Hurricane Idalia

[WxWatcher007]

Tropical Depression Ten Discussion Number   1
NWS National Hurricane Center Miami FL       AL102023
400 PM CDT Sat Aug 26 2023

The cloud pattern of the low pressure area located near the
northeastern Yucatan Peninsula of Mexico has gradually become
better organized today.  Radar observations show a circulation has
developed, although surface observations indicate that the western
semicircle of this circulation is rather weak at this time.  Given 
the increased organization, advisories are being initiated on 
Tropical Depression Ten.  Surface synoptic observations suggest that 
the current intensity is around 25 kt.

The current motion estimate is nearly stationary.  There is a 
weakness in the subtropical ridge to the north of the tropical 
cyclone, leaving the system in a region of very weak steering flow. 
The dynamical guidance indicates that the system will remain in 
weak steering currents for the next 24 to 36 hours, so very little 
motion is predicted during that period.  After that time, a 
mid-level ridge begins to build to the east of the tropical cyclone. 
This should cause a generally northward motion in the next 2 to 3 
days.  Then, a gradual turn to the north-northeast is expected as 
the system moves along the northwestern periphery of the ridge.  The 
official track forecast is a blend of the simple and corrected 
dynamical model consensus guidance.

The tropical cyclone will be moving over very warm waters with only
moderate vertical wind shear anticipated during the next several
days.  Therefore, gradual strengthening is forecast.  The official
forecast is similar to the latest LGEM guidance and shows the 
system becoming a hurricane over the eastern Gulf of Mexico.  Users 
are reminded that there is significant uncertainty in 3-4 day 
intensity predictions and are urged to monitor changes to future 
forecasts.


KEY MESSAGES:

1. Heavy rainfall from Tropical Depression Ten is expected across
the eastern Yucatan Peninsula and western Cuba. The heavy rainfall
may produce areas of flash and urban flooding, as well as
landslides, across western Cuba.  The depression is forecast to
become a tropical storm by Sunday, and tropical storm conditions are
expected over portions of the Yucatan Peninsula where a Tropical
Storm Warning is in effect.  Tropical storm conditions are possible
over portions of western Cuba within the Tropical Storm Watch area.

2. The depression is forecast to strengthen during the next few days
and could become a hurricane over the eastern Gulf of Mexico,
bringing a potential of dangerous storm surge, heavy rainfall, and
strong winds to portions of the west coast of Florida and the
Florida Panhandle by the middle of next week.  Heavy rainfall is
also likely to spread into portions of the Southeast U.S. by mid to
late next week.  Although it is too soon to specify the exact
location and magnitude of these impacts, residents in these areas
should monitor updates to the forecast of this system and ensure
that they have their hurricane plan in place.


FORECAST POSITIONS AND MAX WINDS

INIT  26/2100Z 21.1N  86.1W   25 KT  30 MPH
 12H  27/0600Z 21.0N  86.3W   30 KT  35 MPH
 24H  27/1800Z 20.9N  86.2W   35 KT  40 MPH
 36H  28/0600Z 20.8N  86.1W   40 KT  45 MPH
 48H  28/1800Z 22.0N  85.7W   45 KT  50 MPH
 60H  29/0600Z 24.0N  85.6W   50 KT  60 MPH
 72H  29/1800Z 26.3N  85.3W   65 KT  75 MPH
 96H  30/1800Z 31.5N  83.0W   45 KT  50 MPH...INLAND
120H  31/1800Z 35.0N  79.0W   30 KT  35 MPH...INLAND

$$
Forecaster Pasch

[Windspeed]

First graphic for posterity...

[Ed, snow and hurricane fan]

9 minutes ago, Windspeed said:

First graphic for posterity...

Minimal Cat 1 about 12 hours before landfall.  Anticyclone over the top on 12Z GFS should keep the dry air to the W and SW from mixing in too much, I'd guess strengthening until landfall.  It might be a Cat 1 more than 12 hours before landfall, of course.

[NavarreDon]

Looks like St Marks area for landfall, FD was on point about strength errors.


.

[TheGhostOfJohnBolaris]

ICON with another landfall around Tampa. It’s been very consistent with this track.

[WxWatcher007]

 

[hawkeye_wx]

Oddly, the GFS drops the 500 mb vorticity southward, but keeps the weak surface low stationary, off the northeast tip of the Yucatan.

[TheGhostOfJohnBolaris]

We’ll just be spinning our wheels on track and intensity before the recon gets there tomorrow. Not putting much stock into either before then.

[hawkeye_wx]

This system really lost its core convection this afternoon.

[Eskimo Joe]

 

 

[Nibor]

 

Satellite doesn't look as great but there still seems to be decent core rotation based on radar.

[TheGhostOfJohnBolaris]

HAFS noticeably more SE than the last run

[CheeselandSkies]

HAFS-A is at 956 MB just offshore, at FH078. Next frame, at FH081, is at 954 MB well inland.

[MattPetrulli]

1 hour ago, hawkeye_wx said:

This system really lost its core convection this afternoon.

 

18 minutes ago, Nibor said:

 

Satellite doesn't look as great but there still seems to be decent core rotation based on radar.

It's diurnal minimum, it isn't surprising or anything. Not saying you guys are saying it's surprising, I'm just stating that fact.

[Floydbuster]

Evening video update on TD-10
https://www.youtube.com/watch?v=e9xzL_UNJHQ

[WxSynopsisDavid]

12 minutes ago, MattPetrulli said:

 

It's diurnal minimum, it isn't surprising or anything. Not saying you guys are saying it's surprising, I'm just stating that fact.

Diurnal minimum is correct, this is typically when we see tropical systems lose that photogenic appearance. Big thing here is that during the day the centers of circulation are starting to organize. We are starting to see this system get a tad more symmetrical and some noticeable spin. What we ultimately are waiting for is the low, mid, and upper level circulations to stack. Once this thing starts to ventilate than we will have a better grasp on this system. Big thing everyone should be paying attention to is the environment out ahead of this system. With a lack of dry air and decreasing shear, it sets up a near pristine environment over 90+ degree SST's. There are some noticeable warm eddies in the Gulf too, not to mention how warm the Gulf Loop Current is right now. There are a lot of factors in play working for this thing to take off vs hindering it. 

With that said, recon data will be vital tomorrow. I'm curious to know if indeed we get an anticyclone development and I'm also curious to know if Recon Hunters find that shear and dry air are more significant than what models are showing.

[cptcatz]

HAFS with a potentially catastrophic surge into Tampa Bay...

[WxSynopsisDavid]

5 minutes ago, cptcatz said:

HAFS with a potentially catastrophic surge into Tampa Bay...

Angle of approach is concerning, that would be a strengthening Category 3 approaching landfall. Frictional induced intensification through landfall.

[cptcatz]

8 minutes ago, WxSynopsisDavid said:

Angle of approach is concerning, that would be a strengthening Category 3 approaching landfall. Frictional induced intensification through landfall.

Yeah I mean getting Tampa Bay directly on the south side of a major hurricane is like a needle in a haystack, but if it were to actually happen here, I think a lot of people would brush off the warnings after what happened with Ian less than a year ago. 

[MattPetrulli]

Oh

[Prospero]

15 minutes ago, cptcatz said:

Yeah I mean getting Tampa Bay directly on the south side of a major hurricane is like a needle in a haystack, but if it were to actually happen here, I think a lot of people would brush off the warnings after what happened with Ian less than a year ago. 

I ordered a mix of batteries (D, AA, 9volt, etc.) and a couple basic supplies from Sam's Club when I woke up this morning and they were delivered by mid-afternoon. Sure beats the old days of driving down, parking and hiking across a vast hot parking lot, and being in the aggressive panicking crowds.

But it was not as fun as the old chaos where you could get beat up for grabbing the last pack of D batteries...

 

[Windspeed]

Oh

Yeah, Cowan just noted the tighter core. It's a little anemic on the convective side at the moment, but it does still appear to be organizing. New convective bursts would aid that process. Additionally, convection that was focused east and south of Cuba is getting further away. This may also aid in easing any negative influences and subsidence working against the COC. That being said, it is drifting very close to the Rivera Maya coastline. If it remains offshore, the TC may ramp up on Sunday. If it meanders inland, obviously, that will delay the intensification process. Of course, that is very much what the Globals had been doing for quite a number of OP runs since yesterday.

[WxSynopsisDavid]

Looking at the shear values in the environment around TD 10, there's are a noticeable decrease in shear. Earlier today, the system was completely shrouded in 40kt shear. Now this evening, we see a big time decrease in shear to the northeast and some relaxation to the north. Not a good trend because this falls right in-line with those hurricane models earlier today. They seem to indicate the relaxation of shear this evening/overnight and better organization and development tomorrow. 

[WxWatcher007]

You can see on that graphic that it’s still working under the influence of the ULAC. That’s been key to development given the shear in the region. It’s basically working in a pristine TC genesis environment currently—and land is the only thing that could be reasonably expected to slow this down before it lifts into the Gulf.

[Prospero]

Here in Tampa Bay we who are experienced are preparing a little. Gulfport Florida has been so lucky for too many years. There is a physical reason why we don't get nailed like the panhandle, but it we are still vulnerable even if not as often as the northern Gulf of Mexico.

Storm mode on:

https://thegabber.com/what-you-need-to-know-about-td-10-in-gulfport-st-pete/

 

[Kevin Reilly]

2 hours ago, Nibor said:

 

Satellite doesn't look as great but there still seems to be decent core rotation based on radar.

At first almost looks like there are multiple circulations but at the end of the loop clearly can see one dominant low-pressure system take over and move actually SSW towards Cozumel in Mexico.

[WxSynopsisDavid]

15 minutes ago, WxWatcher007 said:

You can see on that graphic that it’s still working under the influence of the ULAC. That’s been key to development given the shear in the region. It’s basically working in a pristine TC genesis environment currently—and land is the only thing that could be reasonably expected to slow this down before it lifts into the Gulf.

Agreed, and it is not good that as forecasters we have no limiting factors in play here to discuss. It's come down to how long it lingers near the Yucatan....really feels like dejavu from some of the previous big gulf storms we have forecasted.

[cptcatz]

FYI here is the link to the radar Brian used: https://smn.conagua.gob.mx/es/observando-el-tiempo/radares-meteorologicos-separador/visor-radares-v3

Still looks like it's moving almost due south (maybe just a tad west of due south).  Unless it makes a harder turn west, it should continue to stay off shore.

[yoda]

 

 

[Prospero]

20 minutes ago, yoda said:

 

 

That puts us (Tampa Bay) on the surge side. Still, its likely the path will change every day. But they are getting much better last few years.