ATL: SAM - Remnants - Discussion

[cycloneye]

AL, 98, 2021092100, , BEST, 0, 95N, 247W, 25, 1010, DB

[abajan]

Appears to be well on its way. Tropical Depression by 8 AM CVT possible.

[abajan]

Showers and thunderstorms associated with a tropical wave located a
few hundred miles south-southwest of the Cabo Verde Islands continue
to show some signs of organization. Environmental conditions are
expected to become more conducive for development, and a tropical
depression is likely to form later this week while the system moves
westward at 10 to 15 mph across the eastern and central tropical
Atlantic Ocean.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 5 days...high...80 percent.

[AlphaToOmega]

Appears to be well on its way. Tropical Depression by 8 AM CVT possible.

https://i.imgur.com/Sn2hDAB.gif

They likely want ASCAT to prove it.

[Nimbus]

Has at least a relative closed circulation with the forward motion in the lower cloud cover.
Couple of the models are forecasting a ridging pattern that would prevent recurve late in the forecast so initial track probably won't be out to sea once its declared.

[Extratropical94]

Showers and thunderstorms are currently somewhat limited associated
with a tropical wave located a few hundred miles southwest of the
Cabo Verde Islands. However, environmental conditions are expected
to become more conducive for development, and a tropical depression
is likely to form by Thursday or Friday while the system moves
westward at 10 to 15 mph across the eastern and central tropical
Atlantic Ocean.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 5 days...high...90 percent.

[Blown Away]

06Z @9.8N/26.3W

[cane5]

Has at least a relative closed circulation with the forward motion in the lower cloud cover.
Couple of the models are forecasting a ridging pattern that would prevent recurve late in the forecast so initial track probably won't be out to sea once its declared.

High pressure ridge before September kept all the storms South of SFL but this ridge may not be as strong if it’s just starting to build in.

[aspen]

Here are runs from every single model of the track of 98L/Sam over the CDAS SST map, with Larry's cold wake still clearly visible. I did my best to get each forecast point from 48hr to 240hr (180hr on the ICON and 120hr on the HMON/HWRF) correct, but some are probably off by a few tenths of a degree. Regardless, I think I did okay.

Black: 00z Euro
Sky blue: 06z GFS through 240hr
Green: 00z CMC
Navy blue: 00z ICON (I wanted to use the most recent long run)
White: 06z HMON
Yellow: 06z HWRF


If 98L/Sam sticks closer to the Euro/CMC/HMON/HWRF tracks and does not try to recurve early like the GFS/ICON, it could easily be a long-tracking and very dangerous major hurricane. However, we don't have a center yet, and I won't be shocked if the southern runs shift north only to shift back south again over the next 24-48 hours.

[Blown Away]

Map represents tracks of all storms during Oct, Nov, and Dec in the area 98L will be once it nears NE Caribbean. Olga, Kate, 1941, and 1893 the only canes to make it to CONUS...

[cycloneye]

AL, 98, 2021092112, , BEST, 0, 95N, 275W, 25, 1010, DB

[AJC3]

 https://twitter.com/WxmanTony/status/1440299416724803602



 https://twitter.com/WxmanTony/status/1440300166519537673

[aspen]

https://twitter.com/WxmanTony/status/1440299416724803602
https://twitter.com/WxmanTony/status/1440300166519537673

What is it with these late-season SAL outbreaks? There was just one a week or two ago.

[AJC3]

https://twitter.com/WxmanTony/status/1440299416724803602
https://twitter.com/WxmanTony/status/1440300166519537673

What is it with these late-season SAL outbreaks? There was just one a week or two ago.

Not sure, but I suspect there might be a direct correlation between seasonal Sahel rainfall and late season SAL outbeaks. Just an assumption on my part, through.

Has anyone looked at the JJA precip anomaly there?

[ElectricStorm]

Looks like 98L had a rough night. Weaker storms tend to go further west so we'll have to watch for that. It's gonna take a couple days for 98L to build up convection since it has hardly any right now.

[AJC3]

Looks like 98L had a rough night. Weaker storms tend to go further west so we'll have to watch for that. It's gonna take a couple days for 98L to build up convection since it has hardly any right now.

I think the peripheral SAL played a role in the magnitude of the collapse of convection after nocturnal Dmax.

[aspen]

The HWRF initialized this convection-poor structure very well. A hot tower or two pops up by 18z, but convection doesn’t return in full force until tonight.

[AJC3]

Great point made here w/r/t the convective collapse of 98L this morning...

 https://twitter.com/AndyHazelton/status/1440311324064374787

[aspen]

Imagine this suddenly doesn’t develop and becomes another Peter after all of this model support that exceeds what Peter ever had lol

If 98L doesn’t start regaining convection by tonight, the HWRF is probably going to bust (again).

[grapealcoholic]

https://i.imgur.com/vUIq4ah.jpg
Map represents tracks of all storms during Oct, Nov, and Dec in the area 98L will be once it nears NE Caribbean. Olga, Kate, 1941, and 1893 the only canes to make it to CONUS...

We're dealing with a completely different climate now, but yes it seems unlikely