ATL: IAN - Post-Tropical - Discussion

[skyline385]

So with NHC tracking even more west again this run, do we expect to keep that west trend/placement?

I posted an AOML verification in the models thread, basically all models miscalculated the new center location and its north of previous runs.

https://www.storm2k.org/phpbb2/viewtopi ... 2#p2995062

[Chris_in_Tampa]

with stift to right you think cone cover south fl again down in miami dade or wait over night to see more stift to east over night

The NHC forecast cone is always the same during a particular year. It has set radii at each point. It doesn't reflect uncertainty for a current storm. They can't adjust it even if there were greater uncertainty earlier on.

Cone for Ian:
https://www.nhc.noaa.gov/refresh/graphi ... e#contents

See bottom of that page or here for info about the cone:
https://www.nhc.noaa.gov/aboutcone.shtml

If they were to move the cone to also include south Florida, the western Panhandle would be completely out of it. They need to reflect where the models are, combined with their expertise, on where it's going, making gradual shifts when possible. If an area moves out of the cone, it doesn't mean your safe.

Over past 5 years, two thirds of the time the center point of a storm would be inside the circles described in the links I provided. (They create a cone drawing a line around those circles at each forecast point) A third of the time, it wouldn't be. And that is the center point. The center point could be on the edge of the cone, within it, but effects could be felt hundreds of miles outside the cone, depending on the size of the storm, from that center point. So, approximately one third of the time on average the center point will be outside the cone. And again, doesn't consider impacts outside the cone. Unfortunately a lot of people don't really understand that, or emphasize that, even some meteorologists. It's great to be out of the cone, but it doesn't mean you need to stop paying attention. Things will change as they need to. So people always need to pay close attention.

They readjust the radii each year, using last 5 years of data each time.

[tropicwatch]

NHC doesn't usually put this kind of headline up unless they are very confident.
"IAN FORECAST TO BEGIN RAPIDLY INTENSIFYING AND BECOME A
HURRICANE ON SUNDAY... "

[Teban54]

Remember, the 5pm NHC forecast was already east of TVCN (which had a drastic west shift at that time). I think they didn't want to make a huge shift at 5pm, and they're just catching up at 11pm.

Also, while convection is a bit anemic now, I think it might just be a pulse down phase. IIRC, one of Eta or Iota (I can't remember which) was almost devoid of convection at one point.

[cheezyWXguy]

Remember, the 5pm NHC forecast was already east of TVCN (which had a drastic west shift at that time). I think they didn't want to make a huge shift at 5pm, and they're just catching up at 11pm.

Also, while convection is a bit anemic now, I think it might just be a pulse down phase. IIRC, one of Eta or Iota (I can't remember which) was almost devoid of convection at one point.

As wxman pointed out earlier nhc is likely to follow the tvcn as a safe bet, which I imagine holds even more true about n times of uncertainty like this. I have hunch the 0z models will start pushing back east, and if they do the nhc will adjust, but I really don’t want to bet on anything at this point. My personal unofficial view is that still that Sarasota to the big bend should be on high alert, but I’d much rather leave decisive statements to the people who do this for a living.

[birddogsc]

NHC has IAN spinning down from a CAT3 to a CAT1 in less than 8 hours just before landfall? I would think the OHC would be high in that area, and the forward speed should be sufficient to not make upwelling an issue. Shear?

[tolakram]

NHC has IAN spinning down from a CAT3 to a CAT1 in less than 8 hours just before landfall? I would think the OHC would be high in that area, and the forward speed should be sufficient to not make upwelling an issue. Shear?

Basically travelling under the jet streak, so would probably uncouple pretty quickly.

[TallyTracker]

I’m starting to make my detailed evacuation plan now. lol Don’t want to be in Tallahassee for a hurricane. The tree damage could take weeks to restore power in some areas with a Cat 1/2 direct hit. Most of my family lives in the path so I’ll probably be taking a fall trip to MS or west TN if this path holds for another 36 hours.

[skyline385]

NHC has IAN spinning down from a CAT3 to a CAT1 in less than 8 hours just before landfall? I would think the OHC would be high in that area, and the forward speed should be sufficient to not make upwelling an issue. Shear?

Yes 30-40 kts of shear along with the front eroding it combined with dry air getting into the core from the west

[birddogsc]

NHC has IAN spinning down from a CAT3 to a CAT1 in less than 8 hours just before landfall? I would think the OHC would be high in that area, and the forward speed should be sufficient to not make upwelling an issue. Shear?

Basically travelling under the jet streak, so would probably uncouple pretty quickly.

So, the streamlines are showing the jet streak here, but the GFS is not modeling the separation of the centers?

[BobHarlem]

Really think the NHC went conservative (on track, not intensity), there's a lot of new recon data going into the 0z global runs tonight, and they just went with straight TVCN. If the models shift right, so will the consensus. (And left if they go that way) They didn't elaborate (no stewart style discussions) but they did mention the model split.

[chaser1]

NHC doesn't usually put this kind of headline up unless they are very confident.
"IAN FORECAST TO BEGIN RAPIDLY INTENSIFYING AND BECOME A
HURRICANE ON SUNDAY... "

You're right. It's a pretty bold statement.

[StAuggy]

NHC has IAN spinning down from a CAT3 to a CAT1 in less than 8 hours just before landfall? I would think the OHC would be high in that area, and the forward speed should be sufficient to not make upwelling an issue. Shear?

Yes 30-40 kts of shear along with the front eroding it combined with dry air getting into the core from the west



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

The right turn into the peninsula could negate those effects to a degree so don’t bank on a substantial weakening at landfall unless it heads way north

[Teban54]

Remember, the 5pm NHC forecast was already east of TVCN (which had a drastic west shift at that time). I think they didn't want to make a huge shift at 5pm, and they're just catching up at 11pm.

Also, while convection is a bit anemic now, I think it might just be a pulse down phase. IIRC, one of Eta or Iota (I can't remember which) was almost devoid of convection at one point.

This is the closest I can find. Here is Eta about half an hour before it was named:

16 hours later, it was at 50 kts with a developing eyewall. It reached the (official) peak intensity of 130 kts another 30 hours later.

Ian's current appearance for comparison:

[sweetpea]

I’m starting to make my detailed evacuation plan now. lol Don’t want to be in Tallahassee for a hurricane. The tree damage could take weeks to restore power in some areas with a Cat 1/2 direct hit. Most of my family lives in the path so I’ll probably be taking a fall trip to MS or west TN if this path holds for another 36 hours.

We are sitting here down in Sopchoppy deciding what to do. We are about 3.5 miles as the crow flies from the gulf. Think we will decide tomorrow afternoon. Be safe.

[Hurricane Mike]

Here's a midnight update on Ian for the night owls
https://www.youtube.com/watch?v=T-O3CCq0hW8

[LARanger]

I know some people on here like their Hebert box's

New one on me, and I'm iffy on whether it's "a thing", but now I want to see something similar for Louisiana.

Ask and you shall receive, LARanger:

[url]https://i.ibb.co/ryRX7gF/Cajun-boxes.jpg [/url]

2020 Hurricane Season, is that you?

[Patrick99]

Wow it looks like convection is really eroding. Regardless of track....this has some work to do. What's happening? Could it be dry air?

[NFLnut]

NHC doesn't usually put this kind of headline up unless they are very confident.
"IAN FORECAST TO BEGIN RAPIDLY INTENSIFYING AND BECOME A
HURRICANE ON SUNDAY... "

Well .. they're forecasting 130mph in 60 hours and 140 in 72 so it's gotta start intensifying pretty soon to keep with that.

[ScottNAtlanta]

Well, recon is there, but they are not finding a center where it is supposed to be. It is farther south (what they have covered thus far) and not exactly a wind shift either. I'm pretty sure it isn't stacked yet. They aren't reporting surface pressures either so it is kind of hard to tell.