ATL: FIONA - Post-Tropical - Discussion

[galaxy401]

Well even with the unfavorable state of the Atlantic, climatology still has enough force to spit out a new storm.

[ScottNAtlanta]

I'm struck by how much this looks (physically) like Earl. 700 and 500mb vorticity just a little off the east.

[wxman57]

Watch for it to decrease in organization as it encounters periods of stronger shear and dry air.

[Spacecoast]

NHC cone:

[skyline385]

This isn't Dorian. I think it could become a hurricane NE of the Bahamas in 8 days or so. Until it passes the NE Caribbean, it's fighting shear and dry air. I think the NHC jumped the gun on calling it a TD, and I think they're developing it into a TS too quickly. Shear and dry air will continue to impact it for 3-4 days.

Yea was surprised by the TD announcement too. We haven’t had any ASCAT pass or recon which suggested the upgrade, guess they did it because it’s close to PR and we have had constant convection since yesterday?


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There was one that clipped the eastern end and found several 30 knot barbs.


https://s4.gifyu.com/images/TD-7-ASCAT.png

It's theoretically possible that we may have a TS (Next name is Fiona) when the next ASCAT makes a direct hit when the system is looking like this or still improving.

Going to move into a high shear environment with dry air above it, like wxman said I don’t think it will become TS soon.




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[MarioProtVI]

I’d rather not have the latest 12z GFS pan out with this…don’t need an Irene repeat up here

[wx98]

I believe this will be a TS in the next 18 hours given the very fast development overnight and this morning. Any hostile conditions that are forthcoming likely won't affect this for a day or two.

[Kingarabian]

Waves like these almost always have TS force winds confined to certain areas. They usually struggle in establishing a defined LLC. Now that the NHC has acknowledged its circulation is sufficiently organized, this should be a TS soon.

[wxman57]

Watch for a sharper N-NNE turn beyond day 5 of the NHC track, in line with consensus. GFS has been terrible with the upper-level flow beyond 3-4 days. Euro indicates a fairly strong cold front moving off the East U.S. Cost by this time next week, which would accelerate the storm northward, well east of the U.S. That may be when it becomes a hurricane. This is a subtropical hurricane season

I'm not in agreement with it becoming a TS anytime soon. I think it will be battling pulsing wind shear and dry air until it passes north of the DR into the eastern Bahamas. Convection will come and go until then. NHC may well call it a TS, but it will be poorly organized.

[MarioProtVI]

Watch for a sharper N-NNE turn beyond day 5 of the NHC track, in line with consensus. GFS has been terrible with the upper-level flow beyond 3-4 days. Euro indicates a fairly strong cold front moving off the East U.S. Cost by this time next week, which would accelerate the storm northward, well east of the U.S. That may be when it becomes a hurricane. This is a subtropical hurricane season.

I'm not in agreement with it becoming a TS anytime soon. I think it will be battling pulsing wind shear and dry air until it passes north of the DR into the eastern Bahamas. Convection will come and go until then. NHC may well call it a TS, but it will be poorly organized.

Good I don’t need another Irene because the GFS essentially shoved it up here with that strong high to its east

[SconnieCane]

NHC cone:
https://i.ibb.co/rxZdDBL/cch.jpg

Bullseye on the shredder, naturally Of course that's if you go by the center-line of the cone which most storms don't follow except in uncommonly clear-cut steering patterns, which this decidedly is not.

[tolakram]

I don't agree with shear being an issue. If anything shear has lessoned over the last day or so, at least in my estimation.



source: https://tropic.ssec.wisc.edu/real-time/windmain.php?&basin=atlantic&sat=wg8&prod=shr&zoom=&time=

[SFLcane]

 https://twitter.com/antmasiello/status/1570095596643688449

[ElectricStorm]

I don't think we can discount any solution at this point honestly. Especially with these kind of tracks where the islands are in play. I think this will stay fairly weak until it clears the islands, then it will probably have potential to get stronger after that. It wouldn't even surprise me if it goes further south than expected. Hopefully this recurves with minimal impacts but until we actually see a NE turn I think everyone should be paying attention to it.

Remember early NHC cones for Grace last year had it going up towards the eastern Gulf and FL but it ended up in the BOC... I don't think this will be a Grace repeat by any means but it goes to show how drastically track forecasts can change at this range.

[skyline385]

 https://twitter.com/tropicaltidbits/status/1570089202410467330





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[AtlanticWind]

One factor in TDs 7 favor is it will be moving over increasingly warmer waters .

[SFLcane]

 https://twitter.com/OSUWXGUY/status/1570097149580296193

[tolakram]

Saved loop. My work computer is painfully slow so loop is a bit laggy

[ElectricStorm]

12z SHIPS run certainly has moderate shear, but it's not the worst ever, especially if it can get going quicker

GFS version *
* ATLANTIC 2021 SHIPS INTENSITY FORECAST *
* IR SAT DATA AVAILABLE, OHC AVAILABLE *
* INVEST AL962022 09/14/22 12 UTC *

TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120 132 144 156 168
V (KT) NO LAND 30 32 33 34 35 37 41 43 46 47 47 49 50 56 56 62 63
V (KT) LAND 30 32 33 34 35 37 41 43 46 47 47 49 50 39 36 42 43
V (KT) LGEM 30 32 33 34 35 35 36 36 38 39 39 39 40 33 29 34 36
Storm Type TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP

SHEAR (KT) 12 11 11 14 17 11 16 13 17 16 22 17 22 18 20 14 17
SHEAR ADJ (KT) 0 2 0 0 0 1 2 1 -1 0 -4 -2 -3 -4 -3 -2 0
SHEAR DIR 243 244 253 258 277 281 303 310 311 292 282 261 281 256 281 250 255
SST (C) 28.3 28.3 28.3 28.4 28.6 28.8 29.1 29.3 29.7 29.8 29.8 30.0 29.8 29.7 30.1 29.9 29.9
POT. INT. (KT) 142 142 142 143 146 149 153 156 164 165 165 169 165 163 171 166 167
ADJ. POT. INT. 137 137 136 137 140 143 147 150 158 159 159 162 157 152 158 151 151
200 MB T (C) -54.3 -54.0 -54.1 -54.2 -54.3 -54.0 -54.1 -53.9 -53.9 -53.5 -53.5 -53.5 -53.9 -53.3 -53.5 -53.0 -53.1
200 MB VXT (C) -0.1 0.0 0.1 0.1 0.1 0.2 0.3 0.3 0.3 0.3 0.2 0.2 0.4 0.2 0.3 0.1 0.1
TH_E DEV (C) 8 8 8 8 9 9 9 10 10 10 9 9 9 9 8 8 8
700-500 MB RH 58 57 56 55 52 52 52 55 57 59 62 65 67 71 73 78 78
MODEL VTX (KT) 12 12 12 12 12 11 11 10 9 8 6 5 4 6 5 7 7
850 MB ENV VOR 10 4 9 6 3 9 3 3 5 22 16 19 11 28 18 30 23
200 MB DIV 25 24 32 17 10 10 -2 18 7 13 19 56 27 32 37 34 46
700-850 TADV -7 -8 -9 -9 -8 -9 -7 -9 -7 -7 -4 -6 0 -4 -2 -1 -3
LAND (KM) 1304 1287 1223 1117 1017 832 677 586 469 300 159 99 38 -56 7 100 152
LAT (DEG N) 16.4 16.7 16.8 16.8 16.7 16.5 16.2 16.0 16.0 16.2 16.6 17.1 17.9 xx.x xx.x xx.x xx.x
LONG(DEG W) 49.1 50.3 51.5 52.7 53.8 56.0 58.1 60.1 62.0 63.8 65.6 67.3 69.0 xxx.x xxx.x xxx.x xxx.x
STM SPEED (KT) 12 12 11 11 11 11 10 9 9 9 9 9 9 8 8 6 7
HEAT CONTENT 34 37 25 23 29 48 66 60 43 60 93 98 88 58 49 46 57

FORECAST TRACK FROM TABM INITIAL HEADING/SPEED (DEG/KT):290/ 12 CX,CY: -10/ 4
T-12 MAX WIND: 25 PRESSURE OF STEERING LEVEL (MB): 659 (MEAN=620)
GOES IR BRIGHTNESS TEMP. STD DEV. 50-200 KM RAD: 25.8 (MEAN=14.5)
% GOES IR PIXELS WITH T < -20 C 50-200 KM RAD: 51.0 (MEAN=65.0)
PRELIM RI PROB (DV .GE. 35 KT IN 36 HR): 5.4

[skyline385]

Saved loop. My work computer is painfully slow so loop is a bit laggy

Here’s a visible loop from TT, can see the circulation to the west as most of the convection seems to be tilted to the east.