Major Hurricane Delta

[Derecho!]

8 minutes ago, weatherCCB said:

Yeah, no doubt this will probably be a major cane in the Gulf.  Hopefully it will weaken as it nears the coast.  

I actually sort of checked out of the Laura threads right after landfall and missed discussion on why its surge was less than forecast...

But given enough forward speed, weakening on the shelf waters shouldn't lower the surge from Delta nearly as much as the winds, of course, presuming it's a fairly large storm with a large fetch. 

[dan11295]

15 minutes ago, weatherCCB said:

Yeah, no doubt this will probably be a major cane in the Gulf.  Hopefully it will weaken as it nears the coast.  

If without considering shear, shelf temps in the northern GOM are barely 26C. Even if it becomes a major, the water temps would make a major at landfall very unlikely. 12z intensity guidance has a weakening cat 1 at landfall. Hurricane Lili might be a possible Analog to Delta in this regard.

[Superstorm93]

The GFS sounding though...

 

 

[WishingForWarmWeather]

34 minutes ago, Derecho! said:

I actually sort of checked out of the Laura threads right after landfall and missed discussion on why its surge was less than forecast...

But given enough forward speed, weakening on the shelf waters shouldn't lower the surge from Delta nearly as much as the winds, of course, presuming it's a fairly large storm with a large fetch. 

If I recall correctly, it wasn't. They found evidence of 17-18 foot surge, it's just the area was mainly uninhabited and Lake Charles was spared the worst of it.

[Windspeed]

If without considering shear, shelf temps in the northern GOM are barely 26C. Even if it becomes a major, the water temps would make a major at landfall very unlikely. 12z intensity guidance has a weakening cat 1 at landfall.

Yeah the critical issue with Delta will be how intense and how large it becomes during major hurricane status as it traverses from NW Caribbean to the central GOM to drive up surge. Even if it weakens rapidly into landfall, its forward motion and overall circulation could still mean significant storm surge along the N. GOM coast. Additionally, due to the system being less influenced by Gamma, it may also drive further WNW initially putting Cozumel under threat. Still big questions remaining and the potential for the track to shift west in the forecast.

[tiger_deF]

 

[tiger_deF]

Sure looks like an eye is trying to pop out, likely just a warm core feature

[Cheeznado]

9 minutes ago, tiger_deF said:

Sure looks like an eye is trying to pop out, likely just a warm core feature

Way too weak for any real eye to be present. Regarding landfall intensity I think that fairly rapid weakening right at the coast is likely due to cooler water and shear, it all depends on how strong it gets in the central Gulf. I noticed that the HWRF backed off of the intensity quite a bit with the 06Z run.

[CheeselandSkies]

3 minutes ago, Cheeznado said:

Way too weak for any real eye to be present. Regarding landfall intensity I think that fairly rapid weakening right at the coast is likely due to cooler water and shear, it all depends on how strong it gets in the central Gulf. I noticed that the HWRF backed off of the intensity quite a bit with the 06Z run.

06Z hurricane models took a s*** just when it looked like all the stars were aligning for Delta to go nuts. We'll see if they got their systems flushed out properly at 12Z.

[Superstorm93]

11 minutes ago, Cheeznado said:

Way too weak for any real eye to be present. Regarding landfall intensity I think that fairly rapid weakening right at the coast is likely due to cooler water and shear, it all depends on how strong it gets in the central Gulf. I noticed that the HWRF backed off of the intensity quite a bit with the 06Z run.

They may be overestimating the amount of shear coming from Gamma. It's really hard to see this not blowing up. 

 

[Windspeed]

There is virtually no upper tropospheric influence from Gamma now as it is devoid of convection reaching mid-to-upper levels. Therefore, the more dominate upper ridge axis is likely to take over upper wind flow. Delta should be in a low shear environment as it traverses the NW Caribbean towards the channel. Additionally Delta's own intense convection is squashing what remains of the small PV feature. I think the TC models were overdoing Gamma's influence or there is convective feedback issues with what they are modeling as a TC north of the Yucatan when in reality it is just a low level wind / steering feature now with no influence on mid to upper heights.

[NavarreDon]

https://twitter.com/JackSillin/status/1313085909504602113?s=20

[Windspeed]

11 AM EDT discussion. I do think they're underdoing maximum intensity. After recon data is returned this afternoon, I'd imagine they'll bump up the forecasted intensity to a Category 3 on the 5 PM. We'll just have to wait and see how organized the vortex is per recon.

ZCZC MIATCDAT1 ALL
TTAA00 KNHC DDHHMM

Tropical Storm Delta Discussion Number   4
NWS National Hurricane Center Miami FL       AL262020
1100 AM EDT Mon Oct 05 2020

The convective structure of Delta has continued to improve this 
morning.  Earlier microwave data and early-light visible satellite 
imagery showed that the center of the tropical cyclone re-formed 
farther south within the area of deep convection.  Since that time, 
banding has continued to increase around the southern and eastern 
portion of the circulation, and a small CDO-like feature has formed. 
 The intensity has been set at 40 kt, which is a blend of the 
subjective Dvorak estimate from TAFB and objective satellite 
intensity estimates from UW/CIMSS.  A NOAA Hurricane Hunter aircraft 
is scheduled to investigate the tropical storm this afternoon, which 
should provide a better assessment of the cyclone's intensity, 
structure, and wind field.

With the earlier center re-formation, the initial motion estimate is 
a somewhat uncertain 280/6 kt.  Delta is expected to resume a 
west-northwestward motion later today.  A northwestward heading 
around the southwestern portion of a deep-layer ridge should begin 
tonight or Tuesday, and that general motion with some increase in 
forward speed is expected to continue through 60-72 hours.  After 
that time, a broad mid- to upper-level trough is forecast to develop 
over the south-central United States, which should weaken the 
western portion of the ridge and cause Delta to turn northward 
toward the northern Gulf Coast.  After day 4, Delta should begin to 
accelerate north-northeastward or northeastward ahead of the 
aforementioned trough.  The new NHC track forecast has been adjusted 
to the south and west of the previous advisory during the first 
couple of days, primarily due to the recent center re-formation and 
more southward initial position. After that time, the NHC track is 
not much different than the previous forecast and lies near the 
center of the tightly clustered dynamical model envelope.

Delta is forecast to traverse very warm waters over the northwestern 
Caribbean Sea and be in a very low vertical wind shear environment 
during the next couple of days.  These conditions should allow for 
significant strengthening during that time, and the NHC intensity 
forecast is at or above the various intensity aids.  It is somewhat 
surprising that the intensity aids were generally a little lower 
this cycle, but the expected low shear and SHIPS rapid 
intensification index support the higher than climatological rate 
of intensification.  After 72 hours, increasing southwesterly shear 
and the cooler shelf waters over the northern Gulf are likely to 
induce some weakening later in the period.  The updated NHC 
intensity forecast calls for a faster rate of intensification over 
the next 48-60 hours, but is similar to the previous advisory 
thereafter.

Key Messages:

1. Tropical storm conditions are expected in the Cayman Islands
beginning late today or tonight, and a Tropical Storm Warning is
in effect.

2. Dangerous storm surge and hurricane conditions are expected in 
portions of western Cuba by Tuesday afternoon, and a Hurricane 
Warning is in effect.

3. Heavy rainfall will affect portions of Jamaica, the Cayman 
Islands, and western Cuba during the next few days. This rainfall 
could lead to significant flash flooding and mudslides. 

4. Delta is forecast to approach the northern Gulf Coast late this 
week as a hurricane. While there is large uncertainty in the track 
and intensity forecasts at these time ranges, there is an increasing 
risk of dangerous storm surge, wind, and rainfall hazards along the 
coast from Louisiana to the western Florida Panhandle. Residents in 
these areas should monitor the progress of Delta and check for 
updates to the forecast during the week.

FORECAST POSITIONS AND MAX WINDS

INIT  05/1500Z 16.4N  78.6W   40 KT  45 MPH
 12H  06/0000Z 17.1N  79.6W   50 KT  60 MPH
 24H  06/1200Z 18.7N  81.7W   60 KT  70 MPH
 36H  07/0000Z 20.8N  84.3W   75 KT  85 MPH
 48H  07/1200Z 22.8N  86.8W   85 KT 100 MPH
 60H  08/0000Z 24.6N  89.1W   90 KT 105 MPH
 72H  08/1200Z 26.0N  90.7W   90 KT 105 MPH
 96H  09/1200Z 28.8N  91.1W   85 KT 100 MPH
120H  10/1200Z 33.1N  88.2W   40 KT  45 MPH...INLAND

$$
Forecaster Brown

NNNN

 

[CheeselandSkies]

Yeah, no way this peaks as just at Cat. 2 unless shear comes in significantly higher than expected over the next 2-2 1/2 days.

[the ghost of leroy]

Shame this is going to be wasted on the NGOM instead of Florida. 

[nycwinter]

the waters are very warm enough.. this time of year.. even when sally was upwelling the northern gulf it intensified as it made landfall..

[olafminesaw]

Cat1/2 at landfall seems to be the ceiling, even with quick forward speed:

[Superstorm93]

Convection really exploding in the northern portion of the circulation. 

Banding has improved considerably as well. 

[the ghost of leroy]

You can tell this one will actually be dank

[CheeselandSkies]

September may be considered the peak of hurricane season, but October really takes the cake for producing some beasts all around the world. From Tip to Hagibis, to Hurricane Patricia, to Mitch, Wilma, Michael and now Delta.

[It's Always Sunny]

Too early to put Delta in that category. It has potential to be, but those other storms were in a league of their own.

[Amped]

Convecction is rapidly expanding to the NW of a storm.  There is almost a line where it starts.  I remember several other storms showing this type of signature before RI.

[It's Always Sunny]

6 minutes ago, Amped said:

Convecction is rapidly expanding to the NW of a storm.  There is almost a line where it starts.  I remember several other storms showing this type of signature before RI.

Yeah good banding hopefully gets this thing more consolidated and erase that dry air pocket.

[hlcater]

SteveCop bringing the hype. Expecting no less than 900mb in 24hrs.

 

[the ghost of leroy]

Wxtwitter is so garbage

[mappy]

7 minutes ago, hlcater said:

SteveCop bringing the hype. Expecting no less than 900mb in 24hrs.

 

SteveCop = @Superstorm93

[mappy]

5 minutes ago, the ghost of leroy said:

Wxtwitter is so garbage

your posts are garbage per reports  

[hlcater]

Just now, mappy said:

SteveCop = @Superstorm93

Yea I know

[Superstorm93]

Recon is finally departing. Looks like we'll have a fix in a few hours. 

[the ghost of leroy]

14 minutes ago, mappy said:

your posts are garbage per reports  

Lol. Probably the same people who actually tracked Teddy.