ATL: ISAAC - Extratropical - Discussion

[weeniepatrol]

Yeah... NHC is being conservative with everything, not just formative disturbances. We all suspect if we dropped recon in there it would be finding support for 85 kt.

For example, remember when they upped Lee II to a major back in 2017? Does anyone see them ever doing that nowadays?

If they want to be more conservative, fine. I just really wish they would clearly communicate changes in policy, as opposed to the radio silence we get.

[HurricaneAndre2008]

AL, 10, 2024092806, 01, CARQ, 0, 388N, 422W, 90, 968, HU, 64, NEQ, 0, 25, 20, 0, 1012, 240, 15, 0, 0, L, 0, X, 65, 16, ISAAC, D,

[CrazyC83]

This has to be one of the stronger storms to intensify that far north. Agreed with 90 kt, although 95 kt is also reasonable.

[Teban54]

[aspen]

https://i.postimg.cc/85VN2Rxf/image.png

Those crazy HWRF/HAFS runs with a major were right it seems.

[Teban54]

[kevin]

SATCON up to 959mb/93kt and Dvorak CI# is up to 957mb/92kt with raw T# at 5.2 (95 kt). We might see an upgrade to 95 kt if trends continue.

[ChrisH-UK]

Isaac this morning looking to be in good condition, I wonder if it will make to a major.

[aspen]

Isaac this morning looking to be in good condition, I wonder if it will make to a major.

[url]https://imagizer.imageshack.com/img922/6169/JJzuzM.gif [/url]

They won’t, they kept it at 90 kt for 12z.

How Lee ‘17 ever got upgraded to a major is beyond me.

[Hurricane2022]

This is likely a major right now.Not sure what's going on with the NHC. I hope Papin writes the next advisory.

[Sciencerocks]

[aspen]

https://i.imgur.com/9c9T2Z2.gif

Still stuck at 16z yesterday. What’s going on with GOES? So many data outages this year and this is by far the worst.

[Hurricane2022]

[Vince_and_Grace_fan]

The convection became slightly warmer and less-organised in the last hours, while the eye cooled a bit, so I agree with the NHC's estimation of 90 kt at 12Z. https://tropic.ssec.wisc.edu/real-time/adt/movies/odthtml5_10L.html I think it reached Category 2 intensity (85 kt) around 18Z yesterday and it peaked with 95 kt at 06Z today.



Ophelia in 2017 had better structure with slightly deeper convection and larger, symmetrical CDO when it became a major (the upper pair of images is from its TCR, compared to Isaac's best structure at 04-05Z below, lat/lon lines are every 2° in case of Ophelia and 5°in case of Isaac), so I don't think Isaac will be reclassified to a major in the post-season.

[cheezyWXguy]

The convection became slightly warmer and less-organised in the last hours, while the eye cooled a bit, so I agree with the NHC's estimation of 90 kt at 12Z. https://tropic.ssec.wisc.edu/real-time/adt/movies/odthtml5_10L.html I think it reached Category 2 intensity (85 kt) around 18Z yesterday and it peaked with 95 kt at 06Z today.

https://i.imgur.com/AHtslWt.png

Ophelia in 2017 had better structure with slightly deeper convection and larger, symmetrical CDO when it became a major (the upper pair of images is from its TCR, compared to Isaac's best structure at 04-05Z below), so I don't think Isaac will be reclassified to a major in the post-season.

https://i.imgur.com/tnLjinq.png

https://i.imgur.com/8CkWRNx.png

This is a good point, I can see there that Ophelia’s eye looks a bit warmer too. 95kt is probably reasonable

[Ubuntwo]

Yeah... NHC is being conservative with everything, not just formative disturbances. We all suspect if we dropped recon in there it would be finding support for 85 kt.

For example, remember when they upped Lee II to a major back in 2017? Does anyone see them ever doing that nowadays?

If they want to be more conservative, fine. I just really wish they would clearly communicate changes in policy, as opposed to the radio silence we get.

To be fair, Lee did have recon confirmation of major hurricane winds in addition to the superb presentation with deeper convection than Isaac. It took them a while, but I think 90kt is an overall fair assessment if a touch low.

[Travorum]

SAR pass from this morning, 90kts measured:

Platform: RCM-3
Acquisition Date: 2024-09-28 08:49:26 UTC
Storm Name: AL102024 / ISAAC
Storm ID: AL10
Storm Center Longitude: -41.631
Storm Center Latitude: 39.148
Incidence Angle (Degrees): 42.730
Quadrant 1 NE VMax (kts): 88.32
Quadrant 2 SE VMax (kts): 89.27
Quadrant 3 SW VMax (kts): 91.02
Quadrant 4 NW VMax (kts): 84.09
RMax (nmi): 10.00 - 13.00

[cheezyWXguy]

SAR pass from this morning, 90kts measured:

https://i.imgur.com/KMo5gpa.png

Platform: RCM-3
Acquisition Date: 2024-09-28 08:49:26 UTC
Storm Name: AL102024 / ISAAC
Storm ID: AL10
Storm Center Longitude: -41.631
Storm Center Latitude: 39.148
Incidence Angle (Degrees): 42.730
Quadrant 1 NE VMax (kts): 88.32
Quadrant 2 SE VMax (kts): 89.27
Quadrant 3 SW VMax (kts): 91.02
Quadrant 4 NW VMax (kts): 84.09
RMax (nmi): 10.00 - 13.00

Impressively symmetrical windfield imo

[CrazyC83]

All things considered, 90 kt seems reasonable for a peak given the circumstances (if it was over warmer water, 100 kt might have been reasonable). Ophelia had a presentation that could have argued for up to 110 kt but the cooler water may have prevented optimum wind mixing to the surface.

[Travorum]

In line with the NHC's advisories, Isaac's appearance has waned on the SAR pass from 4 hours ago:

Platform: RCM-1
Acquisition Date: 2024-09-28 20:42:08 UTC
Storm Name: AL102024 / ISAAC
Storm ID: AL10
Storm Center Longitude: -38.744
Storm Center Latitude: 40.944
Incidence Angle (Degrees): 53.847
Quadrant 1 NE VMax (kts): 73.52
Quadrant 2 SE VMax (kts): 72.09
Quadrant 3 SW VMax (kts): 79.87
Quadrant 4 NW VMax (kts): 78.42
RMax (nmi): 19.00 - 36.00