ATL: DORIAN - Post-Tropical - Discussion

[chaser1]

Overall look via night-time satellite views along with what appears to be a slight reorganization or shift to the north/east. By itself this bodes worse for downstream potential impact for those of us in Florida. Two biggest keys that will be crucial here are whether Dorian will weaken or strengthen as a result of conditions in the far eastern Caribbean prior to impact with P.R., and will models continue to lock on to building mid level heights forcing Dorian more WNW once it is east of the Bahamas. I'm still reluctant to even look at the upper air over and just east of Florida 5-6 days out from now but the idea of a Cat 2 - Cat 4 approaching Florida from the ESE under building ridging is certainly within the realm of possibility. Just how comforting is the NHC 120 hr. forecast depiction of only a 70 mph storm over or near Freeport at the end of the forecast cycle???

[Kat5]

Which model(s) show(ed) Dorian dissipating and is it? Or too soon to tell. Some post saying it is weaking into a wave others saying it is just trying to find a new center...

Sent from my android using Tapatalk

Just a center relocation while recon were doing the recent pass. And the legacy GFS.

[Frank2]

Dorian seems to be moving NW now - right into a large area of 20-30Kt shear. If you click below, when it opens click on IR and Shear to see the shear map overview:

http://tropic.ssec.wisc.edu/real-time/s ... 000&loop=0

[Stormi]

It indeed appears to be getting ready to thread the needle...not good.

[Frank2]

chaser1, the shift north is actually good because it means it's more likely to move into the trough - TD6 is almost stationary and that is helping to enhance the weakness. An per my previous post Dorian is moving into a large area of strong shear. Sunday the thought was it could dissipate in the NE Caribbean and it might be working out that way but too soon to know for sure.

Earlier tonight one meteorologist did say the storm was not very healthy this evening and for NHC to lower the wind by 10 mph is significant - they usually don't unless the findings are beyond a doubt.

It's looking better for everyone than 6-12 hours ago and hoping and praying it stays that way...

Frank

[Chris_in_Tampa]

1 minute imagery from 1:27am to 2:26am AST:



I used the RAMMB SLIDER:

https://rammb-slider.cira.colostate.edu ... 31.5&y=941

Positioned a browser window really small to create the tiny size and then took the downloaded GIF and used an online GIF optimizer to make the file size smaller and to add 2 seconds of delay at the end of the loop.

[Stormi]

1 minute imagery from 1:27am to 2:26am AST:

https://i.imgur.com/D6WlXmH.gif

I used the RAMMB SLIDER:

https://rammb-slider.cira.colostate.edu ... 31.5&y=941

Positioned a browser window really small to create the tiny size and then took the downloaded GIF and used an online GIF optimizer to make the file size smaller and to add 2 seconds of delay at the end of the loop.

I am a complete newb, but that without a doubt IMHO appears to be an attempt at restructuring an eye.

[Ubuntwo]

1 minute imagery from 1:27am to 2:26am AST:

https://i.imgur.com/D6WlXmH.gif

I used the RAMMB SLIDER:

https://rammb-slider.cira.colostate.edu ... 31.5&y=941

Positioned a browser window really small to create the tiny size and then took the downloaded GIF and used an online GIF optimizer to make the file size smaller and to add 2 seconds of delay at the end of the loop.

I am a complete newb, but that without a doubt IMHO appears to be an attempt at restructuring an eye.

There is no eye. That is a burst of convection.

[Stormi]

1 minute imagery from 1:27am to 2:26am AST:

https://i.imgur.com/D6WlXmH.gif

I used the RAMMB SLIDER:

https://rammb-slider.cira.colostate.edu ... 31.5&y=941

Positioned a browser window really small to create the tiny size and then took the downloaded GIF and used an online GIF optimizer to make the file size smaller and to add 2 seconds of delay at the end of the loop.

I am a complete newb, but that without a doubt IMHO appears to be an attempt at restructuring an eye.

There is no eye. That is a burst of convection.

Thank you!

[Kat5]

1 minute imagery from 1:27am to 2:26am AST:

https://i.imgur.com/D6WlXmH.gif

I used the RAMMB SLIDER:

https://rammb-slider.cira.colostate.edu ... 31.5&y=941

Positioned a browser window really small to create the tiny size and then took the downloaded GIF and used an online GIF optimizer to make the file size smaller and to add 2 seconds of delay at the end of the loop.

I am a complete newb, but that without a doubt IMHO appears to be an attempt at restructuring an eye.

Hot tower.

[Hammy]

1 minute imagery from 1:27am to 2:26am AST:

https://i.imgur.com/D6WlXmH.gif

I used the RAMMB SLIDER:

https://rammb-slider.cira.colostate.edu ... 31.5&y=941

Positioned a browser window really small to create the tiny size and then took the downloaded GIF and used an online GIF optimizer to make the file size smaller and to add 2 seconds of delay at the end of the loop.

I am a complete newb, but that without a doubt IMHO appears to be an attempt at restructuring an eye.

There is no eye. That is a burst of convection.

I'm not sure what it is with these systems with sparse recon coverage--they'll look good on satellite and fall apart right as the plane gets there--only to refire later. It's almost like they're having their own equivalent of feeling sick until the day of your doctor's appointment

[Chris_in_Tampa]

chaser1, the shift north is actually good because it means it's more likely to move into the trough - TD6 is almost stationary and that is helping to enhance the weakness. An per my previous post Dorian is moving into a large area of strong shear. Sunday the thought was it could dissipate in the NE Caribbean and it might be working out that way but too soon to know for sure.

Earlier tonight one meteorologist did say the storm was not very healthy this evening and for NHC to lower the wind by 10 mph is significant - they usually don't unless the findings are beyond a doubt.

It's looking better for everyone than 6-12 hours ago and hoping and praying it stays that way...

Frank

The NHC lowered it by 5 knots at the time because recon supported that, at that time.

The NHC went down from 50 knots to 45 knots. But the way that works out since they have the miles per hour in increments of 5mph is:

50 knots = 57.539 mph = 60 mph
45 knots = 51.7851 mph = 50 mph

It looks like a bigger decrease than it was.

Recon is not currently in there and won't be again until around 7:30am AST. It may have been reorganizing around the time recon was leaving. There's additional cold cloud tops developing. Whether it lasts is unknown, and how organized it might actually be at the surface, I don't know, but I don't think anything looks any better for anyone at this point. There continues to be uncertainty down the road, especially for points after passing over or near Hispaniola or Puerto Rico.

[LarryWx]

Is he already turning to the NW? That radar loop sure makes it look like that may have already turned.

[Stormi]

It looks to be gaining convection & restructuring. I could be wrong, but that's what appears to be happening. I thought it would be shredded already.

[Kingarabian]

Its satellite presentation hasn't changed much and it's only giving off illusions of organization. it still looks like it's a system that's been following a similar pattern where it' becomes disrupted after attempting to organize. Until we see it maintain and expand large round deep convection circles (true hot towers) near the COC, the status-quo will probably remain the same.

[Stormi]

Its satellite presentation hasn't changed much and it's only giving off illusions of organization. it still looks like it's a system that's been following a similar pattern where it' becomes disrupted after attempting to organize.

This makes a lot of sense. Thanks!!

[Chris_in_Tampa]

https://re.ssec.wisc.edu/s/j1ajpd

I tried creating a MP4 movie in RealEarth with the NHC track from 11pm AST and mesoscale floater imagery and then converted it to GIF. Past and forecast positions also on the image as white dots. The one just to the left of Barbados is the 11pm AST position. Time in UTC. (ending at 3:20am AST) I was just trying to see what views I could easily save.

[USTropics]

Its satellite presentation hasn't changed much and it's only giving off illusions of organization. it still looks like it's a system that's been following a similar pattern where it' becomes disrupted after attempting to organize.

This makes a lot of sense. Thanks!!

Essentially what is happening is the low-level circulation attempts to close off and build up to the mid-levels, a stronger vorticity signature at the mid-level requires more inflow, which causes an increase in dry air entrainment and disrupts any attempt at building an eyewall at the mid-levels. This causes a disruption at the low-levels, and Dorian must begin the cycle again, beginning with latent heat processes to create an increase in convection.

[AtlanticWind]

It appears Dorian may already be moving northwest

[Kat5]

I wonder if the easterly trade winds in the eastern Caribbean will keep its structure unsteady.