ATL: KATIA - Post Tropical - Discussion

[Aric Dunn]

major shift in the 12z GFS run ... especially noting the weakness and the trough

Here's a graphic showing the 7-day position from the 06Z and 12Z GFS. 12Z is in purple. It's about 65nm southwest of the 06Z run, but still has it passing well NE of the Caribbean. Not sure I'd identify that as a major shift.

[img]http://myweb.cableone.net/nolasue/gs.gif[/ig]

At 10 days, the 12Z GFS (Purple lines) is a good bit faster than the 06Z and about 290nm farther north, plus a little bit farther west for the recurve point. This shift may be significant, as that it indicates "Katia" may impact the Canadian Maritimes a day earlier than the 06Z run. Also note the quite different pattern across the eastern U.S. on the 12Z vs. the 06Z run.

[img]http://myweb.cableone.net/nolasue/gfs2gif[/ig]

Yes I agree on that part. but notice the rest of my post ..... "especially noting the weakness and the trough" this run the weakness is a lot farther west and the trough/ low near the NE coast is weaker and lifts out faster.

[otowntiger]

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

15N-50W is the benchmark position for the NE Caribbean to be affected or not by a system. Looking at where it is so far south right now,I have it below that position,unless a big weakness opens up.

I agree Luis...at 10N this is such a low lat....we will have to watch it today and tonight to see if she is really taking a WNW course...

I am guessing 1005ish mb right now. Current steering

http://tropic.ssec.wisc.edu/real-time/d ... oom=&time=

According to that set up of steering currents my untrained but seasoned opinion it looks like td 12 will miss the islands to the northeast and pass between Bermuda and the east coast before recurving out to sea.

Storm sk disclaimer here.....I don't know what I'm talking about; pay attention to the NHC and your local officials for the correct info blah, blah.....

[gatorcane]

Out through 120 hours so far, the 12Z Euro is much faster and slightly more south of the 00Z run.

I presume that means it is showing a little more ridging over the top of TD12 at least through 120 hours?

It looks that way. It will miss the islands again to the NE but the 12Z has shifted south and west some from the 00Z. At 144 hours it is NE of the Leewards but notice the gap is closing.

Look how much quicker it gets to the longitude of the islands now...

12Z at 144 hours:


00Z at 192 hours:

[cycloneye]

18z Best Track

AL, 12, 2011082918, , BEST, 0, 100N, 279W, 30, 1008, TD

ftp://ftp.tpc.ncep.noaa.gov/atcf/tcweb/ ... 011.invest

[SouthFloridawx]

Is there some type of chart that shows the history of the troughs graphically? For North America and the North Atlantic. Let's say for 1-3 months time... Sorry if this question is worded strangely.

[gatorcane]

Closer at 168 hours on 12Z Euro:

[Bruiser]

Could the system rolling of off Africa have some effect on 12's development and track? I'm new to this but reminds me vaguely of 92/93L from a couple weeks ago. Is this a common thing? How early can you begin to assume some sort of development/stability for these African storms? I'm always routing for Fujiwhara megastorms (that stay in the middle of the ocean of course).

http://www.ssd.noaa.gov/eumet/eatl/ir2-l.jpg

[Dynamic]

Closer at 168 hours on 12Z Euro:

Gatorcane, the firewall at my office block web pages like Imageshack. Could you please provide the direct link for these images?

[gatorcane]

Much more south and west in the long-range.

12Z Euro at 192 hours:

[SeminoleWind]

Closer at 168 hours on 12Z Euro:

]http://img148.imageshack.us/img148/2360/12zeurotropical850mbvorn.gif

Gatorcane, the firewall at my office block web pages like Imageshack. Could you please provide the direct link for these images?

http://raleighwx.americanwx.com/models.html

[gatorcane]

That is a big shift west:

Euro 12Z, 216 hours:



Euro 00Z, 240 hours:

[gatorcane]

Aric, I agree the 12Z GFS did not shift west alot, but check how much the 12Z ECMWF shifted west (see models thread)

[Dynamic]

Closer at 168 hours on 12Z Euro:

]http://img148.imageshack.us/img148/2360/12zeurotropical850mbvorn.gif

Gatorcane, the firewall at my office block web pages like Imageshack. Could you please provide the direct link for these images?

http://raleighwx.americanwx.com/models.html

Thank You, very good information there...

[gatorcane]

12Z Euro at 240 hours:

[Aric Dunn]

very interesting euro run... farther west and south.. more ridging. and a low developing in eastern gulf at end of run.. really far out but out to 5 days is trending to more ridging to the west.

[SeminoleWind]

i wonder if the west shift on the euro will continue on the next runs and if the gfs will also

[Aric Dunn]

Aric, I agree the 12Z GFS did not shift west alot, but check how much the 12Z ECMWF shifted west (see models thread)

Yeah just saw the Euro... but the GFS track not so important than the ridging and the trough off the NE coast basically not there... what turned the GFS in this 12z was the second trough not the weakness from 6z ...

[gatorcane]

Complete loop of 12Z Euro:

http://img687.imageshack.us/img687/6087 ... 0mbvor.gif

[DESTRUCTION5]

The low associated with the trough that moves from Tx to FL is interesting for early Sept...

[Aric Dunn]

notice the consensus models now.. showing it missing both troughs and bending back west north of PR and recurving later thats a significant shift from 00z .... Also notice the deep Bam