ATL: IAN - Post-Tropical - Discussion

[Jelmergraaff]

Extrapolated pressure now 953 mb with FL-winds of 100kt.

[GCANE]

Looks like eye may be warming up on 6.19um

[Jr0d]

Only good news is we can see the dry air encroaching into the Gulf.

https://imgur.com/1LPxVXr

My eyes might be playing tricks, but I see this as evidence of the trough digging further down than forecast, which would most likely turn Ian more east...and sooner

[d3v123]

Ian has definitely weakened while crossing the mountains of western Cuba. It'll have a short time to regain strength today then shear and dry air will be impacting it by the time it nears landfall tomorrow night. I told someone here from Bradenton to prepare to be without power for days or weeks. That appears to be the case. If it can hit south of Tampa Bay then it won't push up to 18 ft of surge into the bay like a hit just west would.

That would be me! We’ve decided to evacuate today as I have a little one at home and don’t think a possible brush with the eye is worth staying. How much weakening do you think could happen?

[Iceresistance]

Recon staging for another pass, NW quadrant shows only 80 knots FL wind.

Ian may have weakened somewhat, but the eye is still complete.

Personally more interested in pressure rather than FL-wind. I also noticed they gained altitude this time.

The first thing I've noticed is the extreme pressure gradient. Also no sign of a Double Wind Maxima or EWRC.


https://s5.gifyu.com/images/recon_NOAA2-2009A-IAN_zoom.png

Updated: Lowest Extrapolated pressure is 953.2 mb, the pressure has risen quite a bit.

[aspen]

With how much the pressure rose, maybe Ian was a low-mid 940s Cat 4 at landfall.

[Jelmergraaff]

New advisory (8 AM) an even lower pressure (950 mb) with the same sustained winds (125 mph)...

...IAN BATTERING WESTERN CUBA WITH HIGH WINDS AND LIFE-THREATENING
STORM SURGE...


SUMMARY OF 800 AM EDT...1200 UTC...INFORMATION
----------------------------------------------
LOCATION...22.6N 83.6W
ABOUT 10 MI...15 KM NNE OF THE CITY OF PINAR DEL RIO CUBA
ABOUT 130 MI...240 KM SSW OF THE DRY TORTUGAS
MAXIMUM SUSTAINED WINDS...125 MPH...205 KM/H
PRESENT MOVEMENT...N OR 360 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...950 MB...28.05 INCHES

[fllawyer]

To my untrained eye, Ian looks to be moving N-NNE over the last 90 minutes. Can anyone weigh in?

NHC says 8am coordinates are 22.6N/83.6W, which is North and East of 5am which was 22.3N/83.7W.

8:00 AM EDT Tue Sep 27
Location: 22.6°N 83.6°W
Moving: N at 12 mph
Min pressure: 950 mb
Max sustained: 125 mph

[caneman]

To my untrained eye, Ian looks to be moving N-NNE over the last 90 minutes. Can anyone weigh in?

Still due North with a possible slight lean left

[TallyTracker]

That recon pass sure impressed me! And I see a lot of itching for a narrative that Ian isn't going to weaken because of this landfall, but land is land and mountains are mountains and both are not good for TCs.

To set some expectations: both the HWRF (06z) and the HAFS (18z yesterday) have central pressure rising after landfall from around 950mb to the mid-950s before intensification begins anew after 18z today. The best explanation I have for this is that changes to the environment of a storm (that are not too drastic) have a bit of a delay in their impact. Winds weaken because of friction over land (and have less water to evaporate), but it takes time for that to lead to weaker ascent, and that takes time to lead to a rising pressure.

Despite this ~6hr pause, both of these models still take Ian down to the upper 930smb with peak winds in the 120-130kt range just before landfall. This is all to say: if Ian does not begin re-intensifying immediately after it moves over water again, please do not let your guard down!

This is a great discussion! The trend is definitely toward a major hurricane direct landfall in Florida. The RI potentials are still high and Ian will likely peak as a Cat 4. Frankly May landfall as a Cat 4 if the landfall location keeps shifting south. That’s why the rule of thumb is to always prep for a category higher than predicted. Current prediction is a Cat 3 landfall. Everyone from Naples to Cedar Key needs to be prepping for a Cat 4 landfall potential.

[Stormgodess]

Only good news is we can see the dry air encroaching into the Gulf.

https://imgur.com/1LPxVXr

My eyes might be playing tricks, but I see this as evidence of the trough digging further down than forecast, which would most likely turn Ian more east...and sooner

Where is a good place to find forecasts of what that trough will do?

[Beachside]

At which advisories does the NHC update the forecast track? I know for each advisory they update the time stamp on the track graphic, but I know certain ones are not true updates.

Which times is the forecast track actually updated?

[GCANE]

VDM from Kermit, 3 min ago
947mb extrap

[Blown Away]

To my untrained eye, Ian looks to be moving N-NNE over the last 90 minutes. Can anyone weigh in?

Still due North with a possible slight lean left

Slight E component to the due N.

[Jr0d]

Was it John Hope that said a good indicator of steering pattern is to see what direction the high cirrus clouds are traveling in front of the storm? ...

This quote is fom last year, but still relevant.

If we apply John Hope's theorem, we should see Ian turn more east, possibly more than forecast.

I noticed the cirrus clouds going NE with Ian yesterday, and was concerned about this.

The caveat is if this happens, the onshore flow will remain south of Tampa Bay, limiting surge and likely make landfall is a not so densely populated area.

[Category5Kaiju]

Some pretty simple but good amateur advice that has worked for me in wobble watching: get a firm ruler, place it on your computer screen, and see how well the eye of the storm aligns with the ruler and whatever direction you have oriented it in.

[Jelmergraaff]

Eye seems to be warming again, convection on the northern side improving.

[AutoPenalti]

Some pretty simple but good amateur advice that has worked for me in wobble watching: get a firm ruler, place it on your computer screen, and see how well the eye of the storm aligns with the ruler and whatever direction you have oriented it in.

Does not work with IR lol

[TallyTracker]

At which advisories does the NHC update the forecast track? I know for each advisory they update the time stamp on the track graphic, but I know certain ones are not true updates.

Which times is the forecast track actually updated?

The forecast tracks are updated every 6 hours typically. The next regular track update by NHC is at 11 am.

[jdjaguar]

https://cera.coastalrisk.live/s/85ae

For all of those who live in the Tampa/Bradenton/Sarasota area, I have found this site to quite informative
regarding storm surge impacts. It is interactive and you can zoom to neighborhood level.

Warning, it appears to project devastating impact to a broad area.