.

[Scorpion]

JB is now saying that his original ideas of this going to FL may have to be tweaked. He is thinking this may have a better chance of coming through the caribbean and into the GOM now. He has not made an official prediction yet though, as there is still time to watch this.

But of course the forecast would have to be changed at this point. However, I still wouldn't rule out an "Ernesto" occuring, where the models totally get it wrong.

[clfenwi]

13/0615 UTC 12.4N 28.8W T1.5/1.5 90L -- Atlantic Ocean

[Scorpion]

Nice to see the T#'s have risen a bit... should be a TD at 5

[Matt-hurricanewatcher]

I agree scropion that is also possible. It would not suprize me if this did what 96 and 99L at all. Under this ridge this thing will likely go 15-20 knots once it gets into the centeral Atlantic. LLC have a hard time holding together.