ATL: IAN - Post-Tropical - Discussion

[Kazmit]

74 kt FL winds and 69 kt SFMR. Might be enough for an upgrade to 70 kt for the next advisory even though I would also understand keeping it at 65 kt.

Best track puts it at 70kts already.

[Iceresistance]

...IAN FORECAST TO CONTINUE RAPIDLY STRENGTHENING... ...CONDITIONS IN WESTERN CUBA TO DETERIORATE THIS EVENING AND TONIGHT WITH SIGNIFICANT WIND AND STORM SURGE IMPACTS EXPECTED...

11:00 AM EDT Mon Sep 26
Location: 19.1°N 82.7°W
Moving: NW at 13 mph
Min pressure: 980 mb
Max sustained: 80 mph

[kevin]

11am discussion:

000
WTNT44 KNHC 261457
TCDAT4

Hurricane Ian Discussion Number 14
NWS National Hurricane Center Miami FL AL092022
1100 AM EDT Mon Sep 26 2022

The satellite presentation of Ian has improved this morning. Deep
convection has increased within the inner core during the past
several hours, with an expanding central dense overcast noted in
recent satellite imagery. The inner core structure continues to take
shape in radar data, although the eyewall still has a banded
appearance and remains open on the west side. Dropsonde data from
the NOAA and Air Force Hurricane Hunter aircraft indicate that the
minimum pressure has gradually fallen to about 980 mb, and the
initial intensity is raised slightly to 70 kt for this advisory.

The intensity of Ian has increased by 30 kt during the past 18 h.
Further rapid intensification (RI) is expected during the next 24-36
h as Ian crosses the high oceanic heat content of the northwestern
Caribbean Sea within a very low vertical wind shear (VWS)
environment. The latest SHIPS-RI probabilities continue to highlight
the high likelihood of this scenario, with a 73 percent chance of a
35-kt wind speed increase in 24 h and a 79 percent chance of a 45-kt
increase in 36 h. The NHC intensity forecast is similar to the
previous one, and it shows Ian becoming a major hurricane by the
time it reaches western Cuba. Ian is forecast to reach its peak
intensity in 36 h over the southeastern Gulf of Mexico. Then,
increasing southwesterly shear by 36-48 h is expected to bring an
end to the intensification phase. The combination of strong VWS and
drier mid-level air will induce weakening thereafter, but Ian is
expected to remain at or near major hurricane strength as it passes
near the west-central coast of Florida on Wednesday and Thursday.

Ian continues to move northwestward at 325/11 kt. A turn toward the
north-northwest and north is expected during the next day or so as
the hurricane moves around the western extent of a mid-level ridge.
Then, an upper-level trough over the eastern U.S. should cause Ian
to turn more north-northeastward through Thursday. This track brings
the center of Ian close to the west-central coast of Florida during
the middle of the week. An even greater concern is the slower
forward motion that is forecast during this period, as the upper
trough passes north and east of Ian and the steering currents
weaken. This would likely prolong the storm surge, wind, and
rainfall impacts along the affected portions of the west coast of
Florida, although the roughly shore-parallel track still makes it
difficult to pinpoint exactly what locations will experience the
most severe impacts. The track guidance has come into better
agreement during the first 72 h of the forecast period, and only a
minor eastward adjustment was made to the NHC track forecast in line
with the multi-model consensus aids.

The aircraft data indicate that the 34-kt wind radii in the
northeastern quadrant were 20-30 n mi larger than previously
estimated, and this has been reflected in the latest forecast.
Based on these changes, Tropical Storm Watches have been issued for
the middle Florida Keys and extended southward along the
southwestern coast of Florida.


Key Messages:

1. Life-threatening storm surge, hurricane-force winds, flash
floods and possible mudslides are expected in portions of western
Cuba beginning this evening and continuing into Tuesday.
Devastating wind damage is possible where the core of Ian moves
across western Cuba. Efforts to protect life and property should be
rushed to completion.

2. Life-threatening storm surge is possible along much of the
Florida west coast, with the highest risk from Fort Myers to the
Tampa Bay region. Residents in these areas should listen to advice
given by local officials.

3. Hurricane-force winds are possible in the hurricane watch area
in west-central Florida beginning Wednesday morning with tropical
storm conditions possible by late Tuesday. Residents in this area
should ensure that they have their hurricane plan in place.

4. Heavy rainfall will increase across the Florida Keys and south
Florida Tuesday, spreading to central and northern Florida Wednesday
and Thursday, potentially causing flash, urban and small stream
flooding. Significant prolonged river flooding is likely across
central Florida.



FORECAST POSITIONS AND MAX WINDS

INIT 26/1500Z 19.1N 82.7W 70 KT 80 MPH
12H 27/0000Z 20.7N 83.5W 90 KT 105 MPH
24H 27/1200Z 22.7N 84.0W 105 KT 120 MPH
36H 28/0000Z 24.5N 84.0W 120 KT 140 MPH
48H 28/1200Z 26.1N 83.8W 120 KT 140 MPH
60H 29/0000Z 27.2N 83.5W 105 KT 120 MPH
72H 29/1200Z 28.0N 83.2W 90 KT 105 MPH
96H 30/1200Z 29.8N 82.9W 55 KT 65 MPH...INLAND
120H 01/1200Z 32.8N 82.6W 30 KT 35 MPH...INLAND

$$
Forecaster Reinhart

[beachnut]

RI probably gulped-in some remnant dry air from Fiona...


This is a tough call on evacuation here on Sanibel because of the Charley factor...Plus I think this one might have surge unlike Charley, Wilma, and Irma...


The Bermuda High will make us or break us...

Have you studied the CERA website for surge? The bridge causeway off the island is underwater. You'll be cut off given the current NHC 13 track. That's without any Charlie-type deviations.

Karen, do you prefer the CERA map or the NHC inudation map? South Cape below CC Pkwy shows nothing except for a few small areas, yet the NHC map shows yellow (>3') for almost everywhere south of Veterans. I understand this can and will change but I'm trying to understand the discrepancy.

[Iceresistance]

Recon also shows 981 mb as the lowest extrapolated pressure at the eye.

[wxman57]

NHC track is in line with 12Z TVCN, and very close to my track. I do have lots of doubt about the track beyond Tuesday. It bugs me that some models have shifted the track farther offshore Wed/Thu. On the bright side, it would mean less severe impacts to the western Peninsula. It would also mean a weaker hurricane at landfall if it tracks any west of the current forecast, possibly only a TS at landfall. Would likely be hard hit by shear and dry air intrusion. We won't really be confident in where it will eventually go for another day or so.

[CryHavoc]

SE eyewall stronger than last pass, also down to 981 and not at the center yet

The crazy pressure gradient is the part that bothers me the most.

https://s4.gifyu.com/images/recon_AF300-1409A-IAN_zoom.png
https://s4.gifyu.com/images/recon_AF300-1409A-IAN_zoom.png

You see sharp gradients often with developing TCs, especially in areas where there is ample fuel. At times the pressure drops but it takes a while for the winds to match. I believe it was Ike from 2008 that showed repeated pressure drops with a very slow wind speed increase.

[CryHavoc]

Ugh, the evacuation page for the greater Tampa Area is down.

Not great timing to have a server outage.

[KC7NEC]

Ugh, the evacuation page for the greater Tampa Area is down.

Not great timing to have a server outage.

A page that gets maybe 10 hits a day suddenly getting hundreds a minute will do that.

[chris_fit]

NHC track is in line with 12Z TVCN, and very close to my track. I do have lots of doubt about the track beyond Tuesday. It bugs me that some models have shifted the track farther offshore Wed/Thu. On the bright side, it would mean less severe impacts to the western Peninsula. It would also mean a weaker hurricane at landfall if it tracks any west of the current forecast, possibly only a TS at landfall. Would likely be hard hit by shear and dry air intrusion. We won't really be confident in where it will eventually go for another day or so.

How's that jet thing looking that's supposed to push Ian more the E - You had talked about this int he days past. Anything new on that front?

[robbielyn]

NHC track is in line with 12Z TVCN, and very close to my track. I do have lots of doubt about the track beyond Tuesday. It bugs me that some models have shifted the track farther offshore Wed/Thu. On the bright side, it would mean less severe impacts to the western Peninsula. It would also mean a weaker hurricane at landfall if it tracks any west of the current forecast, possibly only a TS at landfall. Would likely be hard hit by shear and dry air intrusion. We won't really be confident in where it will eventually go for another day or so.

How's that jet thing looking that's supposed to push Ian more the E - You had talked about this int he days past. Anything new on that front?

craig seltzer just had a live streaming video on that and it will pull it ne. i found the it interesting that the disco didn’t say uncertainty of the track is evident in days 3-5 this time. seems like they are hovering the hurricane over the tampabay region just offshore with big bend ts landfall.

[AdamFirst]

The core of Ian is now showing up on archaic Cuban radar.

Thanks to the Cayman Islands and Cuba, we have full radar coverage for this storm up until Florida landfall.

http://www.insmet.cu/asp/genesis.asp?TB ... AXw01a.gif

[CryHavoc]

Ugh, the evacuation page for the greater Tampa Area is down.

Not great timing to have a server outage.

A page that gets maybe 10 hits a day suddenly getting hundreds a minute will do that.

Sure but it's an emergency situation, they can anticipate the vastly increased server load and add bandwidth ahead of time.

There's a 0% chance they didn't know that the page was going to get swamped. People need the info, it's a really bad look when they can't get it. At the very least they should have a backup txt only page to send out basic info.

[Aric Dunn]

And there are the Sw and southern eyewall towers been waiting for... the eye will poke out soon...

[Weatherboy1]

It sure seems based on satellite imagery that Ian is going to hit Isla de la Juventud directly, rather than miss it to the west and landfall in western Cuba. That would put it, what? 30 miles or so east of forecast points if so? Just wondering because that could have implications for eventual landfall in Florida

[kevin]

Latest VIS:

[CryHavoc]

Sorry to say that this appears to be a worst case scenario unfolding here if this track holds. Most alarming hurricane forecast I've seen in many years. Shades of Harvey here.

In this forecast Tampa would get torrential rain for 48 continuous hours. There is no way to reliably estimate how much damage that would cause other than catastrophic - and that's nearly independent of how strong Ian is when he comes ashore.

[ElectricStorm]

NW quad has improved as well, with hurricane force FL winds now, looks like the overall wind field has improved dramatically since last night

[pgoss11]

It sure seems based on satellite imagery that Ian is going to hit Isla de la Juventud directly, rather than miss it to the west and landfall in western Cuba. That would put it, what? 30 miles or so east of forecast points if so? Just wondering because that could have implications for eventual landfall in Florida

Looks possible but wouldn’t Ian have to go on a straight north heading for that to happen?

[eastcoastFL]

Looking better and better on radar this morning out of the Caymans