Vigorous tropical wave in Eastern Atlantic

[Hyperstorm]

Hyperstorm, this one is for you. Do you see this accute northern component that the modles are showing or could we see a more southerly track through the isalnds. I do know it is a great ask to survey the dynamics at this point,but you seem to surely know your tropical weather.

Anthony, I am able to tell you that there is nothing that we can do to predict how a system will behave a week from now. Models are less accurate the further you go out in time. Right now, models are hinting at a more northerly component toward the northern islands or even just north of them. Climatology would suggest that an early developer would move WNW and not totally west throughout the Atlantic. A stronger ridge would keep the system almost due west for a while. Keep monitoring it and we'll have a much better idea once there is an actual system to track (as that info will be fed into the models) and of course the closer we are in time.

[Sanibel]

Interesting that this wave is drawing moisture from south of the equator on ir. Hmm. In the past big southern inflow draw-ers tend to form and become strong. It's up to the wave now.

[fci]

Hyperstorm, this one is for you. Do you see this accute northern component that the modles are showing or could we see a more southerly track through the isalnds. I do know it is a great ask to survey the dynamics at this point,but you seem to surely know your tropical weather.

Anthony, I am able to tell you that there is nothing that we can do to predict how a system will behave a week from now. Models are less accurate the further you go out in time. Right now, models are hinting at a more northerly component toward the northern islands or even just north of them. Climatology would suggest that an early developer would move WNW and not totally west throughout the Atlantic. A stronger ridge would keep the system almost due west for a while. Keep monitoring it and we'll have a much better idea once there is an actual system to track (as that info will be fed into the models) and of course the closer we are in time.

Doesn't climatology show that when a CV type storm develops near the CV Islands that they invariably turn Northwest and then North rather quickly?

I am not entirely familiar with the Classic Cape Verde storms but think that most of the ones that have made it to Florida or the Gulf have not developed into Named Storms until well west of the Cape Verde Islands.
Please correct me if I am mistaken, not really sure but seem to remember this.

[El Nino]

It depends on where it forms. If it's South (just like in thid case), then we can have a longtracker until GOM.

[GeneratorPower]

fci, no, that's not the case. In 2004, Frances and Ivan both originated near where this wave is.

[cycloneye]

fci, no, that's not the case. In 2004, Frances and Ivan both originated near where this wave is.

And Georges (9.0n) maybe a tad south of this one.

[CourierPR]

I believe that in 1960, hurricane Donna developed as soon as she hit the water and eventually hit the Keys and Southwest Florida.

[fci]

Thanks all for the info.
Like I said; I was not sure.
FYI:
Frances-2004- named at 11.5 and 39.8
Ivan-2004- named at 9.7 and 30.3
Georges-1998- named at 10.6 and 31.3
Donna-1960- named at 10.3 and 26.9

Storms that DID turn and were Fish:
Debby-2006 named at 14.9 and 28.1
Danielle-2004 named at 12.6 and 24.2
Alberto-2000 named at 12.0 and 22.3
Gert-1999 named at 14.2 and 31.9
Jeanne-1999 named at 11.0 and 19.4

I guess the data above indicates that if a storm is named REALLY far East (basically east of 30.0) or Far North (basically north of 11.0 or 11.5); it seems they are destined to be Fish.

Of course, I know there are exceptions to these assumptions but maybe it gives us a little historical basis to "guess" if a system looks to be a threat based on where it becomes a named system.

[wxmann_91]

I did some research, and my findings suggested that about half of CV storms (defined in my research as those that reached Depression status east of 45W and south of 20N) which peaked at Major status, recurved without affecting any land mass. Out of 61 storms, 28 recurved harmlessly, and 2 more recurved after hitting the Lesser Antilles, but before affecting any other land mass. This is empirical evidence of Beta drift which affects strong cyclones (i.e. a tendency to move poleward). More north equates to greater tendency to get caught by a midlatitude trough... more east equates to longer time/more opportunity for Beta drift to kick in.

In contrast, 38 Majors developed in the Atlantic south of 25N and b/t 45W and 65W (this excludes the Caribbean) from 1950-2006... only 7 recurved harmlessly and an additional storm affected the Maritimes.

[clfenwi]

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT AUG 11 2007

...TROPICAL WAVES...

HIGH AMPLITUDE TROPICAL WAVE IS JUST MOVING OUT OF THE AFRICAN
COAST. IT AXIS IS ALONG 15W S OF 22N WITH A 1008 MB LOW PRES
NEAR 13N. STRONG CLUSTERS OF MODERATE TO ISOLATED STRONG
CONVECTION ARE AHEAD OF THE WAVE AXIS COVERING FROM 10N-14N E OF
19W. SOME OF THE COMPUTER MODELS DEVELOP THIS LOW INTO A
TROPICAL CYCLONE AS IT MOVES WWD ACROSS THE ATLANTIC OCEAN.

[Windspeed]

Thanks all for the info.
Like I said; I was not sure.
FYI:
Frances-2004- named at 11.5 and 39.8
Ivan-2004- named at 9.7 and 30.3
Georges-1998- named at 10.6 and 31.3
Donna-1960- named at 10.3 and 26.9

Storms that DID turn and were Fish:
Debby-2006 named at 14.9 and 28.1
Danielle-2004 named at 12.6 and 24.2
Alberto-2000 named at 12.0 and 22.3
Gert-1999 named at 14.2 and 31.9
Jeanne-1999 named at 11.0 and 19.4

I guess the data above indicates that if a storm is named REALLY far East (basically east of 30.0) or Far North (basically north of 11.0 or 11.5); it seems they are destined to be Fish.

Of course, I know there are exceptions to these assumptions but maybe it gives us a little historical basis to "guess" if a system looks to be a threat based on where it becomes a named system.

Those exceptions should show you why it is important to never assume. The sypnotic pattern will dictate a Cape Verde TCs fate more than its point of origin--at least to a degree. If a developing TC rolls off the African coast between 15 and 20ºN, the Azore's High may already be displaced; and therefore, the Cape Verde TC will have little chance to reach the western Atlantic. But for the most part, Cape Verde TCs that form between 8 and 15ºN are already embedded in the easterlies and are very much dependent on the location and westward extension of the Azores high. When you have strong ridging on the Eastern coast of the U.S. combined with a strong Azores high in the eastern Atlantic, there is usually a weakness in the central Atlantic. Cape Verde TCs that develop at low latitudes will have a better chance to remain embedded in the easterly flow and miss any weakness, or, if latitude is gained, the storm will still be far enough south to avoid being pulled out of the easterly steering layer. At which point ridging over the East Coast or western Atlantic ("Bermuda High") can continue the storm on a general west to north west track and possibly threatening the continent. Such a setup tends to get long tracking TCs at very low latitudes through the Antilles, Caribbean and into Central America; or through the Bahamas and into Florida or the Gulf of Mexico. The higher the latitude a Cape Verde TC forms in the same setup, the better chance a weakness in the central Atlantic will capture the storm, or get it far enough north (30ºN+) to take it out of the easterly trade winds. It will meander until another trough/westerlies can take it poleward into the North Atlantic.

Common patterns: A weak Azores high, or one displaced at a higher latitude will allow a trough dig into the eastern Atlantic and turn Cape Verde TCs poleward as soon as they form. Another common setup up is a strong Azores dominating the Atlantic with a strong trough over the eastern US. 1996 was a very active year with a similar setup where all Cape Verde TCs turned north and east of the continent. Sometimes the Azores high will extend across the central Atlantic without a significant weakness. In such a pattern, Cape Verde TCs can form at higher latitudes than 12ºN and still make it all the way across. Sometimes you get a situation like in 2003 where there isn't necessarily a strong East Coast trough, but weakness that fluctuates with each successive short wave that rolls off the coast. Isabel formed at 14N, 30W and was a long tracker that felt the effects of two shortwaves that were not strong enough to entirely break down ridging in the western Atlantic, but were significant enough to bring Isabel NW into the Carolinas.

Just realize that there can and will be storms form higher than 12ºN and east of 30ºW and not be destined to die in the North Atlantic. Though it is obviously more likely that such Cape Verde TCs will not make it across, some do. A classic example is the Cape Verde long tracker, possibly the epitome of such, Hurricane Hugo. The surface low that became Hugo organized as it moved off the African coast and was classified a tropical depression at 13.3N, 20.0W. The Azores dominated the entire Atlantic until a weakness moved off the East coast just as Hugo was reaching the Lesser Antilles. Hugo slowed and turned NW towards the weakness, but strong ridging held NE of the storm, driving it into South Carolina.

[P.K.]

Warnings now out on this low.

WONT50 LFPW 110815

A
SECURITE ON METAREA 2, METEO-FRANCE,

WARNING NR 383 , SATURDAY 11 AUGUST 2007 AT 0812 UTC

GENERAL SYNOPSIS, SATURDAY 11 AT 00 UTC
LOW AREA NEAR 1008 OVER WEST OF MAURITANIA SLOW-MOVING, EXPECTED
1003 NEAR 12 NORTH AND 24 WEST BY 12/12 UTC. ASSOCIATED TROPICAL
WAVE EXPECTED NEAR 20 WEST, SOUTH OF 14 NORTH. TROPICAL WAVE ALONG
28W SOUTH OF 17 NORTH MOVING WEST AT 5-10 KT. ITCZ ALONG 10N17W
11N26W 11N36W.

SIERRA LEONE
FROM 11/18UTC TO 12/18UTC AT LEAST.
CYCLONIC 8. SEVERE GUSTS. THUNDERSQUALLS.=

[punkyg]

Oh man i stuck around man i thought this wave was gonna be gone, but as you see when you click the link and see the pic you see its there with
some heavy convection. i'll bee waiting for this baby to develop.

http://www.ssd.noaa.gov/PS/TROP/DATA/RT/EATL/IR4/20.jpg

Wait! is this an old picture?

[Matt-hurricanewatcher]

Looks like we have a developing cyclone.

[punkyg]

You really think that matt?

[Thunder44]

Oh man i stuck around man i thought this wave was gonna be gone, but as you see when you click the link and see the pic you see its there with
some heavy convection. i'll bee waiting for this baby to develop.

http://www.ssd.noaa.gov/PS/TROP/DATA/RT/EATL/IR4/20.jpg

Wait! is this an old picture?

This image is from 8:45 UTC. Convection has diminsihed somewhat but still looks healthy:

http://wwwghcc.msfc.nasa.gov/GOES/goeseastfullir.html

[bvigal]

Windspeed, excellent post!! Now, can we just make sure everyone reads it?
For those "Oh no, it's going to be a C5 headed right at me!" - way too soon to worry!!
For those "It's going to turn north and go out to sea." or "It's going to fizzle by 50W due to shear, SAL, etc." - way too soon to assume!!

All we can do is watch changes in actual indicators, post them when they are significant (we are ALL looking at satellite, after all), and discuss how those changes will effect development and track if we have some knowledgable insight.

But please, let's avoid those "I think it's going to ____" and "Yep, I agree" and "Wow, look at that!" and the other wasteful one-liner posts. If one feels the need to CHAT, there is a CHAT ROOM for that purpose.

There are a lot of really good "amateurs" on this site (some I give as much credence as the "pros") who have opinions I really wish to hear. But for every one of them, there are 10 others posting 10 times as much, with 1/10th the value, and unable to recognize that they themselves, fall in this 1/10th classification! Let's all read, listen, learn, (count to 100), and keep one window open in chat to expell that excess adrenaline.

[cycloneye]

HIGH AMPLITUDE TROPICAL WAVE IS JUST MOVING OUT OF THE AFRICAN
COAST. IT AXIS IS ALONG 16W S OF 20N WITH A 1006 MB LOW PRES
NEAR 11N. CONVECTION HAS SLIGHTLY DIMINISHED EARLY THIS MORNING.
SATELLITE IMAGERY SHOWS SCATTERED MODERATE CONVECTION FROM 8N TO
13N E OF 20W. SOME OF THE COMPUTER MODELS CONTINUE TO DEVELOP
THIS LOW INTO A TROPICAL CYCLONE AS IT MOVES WNW ACROSS THE
ATLANTIC OCEAN ALONG THE PERIPHERY OF THE SUBTROPICAL RIDGE. VIS
SATELLITE IMAGERY EARLY THIS MORNING INDICATES THAT THE SFC LOW
IS NEAR 11N18W.

I said sunday morning but as I see it today,invest 90L may be up later today or tonight.

[Aquawind]

Good morning Luis, Looks to be a threat to the island yet. TD soon to be..

I hear ya bvigal.. Windspeed does a good job explaining things. He will be on Talkin Tropics next week when we expect to have Dean on the board. Well if Mike let's him..lol

[DrewFL]

00Z ECMWF. Remember.....this is 10 days out: