ATL: HELENE - Post-Tropical - Discussion

[Hurricane2022]

Latest sat loop shows the inner eye rapidly dying and the outer eyewall likely doing the expected RI.

[GCANE]

What are you thinking about peninsula tornado threats?

Not seeing any helicity with the storm yet and CAPE is relatively low in the GoM.
As of now, doesn't look too bad for the state.
Not to say there could be some EF1's as feeder bands roll ashore.
I think SPC is correct for late today and tomorrow concerning GA and SC.
There will be a massive shear setup and high CAPE there.

If I see something develop today for tornadoes I will surely post it.

That’s good to hear. Appreciate the update!

You are welcome

[eastcoastFL]

Rather large and growing wind field

*Hurricane-force winds extend outward up to 60 miles (95 km) from the
center and tropical-storm-force winds extend outward up to 345 miles
(555 km). The Key West Naval Air Station recently reported
sustained winds of 41 mph (66 km/h) and a wind gust of 64 mph
(103 km/h).*

[Hurricane2022]

What are you thinking about peninsula tornado threats?

Not seeing any helicity with the storm yet and CAPE is relatively low in the GoM.
As of now, doesn't look too bad for the state.
Not to say there could be some EF1's as feeder bands roll ashore.
I think SPC is correct for late today and tomorrow concerning GA and SC.
There will be a massive shear setup and high CAPE there.

If I see something develop today for tornadoes I will surely post it.

That’s good to hear. Appreciate the update!

Now take a look at the post made immediately after yours

[otowntiger]

NHC now says low end cat 3 at landfall instead of cat 4.

[eastcoastFL]

5am disco

Helene remains in an atmospheric and oceanic environment over the
eastern Gulf of Mexico that is very conducive for strengthening,
with the system forecast to traverse the Loop Current while it
remains in a moist and low-shear environment. The main restraining
factor on intensification is the current concentric eyewall status.
All of the intensity guidance continues to forecast strengthening
until landfall. Based on this, the new intensity forecast calls
for Helen to become a major hurricane in about 12 h, and additional
intensification is expected in the ensuing 6 h period or so before
landfall. After landfall, Helene should weaken and undergo
extratropical transition as it merges with the baroclinic system
over the Tennessee Valley, and this is expected to be complete by
about 36 h. The remnant extratropical low is forecast to dissipate
after 72 h based on global model forecasts.

[eastcoastFL]

NHC now says low end cat 3 at landfall instead of cat 4.

Not exactly. They expect it to be 115mph cat 3 in 12 hours and expect additional strengthening after that as well.

“ new intensity forecast calls
for Helen to become a major hurricane in about 12 h, and additional
intensification is expected in the ensuing 6 h period or so before
landfall. ”

[Jr0d]

Rather large and growing wind field

*Hurricane-force winds extend outward up to 60 miles (95 km) from the
center and tropical-storm-force winds extend outward up to 345 miles
(555 km). The Key West Naval Air Station recently reported
sustained winds of 41 mph (66 km/h) and a wind gust of 64 mph
(103 km/h).*

My neighborhood is the 1st to lose power in the Key West area. Tomorrow evening at the earliest is when we will get it back.

[caneman]

Loos like landfall shifted east a little from west side of Tallahassee to east side. Maybe 10 or 15 miles?

[kevin]

Inner eyewall went from being the leading eyewall just 1.5 hours ago to almost being completely gone on IR. Large convection burst in the outer eyewall, which has likely taken over by now. Eyewall meld nearing completion, will be interesting to see if the current recon pass also reflects this IR development.

[Jr0d]

Never mind... I forget how to read the hdobs

[otowntiger]

NHC now says low end cat 3 at landfall instead of cat 4.

Not exactly. They expect it to be 115mph cat 3 in 12 hours and expect additional strengthening after that as well.

“ new intensity forecast calls
for Helen to become a major hurricane in about 12 h, and additional
intensification is expected in the ensuing 6 h period or so before
landfall. ”

ok, understood- but their graphic is a bit misleading. It shows the last forecast point (with 115 mph winds)prior to landfall at 7:00 tonight seemingly just a few miles offshore. Doesn’t seem like it would have 6 more hours from that point worth of strengthening time before landfall. But I still think intensity is having to be adjusted downward due to the apparent EWRC that is occurring and resulting in a near steady state since last night.

[eastcoastFL]

Rather large and growing wind field

*Hurricane-force winds extend outward up to 60 miles (95 km) from the
center and tropical-storm-force winds extend outward up to 345 miles
(555 km). The Key West Naval Air Station recently reported
sustained winds of 41 mph (66 km/h) and a wind gust of 64 mph
(103 km/h).*

My neighborhood is the 1st to lose power in the Key West area. Tomorrow evening at the earliest is when we will get it back.

Is it out already? Hopefully it will at least stay cloudy today so it’s not so hot.

[eastcoastFL]

NHC now says low end cat 3 at landfall instead of cat 4.

Not exactly. They expect it to be 115mph cat 3 in 12 hours and expect additional strengthening after that as well.

“ new intensity forecast calls
for Helen to become a major hurricane in about 12 h, and additional
intensification is expected in the ensuing 6 h period or so before
landfall. ”

ok, understood- but their graphic is a bit misleading. It shows the last forecast point (with 115 mph winds)prior to landfall at 7:00 tonight seemingly just a few miles offshore. Doesn’t seem like it would have 6 more hours from that point worth of strengthening time before landfall.

Ya, it’s hard to tell with these graphics sometimes. If you look at the SFWMD radar it shows the NHC track pretty well zoomed in. Looks like that bend to the west just before landfall is no longer in the cards and if it goes to the right side of the track it might buy itself a bit more time over the gulf waters.

https://www.sfwmd.gov/weather-radar/cur ... conditions

[xironman]

963.5 Extrap

[Chemmers]

963.5 Extrap

Think it is definitely starting to RI now, stay safe everyone

[kevin]

Really intensifying fast now, an intensification rate of 2.4 mb/hr between the last two passes. Here are the recent recon passes:

09:14z = 963.3 mbar (3 kt winds) -> 963 mb
07:35z = 967.7 mbar (4 kt winds with 967.8 mb) -> 967 mb
05:49z = 969.1 mbar (7 kt winds with 970 mb) -> 969 mb

[eastcoastFL]

Really intensifying fast now, an intensification rate of 2.4 mb/hr between the last two passes. Here are the recent recon passes:

09:14z = 963.3 mbar (3 kt winds) -> 963 mb
07:35z = 967.7 mbar (4 kt winds with 967.8 mb) -> 967 mb
05:49z = 969.1 mbar (7 kt winds with 970 mb) -> 969 mb

I wonder how long it will take for the winds to catch up with the pressure drops. Last night the pressure was falling and winds stayed steady until this morning. I wonder if it will happen faster now that she has a better structure.

[eastcoastFL]

[kevin]

Current structure looking very good according to Dvorak. CI# at 4.4, but the last two raw T# were 6.4 and 6.5.