ATL: IDA - Models

[Steve]

My thinking is for this to be more like a low to mid end cat2 by landfall. I wouldn't be shocked if it got stronger but chances are it won't be a cat4 or 5.

Yeah, I think 4 or 5 are unlikely as well if not impossible. Earlier I guessed 70% at Cat 3. Not sure I'm that high anymore - probably more like 40-45%. But since they sample so much stuff now, they may be able to find at least an extended gust into Cat 3 territory over the Gulf. Glad to see an extreme slowdown is probably off the table too. I'm a wuss and not really ready to make a call like I have for the last 25 years on here or CFHC. But I feel like it will landfall between Slidell and Marsh Island with the zoomed in range of Cocodrie to Centerville/Patterson (just west of Morgan City).

Are we sure that a 4 is impossible? Grace nearly did it in 24 hours, and the models had higher pressure estimates at landfall than with Ida. Also, even the ICON shows 963...

What I meant by if not impossible was that it wasn't impossible - just not likely. That's my opinion. I'm curious to see what might be the hold-back if there is any. Lots of things look good for intensification and probably a peak about landfall. But how low can the pressure get? 950 maybe? Otherwise, Pysclone eloquently represented what I was thinking.

[Blinhart]

GFS has it deepening at about 1mb/hour in the gulf, and gets it to 953. Any brief period of faster intensification could get it to Cat 4 a similar scenario to this run plays out. Yeah it's not looking good

If it deepens at 2mb/hr then we could see a 5 and I don't want to see a 5, I really don't want to see a 3 but I don't see how this doesn't become a 3.

[PTrackerLA]

I probably spent too much on a portable air conditioner at Costco today, but the 00z runs so far are making me take it out the back of the car before bed. Still too early to pinpoint our impacts but I'm going to continue to prepare for hurricane conditions equal to our greater than Delta 2020. I noticed the 00z UKMET appears to have a very similar track to the 18z HWRF as well

[BobHarlem]

Canadian a bit stronger, and to the left slightly.

[Meteorcane]

Yeah, I think 4 or 5 are unlikely as well if not impossible. Earlier I guessed 70% at Cat 3. Not sure I'm that high anymore - probably more like 40-45%. But since they sample so much stuff now, they may be able to find at least an extended gust into Cat 3 territory over the Gulf. Glad to see an extreme slowdown is probably off the table too. I'm a wuss and not really ready to make a call like I have for the last 25 years on here or CFHC. But I feel like it will landfall between Slidell and Marsh Island with the zoomed in range of Cocodrie to Centerville/Patterson (just west of Morgan City).

Are we sure that a 4 is impossible? Grace nearly did it in 24 hours, and the models had higher pressure estimates at landfall than with Ida. Also, even the ICON shows 963...

What I meant by if not impossible was that it wasn't impossible - just not likely. That's my opinion. I'm curious to see what might be the hold-back if there is any. Lots of things look good for intensification and probably a peak about landfall. But how low can the pressure get? 950 maybe? Otherwise, Pysclone eloquently represented what I was thinking.

These systems are some of the most challenging to forecast intensity for... on one hand a relatively disorganized system at the moment with at least some land interaction in its future... on the other hand it will be traversing over an area of enhanced OHC in the Gulf, with a favorable upper-lvl wind pattern/outflow expected. I think like a 90-105kt storm at peak intensity seems like a good hedge given the competing factors, but the error bars would be even higher than usual.

[PTrackerLA]

18z GEFS still seems focused well west of OP run

[CrazyC83]

Canadian a bit stronger, and to the left slightly.
https://i.imgur.com/Oqk3jb9.png

That would be around Port Fourchon instead of the mouth of the Mississippi - about a 50 mile shift. Still a hard hit for NOLA there though.

[drezee]

 https://twitter.com/crownweather/status/1431108798198992896

[PTrackerLA]

Canadian a bit stronger, and to the left slightly.
https://i.imgur.com/Oqk3jb9.png

That would be around Port Fourchon instead of the mouth of the Mississippi - about a 50 mile shift. Still a hard hit for NOLA there though.

3rd major model with a West shift at 00z tonight. Not exactly what I expected given thoughts on here and twitter this evening, but can't be discounted. Time for bed as tomorrow is a day of continued preparations.

[Blinhart]

I probably spent too much on a portable air conditioner at Costco today, but the 00z runs so far are making me take it out the back of the car before bed. Still too early to pinpoint our impacts but I'm going to continue to prepare for hurricane conditions equal to our greater than Delta 2020. I noticed the 00z UKMET appears to have a very similar track to the 18z HWRF as well

https://imgur.com/kseNBQM

Yeah I'm thinking we will get about the same as Delta or maybe a little stronger.

[Craters]

Yeah, I think 4 or 5 are unlikely as well if not impossible. Earlier I guessed 70% at Cat 3. Not sure I'm that high anymore - probably more like 40-45%. But since they sample so much stuff now, they may be able to find at least an extended gust into Cat 3 territory over the Gulf. Glad to see an extreme slowdown is probably off the table too. I'm a wuss and not really ready to make a call like I have for the last 25 years on here or CFHC. But I feel like it will landfall between Slidell and Marsh Island with the zoomed in range of Cocodrie to Centerville/Patterson (just west of Morgan City).

Are we sure that a 4 is impossible? Grace nearly did it in 24 hours, and the models had higher pressure estimates at landfall than with Ida. Also, even the ICON shows 963...

It's probably more pragmatic to focus on a reasonable range (probabilities) instead of high end possibilities. that's how i always try to think. to that end the system is far more likely to end up a 2 or perhaps low end 3 rather than a 4 or a 5. these sorts of details are impossible to resolve at this point and a more sensible solution may not be to talk about some extreme event and instead focus on just how bad a 90-100kt cane can be. That, over one's neighborhood is an extreme event. 8-12" rain, 7-11' surge, triple digit wind gusts, far flung tornadoes... I'd bet on a 90-100kt storm at this point. and that's bad. really bad. For some historical reference, Camille crossed western Cuba as a 100kt cat 3... so it was already a major as it entered the gulf. Of course i know about Michael but for every memorable exceptional event like that there are many others that came up short of that...but were still bad and warrant respect and preparation.

Storm2K has a lot of great posts, but this one, short as it is, is exceptionally good. Yay, Psyclone!

[Meteorcane]

Canadian a bit stronger, and to the left slightly.
https://i.imgur.com/Oqk3jb9.png

That would be around Port Fourchon instead of the mouth of the Mississippi - about a 50 mile shift. Still a hard hit for NOLA there though.

3rd major model with a West shift at 00z tonight. Not exactly what I expected given thoughts on here and twitter this evening, but can't be discounted. Time for bed as tomorrow is a day of continued preparations.

We actually do have some legit recon fixes of the center being assimilated finally into guidance... still not completely organized enough to rule out some center relocations with convective bursts. But, assuming the center does stay where RECON analyzed it, a big factor in how much longitude the system can get (even more so than system intensity) is how fast it progresses northward into the weakness formed by the departing High. The quicker it is (think Sunday landfall) the better chance it is able to drift further west before the shortwave in the Central US sends it more NNE, a slower storm will turn NNE further east and thus track further east.

It should be noted we are solidly in the mid-range from a time standpoint and even approaching the short-range, so the synoptics are probably being modeled decently enough, and/or sampled by the RAOB network (although the shortwave which will amplify the trough over the mountain west is still in the Gulf of Alaska). So unless the LLC really relocates Northward into a convective burst, I would be surprised if the landfall is not somewhere in Louisiana (which is supported by the ensemble envelopes)

[PTrackerLA]

One more, 00z UKMET from pivotal weather, much stronger this run and as least as deep as 962mb with a slight shift West. I'd imagine pressures could be in the high 950's since the center is at least 20 miles inland on this timestamp. My house is entering the eye on this frame so this wouldn't be a pleasant experience...

[PTPatrick]

0z Hwrf running a hair east and slower than it’s 18z run. Guessing it comes in somewhere near 0z gfs, as it was a good bit west of it on prior run.

[skyline385]

HMON 0Z going nuts, 116 kt with a large storm and still not close to landfall especially if Ida takes a western path

[IcyTundra]

00Z HMON heading for Vermillion Bay.

[CrazyC83]

00Z HMON: ~950 mb SW of Centerville (SE of New Iberia). 18Z had it landfall at Cocodrie - it's a west shift of 65 miles.

[Steve]

00Z HMON heading for Vermillion Bay.

Looks like the HWRF is geared toward Terrebonne or St. Mary. Sometimes it's good with intensity within 3 days. If it's right, it drops from 971mb to 967 from 60-63h. It looks to be tightening up with maybe 12 more hours or so over water. Maybe it will get it to 955 or so? Also of note (if the HWRF is right), this will be another storm that got better coming up in the subtropics north of 28. It's something to continue to watch for this season.

[Steve]

Oh ****. 955 at 69 hours (valid for 4pm Sunday). Still looks to have 6 hours or so over water. Could HWRF get it down in the 940's? Seems like Cat 3 world.

https://www.tropicaltidbits.com/analysi ... 2700&fh=69

[CrazyC83]

00Z HMON heading for Vermillion Bay.

Looks like the HWRF is geared toward Terrebonne or St. Mary. Sometimes it's good with intensity within 3 days. If it's right, it drops from 971mb to 967 from 60-63h. It looks to be tightening up with maybe 12 more hours or so over water. Maybe it will get it to 955 or so? Also of note (if the HWRF is right), this will be another storm that got better coming up in the subtropics north of 28. It's something to continue to watch for this season.

If the Euro also shifts west, I'd expect a track adjustment at the next advisory.