ATL: DON - Post-Tropical - Discussion

[MarioProtVI]

TXNT21 KNES 221818
TCSNTL

A. 05L (DON)

B. 22/1800Z

C. 39.5N

D. 50.1W

E. THREE/GOES-E

F. T3.5/3.5

G. IR/EIR/VIS

H. REMARKS...9/10 BANDING RESULTS IN A DT OF 3.5. THE MET IS 3.0 BASED
ON A STEADY 24 HOUR TREND. THE PT IS 3.5. THE FT IS BASED ON THE DT.

I. ADDL POSITIONS

NIL


...BROWN

Worst fix I’ve ever seen. No mention of the eye??? This has to be thrown out as it’s garbage.

[cycloneye]

No hurricane but I think they may raise at Post-Season TC Report.

AL, 05, 2023072218, , BEST, 0, 395N, 501W, 60, 991, TS

[MarioProtVI]

No hurricane but I think they may raise at Post-Season TC Report.

AL, 05, 2023072218, , BEST, 0, 395N, 501W, 60, 991, TS

And just as I suspected the garbage fix I mentioned seems to be why they held it back.

[Yellow Evan]

There’s still one more DMax tomorrow when I expect peak intensity but yes not using an eye scene here is questionable.

[cycloneye]

I would not be surprised if they pull the trigger at 5 PM and upgrade despite the SSD and Best Track.

[LarryWx]

No hurricane but I think they may raise at Post-Season TC Report.

AL, 05, 2023072218, , BEST, 0, 395N, 501W, 60, 991, TS

Also, the 12Z models don't have Don reach peak strength for still another 12 hours (DMAX):

-HWRF has it drop from 995 mb at 18Z to 988 mb at 6Z along with an increase from 70 knots at 18Z to 95 knot winds tonight
-HMON rises from 80 to 90 knots
-HAFS A rises from 65 to 95 knts
-HAFS B rises from 70 to 95 knots

[aspen]

I don’t get why the NHC is so conservative with these subtropical systems this year. First calling a borderline hurricane a 20/20 invest in January, now calling a 70+ kt hurricane a 60 kt TS. I don’t recall any instance in previous years where they didn’t upgrade such an obvious hurricane. Hopefully the official advisory is 5 kt higher than the BT like last advisory and we get an official hurricane. This will need some post-season revisions though. And at least this time, the system in question isn’t a threat to land, so significant underestimates aren’t as bad.

[cycloneye]

This is very important from UWCIMSS that explain in three tweets very good all of this.

 https://twitter.com/UWCIMSS/status/1682830843830497281

UWCIMSS
1/3 Some discussion today about why #Don has not been upgraded to a hurricane despite looking very much like a hurricane. Storm intensity in the absence of any observations such as aircraft recon relies on satellite estimates. None of these methods show Don has reached hurricane

 https://twitter.com/UWCIMSS/status/1682830846040977409

@UWCIMSS
intensity yet, though they are getting close. The presence of an eye does not guarantee hurricane intensity. The intensity assessment rules so far have not permitted the use of an eye in the imagery by the Dvorak analysts. That is likely to change now and in the next few hours as

 https://twitter.com/UWCIMSS/status/1682830848582729733

@UWCIMSS
Don continues to improve in organization. Recent microwave intensity estimates are also approaching hurricane intensity including the CIMSS AI-based method D-PRINT (grey circles in first image). Don is moving over the warmest water yet so there is still time to strengthen.

[Kingarabian]

ADT is using a curved band which shouldn't be factored here. Any manual fixes should be doing an eye scene because the system has an eye and the eye is visible and warm on satellite.

Tropical storms don't have eyes.

[LarryWx]

Even if they don't go to a H at 5PM, they could still do so at 11PM as the models all have it stronger then vs 5PM. And they could even do it at 5AM, when the models still have it near peak just after DMAX. Only after that do they finally have it weaken.

[Yellow Evan]

ADT misses the eye a large percentage of the time nowadays.

DPrint/DMint seem to lag behind in quickly intensifying systems in my limited observation.

[Sciencerocks]

My estimate is now 75 knots....If it can wrap deeper convection I wouldn't be shocked if it tries for cat2.

[Woofde]

I'm no met, but at some point you have to call a spade a spade. I think we've grown too dependant on using technology to estimate and predict systems if they're saying a system with a very clear eye and solid convection is not a hurricane. Out of these two systems below which one would you say is the tropical storm?

[cycloneye]

Is a Hurricane at 5 PM

BULLETIN
Hurricane Don Advisory Number 35
NWS National Hurricane Center Miami FL AL052023
500 PM AST Sat Jul 22 2023

...DON BECOMES A HURRICANE JUST BEFORE REACHING COOLER WATERS...

[MarioProtVI]

I would not be surprised if they pull the trigger at 5 PM and upgrade despite the SSD and Best Track.

Bingo

[cycloneye]

The important paragrafh.

Don's cloud pattern continued to become better organized after the
release of the previous advisory with convection wrapping around an
eye in infrared imagery. Since that time, the cloud tops over the
western semicircle have warmed somewhat, but a 1648 UTC AMSR2
microwave pass showed a well-defined low- to mid-level eye with deep
convection surrounding it. Subjective Dvorak estimates at 1800 UTC
ranged from T4.0 (65 kt) from TAFB and T3.5 (55 kt) from SAB, with
objective estimates in the 60 to 63 kt range. Since subjective
estimates have yielded a T4.0 throughout much of the afternoon, the
initial intensity has been raised to 65 kt, making Don a hurricane

[Sciencerocks]

 https://twitter.com/FerragamoWx/status/1682855831568613380

[Teban54]

Subtropical Storm Don Advisory #1, when it was 45 kt:

The storm is likely near its peak intensity already.

[cycloneye]

Maybe 70kt or 75kt with this look?

[LarryWx]

My estimate is now 75 knots....If it can wrap deeper convection I wouldn't be shocked if it tries for cat2.
https://imagizer.imageshack.com/img924/6169/5x0WoY.gif

The 4 12Z hurricane models all have it strengthening well into cat 2 tonight with 90-95 knot winds.