ATL: IAN - Post-Tropical - Discussion

[Iceresistance]

Recon is about to make an eye pass over Cuba, has this happened before?

[GCANE]

Looks like slight risk for tornadoes in the Keys

[Smurfwicked]

Recon is about to make an eye pass over Cuba, has this happened before?

Curious to see what they find. Structurally looks like Cuba has had minimal impacts and appears to already be improving again.

[Iceresistance]

Recon is about to make an eye pass over Cuba, has this happened before?

Curious to see what they find. Structurally looks like Cuba has had minimal impacts and appears to already be improving again.

*Flashbacks to what Fiona did over Puerto Rico and the Dominican Republic*

[Jelmergraaff]

Recon is about to make an eye pass over Cuba, has this happened before?

Curious to see what they find. Structurally looks like Cuba has had minimal impacts and appears to already be improving again.

Convection has definitely decreased (warmer cloud tops), but indeed still a pretty well-defined core and overall very good circulation. Waiting on recon to see what pressure they find.

[weeniepatrol]

[GCANE]

Mesoscale Discussion 1832
NWS Storm Prediction Center Norman OK
0524 AM CDT Tue Sep 27 2022

https://www.spc.noaa.gov/products/md/md1832.html

Areas affected...Portions of the FL Keys and the southern FL
Peninsula

Concerning...Severe potential...Tornado Watch likely

Valid 271024Z - 271300Z

Probability of Watch Issuance...80 percent

SUMMARY...The threat for a few tornadoes will gradually increase
this morning in association with Hurricane Ian. A Tornado Watch will
likely be issued before 13Z (9 AM EDT) for the Florida Keys and much
of south Florida.

DISCUSSION...Recent radar and satellite imagery show the core of
Hurricane Ian moving northward across western Cuba. Transport of
very rich low-level moisture, with mid to upper 70s surface
dewpoints noted across the Keys into parts of south FL, will
continue through the morning hours. Modifying the 06Z observed
soundings from KEY/MFL for current conditions shows a weakly
unstable airmass present, with latest mesoanalysis estimating MLCAPE
generally ranging from 500-1000 J/kg across this area. Surface-based
convection will be possible wherever even modest daytime heating can
occur later this morning given the very moist low-level airmass.

Radar reflectivity/velocity trends from KBYX/KAMX over the past few
hours have shown low-topped cells over the FL Straits occasionally
approaching the Keys. Some of this activity had modest low-level
rotation. VWPs from KBYX show the low/mid-level east-southeasterly
flow has gradually strengthened this morning as Hurricane Ian
approaches. A corresponding increase in the low-level hodograph and
effective SRH has also occurred, especially with any cells that
maintain a more northward motion compared to northwestward. With
further strengthening of the low-level wind field expected this
morning, current expectations are for the tornado threat to
gradually become greater with any low-topped supercells that can
develop and be sustained in Ian's outer rain bands. Accordingly, a
Tornado Watch will likely be needed for the FL Keys and much of
south FL before 13Z (9 AM EDT).

..Gleason/Guyer.. 09/27/2022

[gatorcane]

Difference with Charley here is that there will be some amount of ridging building back in so IAN could turn more N as it approaches the west coast rather than NNE or
NE

[Jelmergraaff]

What??? Extrapolated pressure of 947 mb with FL-winds of 105+ kts...

[aspen]

Jeez I was not expecting to wake up to a Cat 3 over Cuba and a track showing a major into Tampa. I’m now really concerned about a Florida landfall near peak intensity, because Ian will be further east and spending less time in high shear. I hope everyone there is prepared.

Also wow 947mb extrapolated.

[Iceresistance]

What??? Extrapolated pressure of 947 mb with FL-winds of 105+ kts...

I'm getting strong flashbacks with Fiona, she kept improving over the DR despite being over land!

[weeniepatrol]

[Iceresistance]

Final T# Adj T# Raw T#
5.8 5.9 7.2

Last time I saw the ADT, it was at a 4.4 with Raw T# 3.8. that escalated very quickly.

[Jr0d]

Looks like slight risk for tornadoes in the Keys

Had a warning earlier in the middle Keys. Given how these bands look on radar, i expect many more.

[Smurfwicked]

Recon is about to make an eye pass over Cuba, has this happened before?

Curious to see what they find. Structurally looks like Cuba has had minimal impacts and appears to already be improving again.

Convection has definitely decreased (warmer cloud tops), but indeed still a pretty well-defined core and overall very good circulation. Waiting on recon to see what pressure they find.

Northern eye wall looks to already be getting colder cloud tops from tapping into GOM to its north. At least to my untrained eyes looking at last few frames of IR loop.

[GCANE]

Trough is sitting on the MS Delta. PV streamers getting better defined.
Outflow from Ian should improve as he hits the water.

[kevin]

Remember that winds are often quite reduced once a storm is above land. The crucial number to look at above land in terms of intensification is pressure which is still deepening. If Ian's core survives semi-intact the winds will rapidly catch up to the pressure again once its above water.

[weeniepatrol]

Some outflow restriction equatorward.

Poleward is another story...

[Iceresistance]

Eye is getting warmer and Northern Eyewall is getting colder again.

[hurricaneCW]

What??? Extrapolated pressure of 947 mb with FL-winds of 105+ kts...

It means pressure was prob quite a bit lower before landfall as he definitely weakened a tad over Cuba. A little more weakening is likely before it emerges.