Little change to TD 7; 93L may develop off the coast of Africa
Tropical Depression Seven continues westward across the central tropical Atlantic with little change in appearance. Looking remarkably like the tropical depression that became Tropical Storm Ernesto last week, TD 7 has a limited region of heavy thunderstorms, as seen on satellite loops. A large amount of dry air to the west and north is visible on water vapor satellite loops, and this dry air is interfering with TD 7's heavy thunderstorms. Wind shear is a light 5 - 10 knots, which is favorable for intensification. Ocean temperatures are 26.5°C, which is a bit on the cool side, but these temperatures are 0.5° warmer than on Thursday. Winds at the Middle Atlantic buoy 41041 peaked at 29 mph, gusting to 38 mph, at 1:50 am EDT this Friday morning, when the center of TD 7 passed about 40 miles to the south. TD 7 will pass about 60 miles south of buoy 41040 near midnight tonight. The first hurricane hunter mission into TD 7 is scheduled for Saturday morning.
Figure 1. Morning satellite image of TD 7.
Forecast for TD 7
TD 7 formed about 400 miles east-northeast of where Ernesto became a tropical depression, as seen on our wundermap. Atmospheric and oceanic conditions are currently quite similar to what Ernesto experienced, and I expect TD 7 will struggle with dry air like Ernesto did. The SHIPS model predicts that shear will remain light through tonight, then rise to the moderate range on Saturday, when the storm will encounter upper-level southwesterly winds associated with a trough of low pressure. However, ocean temperatures will warm to 28°C, which may partially counteract the increase in shear, as far as maintaining a favorable environment for development. Dry air and shear may be significant enough to destroy TD 7 on Sunday, as predicted by the GFS and ECMWF models. These models tried to kill off Ernesto in a similar situation last week, so I am inclined to believe TD 7 will survive for the coming five days, but struggle. The official NHC forecast of a 45 mph tropical storm moving through the Lesser Antilles Islands Saturday night and Sunday is a reasonable one.
Figure 2. Morning satellite image of Invest 93L.
93L
A strong tropical wave in the far Eastern Atlantic that emerged off the coast of Africa Thursday night was designated Invest 93L by NHC. In their 8 am Tropical Weather Outlook, NHC gave 93L a 50% chance of becoming a tropical depression by Sunday morning. Satellite loops show a pronounced spin to the atmosphere at mid levels, but little in the way of heavy thunderstorm activity. The latest Saharan Air Layer Analysis from the University of Wisconsin shows that while the atmosphere immediately surrounding the disturbance is moist, there is a large area of dry air from the Sahara to the west and north. This dry air will be a significant impediment to development during the coming week. The ECMWF model shows some weak development of 93L over the coming week, and predicts a general west-northwesterly track. The storm may be something Bermuda needs to be concerned about in eight or so days.
I'll have a new post this afternoon.
Jeff Masters
Reader Comments
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bouy Station 41040 located at 14.477 N 53.008 W (14%uFFFD28'38" N 53%uFFFD0'28" W)
the TD is at 13.7N 50.9W
Link
Did you read his memories on Katrina? Impressive.
http://28storms.com/about/
I just read Jason's memoirs of Katrina. They are more than just impressive. I teared-up when I finished reading the piece.
If the lad ever tires of met, he could have a helluva future as a writer.
Yes, as you say its been booming here all morning and my weather alert has been going off every 5 min.
Despite the fact that below average coverage was expected into to the weekend, I guess we are finally going to be headed back to where we should, which is great because August has started way too dry after having so much rain in June and July over much of the area
Stop fussing about politics and stick to weather, the other major sources are no better, just from a different end of the political spectrum.
It's only been there for a couple days, no matter how lonw it seems... lol
I thought they were poisonous...
How come it's only wrong to forecast a storm getting close to the Caymans when you're from the Caymans???
uh...
just sayin?
...
When I was a kid (early teen) I spent a week down there, camped on the beach, the Fort was my playground, the ocean my swimming pool. I understand they have roped off a lot of it now, for many reasons, to protect it. It is a very special place, and it would be a shame if the storms damaged it.
you know so when I forecast it its wrong I don't think so
An upper-level trough which brought heavy rain to the northern Caribbean islands, and whose strong high-altitude winds "sheared" the remnants of Florence, has now, on its southern periphery, contributed to the formation of a concentrated area of convection (thunderstorms) over the western Caribbean. Satellite loops show that cluster of tstorms spinning, i.e. what meteorologists call a "mesoscale convective vortex" (MCV) has formed, which can sometimes lead to surface low pressure forming. That's what happened with the recent tropical storm wannabe in the Bahamas and Florida. On the other hand, such features can dissipate after a few hours. We'll watch to see what this one does.
Do you know what that term means, or could mean? I'm only asking because one definition of it is a vulgar slur that could get you banned from this site. I won't report you (I still believe in freedom of speech) but others may and have the right to try because of the site rules.
+1000
Quickest way to get banned from this site is by talking politics. jrweatherman should not have started this garbage.
If we could beg, borrow or steal a decent anti-cyclone over the GOM it would make use of all the moisture thrashing about. Anything for even clouds, if we can't have rain....
Here Here Im with you on this one!!
+1000
10August06pmGMT's 13.6n48.6w-13.7n50.9w are now the most recent positions
(Vectors and straightline projections have been corrected from the previous mapping)
Derived from (NHC) ATCF data for TropicalDepressionSeven for 10August6pmGMT:
MinimumPressure remained 1009millibars
MaxSusWinds held at 30knots(35mph)56km/h
Vector changed from 270.3°West@25.8mph(41.5km/h) to 272.8°West@25.8mph(41.5km/h)
POS-Trinidad :: GND-Grenada :: BGI-Barbados :: SLU-St.Lucia
The easternmost dot on the connected;omes is where 92L became AL07
The next dot to the right is where AL07 became TD.7
The easternmost dot on the longest line is TD.7's most recent position
The longest line is a straightline projection through TD.7's 2 most recent positions to its closest approach (within 18miles or 29 kilometres) to a coastline
9August6pmGMT: TD.7 had been headed for passage over GrantleyAdamsInternationalAirport (bottomBGIblob)
10August12amGMT: TD.7 had been headed for passage over Bathsheba (middleBGIblob)
10August6amGMT: TD.7 had been headed for passage over HighCliffPoint (topGNDdumbbell)
10August12pmGMT: 10August12pmGMT: TD.7 was heading for passage over LittleBay (topBGIblob)
10August6pmGMT: TD.7 was heading for passage over LinnisPoint,Dennery(town) in ~23hours from now (when this comment was posted)
Copy&paste pos-10.595n61.023w, bgi-13.09n59.457w-13.198n59.488w-13.31n59.579w, gnd-12.191n61.602w,slu,axa, 13.7n41.7w-13.7n42.9w, 13.7n42.9w-13.7n44.6w, 13.7n44.6w-13.6n46.3w, 13.6n46.3w-13.6n48.6w, 13.6n48.6w-13.7n50.9w, 13.6n48.6w-13.89n60.883w into the GreatCircleMapper for a larger-scale map and other information
The previous mapping for comparison
Viewing: 701 - 724
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