ATL: SAM - Remnants - Discussion

[kevin]

First visual of Sam today. Still has to clear out the eye on visual, but it's already cleared out on IR. Looks quite healthy. I think ~7 hours from now might be the perfect time for recon to catch Sam at another peak as it'll give the Wring time to fix itself (broken to the NE right now) and the eye time to clear out. Raw T# up to 6.4 btw.

[tolakram]

AL, 18, 2021092618, , BEST, 0, 140N, 503W, 135, 929, HU,

I think is an old one.

Yeah, the date is "2021092618" - 2021 Sept 26, 18Z. That's 2 PM EDT yesterday.

I'm bringing this back up because many people thought this was a mistake post. Nancy was trying to point out that the NHC had adjusted an older best track to raise the intensity to 135 kts. Just in case anyone missed that. I picked a random post to quote here, not replying to anyone in particular.

[skyline385]

Think Sam is a good example of why ACE needs to be updated (with wind radii at the very least), its so tiny and is just chilling out there massively inflating the ACE for the season and will end up having much more ACE than even Ida which was a stronger system...

[aspen]

Think Sam is a good example of why ACE needs to be updated (with wind radii at the very least), its so tiny and is just chilling out there massively inflating the ACE for the season and will end up having much more ACE than even Ida which was a stronger system...

The NHC updated Sam’s BT to 135kt/929mb after the recon flight two nights ago found 929mb as Sam began to weaken, meaning it is officially the stronger system. It likely maintained 130+ kt winds for nearly 24 hours, and assuming the pressure was a few mbar lower prior to the 22z recon flight, it was a mid-920s Cat 5.

[kevin]

Think Sam is a good example of why ACE needs to be updated (with wind radii at the very least), its so tiny and is just chilling out there massively inflating the ACE for the season and will end up having much more ACE than even Ida which was a stronger system...

On the one hand I get what you mean (which is also why I experimented with a system that's simply the seasonal sum of the peak wind speed in kt squared of each system instead of the sum of the squared wind speed every 6 hours, the latter being the definition of ACE), but on the other hand I kinda disagree in this specific case. Ida was an extremely impressive 130 kt high-end cat 4, but I don't think it ever looked as good as Sam did at his peak a few hours before recon arrived.

[kevin]

Is it an IR illusion or does it seem like Sam is indeed trying to close off a smaller eye, similar in size to its eye before the EWRC?

[zzh]

[InfernoFlameCat]

Sam likes small eyes

[kevin]

Sam likes small eyes

The anti-Larry

[kevin]

We're now seeing a rapid decrease in dvorak raw T numbers. This was also visible the previous 2 times just before RI started since what was going on those times is that the eye shrunk and got obscured on IR which dvorak hates. However, it could also be a sign of actual sustained weakening. What do you think? I have a hunch that this might be another 'drop before RI' case.

[aspen]

The milky blob of cirrus clouds to Sam’s SE, as well as its not totally cleared eye, suggest that ventilation and its outflow setup isn’t as good as before and could struggle to clear out its eye. Or it’ll just be a slow process. The 06z HWRF does suggest it’ll get a little better.

[kevin]

Dvorak seems to indicate that the Wring is trying to connect again since about 1 hour ago.

1 hour ago


30 minutes ago (most recent available image)

[tolakram]

10 to 15 kts of shear seems to be enough to prevent a perfect presentation like yesterday. This is why I don't think Sam ever made it to cat 5, conditions are good, but not perfect.

[Teban54]

10 to 15 kts of shear seems to be enough to prevent a perfect presentation like yesterday. This is why I don't think Sam ever made it to cat 5, conditions are good, but not perfect.

I disagree about there being a random threshold of "perfect" vs "good" conditions for reaching 140 kt vs 135 kt. Michael was essentially sheared its whole life and that didn't stop it from reaching 140. Every storm faces different conditions, even those that do become Cat 5s, and there's not much point in estimating whether a storm reached Cat 5 based on how good the conditions are when we have better information about how strong it actually is from recon and satellite estimates.

Plus, there didn't appear to be much shear at all when Sam looked the best.

[tolakram]

10 to 15 kts of shear seems to be enough to prevent a perfect presentation like yesterday. This is why I don't think Sam ever made it to cat 5, conditions are good, but not perfect.

I disagree about there being a random threshold of "perfect" vs "good" conditions for reaching 140 kt vs 135 kt. Michael was essentially sheared its whole life and that didn't stop it from reaching 140. Every storm faces different conditions, even those that do become Cat 5s, and there's not much point in estimating whether a storm reached Cat 5 based on how good the conditions are when we have better information about how strong it actually is from recon and satellite estimates.

Plus, there didn't appear to be much shear at all when Sam looked the best.

Don't disagree with something I didn't say please. I didn't provide some magic threshold, and I also didn't say not to use the best tools that we have to predict intensity.

[kevin]

AF301 recon just departed. If Sam gets its act together and starts strengthening this recon will probably be there too soon to see the real results in terms of wind speed, but it should still give a good idea what the current situation is. The upside is that, unlike a few days ago, we now have a very frequent recon schedule with the plane after this one arriving in about 9 hours.

[aspen]

Sam’s eye on IR has degraded since sunrise, with only tiny portions warmer than -20C thanks to suppresses ventilation. It won’t strengthen behind 115-120kt unless outflow improves in some way.

Still looks nice on visible.

[cheezyWXguy]

Sam’s eye on IR has degraded since sunrise, with only tiny portions warmer than -20C thanks to suppresses ventilation. It won’t strengthen behind 115-120kt unless outflow improves in some way.

Still looks nice on visible.

I think IR is a bit deceiving at the moment, as it makes it look like Sam’s eye is collapsing. However, visible clearly shows that’s not the case, and that it’s just becoming cloud filled. Sam actually looks to be improving in my opinion, outflow to the southwest looks a little better, a band is setting up there, and the cdo is a bit rounder than this morning.

I think today will be a lot like yesterday where we see some steady improvement through the day, although I can’t help but feel like its current structure will lend itself to another Erc in less than 24 hours.

[Teban54]

If I had a dollar every time Sam decides to look worse when recon is en route...

[sikkar]

The most recent visible frames show a hint of the low level circulation, eye maybe clearing right now, or at least trying.