ATL: IDA - Remnants - Discussion

[tolakram]

Lots of hot water ahead, and I am unsure if the forward speed, which I don't think is inhibiting, will actually help eliminate most of the shear. My best guess is a low cat 4, I really can't see a cat 5 either, but then most of us (except the exclaimers of every storm) never really see that cat 5 until it happens. Regardless, everyone in the path should be treating this as a worse case scenario.



Latest shear analysis

[Shell Mound]

I’m seeing the following limiting factors at this point:

• A somewhat fast forward speed of ~14 kt
• Relatively high background pressures
• Mid-level dry air, as mentioned previously
• Somewhat restricted outflow

Given all these factors, I think Cat-5 status has become much more unlikely than I thought yesterday. The NHC’s intensity forecast looks to be quite reasonable.

Take this storm seriously!

14knots is not inhibiting at all.

When Irma was a CAT 5 in 2017, she was moving at 15 knots . . .

...HURRICANE IRMA BECOMES A CATEGORY 5 ON THE SAFFIR-SIMPSON
HURRICANE WIND SCALE...

PRESENT MOVEMENT...W OR 270 DEGREES AT 14 MPH...22 KM/H

Source

Irma’s movement: 12 kt
Ida’s at present: 14 kt

[MississippiWx]

Looks like Ida is about to blow up. Structure has recovered following the Cuba passage. New hot towers are firing around the eye. Get ready for a show.

[StAuggy]

It's good to see it at least took some time to get going again after Cuba, I'm guessing it took a bit longer since it developed a core before it got there so it got disrupted a bit more. Unfortunately it looks like it's gonna bomb soon. I don't really think Cuba lowered the ceiling and I still expect a 130kts+. I think the only thing Cuba did was prevent an ERC before landfall. With less time, I'm thinking Ida intensifies all the way to landfall now, where if it got going earlier overnight, it could have peaked earlier, and then undergo an ERC before landfall, which arguably would be worse bringing in more surge. Lose-lose situation all around here.

Yes. With the lack of ERC and larger wind field, it creates serious implications for landfall damage potential.

More violent surge at the point of landfall! That’s worse for those choosing not to leave which elevates the risk of death in that specific area.

I got roasted earlier for hoping that an EWRC that started right before the eye made landfall would briefly knock down/level off intensity without having time to broaden the wind field. I’m sticking by that statement in hopes of who ever takes this on the nose.

[grapealcoholic]

Looks like the eye just closed off.

[Kohlecane]

Oh, and I've seen hurricanes reach Cat 5 moving at 25 kts. Speed is not a factor if the relative shear is low.

Paraphrased it a tad by taking out his personal stuff, but yeah you get the point, I always thought speed would inhibit it, but in the environment she is currently in

[kevin]

Looks like the eye has closed off.

[ElectricStorm]

985mb extrap on AF plane which matches the NOAA drop. I'm guessing the AF drop will show the same. Still in rebuild mode

[Blinhart]

I know the NHC usually does hourly advisories when the system is getting closer to landfall, any idea when that will start happening today?

[Comradez]

Ida definitely had a little bit of a dry slot coming off of Cuba (perhaps caused by orographic lifting on the south side of those small mountains, and then drier sinking of that air as it left the north side of those small mountains, depleting the moisture of the air heading northward into Ida somewhat). But, it looks like Ida is having no problem mixing out that dry slot with the hot towers firing right around the eyewall, and the CDO expanding in size. The forecast for a solid Cat 4 is still looking likely, in my opinion. Could easily see a 2 mb drop per hour over the next 24 hours, which would put Ida at ~937 mb tomorrow morning.

Tropical systems are kind of like fire. Their gasoline is the warm moist air and a steep lapse rate (temperature gradient) heading up to cold upper levels, which causes air at the core to rise and pull in additional fuel. But even with all that fuel, sometimes tropical systems can smolder for a while if the air flow/venting isn't ideal, kind of like how a campfire can have a hard time getting going if the air flow around it is too turbulent or if the fuel is too smothered and oxygen can't get to it. But like a fire with good airflow, once a symmetrical eyeball gets established, this thing will jump to a Cat 3 in no time.

[Kohlecane]

Interested to see what reading are closer to 25N- 86-85.8W, looks like they are turning to sample near those towers

[cycloneye]

SSD at 5.0.

A. 09L (IDA)

B. 28/1130Z

C. 24.3N

D. 85.5W

E. ONE/GOES-E

F. T5.0/5.0

G. IR/EIR/SWIR

H. REMARKS...SYSTEM HAS A LG EYE TEMP SURROUNDED BY A BLACK RING
TEMP RESULTING IN AN EYE ADJUSTMENT OF -0.5. THE EMBEDDED TEMP IS BLACK
RESULTING IN AN EYE PATTERN DT OF 5.0 WITH THE EYE ADJUSTMENT. SYSTEM HAS
AN EXPANDING BLACK RING AND HAS 3/4 WHITE RING AROUND LLCC. ADDITIONALLY,
EIR IMAGERY INDICATES CMG EMBEDDED IN THE 3/4 WHITE RING REVEALING A
STRENGTHENING SYSTEM AS IT BEGINS TO WRAP AROUND THE EYE. THE 24 HR
TREND IS DEVELOPING RAPIDLY. MET IS 4.5 AND PT IS 5.0. FT IS BASED ON DT.

I. ADDL POSITIONS

NIL


...PATEL

[hohnywx]

I know the NHC usually does hourly advisories when the system is getting closer to landfall, any idea when that will start happening today?

I would think not until tomorrow...per the NHC: https://www.nhc.noaa.gov/aboutnhcprod.shtml#TCU

[Clearcloudz]

Take a look at the Evacuation Traffic from New Orleans

[KWT]

14knots is not inhibiting at all.

When Irma was a CAT 5 in 2017, she was moving at 15 knots . . .

...HURRICANE IRMA BECOMES A CATEGORY 5 ON THE SAFFIR-SIMPSON
HURRICANE WIND SCALE...

PRESENT MOVEMENT...W OR 270 DEGREES AT 14 MPH...22 KM/H

Source

Irma’s movement: 12 kt
Ida’s at present: 14 kt

As much as I do think your probably right overall with regards to the balance, lets be honest a 2kts difference is basically non existent in the grand scheme of things.

Lets just say 14kts forward speed won't stop a 5 on its own if everything else is good aloft. The other factors you mention will.

[loon]

The last few frames she's really coming together. She is enjoying the hot bath it seems. I hope all in the path were able to prepare in their own way and choices... She looks determined.

[Kohlecane]

SSD at 5.0.

A. 09L (IDA)

B. 28/1130Z

C. 24.3N

D. 85.5W

E. ONE/GOES-E

F. T5.0/5.0

G. IR/EIR/SWIR

H. REMARKS...SYSTEM HAS A LG EYE TEMP SURROUNDED BY A BLACK RING
TEMP RESULTING IN AN EYE ADJUSTMENT OF -0.5. THE EMBEDDED TEMP IS BLACK
RESULTING IN AN EYE PATTERN DT OF 5.0 WITH THE EYE ADJUSTMENT. SYSTEM HAS
AN EXPANDING BLACK RING AND HAS 3/4 WHITE RING AROUND LLCC. ADDITIONALLY,
EIR IMAGERY INDICATES CMG EMBEDDED IN THE 3/4 WHITE RING REVEALING A
STRENGTHENING SYSTEM AS IT BEGINS TO WRAP AROUND THE EYE. THE 24 HR
TREND IS DEVELOPING RAPIDLY. MET IS 4.5 AND PT IS 5.0. FT IS BASED ON DT.

I. ADDL POSITIONS

NIL


...PATEL

Took me a while to understand what these meant, thanks for posting Cycloneye.

[kevin]

New pass by recon, 984.5 mb extrapolated.

[KWT]

When Irma was a CAT 5 in 2017, she was moving at 15 knots . . .

...HURRICANE IRMA BECOMES A CATEGORY 5 ON THE SAFFIR-SIMPSON
HURRICANE WIND SCALE...

PRESENT MOVEMENT...W OR 270 DEGREES AT 14 MPH...22 KM/H

Source

Irma’s movement: 12 kt
Ida’s at present: 14 kt

As much as I do think your probably right overall with regards to the balance, lets be honest a 2kts difference is basically non existent in the grand scheme of things. An example of a faster moving 5 is Emily which was quicker by a smidge compared to Ida when it went to a 5.

Lets just say 14kts forward speed won't stop a 5 on its own if everything else is good aloft. The other factors you mention will.

[LARanger]

Take a look at the Evacuation Traffic from New Orleans

Securing potential debris so pardon me for short messages, but St. Charles Parish (west of NO) at least is under mandatory evac which may explain some traffic observed as well.