High wind shear ripping into 97L
A strong tropical wave (97L) a few hundred miles east of Barbados in the Lesser Antilles Islands has grown less organized today as it tracks west at 15 - 20 mph. The wave is moving underneath an upper-level trough of low pressure, which is bringing 30 knots of wind shear to 97L. While there is a respectable amount of heavy thunderstorm activity associated with 97L, there is no longer any low-level spiral banding or rotation of the cloud pattern. This morning's QuikSCAT pass at 5:35 am EDT showed sustained winds of 35 mph a few hundred miles east of Barbados, but there was no surface circulation evident. The islands of Barbados, St. Vincent and the Grenadines, St. Lucia, and Martinique can expect heavy rain and wind gusts to 50 mph as 97L moves through the Lesser Antilles Islands this afternoon and tonight, but 97L will not become a tropical depression.
Wind shear along the path of 97L is forecast to remain in the high 25 - 35 knot range for at least the next three days. This should prevent further development of 97L, and I expect the disturbance will be gradually torn apart during the next few days. The National Hurricane Center gives 97L a low (less than 30% chance) of developing into a tropical depression in the next 48 hours. None of the computer models are forecasting any tropical storm development over the next seven days.
Figure 1. Current satellite image of African wave 97L.
I'll have an update Tuesday morning. As 97L moves through the islands, you may want to follow local observations there using our wundermap for the region.
Jeff Masters
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From like, 4 blogs ago. Not sure about the rest of it. Who knows?
989. beell 9:32 PM GMT on July 17, 2009
Big ridge out west, big ridge over the Atlantic. Big trough in between has no choice but to dig south almost to the Yucatan. Very strong. Probably cut off a strong upper low over the central GOM. Wonder how much this trough will affect the future health of 97L. And also wonder how much erosion of the western edge of the ATL ridge will take place. Enough to turn this wave up through the Bahamas-as modeled?
Long Beach, Chancery Lane
77.1 °F 76 °F 96% WSW at 3.0 mph
29.89 in 0.00 in / hr
Barbados, Rockley
76.7 °F 75 °F 94% North at 0.0 mph
29.90 in 1.69 in / hr
Grantley Adams
78 °F 75 °F 92% SSE at 2 mph
29.84 in 0.00 in / hr
Barbados, Lodge Hill
75.6 °F 75 °F 98% SSW at 3.1 mph
29.91 in 0.54 in / hr
One station in Trinidad is reporting true westerlies
Yes those westerlies sure are interesting though.
When do CIMSS maps update? every 3 hours?
Yes.
Westerlies would indicate that the actual coc is now west of Barbados. That radar seems to indicate a location just slightly nwest of the island and would produce westerly winds there. It just has little or no convection over the center.
when would the 1500UTC map come out?
good to know, keep us posted, 97L hasnt really gotten to your location at this point
There is not enough images on the radar animation for me to determine a low pressure center.
As Drak said, we would need more radar frames to point out any COC. However, radar can prove tricky when trying to find a low level center since eddies caused by convection can mimic LLC's.
Me to Extreme... Since it is moving at lets say 20 mph then that would make the shear seem even stronger and it just doesn't look that way looking at the cloud tops... I'm not saying there is no shear since it is obvious there is but you catch my drift. :)
Personally doubt that it is I would say 15-20 at most.
Here's the link: Link
Seems like some type of low is there?? Wouldn't the shear rip it apart I don't get how it is still circular?
Imo, this would indicate that the coc is now west of Barbados - just without convection over it.
as that ULL lifts NW, it should allow that trough in the Caribbean to lift northward
I don't think that radar stores that many frames. In that case you or somebody else may want to save them and then merge them into a GIF animation using online tools such as this one.
I meant as many clear frames as we can get on the system but i'll try and work on that GIF.
Nahh.. let him live - he is trainable
___________________
Now for Stupid Question Time:
Looking at the models, tomorrow morning (8am EDT, 12UTC) 97L would be at about 15N 66W 'ish, Right?
Currently the shear at 15N 66W is about 30-40kts, Right?
Looking at GFS forecast model for shear, tomorrow morning (8am EDT, 12UTC) at 15N 66W 'ish we would have:
I am shearly confused. (Senior moment?) How hostile could that shear be?
Thanking you in advance.
EATL
latest as of 1131 am est
Even with all that convection it has? Is the shear really enough to tear it apart?
Not being a smart-ass. Just asking to learn.
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