ATL: HELENE - Post-Tropical - Discussion

[bjackrian]

Also that SW eyewall drop had instantaneous winds of 60kt at surface and 71 kt at about 160 m above the surface. It's getting there.

[Poonwalker]

This storm reminds me of Katrina when it emerged into the Gulf and was doing that wsw move north of western Cuba. Absolutely enormous and everyone knew they were watching something exceptional

I get the same vibes as well. When Katrina underwent initial RI then did that almost pause and turn it kinda took your breath away.

[technikal]

That was a pretty significant pulse up phase, Helene is well on its way towards establishing an inner core now. From radar and recon data it does look like there might be some faint mid-level dry air entrainment that it's still working through. Latest recon pass is holding pressure steady at about 979mb:
https://i.imgur.com/d16BF18.png

That dry air over the YP that Levi discussed in his video yesterday definitely got partially ingested, and that is probably the only factor has inhibited development so far since the shear went down. Still looking like a beast though.

[REDHurricane]

It’s crazy how on visible it looked destined to plow into the western tip of Yucatan and radar shows a completely different northward motion.

I am wondering if she is still tilted or something because you are right one looks to be heading westward (sat) and radar shows it moving northward through the channel

Yep, looking at the GOES vorticity product you can see that the 500mb vorticity is slightly to the NW of the 925mb vorticity, so on visible we're seeing the MLC pass over the tip while the LLC stays just offshore: https://tropic.ssec.wisc.edu/real-time/ ... oom=&time=

[jdjaguar]

That was a pretty significant pulse up phase, Helene is well on its way towards establishing an inner core now. From radar and recon data it does look like there might be some faint mid-level dry air entrainment that it's still working through. Latest recon pass is holding pressure steady at about 979mb:
https://i.imgur.com/d16BF18.png

That dry air over the YP that Levi discussed in his video yesterday definitely got partially ingested, and that is probably the only factor has inhibited development so far since the shear went down. Still looking like a beast though.

that dry air is gone. really nothing to hold her back after she clears the tip in the next few hours. friends in Tally are bugging out to Pensacola.

[USTropics]

It’s crazy how on visible it looked destined to plow into the western tip of Yucatan and radar shows a completely different northward motion.

I am wondering if she is still tilted or something because you are right one looks to be heading westward (sat) and radar shows it moving northward through the channel

It's difficult to assess true storm motion with satellite imagery, especially when we are dealing with a rapidly expanding CDO. This is why radar and recon are so valuable (we can see the mid and lower levels now). The cool thing is, we have two separate radar sites in this instance.

The Cuban radar lets us assess the mid-levels:


While Cancun radar we get more of a representation of the lower levels:


Matches with what recon is finding as well:

[Travorum]

That was a pretty significant pulse up phase, Helene is well on its way towards establishing an inner core now. From radar and recon data it does look like there might be some faint mid-level dry air entrainment that it's still working through. Latest recon pass is holding pressure steady at about 979mb:
https://i.imgur.com/d16BF18.png

That dry air over the YP that Levi discussed in his video yesterday definitely got partially ingested, and that is probably the only factor has inhibited development so far since the shear went down. Still looking like a beast though.

that dry air is gone. really nothing to hold her back after she clears the tip in the next few hours. friends in Tally are bugging out to Pensacola.

On radar it does look like some dry air is trying to wrap in from the southeast:
 https://x.com/cyclonicwx/status/1838934556101034014



This seems to have been fairly well forecasted by models, and should mix out fairly quickly:
 https://x.com/AndyHazelton/status/1838915235870028167

[cycloneye]

Latest VDM from Air Force plane. Will not pass thru NE corner of Yucatán.

[Travorum]

Recon is now reporting an elliptical eyewall open NE and SE:

953
URNT12 KNHC 251354
VORTEX DATA MESSAGE AL092024
A. 25/13:12:50Z
B. 21.33 deg N 086.16 deg W
C. 700 mb 2941 m
D. 982 mb
E. 360 deg 22 kt
F. OPEN NE-SE
G. E36/50/30
H. 47 kt
I. 036 deg 46 nm 13:00:00Z
J. 128 deg 51 kt
K. 042 deg 94 nm 12:46:30Z
L. 60 kt
M. 204 deg 29 nm 13:21:30Z
N. 284 deg 68 kt
O. 205 deg 39 nm 13:24:30Z
P. 10 C / 3049 m
Q. 16 C / 3049 m
R. 6 C / NA
S. 12345 / 7
T. 0.02 / 2 nm
U. AF309 1109A HELENE OB 11
MAX FL WIND 68 KT 205 / 39 NM 13:24:30Z
;

[Pipelines182]

It’s crazy how on visible it looked destined to plow into the western tip of Yucatan and radar shows a completely different northward motion.

I am wondering if she is still tilted or something because you are right one looks to be heading westward (sat) and radar shows it moving northward through the channel

This is very common, always follow the center, not the CDO. What you're seeing is the (light) shear pushing the cloud tops to the west while the steering currents guide the center north.

[MGC]

Helene is one of the more impressive tropical storm you will see. Classic satellite presentation. Very little shear if any impacting the cyclone. Once Helene moves clear of the Yucatan it should ramp up quickly. Could peak out as a Cat-4. Lets hope it falls apart before landfall......MGC

[Sciencerocks]

[Canelaw99]

Does anyone know if Palm Beach District schools will be closed tomorrow, 9/26/24?

I work in Miami-Dade County Schools and we haven’t heard yet. Not sure about Palm Beach. I’m sure those decisions will be made today.

I just got a text that after school programs are cancelled today and tomorrow and they'll decide on school closures this afternoon.

Which county?

[Pipelines182]

Helene is one of the more impressive tropical storm you will see. Classic satellite presentation. Very little shear if any impacting the cyclone. Once Helene moves clear of the Yucatan it should ramp up quickly. Could peak out as a Cat-4. Lets hope it falls apart before landfall......MGC

not according to the shear map, granted it doesn't look nearly as sheared as this map indicates it should be. It's also supposed to enter an area of high shear just to the north, what's going to cause that shear to drop today?

[cycloneye]

Now moving NNE.

[Lance]

Now moving NNE.

https://i.imgur.com/sKDcvUj.png

Well that would be unfortunate if it were to continue. Going to be east of forecast track, kinda like the Icon has been hinting at. Just my opinion though.

[StPeteMike]

Now moving NNE.

https://i.imgur.com/sKDcvUj.png

That’s sooner than forecasted, right? Not by much, but I feel like they had a turn to the east starting later in the day.

[jasons2k]

Now moving NNE.

Earlier than the models anticipated. Not good.

She’s a monster.

[Zonacane]

Dual rotating VHT spotted

[Ubuntwo]

Helene is one of the more impressive tropical storm you will see. Classic satellite presentation. Very little shear if any impacting the cyclone. Once Helene moves clear of the Yucatan it should ramp up quickly. Could peak out as a Cat-4. Lets hope it falls apart before landfall......MGC

not according to the shear map, granted it doesn't look nearly as sheared as this map indicates it should be. It's also supposed to enter an area of high shear just to the north, what's going to cause that shear to drop today?
https://tropic.ssec.wisc.edu/real-time/atlantic/winds/wg8shrZ.GIF

The map registers outflow as shear, so ‘felt’ shear is under 10kt per SHIPS analysis. It will be moving with its anticyclone, the area of lower shear will follow the storm. Reduction in shear is I believe caused by alignment of direction of motion with the upper level flow out of the south/southwest.