97L growing more organized, will bring heavy rain to the Lesser Antilles
The tropical wave near 12N 52W, about 600 miles east of the Lesser Antilles Islands (97 L), has grown more organized this morning as it tracks west at about 20 mph. This wave is surrounded by an area of very dry air from the Sahara Desert, but 97L has been able to steadily moisten a large region of the atmosphere over the past day, insulating itself from the dry air. This moistening process has been aided by sea surface temperatures (SSTs) that have steadily increased from 26.5°C to 27.5°C, plus the presence of only 10 knots of wind shear. The system now has a small area of intense thunderstorms near its center, with some rotation of the cloud pattern evident at mid-levels of the atmosphere. An upper-level outflow channel has opened to the north, and there is evidence that surface spiral bands are beginning to form. This morning's QuikSCAT pass missed 97L, so we don't know what is happening at the surface.
Wind shear is a modest 10 knots over the disturbance, and is forecast to remain in the moderate 10 - 15 knot range through Monday morning. This should allow further development to occur today, and 97L could be approaching tropical depression strength on Monday as it moves through the central Lesser Antilles Islands. Monday night, shear is expected to rise to 20 - 30 knots, thanks to the presence of a trough of low pressure at upper levels of the atmosphere over the eastern Caribbean. Since 97L is a relatively small system, it is very vulnerable to wind shear. This shear may be able to drive some of the dry air west of 97L deep into its interior, significantly disrupting the disturbance. Shear will remain high along 97L's path through Thursday, when the storm should be in the western Caribbean near Cuba. If there is anything left of 97L by then, some development is possible. The National Hurricane Center gave 97L a low (less than 30% chance) of developing into a tropical depression in the next 48 hours in their 8am Tropical Weather Outlook. However, I'd say the odds are now in the medium range (30 - 50%).
None of the computer models are forecasting tropical storm development over the next seven days.
Figure 1. Current satellite image of African wave 97L.
I'll have an update Monday morning. As 97L approaches the islands, you may want to follow local observations there using our wundermap for 97L.
Jeff Masters
Reader Comments
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LMAO you caught that huh? No ignorance means not admitting something that is right in front of you
shear maps and the visible clearly shows that there is shear in the immediate vicinity of 97L, yet he claims over and over there is no shear
that is being ignorant, it is taken out of context as being an insult
Link
Thanks Storm - appreciate the time
this situation with the shear is very fickle and it could go either way, right now though it looks like shear will prevent 97L from organizing further in the short term
of course I could be wrong, we will see
Anticyclones are basically shields for tropical systems.
As long as it stays south of 17N, it will be okay.
not a problem, I probably shouldnt have said it anyway
Ahhem... not everyone ;)
For days, I've been saying that 97L isn't going to develop until at least 75W. The GFS and NOGAPS continue to forecast a dramatic decrease in shear in that general area over the next few days.
I'm obviously no expert, and the NHC is definitely smarter, this is just my opinion from my experience and observations.
I'm fully prepared to be wrong, however, if the system unexpectedly develops prior to approaching the Windwards.
It also shows that the models are not perfect, because there is obviously a tropical event occurring, regardless of whether it ever becomes a full blown tropical storm.
Yes, exactly.
I am in the camp you are, development around 75W, SSE of Jamaica
The mid-level shear map might -- for now -- be the one to actually look at in terms of it affecting 97L. It goes from 850 to 500 mb.
I think that if 97L DOES bomb out tonight and then it hits whatever high shear may be there, it would have a greater impact on it than if it had not bombed out. Of course, if the TUTT lifts out quickly as some models suggest, that's a moot point.
97L really needs a good DMAX to get going again....
I have a question...while I see plenty of shear from avil blow off, how do you know the shear maps are accurate? Do they launch ballons over the water? Do they cover every 10 square miles? What is the process? Seems like a lot of estimation to me.
Hmmm, that's pretty sweet deal for the cyclone lol. when is it predicted to form?
Quoting Nolehead:
everyone wrote 97l off last night and WALLA today..so lets see what it does tonight and wait to see what the new models are saying..before you bash the daylights out of it...
Ahhem... not everyone ;)
oh i was with ya on it too..let's just sit back and wait...
where is this map from?
The Satellite Services decision's. Tropical Formation branch
Look on the shear map near Costa Rica.. Notice the arrows circulating in a clockwise fashion, that is an anticyclonic flow, and I think the reason why models forecasted low shear was maybe they noticed the Anticyclone.
Am I missing something?
NCEP COUPLED GFDL HURRICANE MODEL FORECAST MADE FOR
TROPICAL DEPRESSION INVEST 97L
INITIAL TIME 18Z JUL 19
DISCLAIMER ... THIS INFORMATION IS PROVIDED AS GUIDANCE. IT
REQUIRES INTERPRETATION BY HURRICANE SPECIALISTS AND SHOULD
NOT BE CONSIDERED AS A FINAL PRODUCT. PLEASE SEE THE TPC/NHC
OFFICIAL FORECAST.
FORECAST STORM POSITION
HOUR LATITUDE LONGITUDE HEADING/SPEED(KT)
0 11.9 52.2 270./21.0
STORM DISSIPATED AT 0 HRS AT THE ABOVE PSN.
In my opinion, it's survival is in question if it is inable to fire up convection before that shear is over the bulk of the storm.
Wait and see! This should be interesting!
The GFDL is really that reliable until they have a LLC. Isn't it?
AVN
well its been 0 ours and its still alive.. XD
WHXX04 KWBC 192322
CHGQLM
ATTENTION...NATIONAL HURRICANE CENTER
NCEP COUPLED GFDL HURRICANE MODEL FORECAST MADE FOR
TROPICAL DEPRESSION INVEST 97L
INITIAL TIME 18Z JUL 19
DISCLAIMER ... THIS INFORMATION IS PROVIDED AS GUIDANCE. IT
REQUIRES INTERPRETATION BY HURRICANE SPECIALISTS AND SHOULD
NOT BE CONSIDERED AS A FINAL PRODUCT. PLEASE SEE THE TPC/NHC
OFFICIAL FORECAST.
FORECAST STORM POSITION
HOUR LATITUDE LONGITUDE HEADING/SPEED(KT)
0 11.9 52.2 270./21.0
STORM DISSIPATED AT 0 HRS AT THE ABOVE PSN
here it is a second time just in case you don't see it the first
Can you take either one of those images & post one from yesterday at the same time?
interesting. just more factors in the possible development of 97L.. very complex situation. im just gonna lay back and see what it does. thanks for the help :)
As they should.
Thanks anyway!
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