ATL: LEE - Post-Tropical - Discussion

[cycloneye]

Lee will be with the very biggies.

 https://twitter.com/philklotzbach/status/1699801246616736037

[MarioProtVI]

Lol at this point people should lower their expectations. The reason why? Since 2007, EVERY single storm the NHC has forecasted to intensify into a C5 has underperformed/failed to achieve it because of various reasons, including Gustav 2008, Igor 2010, Blanca 2015, and Eta 2020. Some people might call me crazy but the last time they predicted a Cat 5 to occur from a RI’ing storm that ended up verifying was Dean 2007. Every other C5 that’s occurred since had achieved it without NHC expecting it too. So just warning you all that you’re setting yourself up for disappointment when Lee peaks at 130-135 kt and recon finds it on the threshold causing another endless debate.

A bit superstitious but still an interesting observation.

Yes and it makes this even harder now because NHC is very picky with C5 upgrades ever since 2017 when the flaws of SFMR were exposed and that ended up (unfairly) costing Iota its C5 status. They’ll only upgrade if they find several 700-mb FL winds exceeding 156-158 kt (reducing to 140-142 kt at the surface) and SFMRs beyond 140 kt, as they will blend to get the intensity. Any lower then that and you end up with 135 kt (see operational Michael and Ian, as well as Sam 2021).

[TheDreamTraveler]

Lol at this point people should lower their expectations. The reason why? Since 2007, EVERY single storm the NHC has forecasted to intensify into a C5 has underperformed/failed to achieve it because of various reasons, including Gustav 2008, Igor 2010, Blanca 2015, and Eta 2020. Some people might call me crazy but the last time they predicted a Cat 5 to occur from a RI’ing storm that ended up verifying was Dean 2007. Every other C5 that’s occurred since had achieved it without NHC expecting it too. So just warning you all that you’re setting yourself up for disappointment when Lee peaks at 130-135 kt and recon finds it on the threshold causing another endless debate.

A bit superstitious but still an interesting observation.

It drives home the point just how hard intensity is to predict. It's still the trickiest part of forecasting a hurricane. We have storm tracks nailed down extremely well now but intensity can be a mixed bag for whichever reason.

[ScottNAtlanta]

It will all depend on when EWRCs occur. Sometimes they happen frequently sometimes (Laura) not at all.

[cheezyWXguy]

With Lee’s eye already this clear, I wonder if it’s already approaching cat3. I’ve seen worse looking 4s to be honest

[Ntxw]

Probably a major, Lee will have a large eye.

[Beef Stew]

With Lee’s eye already this clear, I wonder if it’s already approaching cat3. I’ve seen worse looking 4s to be honest

I imagine it's not quite there yet, but just a brief matter of time as the winds catch up to visible structure. I'm starting to expect Lee to be one of those storms that "skips" cat 3- I think recon finds a 115 kt+ storm this evening.

[BobHarlem]

Recon is going to be one for the ages I think.

[aspen]

It will all depend on when EWRCs occur. Sometimes they happen frequently sometimes (Laura) not at all.

The hurricane models don’t show a full-blown EWRC for a few days. An eyewall meld might take place before then, but it doesn’t weaken Lee much or at all on the model runs.

[Iceresistance]

HOLY-

Final T# Adj T# Raw T#
4.6 4.6 6.2

[TallyTracker]

HOLY-

Final T# Adj T# Raw T#
4.6 4.6 6.2

The T numbers are pushing against the constraint rules now. Probably intensifying faster than the rules allow. I’d lean more toward the raw T# for now until the Final and Adjusted catch up.

[kevin]

HOLY-

Final T# Adj T# Raw T#
4.6 4.6 6.2

Lee was getting jealous of Jova's RI.

[Beef Stew]

Whats crazy to me is that Lee appears to be intensifying much faster than even the most bullish hurricane model runs. 12 hours from now we could be staring at a monster, as opposed to 24+...

[Hurricane2022]

[aspen]

When will the next few planes after the 5pm flight take off? I think the second or third flight should have the best shot of getting Lee’s peak.

[cycloneye]

When will the next few planes after the 5pm flight take off? I think the second or third flight should have the best shot of getting Lee’s peak.

At 4 AM NOAA plane and at 5:15 AM the Air Force plane.

FLIGHT THREE - NOAA 43 FLIGHT FOUR - TEAL 76
A. 08/1200Z A. 08/1130Z,1730Z
B. NOAA3 0313A LEE B. AFXXX 0413A LEE
C. 08/0800Z C. 08/0915Z
D. 17.6N 54.8W D. 17.6N 54.7W
E. 08/1000Z TO 08/1400Z E. 08/1100Z TO 08/1730Z
F. SFC TO 15,000 FT F. SFC TO 15,000 FT
G. TAIL DOPPLER RADAR G. FIX

[Tireman4]

000
WTNT43 KNHC 071459
TCDAT3

Hurricane Lee Discussion Number 9
NWS National Hurricane Center Miami FL AL132023
1100 AM AST Thu Sep 07 2023

Lee is rapidly intensifying. Early this morning, a well-defined
low-to mid-level eye was observed in microwave imagery, a signal
that is often a precursor rapid intensification (RI). Since then,
Lee has developed an eye in visible and infrared imagery, with
subjective Dvorak Data-T estimates quickly increasing to as high as
5.5 during the past hour or so. Satellite classifications supported
an intensity of around 80 kt at 1200 UTC, but given the significant
improvement in Lee's appearance since then, the advisory intensity
is set at 90 kt.

The track guidance remains in very good agreement on the forecast
for Lee through the weekend and confidence in the track forecast is
high. Lee should continue west-northwestward, gradually slowing its
forward speed, moving along the southern periphery of a subtropical
ridge over the central Atlantic. Confidence continues to increase
that Lee will pass north of the northern Leeward Islands, though
swells associated with Lee will affect the islands starting
tomorrow. By the end of the forecast, the uncertainty is a little
higher, with the hurricane models (HAFS, HWRF) generally being
farther south than the global models. Very small changes were made
to the NHC track forecast, which is between the HCCA and simple
consensus aids.

As stated above, RI is occuring, and will likely continue today. The
question doesn't appear to be if RI continues, but rather how
strong Lee will get, and how quickly will it get there. Many of the
models are calling for remarkable rates of intensification, beyond
rates normally seen with model forecasts. Both HAFS models forecast
Lee to exceed 150 kt within the next 2 days, and even HCCA brings
the hurricane above the category 5 threshold. The NHC intensity
forecast has been shifted significantly higher, but is actually
within the guidance envelope. It should be stressed that internal
dynamics (eyewall replacement cycles) will become a factor with the
maximum strength of Lee as it becomes a major hurricane. This
is almost certain to lead to fluctuations in intensity that are
beyond our ability to forecast at these lead times. Hurricane Hunter
aircraft are scheduled to investigate Lee beginning this evening and
overnight, which should provide extremely useful information about
Lee's intensity during the coming days.


KEY MESSAGES:

1. Lee is forecast to become a major hurricane later today, with
its core moving north of the northern Leeward Islands, the Virgin
Islands, and Puerto Rico this weekend and early next week. The
potential for tropical storm conditions to occur in the islands is
decreasing, but residents there should continue to monitor updates
on Lee.

2. Swells generated by Lee are expected to reach portions of the
Lesser Antilles on Friday, and the British and U.S. Virgin Islands,
Puerto Rico, Hispaniola, the Bahamas, and Bermuda this weekend.
These swells are likely to cause life-threatening surf and rip
current conditions.


FORECAST POSITIONS AND MAX WINDS

INIT 07/1500Z 16.4N 50.0W 90 KT 105 MPH
12H 08/0000Z 17.1N 51.7W 115 KT 130 MPH
24H 08/1200Z 18.2N 54.0W 130 KT 150 MPH
36H 09/0000Z 19.2N 56.1W 140 KT 160 MPH
48H 09/1200Z 20.1N 58.1W 140 KT 160 MPH
60H 10/0000Z 20.9N 59.8W 135 KT 155 MPH
72H 10/1200Z 21.5N 61.2W 135 KT 155 MPH
96H 11/1200Z 22.6N 63.7W 125 KT 145 MPH
120H 12/1200Z 23.6N 66.0W 120 KT 140 MPH

$$
Forecaster D. Zelinsky

[Iceresistance]

Lightning in the eyewall


https://s11.gifyu.com/images/SgPUb.gif

[SouthDadeFish]

Seeing lightning in both northern and southern eyewall now. Extreme RI ongoing.

[Michele B]

HOLY-

Final T# Adj T# Raw T#
4.6 4.6 6.2

The T numbers are pushing against the constraint rules now. Probably intensifying faster than the rules allow. I’d lean more toward the raw T# for now until the Final and Adjusted catch up.

I found a video explaining the "T" number thingy (since I didn't understand it), and according to this video, that number CAN go all the way up to 8.

Here is a link to the video:

https://severeweather.wmo.int/TCFW/RAIV ... kBeven.pdf