ATL: IDALIA - Post-Tropical - Discussion

[ColdMiser123]

00985 10017

Center drop 985 mb with 17 knots. Pressure around 983.

About 11 mb lower than the 18z GFS forecast pressure at 8 pm eastern.

[USTropics]

There are clear signs on satellite imagery that Idalia is on the cusp of hurricane strength. Infrared shows an expanding canopy, with building cloud tops in the southern quadrant:


Using meso sector visible imagery, we can also see clear gravity wave oscillations that are causing perturbations in the developing CDO of Idalia this evening:

[Zonacane]

Very healthy core taking shape

[zzzh]

Global models are not the best for intensity right now. 12z gfs simply had 971mb for Franklin and in reality it was 937mb.

[eastcoastFL]

Gonna go out on a limb and guess 75 knots by the time the current mission has ended this evening.

It will be the ugliest hurricane on radar lol.

I feel like it's presentation will be more impressive once it's in range of Key West radar.

[ChrisH-UK]

The cloud tops are getting colder.

source - https://col.st/r65Ka

[NDG]

Don't see any real shear on the two dropsonde to the north of the storm

Yes there is, look at all that northerly winds between h40-h20.

[zzzh]

847
URNT12 KWBC 282241
VORTEX DATA MESSAGE AL102023
A. 28/22:10:26Z
B. 21.52 deg N 085.14 deg W
C. 700 MB 3014 m
D. 985 mb
E. 100 deg 17 kt
F. NA
G. NA
H. 51 kt
I. 342 deg 13 nm 22:07:18Z
J. 074 deg 36 kt
K. 340 deg 31 nm 22:03:07Z
L. 43 kt
M. 177 deg 79 nm 22:29:22Z
N. 264 deg 42 kt
O. 174 deg 26 nm 22:16:38Z
P. 14 C / 3070 m
Q. 20 C / 3065 m
R. 10 C / NA
S. 12345 / 7
T. 0.01 / 1 nm
U. NOAA3 0810A IDALIA OB 05
MAX FL WIND 42 KT 174 / 26 NM 22:16:38Z

[Laser30033003]

Does anyone know the size of the storm ..it looks so big on the satellite image

[ColdMiser123]

Global models are not the best for intensity right now. 12z gfs simply had 971mb for Franklin and in reality it was 937mb.

This matters a lot more when you have a very tight inner core that a global model can't fully resolve, like with Franklin. We're not at the point yet where globals should be missing by this much.

Most of the hurricane models were also generally too high with pressure at 8 pm today as well, which fully resolve inner core pressure gradients.

[Zonacane]

Don't see any real shear on the two dropsonde to the north of the storm

Yes there is, look at all that northerly winds between h40-h20.

Not really. Winds are mostly Easterlies. I'm talking about dropsonde 1 and 2

[Nimbus]

https://www.tropicaltidbits.com/recon/recon_NOAA3-0810A-IDALIA_dropsonde3_20230828-2210.png
Very healthy core taking shape

700 mb relative humidity is 49% in the center of the storm yet the mid gulf buoy RH is over 73% so why is the core dry there?
G-IV mission will have more data.

[jdjaguar]

Just wanted to mention two useful tips for those in the path of the storm. Cheap flashlights can be found in Home Depot or Lowes in the landscape section, buy the solar landscape lights. They are really cheap, can be charged during the day outside, and used inside where needed. Also make sure your fence is attached to your house with Tapcons. Oftentimes the post is only cemented in the ground next to the house but not physically attached to it. In many cases it changes how the insurance carrier grants coverage. I've had many clients get the fence covered by their policy or even lose coverage of thousands of dollars for just a couple dollars of screws.

good idea, but my termite bond requires the fence to not be attached to the main structure. must have minimum distance, can't remember how much 2-4 inches or so.

[Zonacane]

https://www.tropicaltidbits.com/recon/recon_NOAA3-0810A-IDALIA_dropsonde3_20230828-2210.png
Very healthy core taking shape

700 mb relative humidity is 49% in the center of the storm yet the mid gulf buoy RH is over 73% so why is the core dry there?
G-IV mission will have more data.

 https://twitter.com/EthanKerr2003/status/1696290341052178638

[CrazyC83]

That suggests a pressure of 983 mb with that dropsonde. But nothing to support stronger winds.

[NDG]

Don't see any real shear on the two dropsonde to the north of the storm

Yes there is, look at all that northerly winds between h40-h20.

Not really. Winds are mostly Easterlies. I'm talking about dropsonde 1 and 2

Those Dropsondes are only from 10k feet (h70), is not going to show the shear above that height.
You have to look at the one currently sampling the whole atmosphere which shows northerly dry shear still present directly on the NW quadrant of the storm pinching on its circulation.

[Fancy1002]

That suggests a pressure of 983 mb with that dropsonde. But nothing to support stronger winds.

In your professional opinion, how far can the pressure drop before the winds catch up?

[Zonacane]

Yes there is, look at all that northerly winds between h40-h20.

Not really. Winds are mostly Easterlies. I'm talking about dropsonde 1 and 2

Those Dropsondes are only from 10k feet (h70), is not going to show the shear above that height.
You have to look at the one currently sampling the whole atmosphere which shows northerly dry shear still present directly on the NW quadrant of the storm pinching on its circulation.

Oh, I didn't realize Gonzo had conducted upper-air recon. That would certainly explain it. Thank you for the correction.

[CrazyC83]

That suggests a pressure of 983 mb with that dropsonde. But nothing to support stronger winds.

In your professional opinion, how far can the pressure drop before the winds catch up?

It could take some time as long as it is getting organized. In 2021, Ida's pressure dropped about 20 mb in the first 12 hours of intensification but the winds only increased slightly before taking off overnight.

[eastcoastFL]

Does anyone know the size of the storm ..it looks so big on the satellite image

It's still pretty small but it's continuing to grow.