Tropical Wave off the Coast of Africa (Is Invest 90L)

[SconnieCane]

https://i.imgur.com/heFRriA.gif
00z EURO... Still fishy, but a sizeable slow down and SW adjustment from 192-240 hours compared to previous runs... Something to watch...

I get the feeling the western extent of its track depends to some degree on the evolution of Kate. Euro hardly even recognizes it exists, but models like the gfs and icon that develop Kate into a hurricane have Larry recurving earlier. It seems that a stronger Kate that sticks around for a little longer might have some influence on keeping the weakness open

A bit like Jose stalling off New England in 2017 helped allow post-PR Maria to miss the CONUS completely despite the fact that it came into the LAs well south of Irma which just a few weeks earlier turned into a SW Florida hit.

[aspen]

I think the GFS is way overdoing the potential for a recurve and having it too early, and the 12z run showcases the reasoning the best.

In about three days, the forming Larry is followed by another wave/some blob of vorticity. There is a ridge at this point in time which would steer Larry west, although not all the way to land due to Kate and a trough eroding the western edge (the trough will come into play later).


The vort blob starts to get caught in a ridge gap behind Larry. This wouldn't really be a concern for Larry under normal circumstances, since the ridge is right above it and steering it WNW to NW. However, this second vort widens the gap behind Larry and interacts with it, to the point that the vort (which in this run becomes a weak TC) drags Larry NNW/N before it even reaches 40W. This is when the trough comes in and would probably open up a further west exit point for Larry (probably around 45-50W), if it was still on its original WNW/NW track.



So far, only the GFS has shown this second vort/TC existing or having this much of an impact. However, if it verifies, it will also have a huge impact on Larry's future intensity and ACE. A GFS recurve around 35-40W will send Larry over waters as cool as 26C much sooner, but a 45-55W recurve like the Euro/EPS/CMC/ICON send it into the 27-28+C SSTs of the NW Atlantic before eventually recurving (hopefully). The ICON has a much sharper recurve between 45-50W because it turns Kate into a hurricane, creating a bigger gap for Larry to escape into.

[cycloneye]

 https://twitter.com/pppapin/status/1432391122769252353

[cycloneye]

Satellite-derived wind data and satellite imagery indicate that an
area of low pressure has formed over the far eastern Tropical
Atlantic in association with a tropical wave that recently moved off
the west coast of Africa. Environmental conditions are conducive
for development, and a tropical depression is likely to form within
the next couple of days while the system moves west-northwestward at
10 to 15 mph over the eastern tropical Atlantic.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 5 days...high...90 percent.

[cycloneye]

Invest 90L is up