ATL: EARL - Post-Tropical - Discussion

[kevin]

Eye dropsonde found 969 mb at the surface with 4 kt surface winds, supports 968-969 mb.

[kevin]

ADT up to 5.4, which means 100 kt. And it certainly looks the part on IR. A very big eye is clearing on IR, kinda reminds me of Larry. If the winds are mixing down better I wouldn't be surprised if the next recon (should arrive in ~4 hours) finds a MH.

Edit: 09z, raw T# now up to 5.9 (112 kt). Very excited for the next recon flight.

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 9.0
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 08 SEP 2022 Time : 072020 UTC
Lat : 27:50:51 N Lon : 65:19:47 W


CI# /Pressure/ Vmax
5.4 / 953mb / 100kts


Final T# Adj T# Raw T#
5.4 5.5 5.5

Estimated radius of max. wind based on IR :N/A km

Center Temp : -27.1C Cloud Region Temp : -63.1C

[kevin]

BULLETIN
Hurricane Earl Advisory Number 22
NWS National Hurricane Center Miami FL AL062022
500 AM AST Thu Sep 08 2022

...EARL CONTINUES TO STRENGTHEN...
...TROPICAL STORM CONDITIONS EXPECTED TO BEGIN ON BERMUDA THIS
AFTERNOON...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...28.2N 65.4W
ABOUT 285 MI...460 KM S OF BERMUDA
MAXIMUM SUSTAINED WINDS...105 MPH...165 KM/H
PRESENT MOVEMENT...N OR 5 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...969 MB...28.62 INCHES

Also another interesting excerpt from the discussion:

That said, this particular
flight measured a peak 700-mb flight-level wind of 97 kt and SFMR
winds as high as 82 kt, while the central pressure dropped to 969
mb. Recent research on SFMR measurements from the NOAA Hurricane
Research Division and the University of Miami has shown that the
SFMR undersampling for a hurricane of Earl's size is typically
about 10 percent, which would suggest that the maximum winds are up
to around 90 kt. This estimate also more closely aligns to the
107-kt flight-level wind measured by the NOAA Hurricane Hunter
flight last evening.

So if the FL winds support it, it seems the NHC is willing to use a 10 percent undersampling percentage in SFMR for Earl. Might be good to keep in mind for the coming recon flights.

[kevin]

Earl has a very large windfield, recon already found consistent TS winds starting a 180 miles to the SE of Earl's center. For reference Larry has 230 mi TS winds.

[kevin]

First pass 959.0 mb extrapolated

[aspen]

Earl’s pressure isn’t the only thing that’s down. This pass didn’t find any FL winds higher than 80 kt, which is very odd. Convection is improving, the pressure is falling, why aren’t the winds increasing?

[kevin]

Earl’s pressure isn’t the only thing that’s down. This pass didn’t find any FL winds higher than 80 kt, which is very odd. Convection is improving, the pressure is falling, why aren’t the winds increasing?

Maybe just an unfortunate pass or maybe those were the two weaker quadrants? But tbh I'm also not sure. I can't imagine how a storm which is visibly improving and deepening at a rate of more than 1 mb/hr would weaken in terms of its winds.

[wxman57]

Perhaps Earl's wind field is expanding, which decreases the pressure gradient? I agree that pressures would typical support a higher wind, but it's the pressure gradient that determines wind speed. Recon indicates that Earl barely has hurricane force winds in its SE and NW quadrants. Satellite appearance can often be quite deceiving.

[aspen]

Eye drop of 966/9 supports 964 or 965 mbar.

[Iceresistance]

2nd pass down to 958.2 MB Extrapolated

[NDG]

Earl has a huge eye this morning, 47 nautical miles (54 miles) across.

371
URNT12 KWBC 081108
VORTEX DATA MESSAGE AL062022
A. 08/10:37:01Z
B. 28.35 deg N 065.31 deg W
C. 700 MB 2799 m
D. 966 mb
E. 225 deg 9 kt
F. CLOSED
G. C47
H. 62 kt
I. 145 deg 20 nm 10:32:19Z
J. 241 deg 78 kt
K. 144 deg 54 nm 10:23:33Z
L. 64 kt
M. 329 deg 29 nm 10:43:41Z
N. 073 deg 76 kt
O. 329 deg 31 nm 10:44:23Z
P. 10 C / 3073 m
Q. 16 C / 3064 m
R. 11 C / NA
S. 1234 / 7
T. 0.01 / 0.25 nm
U. NOAA2 2006A EARL OB 06
MAX FL WIND 78 KT 144 / 54 NM 10:23:33Z
MAX FL TEMP 21 C 144 / 16 NM FROM FL CNTR

[NDG]

Not a bad looking Hurricane this morning, due south of Bermuda.

[wxman57]

So far, recon is finding a 70 kt hurricane. The large eye suggests an eyewall replacement cycle. That would result in an expansion of the wind field and a decreasing pressure gradient. Thus, the lower winds. If it is an ERC, then we should expect to see the eye shrink today, corresponding to a wind increase.

[aspen]

Pressure keeps going down. This eye drop yielded 964/18, so probably down to 960-962 mbar now. Oddly low for a system with Cat 1 that hasn’t even peaked yet; usually these low pressure/wind combos happen with weakening systems, like Florence.

[NDG]

So far, recon is finding a 70 kt hurricane. The large eye suggests an eyewall replacement cycle. That would result in an expansion of the wind field and a decreasing pressure gradient. Thus, the lower winds. If it is an ERC, then we should expect to see the eye shrink today, corresponding to a wind increase.

Makes sense with the double wind maxima in the SE & NW quadrant of the hurricane the recon found.

[Iceresistance]

Advisory 22A now has Earl at 105 mph and 965 MB.

[cheezyWXguy]

So far, recon is finding a 70 kt hurricane. The large eye suggests an eyewall replacement cycle. That would result in an expansion of the wind field and a decreasing pressure gradient. Thus, the lower winds. If it is an ERC, then we should expect to see the eye shrink today, corresponding to a wind increase.

Makes sense with the double wind maxima in the SE & NW quadrant of the hurricane the recon found.

https://i.imgur.com/fl7CRrb.png

I don’t know if I see a double wind maximum there, is there any microwave imagery available?

[tolakram]

floater: https://weather.cod.edu/satrad/?parms=meso-meso2-02-96-1-100-1&checked=map&colorbar=undefined

[wxman57]

Advisory 22A now has Earl at 105 mph and 965 MB.

Advisory was typed before recon data was available. It's clearly not a 105 mph hurricane. More like 85 mph now. NHC never indicates weakening when a storm is passing near land.

[Iceresistance]

So far, recon is finding a 70 kt hurricane. The large eye suggests an eyewall replacement cycle. That would result in an expansion of the wind field and a decreasing pressure gradient. Thus, the lower winds. If it is an ERC, then we should expect to see the eye shrink today, corresponding to a wind increase.

Makes sense with the double wind maxima in the SE & NW quadrant of the hurricane the recon found.

https://i.imgur.com/fl7CRrb.png

I don’t know if I see a double wind maximum there, is there any microwave imagery available?

Perfect timing!


https://s4.gifyu.com/images/Earl-Microwave-pass.jpg