2021 Global Model Runs Discussion (Out thru day 16)

[LarryWx]

OTOH, unlike the fairly active GEFS runs, the 12Z EPS for the same time is very quiet, especially keeping in mind 51 members vs only 31 for the GEFS! Which is closer to reality?

[Category5Kaiju]

Not sure what the models think, but here's one thing that seems to be a thing:

 https://twitter.com/philklotzbach/status/1443626904494374913




At least according to CSU, activity in October is certainly a possibility; maybe not the first week, but by mid month I think things will change.

[Spacecoast]

From the CSU report:

(This chart indicates 2020 Caribbean ACE was between 30-35)

"The median 1991-2020 ACE is 2, while the mean 1991-2020 ACE is 8.
The final forecast for October-November Caribbean ACE in 2021 is 9, meaning a slightly above-average and well above-median October-November ACE is forecast this year. "

A Oct-Nov Caribbean ACE of 9 would also be 'only' ~1/3 that of last years Oct-Nov ACE of ~32..

[LarryWx]

Ready or not, it's Happy Hour!

[CourierPR]

Not sure what the models think, but here's one thing that seems to be a thing:

https://twitter.com/philklotzbach/status/1443626904494374913

At least according to CSU, activity in October is certainly a possibility; maybe not the first week, but by mid month I think things will change.

Interesting considering all the posts indicating the season is virtually over.

[Hammy]

From the CSU report:
https://i.ibb.co/Z8yd6Pj/ecmja.jpg
(This chart indicates 2020 Caribbean ACE was between 30-35)

"The median 1991-2020 ACE is 2, while the mean 1991-2020 ACE is 8.
The final forecast for October-November Caribbean ACE in 2021 is 9, meaning a slightly above-average and well above-median October-November ACE is forecast this year. "

A Oct-Nov Caribbean ACE of 9 would also be 'only' ~1/3 that of last years Oct-Nov ACE of ~32..

What does Hindcasting refer to here?

[Category5Kaiju]

Not sure what the models think, but here's one thing that seems to be a thing:

https://twitter.com/philklotzbach/status/1443626904494374913

At least according to CSU, activity in October is certainly a possibility; maybe not the first week, but by mid month I think things will change.

Interesting considering all the posts indicating the season is virtually over.

Yeah, I personally am not sure where this general sense of this season virtually coming to a close is coming from. Is it because the operational models don't show anything?

[Spacecoast]

From the CSU report:
https://i.ibb.co/Z8yd6Pj/ecmja.jpg
(This chart indicates 2020 Caribbean ACE was between 30-35)

"The median 1991-2020 ACE is 2, while the mean 1991-2020 ACE is 8.
The final forecast for October-November Caribbean ACE in 2021 is 9, meaning a slightly above-average and well above-median October-November ACE is forecast this year. "

A Oct-Nov Caribbean ACE of 9 would also be 'only' ~1/3 that of last years Oct-Nov ACE of ~32..

What does Hindcasting refer to here?

It's backtesting the CSU's prediction algorithm to see how well it 'would have' predicted seasons past.
It looks like it's pretty good at predicting zero, or close to zero, but there is a significant margin of error (either over, or under predicting) in active seasons.
Last year, it would have underpredicted ~25 of the observed ~30-35
It seems that the 18z GEFS ensembles strongly disagree..

[toad strangler]

Not sure what the models think, but here's one thing that seems to be a thing:

https://twitter.com/philklotzbach/status/1443626904494374913

At least according to CSU, activity in October is certainly a possibility; maybe not the first week, but by mid month I think things will change.

Interesting considering all the posts indicating the season is virtually over.

CONUS season has BARELY 4 weeks left barring a very anomalous situation. That's solid climo.

[LarryWx]

That last GEFS ensemble run had my hair stand up

Indeed, later in the Happy Hour GEFS:

[LarryWx]

And still lots of Happy Hour action way out at 360: So, the Happy hour reputation is firmly intact! Get your shut-eye now while you can!

[SFLcane]

I'm always hesitant when it's only GFS this time of year. Often means a bias.

[jhpigott]

06z GEFS with a pretty strong signal for TC activity close to SEFL on October 11/12 https://www.tropicaltidbits.com/analysi ... 00106&fh=6

06 GFS op has a 983mb storm just off the coast of SEFL on October 10 https://www.tropicaltidbits.com/analysi ... 00106&fh=0

[aspen]

I'm always hesitant when it's only GFS this time of year. Often means a bias.

https://i.postimg.cc/DyrXghXM/64-C353-C5-6072-478-D-A355-048-F3-D80-D6-CD.png

Regardless if it’s a bias or not, the signal definitely seems sparked by the strong Kelvin Wave coming in to the basin around this time.

[chris_fit]

Here's an animation of the 06z GEFS Run.
* Strongest Signal Yet
* Time frame is not really being pushed back.




00Z EPS are lackluster - although maybe slightly more active than yesterday's 12Z run

[AutoPenalti]

We should be close to the point where models other than the GFS should start sniffing something.

So far it's just the GFS.

[kevin]

06zGFS, probably the busiest GFS ensemble we've had in the last few weeks since Sam formed. It consists of three independent clusters within the next 200 hours: WCar activity around +120 (11 members, 50%), weak subtropical development N of the Bahamas around +132 (13 members, 59%), even more WCar activity around +180 (not really sure how many members since it's difficult to distinguish from the first AOI). However the Euro is still very quiet so we'll see what happens.

[Category5Kaiju]

Ok, I hate the last GFS operational, being in Eastern Virginia.

[Blown Away]

06z GFS has a Caribbean Low in @4-5 days and a Cat1/2 hurricane moves just E of Florida and into Outer Banks...

[LarryWx]

06zGFS, probably the busiest GFS ensemble we've had in the last few weeks since Sam formed. It consists of three independent clusters within the next 200 hours: WCar activity around +120 (11 members, 50%), weak subtropical development N of the Bahamas around +132 (13 members, 59%), even more WCar activity around +180 (not really sure how many members since it's difficult to distinguish from the first AOI). However the Euro is still very quiet so we'll see what happens.

https://i.imgur.com/2iFoNXm.png

Good post. To add, the GEFS now has 31-32 members instead of just 21-22. And that 6Z run has the classic “Ridge Over Troubled Waters” pattern in the 6-10, often a worrisome pattern in La Niña especially.