ATL: MICHAEL - Post-Tropical - Discussion

[tropicwatch]

Landfall uncertainty has surely increased.

[robbielyn]

tropical storm watch for Suwanee South to Ana Maria island. hurricane watch AL/FL border to suwanee river.

[GCANE]

Entrainment of the afternoon popup convection over the Yucatan and sitting on top of a massive hot-water pump and what else do you expect other than RI.
I am a bit surprised NHC commented that they weren't expecting such a pressure drop.
So, next stop, the Loop Current with a possible anti-cyclone overhead and possible outflow channel.
Time to start looking at the moisture and instability conditions in the GOM.

[tropicwatch]

Thankfully there is another recon already on the way. Get to see if the pressure drops continue.

[GCANE]

Classic case of a TC pushing shear out of the way.
IR showing outflow on the SW quad.
I wonder if we get one of those Siamese-twin TCs that no one can explain.

[jlauderdal]

today we have a real timing battle underway that should be settled by tonight, uk vs euro vs gfs

keep in mind intensity is a real forecasting issue even for the nhc as we saw as recently as the last 12h and they admitted they were surprised...anything from a 1-4 is possible at landfall, we have seen weakening in the past as systems approach the coast in this part of the basin, conditions seem favorable for a major but the fast gfs motion if it verifies might hinder something larger than a 2 at landfall

[psyclone]

I wouldn't be surprised if the NHC uses the Suwannee river as the eastern extent of the hurricane watch (that makes geographic sense and happens to be the border between the TPA and TLH CWAs.) But I wouldn't be shocked to see TS and storm surge watches extend south of there into the TPA CWA as the system is expected to have a pretty solid gale windfield in the northeast and southeast quads and the nature coast is very surge prone. Recall the big surge at cedar key during Hermine...there were no hurricane conditions there but Levy, Citrus and Hernando counties had a very respectable water rise

I want a prize! In all seriousness I am a believer in the nhc track. It's been rather consistent and such continuity often translates to accuracy. St Marks landmarks are going to get another high water line and I'm guessing you won't need to convince long time residents up that way of the danger headed their way. Best of luck to all in the hot zone.

[GCANE]

Looks like its about to fire up another cylinder.
Just about to couple into the ULL just east of the Bahamas

[Shell Mound]

Major Hurricane Landfalls Between Destin and Cedar Key, FL (1851–2017)

Unnamed (1851) – 23 August – 100 knots / ??? mb
Unnamed (1877) – 3 October – 100 knots / ??? mb
Unnamed (1894) – 9 October – 105 knots / ??? mb
Unnamed (1896) – 28 September – 110 knots / 960 mb
Eloise (1975)* – 23 September – 110 knots / 955 mb

*May have been Cat-4 at landfall, based on small size and fast movement, pending reanalysis

Three of the five cases made landfall very close to Panama City, FL. The 1896 hurricane struck Cedar Key and Eloise hit Destin.

[jlauderdal]

I wouldn't be surprised if the NHC uses the Suwannee river as the eastern extent of the hurricane watch (that makes geographic sense and happens to be the border between the TPA and TLH CWAs.) But I wouldn't be shocked to see TS and storm surge watches extend south of there into the TPA CWA as the system is expected to have a pretty solid gale windfield in the northeast and southeast quads and the nature coast is very surge prone. Recall the big surge at cedar key during Hermine...there were no hurricane conditions there but Levy, Citrus and Hernando counties had a very respectable water rise

I want a prize! In all seriousness, I am a believer in the nhc track. It's been rather consistent and such continuity often translates to accuracy. St Marks landmarks are going to get another high water line and I'm guessing you won't need to convince long-time residents up that way of the danger headed their way. Best of luck to all in the hot zone.

nhc is awesome on track especially 72h in but 5-day track is outstanding too...residents there will evacuate, this isnt the keys

btw, we have seen 40-50 mph gusts this morning which is a proof the gradient is tightening

[BobHarlem]

I woke up looking to looking at models and thinking ok a lot of cat 3/4s here, then I glanced at the 983 pressure which I thought was a typo -- it was 997 when I saw it last. Wow, can't believe they still are calling it a TS. It may start out upgraded as a cat 2 at this rate.

[GCANE]

AMSU analysis of satellite sounders showing a high altitude warm core.
Pushing up the tropopause.
Good setup to create a massive and stacked vort column.
With the Loop Current ahead, Michael will likely rip.

[KWT]

Im feeling shades of those 2005 storms that bombed in this area. I remember Katrina in particular dropping like a stone a little to the north of where Michael is. It took a bit if time but the winds did eventually respond as well...

[GCANE]

More significant than the low-pressure measured by AF305 was the 70mm/hr rain rate.

[GCANE]

Im feeling shades of those 2005 storms that bombed in this area. I remember Katrina in particular dropping like a stone a little to the north of where Michael is. It took a bit if time but the winds did eventually respond as well...

Katrina also took a due north track.
There is a secondary effect on Coriolis forcing when a TC tracks north.
Makes it spin up even more.

[AJC3]

Wow, can't believe they still are calling it a TS. It may start out upgraded as a cat 2 at this rate.

This shouldn't be hard to believe at all. There was recon in the storm at the time leading up to the 5 AM advisory package, and their solid intensity analysis of 60KT was based on said data. While there's little doubt this will be a hurricane very soon, it's well-known that sharp MCP falls precede the ramp up in winds. A MCP in the low 980s, as in this case, doesn't always correspond to MSW of 65KT.

[Shell Mound]

Im feeling shades of those 2005 storms that bombed in this area. I remember Katrina in particular dropping like a stone a little to the north of where Michael is. It took a bit if time but the winds did eventually respond as well...

Actually, the projected synoptic setup, time of year, and probable region of U.S. impact are potentially reminiscent of Eloise (1975), with the 1896 Cedar Keys hurricane being a secondary contender. Satellite imagery indicates that vertical wind shear is finally lessening, owing to rising heights (via retrogression of the upper low over the Gulf) and diabetic heating via convection, with the cirrus canopy expanding on the western side of the nascent CDO. Given the already-low pressure, the system could deepen more significantly than I earlier thought, once it enters the prime region of the Gulf in thirty-six hours and beyond. Significantly, virtually all of the dynamical models—EPS/ECMWF, GFS/GEFS, FV3-GFS, and HWRF—have been insistent that Michael does not weaken before FL landfall, instead maintaining its intensity or even deepening, like Eloise. This likely has something to do with the projected dual outflow channels, abundant Caribbean moisture (PW inflow channel), and baroclinic, pre-frontal forcing, along with the well-above-average SST anomalies and heat content over the offshore Gulf waters. Given diminishing shear and the evolving convective pattern, an inner core is likely to begin forming later today and early tomorrow morning, making rapid intensification more plausible afterward. At this point, I'm going to raise the stakes and call for a peak intensity of 105 to 120 knots (Cat-3/Cat-4) and a major-hurricane landfall between Destin and Cape San Blas, FL, likely sometime early on Wednesday, October 10 (local time in the FL Panhandle).

 https://twitter.com/pppapin/status/1049201004422393858



 https://twitter.com/pppapin/status/1049205767826362370



 https://twitter.com/JimCantore/status/1049229200740294657

[NotoSans]

Flight-level (850mb) winds in the low 70s and SFMR winds support the initial intensity. Satellite presentation is switching from a shear pattern to a typical curved band pattern, but the latest VDM shows that an eyewall hasn't formed yet, so it may still take some time for an inner core to become established. Nevertheless, VWS is surely abating, and once an inner core forms the possibility of RI cannot be ruled out.

[NDG]

It will be interesting to see if the recon en route right now finds Michael's pressure down to 973 mb like the latest HWRF is forecasting it to be about now since it was initiated with the correct 983 mb.

[Nimbus]

Flight-level (850mb) winds in the low 70s and SFMR winds support the initial intensity. Satellite presentation is switching from a shear pattern to a typical curved band pattern, but the latest VDM shows that an eyewall hasn't formed yet, so it may still take some time for an inner core to become established. Nevertheless, VWS is surely abating, and once an inner core forms the possibility of RI cannot be ruled out.

06z HWRF is slower, further east with a symmetric structure by 42 hours.
Initialized with a hurricane the landfall pressures will likely be lower for 12Z runs of all models.
I can understand the reasoning behind not forecasting a major hurricane at landfall given the usual climatology though.