ATL: LEE - Post-Tropical - Discussion

[Sciencerocks]

[cheezyWXguy]

It’s interesting to see the whole envelope rotating so aggressively with just a weak ts. Usually it takes a while to see this happen, and they usually just look like stagnant blobs at this stage with an llc underneath. Idalia’s envelope didn’t really cranking like this until it was around hurricane intensity

[cycloneye]

He says, long way to go.

 https://twitter.com/webberweather/status/1699135527776313535

[mantis83]

lee looks to become super powerful. can't wait for hurricane hunters to get in there, hopefully when it's near peak intensity!

[aspen]

https://imagizer.imageshack.com/img924/261/KntjPv.gif

Lee already has an excellent structure to work with. Perhaps we could see RI into a hurricane or a major ahead of even the hurricane models’ timeframes.

[USTropics]

The lower the MB number, the higher up in the atmosphere, right?

So 850 mb is like ~4800 ft and 700 mb is ~9900 feet, right?

Kind of. The more intense the storm, the lower the height the mb is. For example, typhoon tips 850mb was only a few hundred feet above the surface.

Well, this is different, this is the atmospheric height level.

Yes, these maps are standard atmospheric heights from MSLP. Keep in mind, when referring to cyclones, a cyclone typically peaks at 500mb in height (i.e., it does not extend beyond this point in the atmosphere), so we consider this the upper levels. Truly, 200mb is a more accurate description of the upper levels of the atmosphere, but the features at 200mb are completely different (jet streams, Rossby waves, upper/lower-level highs/lows, atmospheric fronts, etc.) . While the levels of the atmosphere are not uniform throughout all location points on earth, a general guideline for tropical systems is:

Surface (950-1000mb) < 5k ft (1.5 km)
Low levels (850mb) < 10k ft (3 km)
Mid levels (700mb) < 18k ft (5.5 km)
Upper levels (500mb) < 30k ft (9.2 km)
Upper troposphere (200mb) > 39k ft (11.8 km)

[Emmett_Brown]

https://imagizer.imageshack.com/img924/261/KntjPv.gif

Lee already has an excellent structure to work with. Perhaps we could see RI into a hurricane or a major ahead of even the hurricane models’ timeframes.

Yeah, the upper level outflow is really getting established and banding features continue to form; it's starting to wrap very nicely. Lee has days before he even gets to the 60/20 area; he really has so much time and room to explode

[underthwx]

https://imagizer.imageshack.com/img924/261/KntjPv.gif

Lee already has an excellent structure to work with. Perhaps we could see RI into a hurricane or a major ahead of even the hurricane models’ timeframes.

I agree, I think it will be an over achiever on intensity fairly quickly...

[canebeard]

https://imagizer.imageshack.com/img924/261/KntjPv.gif

Lee already has an excellent structure to work with. Perhaps we could see RI into a hurricane or a major ahead of even the hurricane models’ timeframes.

Yeah, the upper level outflow is really getting established and banding features continue to form; it's starting to wrap very nicely

It is a

[kevin]

The shear ahead of Lee is quickly falling and the moderate shear area is decreasing in size as well. Not sure if this was forecast to happen this soon, because shear seems to keep Lee under control in most models for the next 24 hours. Maybe this could aid faster than expected intensification?

Now


6 hours ago

[Iceresistance]

The shear ahead of Lee is quickly falling and the moderate shear area is decreasing in size as well. Not sure if this was forecast to happen this soon, because shear seems to keep Lee under control in most models for the next 24 hours. Maybe this could aid faster than expected intensification?

Now
https://i.imgur.com/OwLONLo.gif

6 hours ago
https://i.imgur.com/RLJI58l.gif

I don't like this forecast either.

TROPICAL DEPRESSION 13L 18:00UTC 05September2023
UW-CIMSS Experimental Vertical Shear and TC Intensity Trend Estimates

Current Conditions (from NHC) :
Latitude : 12:46:52 N
Longitude : 41:01:26 W
Intensity (MSLP) : 1009.0 hPa

Max Pot Int (MPI,from Emanuel) : 901.9 hPa
MPI differential (MSLP-MPI) : 107.1 hPa

CIMSS Vertical Shear Magnitude : 3.2 m/s ( 6.3 kts)
Direction : 74.6 deg

Outlook for TC Intensification Based on Current
Env. Shear Values and MPI Differential
Forecast Interval : 6hr 12hr 18hr 24hr
F VF VF VF

Legend : VF-Very Favorable F-Favorable N-Neutral
U-Unfavorable VU-Very Unfavorable

-- Mean Intensity Trend (negative indicates TC deepening) --
6hr 12hr 18hr 24hr
VF <-3.0mb/ 6hr <-6.0mb/12hr <-9.0mb/18hr <-12.0mb/24hr
F -3.0 - -1.0 -6.0 - -2.0 -9.0 - -3.0 -12.0 - -4.0
N -1.0 - +1.0 -2.0 - +2.0 -3.0 - +3.0 -4.0 - +4.0
U +1.0 - +3.0 +2.0 - +6.0 +3.0 - +9.0 +4.0 -+12.0
VU >+3.0 >+6.0 >+9.0 >+12.0

- Current shear charts for the ATLANTIC BASIN can be found at :
http://cimss.ssec.wisc.edu/tropic2/real ... oom=&time=
- Additional information about this product can be found at :
http://cimss.ssec.wisc.edu/tropic2/misc ... s.shr.html
- Contact : Chris Velden (chrisv@ssec.wisc.edu)
CIMSS Internal Code : Basin - atlantic Storm - 13L

[underthwx]

He says, long way to go.

https://twitter.com/webberweather/status/1699135527776313535

Does that suggest a more gradual intensification, rather than a rapid one?

[zzzh]

[Iceresistance]

https://i.imgur.com/g1uxPQa.png

That is literally the most organized Tropical Depression I have ever seen

[caneseddy]

He says, long way to go.

https://twitter.com/webberweather/status/1699135527776313535

Does that suggest a more gradual intensification, rather than a rapid one?

He meant a long way to go as to what the end game will be for Lee as in land impacts

[msbee]

To our members in the Leeward Islands, please read this.

The depression is forecast to become a major hurricane by
this weekend and could bring impacts to the Leeward Islands by that
time. While it is too soon to determine the location and magnitude
of these possible impacts, interests in this area should monitor
the progress of the depression and updates to the forecast.

Today in 1995, Hurricane Luis hit us dead on.
Tomorrow in 2017, Hurricane Irma hit us dead on.
Incredible destruction from both storms.
To say that people here are watching and worrying about this storm, is an understatement.

"Hurricane Fatigue" is a real thing.

Those of us who have ever experienced a Cat 3 or higher storm know it.

I'm calling it a form of PTSD. We in FL are watching this one, too.

It is definitely PTSD. Anyone who has experienced a destructive cane has it.
It might be too early to say definitively that the NE Caribbean has dodged a bullet, but I am so thankful it looks that way right
now. Hopefully FL will dodge that bullet too.
After Irma, I never need to go through another hurricane again.

Thanks everyone for the helpful hints on good ways to get the NHC updates.

[cycloneye]

 https://twitter.com/DerekOrtt/status/1699148986550988900

[kevin]

[ElectricStorm]

OUTLOOK VALID 10/1800Z 22.2N 64.3W
MAX WIND 125 KT...GUSTS 150 KT.

[Iceresistance]

...TROPICAL STORM LEE EXPECTED TO RAPIDLY INTENSIFY INTO AN EXTREMELY DANGEROUS HURRICANE BY THE WEEKEND...

5:00 PM AST Tue Sep 5
Location: 13.2°N 41.8°W
Moving: WNW at 16 mph
Min pressure: 1005 mb
Max sustained: 45 mph