Strong wave near Leeward Islands - Is Invest 97L

[cycloneye]

Finnally,TPC introduces this wave.


TROPICAL WAVE EXTENDS FROM 09N-16N ALONG 16W MOVING W AT 10-15
KT. WHILE METEOSAT-9 VISIBLE IMAGERY SHOWS BROAD SCALE CYCLONIC
TURNING OF THE LOW-LEVEL CLOUD FIELD IN THE VICINITY OF THE
WAVE...UPPER AIR TIME SECTION ANALYSES FROM DAKAR SENEGAL
INDICATES THE WAVE HAS NOT YET PASSED DAKAR. A 1010 MB LOW IS
ANALYZED NORTH OF THE WAVE NEAR 20N18W THAT IS LIKELY THE
NORTHERN VORTEX OF VORTICITY ASSOCIATED WITH THE WAVE. GLOBAL
MODEL GUIDANCE INDICATE THE NORTHERN VORTEX OF THE WAVE WILL
SLIDE SW OVER THE NEXT 24-36 HOURS AND THE ENERGY WILL BECOME
ABSORBED INTO THE MAJORITY OF THE WAVE ENERGY LOCATED FARTHER
EASTWARD. SCATTERED MODERATE CONVECTION COVERS A LARGE AREA FROM
05N-17N BETWEEN 12W-22W.

[rockyman]

[Scorpion]

Poof

[KWT]

Looks a mess now, of course its always going to be difficult to get this one going given it has pretty horrendous SAL to the north.

[Nimbus]

Usually the wave train out of Africa doesn't get started till August. As successive waves roll off Africa the SAL will retreat north but that usually takes several waves to moisten the environment. The high SST's combined with the strong Atlantic ridge may spin up a wave further west though.

[jinftl]

Those systems that immediately develop off of the coast of africa are usally the first to recurve and become 'fish'. Of course, there are exceptions to that (though July is not really a month to be looking so far east for development). It's the "Bahama Bombers" like Katrina and Rita in August and September that should really command our attention....i.e., waves that come off of africa and don't find overall favorable conditions for development until they are west of 60W. These systems tend to 'ride the ridge' west and once they are in our backyard, take advantage of overall favorable atmospheric and oceanic conditions for impressive development just offshore.

Case in point...the NHC Discussion for Tropical Storm Andrew when he was at 56W longitude:

TROPICAL STORM ANDREW DISCUSSION NUMBER 10
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT WED AUG 19 1992

A RATHER STRONG UPPER LOW NEAR 28N57W...AS INDICATED BY WATER VAPOR
IMAGES...IS INDUCING UPPER LEVEL SHEAR OVER ANDREW. THIS IS
REFLECTED BY THE POSITION OF THE LOW LEVEL CENTER OF THE STORM WHICH
APPEARS TO BE REMOVED FROM THE CONVECTION. THERE ARE SOME
UNCERTAINTIES ON THE LOCATION OF THE LOW LEVEL CENTER BUT THE BEST
ESTIMATE OF THE INITIAL MOTION IS 295/18 OR PERHAPS A LITTLE BIT
FASTER.

IF ANDREW IS ABLE TO PERSIST...THEN SOME SLOW STRENGTHENING MAY BEGIN AND THAT
IS INDICATED IN THE OFFICIAL INTENSITY FORECAST. HOWEVER...IF
VISIBLE SATELLITE IMAGES AND RECONNAISSANCE DATA SHOW THAT INDEED
THE CIRCULATION CENTER IS WELL REMOVED FROM THE CONVECTION..THEN THE
CHANCES OF INTENSIFICATION ARE VERY SMALL.


AVILA

FORECAST POSITIONS AND MAX WINDS

INITIAL 19/0900Z 17.6N 56.3W 45 KTS

[wxman57]

Usually the wave train out of Africa doesn't get started till August. As successive waves roll off Africa the SAL will retreat north but that usually takes several waves to moisten the environment. The high SST's combined with the strong Atlantic ridge may spin up a wave further west though.

I've kept track of all semi-significant waves coming off the coast of Africa since around 2003. On this date in 2009, the 21st wave had just moved off the west coast of Africa the day before (starting May 15th). In 2010, the 21st wave just moved off the coast of Africa yesterday. So there isn't much difference from last year. Now let's look at 2005...

In 2005, the 19th wave was just moving off the west coast of Africa today. So not much difference from year to year in wave numbers.

[jinftl]

In the wrong hands that data could become a sensationalized news headline...."More waves have emerged off of africa in 2010 than compared to the same time during the record-setting 2005 season"

Usually the wave train out of Africa doesn't get started till August. As successive waves roll off Africa the SAL will retreat north but that usually takes several waves to moisten the environment. The high SST's combined with the strong Atlantic ridge may spin up a wave further west though.

I've kept track of all semi-significant waves coming off the coast of Africa since around 2003. On this date in 2009, the 21st wave had just moved off the west coast of Africa the day before (starting May 15th). In 2010, the 21st wave just moved off the coast of Africa yesterday. So there isn't much difference from last year. Now let's look at 2005...

In 2005, the 19th wave was just moving off the west coast of Africa today. So not much difference from year to year in wave numbers.

[Nimbus]

Can the start of the Cape Verde season when the waves coming off of Africa seem to immediately explode into active systems always be predicted accurately? Seems as though we should have all the variables including SAL, SST's MJO, moisture over Africa, etc a couple weeks ahead of time.

[jinftl]

How many seasons have seen that - immediate explosive development off of the coast of africa, though? 2005 didn't. If more than a handful of waves travel west 2000 miles and then explode and develop into monsters, i would still consider that an active cape verde season.

Can the start of the Cape Verde season when the waves coming off of Africa seem to immediately explode into active systems always be predicted accurately? Seems as though we should have all the variables including SAL, SST's MJO, moisture over Africa, etc a couple weeks ahead of time.

[KWT]

Even busy CV seasons doesn't tend to get more then 3-4 *true* CV storms develop, most don't really develop till they are west of say 35W even in active CV seasons.

[Nimbus]

Its a little dry out there in the middle at the moment. The current wave moving west out of Africa may moisten things up some but typically the waves go poof in July.

[jinftl]

Yep...more often than not, if you want to keep a cape verde system east of the caribbean and u.s. coastlines, have it develop east of 35W....chances are it will be a 'fish'.

Even busy CV seasons doesn't tend to get more then 3-4 *true* CV storms develop, most don't really develop till they are west of say 35W even in active CV seasons.

[Cryomaniac]

In the wrong hands that data could become a sensationalized news headline...."More waves have emerged off of africa in 2010 than compared to the same time during the record-setting 2005 season"

Then make sure it doesn't get into the wrong hands lol.

[AJC3]

Usually the wave train out of Africa doesn't get started till August. As successive waves roll off Africa the SAL will retreat north but that usually takes several waves to moisten the environment. The high SST's combined with the strong Atlantic ridge may spin up a wave further west though.

I've kept track of all semi-significant waves coming off the coast of Africa since around 2003. On this date in 2009, the 21st wave had just moved off the west coast of Africa the day before (starting May 15th). In 2010, the 21st wave just moved off the coast of Africa yesterday. So there isn't much difference from last year. Now let's look at 2005...

In 2005, the 19th wave was just moving off the west coast of Africa today. So not much difference from year to year in wave numbers.

This is good to see. It's been my experience after looking closely at the East Atlantic for more than decade that neither the vigor nor frequency of AEW's coming off the west African coast varies that much on a year to year basis. Nor does aything seem to be more vigorous "for this early in the season". I've seen my share of "monster waves", and out-and-out monsoon type depressions roll off the African coast - some well before the meat of the season, and some well after.

[KWT]

I do think we've had a couple of strong waves actually, 92L was a very potent wave for the time of year when it came off, it weren't that far off from developing really and its very rare to get that sort of system like that as far east as it was when it looked close to developing. If I remember pre-Alex wave was also very potent for the time of year...

That being said I'm not a big fan at this time of year of watching big waves, because nearly every time conditions will not be condusive in July with the large SAL outbreaks, Bertha in 2008 was a really big anomaly given how far east it developed.

[cycloneye]

Ok folks, as promised I would wait 12 hours since early this morning to see any progress on this wave but it hasn't done anything that merits organization into a tropical cyclone anytime soon, I say,it was not for real so next. Yes,it was a good wave to watch especially on Saturday with the big convective area that it covered and with some turning,but the sal was the winner. However, this wave should be watched down the road in the Caribbean in case conditions turn favorable in that area.What it can do is to clear the path of the sal for the future waves. Comments can continue to be posted here but if a new wave emerges Africa in the future and anyone wants to post about it, you can make a new thread.

[MGC]

Worry not my friends.....this wave has a few thousand miles of ocean to tranverse...plenty of time to worry.....MGC

[ROCK]

once the SAL abates as it gets passed the windwards and if it still holding some sort of signature we might see something out of it. Lower pressures abound in the carib....all it takes is for an ULL to aid in some convection that is persistant...you never know...I think everyone should enjoy this lull while we can. It wont be long and thats one prediction I wont have to eat crow on...

[Sanibel]

Worry not my friends.....this wave has a few thousand miles of ocean to tranverse...plenty of time to worry.....MGC

I agree. If we see something pop up near the Caribbean in a few days we'll know where it came from...