Glob Models have strong lows in E Atlantic,first 2 weeks,Aug

#41 Postby **curtadams** » Tue Jul 25, 2006 9:30 am

gatorcane wrote:What I want to know is how the GFS can predict a Low that far out that hasn't even fully developed in Africa yet?

Well, that's what numerical sims are supposed to be able to do, right? 5-6 days isn't really a big stretch for the good sims when predicting areas of low pressure and rainfall (actual cyclogenesis is always a stretch) I think the dynamics of wave formation are fairly well understood, although not by me. There is a candidate convective concentration over Nigeria or thereabouts, too.

#42 Postby **gatorcane** » Tue Jul 25, 2006 10:01 am

Thanks for the explanation. Based on this visible loop, looks like the African dust is starting to clear out east of 30W - could this be another sign or am I just seeing things?

http://www.ssd.noaa.gov/PS/TROP/DATA/RT ... -loop.html

Frank2 · #43 Postby **Frank2** » Tue Jul 25, 2006 10:07 am

That convection has since dissipated and is moving WNW...

#44 Postby **gatorcane** » Tue Jul 25, 2006 10:09 am

Frank2 wrote:That convection has since dissipated and is moving WNW...

Frank2 the candidate low will come from something over the Nigeria area or central Africa region and will move offshore Africa over the weekend.

wxmann_91 · #45 Postby **wxmann_91** » Tue Jul 25, 2006 10:19 am

What I want to know is how the GFS can predict a Low that far out that hasn't even fully developed in Africa yet?

It can't. GFS is known to spuriously spin up TC's in August.

BTW, the westerlies still dominate the MDR due to TUTT's that are dominating the western and central Atlantic. Though it may relax over the next few days, it's certainly nowhere near favorable for any tropical development.

Frank2 · #46 Postby **Frank2** » Tue Jul 25, 2006 10:22 am

I agree - with all due respect, threads like this are useless, because while the output of these 384-hour models might not change from run to run, they definitely change from day to day...

Frank

#47 Postby **gatorcane** » Tue Jul 25, 2006 10:42 am

Frank2 wrote:I agree - with all due respect, threads like this are useless, because while the output of these 384-hour models might not change from run to run, they definitely change from day to day...

Frank

Perhaps but this low has been showing up for *many* runs now so we'll have to see what happens

Hohwxny · #48 Postby **Hohwxny** » Tue Jul 25, 2006 10:51 am

gatorcane wrote:
Frank2 wrote:I agree - with all due respect, threads like this are useless, because while the output of these 384-hour models might not change from run to run, they definitely change from day to day...

Frank

Perhaps but this low has been showing up for *many* runs now so we'll have to see what happens

Exactly how many is "many"? Five? Ten?

I haven't really been paying to this disturbance, so I am just trying to catch up.

#49 Postby **curtadams** » Tue Jul 25, 2006 10:53 am

I don't trust the GFS to predict a TC 2 weeks out. After seeing a GFS-CMC-NAM multirun consensus bomb out on a mid-Atlantic system a few weeks back I'm not sure I'd trust it to predict a TC tomorrow!

My interpretation is that the GFS thinks that conditions in the Atlantic will allow a TD/ weak TS Cape Verde system starting next week - not that there will actually be one (the wave itself doesn't appear remarkable). That will be a change as we've seen quite a few vigorous waves - nascent TD's, IMO - get snuffed, totally and quickly, by currently quite hostile conditions. I *do* trust the GFS to have something to say about whether conditions will permit a TC, even more than 1 week out. So I figure the GFS is making an informed and plausible claim that the Cape Verde season will be open as of next week.

kenl01 · #50 Postby **kenl01** » Tue Jul 25, 2006 11:10 am

I wouldn't take anything seriously the GFS indicates as to tropical systems unless a major tropical cyclone is within 72 hours in advance. Even then there can be great uncertainty. If all these models were absolutely correct as to future development, the average number would be something like 50 named storms each year.
Like Bob Sheets once mentioned in the late 80's, "in meteorology, you never know for certain until after it hits........"

#51 Postby **gatorcane** » Tue Jul 25, 2006 11:46 am

I think if anything, the GFS is telling us that it thinks the Cape Verde Season will kick off next week with a weak TS.

#52 Postby **gatorcane** » Tue Jul 25, 2006 4:11 pm

unless I am seeing things, looks like the 00z run today loses this Low but still develops something near the Cape Verde Islands around Aug 9th-10th:

http://www.nco.ncep.noaa.gov/pmb/nwprod ... loop.shtml

#53 Postby **gatorcane** » Tue Jul 25, 2006 4:12 pm

actually it looks like it still brings the low but quite a bit weaker in this run passing south of Florida into Cuba.

#54 Postby **cycloneye** » Tue Jul 25, 2006 6:07 pm

http://www.nco.ncep.noaa.gov/pmb/nwprod ... loop.shtml

This is the 18z run.Shows the low getting stronger as it moves westward in the Tropical Atlantic.However it turns more WNW passing just north of the Leewards,VI and Puerto Rico.And later turning more NW avoiding the Bahamas and the EC of the U.S.

#55 Postby **storms in NC** » Tue Jul 25, 2006 6:10 pm

cycloneye wrote:http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/carib/gfs/18/index_slp_l_loop.shtml

This is the 18z run.Shows the low getting stronger as it moves westward in the Tropical Atlantic.However it turns more WNW passing just north of the Leewards,VI and Puerto Rico.And later turning more NW avoiding the Bahamas and the EC of the U.S.

That sound great to me :wink:

TS Zack · #56 Postby **TS Zack** » Tue Jul 25, 2006 11:59 pm

00z GFS picks-up on a few storms developing. Finally, looking like things are turning more like August around here.

#57 Postby **gatorcane** » Wed Jul 26, 2006 12:21 am

Africa is picking up tonight, looks like the huge blob at about 15N and 5W could be the candidate Low the GFS is calling for...its looking rather good tonight

http://cimss.ssec.wisc.edu/tropic/real- ... rmet7n.GIF

#58 Postby **SouthFloridawx** » Wed Jul 26, 2006 3:00 am

Sorry guys maybe this is where this stuff belongs... I will post about this topic here.

Towards the end of the 18Z GFS spins up a new area of low pressure just to the SE of the Cape Verde Islands. I'll be interested to see if this feature is depicted on the 00Z or any of the other models. I guess what I should be eluding to is if the Azores high is not as powerful as in recent weeks we may see some of these waves coming off of Africa developing.

18Z GFS 850mb Vorticity
http://moe.met.fsu.edu/cgi-bin/gfstc2.c ... =Animation

12Z CMC shows nothing closed but, is hinting at the same area of Vorticity in the lower levels.
http://moe.met.fsu.edu/cgi-bin/cmctc2.c ... =Animation

12Z UKMET shows even less vorticity than the CMC or GFS but, same general Idea.
http://moe.met.fsu.edu/cgi-bin/ukmtc2.c ... =Animation

Either of the sites I went to had the nogaps out that far.

00Z Model stuff

GFS continually developing an area of low pressure near the cape verde islands and moving it west.
http://www.nco.ncep.noaa.gov/pmb/nwprod ... loop.shtml

CMC also showing a lot of vorticity near the cape verdes at the end of it's run.
http://moe.met.fsu.edu/cgi-bin/cmctc2.c ... =Animation

UKMET showing the same type of thing at the end of it's run also.
http://moe.met.fsu.edu/cgi-bin/ukmtc2.c ... =Animation

MM5FSU - (not to be confused with the supre ensamble)
This model is much like the GFS.
http://moe.met.fsu.edu/cgi-bin/mm5fsutc ... =Animation

jimvb · #59 Postby **jimvb** » Wed Jul 26, 2006 6:36 am

The 2006 July 26 06Z run of the GFS now shows this CV storm heading for the Carolinas.

MortisFL · #60 Postby **MortisFL** » Wed Jul 26, 2006 7:07 am

Theres a wave along the ITCZ that the 06 GFS develops, already looks fairly impressive.

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

Glob Models have strong lows in E Atlantic,first 2 weeks,Aug

Now it's the Carolinas

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