Hurricane Idalia

[Kevin Reilly]

4 minutes ago, MANDA said:

Looks like a rather disjointed mess attm.  Of note though is that it is solidly in the NW Caribbean.  If some sort of core can get together before it starts to lift north that will allow it to enter the southern GOM ready to go.  If it is still disjointed upon entering the southern GOM the odds of a major hit IMO go down.  If it enters the GOM as an intensifying more or less well developed system I'd be concerned!

Looking at the water vapor map looks like the main vortex is a naked swirl for now a bit of NNE shear... also I am assuming the upper level low over Louisiana will be the feature that drags Depression #10 north.  

[WxWatcher007]

Some evidence of minimal TS intensity on the latest set of obs from recon but it’s still early in the flight. 

[TheGhostOfJohnBolaris]

Should have Idalia very shortly 

[WxWatcher007]

995.4mb extrapolated

[WxWatcher007]

Holding at TD 10 at 11am

Tropical Depression Ten Discussion Number   4
NWS National Hurricane Center Miami FL       AL102023
1000 AM CDT Sun Aug 27 2023

So far this morning, the overall cloud pattern of the tropical
cyclone has not become significantly better organized.  The small
center is partially exposed on GOES-16 visible imagery, and
convective banding features are still not very well defined.  The 
current intensity is held at 30 kt for this advisory which is in 
line with the latest Dvorak Satellite estimates.  A NOAA Hurricane 
Hunter aircraft, flying at around 12000 ft, is near the center of 
the system taking Doppler radar wind velocity measurements.  These 
data should provide valuable information on the structure of the 
cyclone for initializing the numerical weather prediction models.

The center of the cyclone appears to have been moving in a small
clockwise loop overnight and into this morning, and it will
probably complete this loop today.  The initial motion estimate is
now around 090/2 kt.  Steering currents should remain weak through
today and tonight.  Beginning on Monday, a mid-level ridge starts to
build near southern Florida and eastward.  This evolution should
cause a generally northward motion during the next couple of days.
In 48 to 72 hours, a mid-level trough dropping into the eastern U.S.
will likely induce a turn toward the north-northeast and take the
system across the northeast Gulf of Mexico coast on Wednesday.  The
official forecast track has been nudged to the right of the
previous one, but is not quite as far east as the latest corrected
consensus, HCCA, prediction.  Users are reminded not to focus on
the exact forecast track, since strong winds, heavy rains and
dangerous storm surges extend well away from the center.

The cyclone will be moving over waters of high oceanic heat content 
over the eastern Gulf of Mexico and within a moist mid- to 
low-level air mass for the next few days.  An upper-tropospheric 
trough is predicted to develop over the western Gulf of Mexico in 48 
to 72 hours.  Although this feature could produce some moderate 
southwesterly vertical wind shear over the system,  positive 
vorticity advection and diffluent upper-level flow to the east of 
the trough will likely be conducive for strengthening.  The 
official forecast, like the previous one, calls for the cyclone to 
reach hurricane status over the eastern Gulf of Mexico in 48 to 72 
hours.  This is at the high end of the latest intensity model 
guidance.


KEY MESSAGES:

1. The depression is forecast to become a hurricane over the eastern 
Gulf of Mexico, and there is an increasing risk of life-threatening 
storm surge, flooding from heavy rainfall, and hurricane-force winds 
along portions of the west coast of Florida and the Florida 
Panhandle beginning as early as  Tuesday.  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, 
have their hurricane plan in place, and follow any advice given by 
local officials.  Storm surge and hurricane watches may be required 
for portions of the Gulf coast of Florida later today.

2. Heavy rainfall is expected across the eastern Yucatan Peninsula 
and western Cuba and may produce areas of flash and urban flooding 
and landslides across western Cuba.  The depression is forecast to 
become a tropical storm later today, and tropical storm conditions 
are expected over portions of the Yucatan Peninsula and extreme 
western Cuba with tropical storm conditions possible on the Isle of 
Youth. 

3. Scattered flooding from heavy rainfall is likely over in 
portions of the southeast U.S. by mid to late week. 


FORECAST POSITIONS AND MAX WINDS

INIT  27/1500Z 19.9N  85.8W   30 KT  35 MPH
 12H  28/0000Z 19.7N  85.9W   40 KT  45 MPH
 24H  28/1200Z 20.6N  85.7W   45 KT  50 MPH
 36H  29/0000Z 21.9N  85.5W   50 KT  60 MPH
 48H  29/1200Z 24.0N  85.2W   60 KT  70 MPH
 60H  30/0000Z 26.2N  85.0W   75 KT  85 MPH
 72H  30/1200Z 28.9N  84.0W   80 KT  90 MPH
 96H  31/1200Z 33.0N  79.5W   45 KT  50 MPH...INLAND
120H  01/1200Z 34.5N  74.0W   45 KT  50 MPH...OVER WATER

$$
Forecaster Pasch

 

[MattPetrulli]

11 am stays at TD. I don’t like criticizing the pros much but I do not understand at all why this hasn’t been upgraded. Pressure and SFMR are in full support.


.

[WxWatcher007]

Dropsonde shows center pressure ~995mb

[hawkeye_wx]

That's a pretty good surface pressure for a young, disjointed system with a naked center.

[George BM]

000
WTNT65 KNHC 271513
TCUAT5

Tropical Storm Idalia Tropical Cyclone Update
NWS National Hurricane Center Miami FL       AL102023
1015 AM CDT Sun Aug 27 2023


...DEPRESSION STRENGTHENS TO A TROPICAL STORM...

Observations from a NOAA Hurricane Hunter aircraft indicate that 
Tropical Depression Ten has strengthened into Tropical Storm Idalia.
The maximum winds are estimated to be 40 mph (65 km/h) with higher
gusts.

SUMMARY OF 1015 AM CDT...1515 UTC...INFORMATION
---------------------------------------------------
LOCATION...19.9N 85.8W
ABOUT 80 MI...135 KM ESE OF COZUMEL MEXICO
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...E OR 90 DEGREES AT 2 MPH...4 KM/H
MINIMUM CENTRAL PRESSURE...996 MB...29.41 INCHES

$$
Forecaster Pasch

[WxWatcher007]

That was fast  

[gymengineer]

It happens quite a bit… when recon is investigating but the package has to go out. The NHC isn’t shy about issuing updates whenever. 

[WxWatcher007]

1 minute ago, gymengineer said:

It happens quite a bit… when recon is investigating but the package has to go out. The NHC isn’t shy about issuing updates whenever. 

I know, just a little funny to see. They telegraphed it at 11am by saying it could happen at anytime. 

[PackGrad05]

6Z EPS model consensus is tight around a big bend landfall and then riding the GA/SC/NC coast up to Cape Fear.  ECMWF, UKMET, and ICON largely agree.

6Z GEFS model consensus slightly west of this.  

[shaggy]

6 minutes ago, PackGrad05 said:

6Z EPS model consensus is tight around a big bend landfall and then riding the GA/SC/NC coast up to Cape Fear.  ECMWF, UKMET, and ICON largely agree.

6Z GEFS model consensus slightly west of this.  

I've recently relocated to the cape fear region and am curious as to what intensity it can bring up this way. It's steady forward motion and coast riding gives me hope for at least a few TS force gusts Thursday 

[Windspeed]

HAFS A and B both suggested a slow evolution of the vortex with persistent runs with convection lopsided just to the east. Some runs even losing and redeveloping the LLC, though the most recent runs have not lost it. The main point is that neither have shown significant intensification until the TC is lifting NNE through the SE GOM into Tuesday. We'll just have to see if this plays out IRL. Also, data should be injected from reconnaissance flights today into the parent universal GFS to get an even better handle.

[WxWatcher007]

It’s no surprise that the vortex is tilted, and that’ll limit the risk of rapid intensification in the near term. That said I’d watch the development of shallow convection near the center. Sometimes that can be a precursor for greater convective activity that can organize the center. I’m guessing we see it in spurts however given the apparent northerly shear that’s currently tilting Idalia. 
 

 

[NJsnow89]

Sorry for the banter but are we going to see any effects in central NC? Thanks 

[CheeselandSkies]

12Z GFS down to 960 MB, deepening on approach.

IMO surge risk to Big Bend is higher with this storm than any for a long time. The coast is sparsely populated, but if this does come in as a strong major and causes a swath of intense wind damage deep inland, as others pointed out it's all mobile homes and RV parks in there.

[PackGrad05]

12Z GFS is almost identical to ECMWF and EPS.  Rides GA/SC coast and then turns east at Cape Fear out to sea.

[eyewall]

38 minutes ago, PackGrad05 said:

6Z EPS model consensus is tight around a big bend landfall and then riding the GA/SC/NC coast up to Cape Fear.  ECMWF, UKMET, and ICON largely agree.

6Z GEFS model consensus slightly west of this.  

Yeah I am hoping for some outer bands like I saw in Isiais in 2020.

[shaggy]

3 minutes ago, eyewall said:

Yeah I am hoping for some outer bands like I saw in Isiais in 2020.

I'm about 10 miles west off the beach at Wrightsville and about 15 miles north of Caswell beach now. Just moved down here a month ago.

[Buddy1987]

3 minutes ago, shaggy said:

I'm about 10 miles west off the beach at Wrightsville and about 15 miles north of Caswell beach now. Just moved down here a month ago.

Beautiful place! We stayed in North Topsail two weekends ago and took a drive down to Wrightsville Beach for the day. North Topsail had a lot of construction and renovations going on. Read something they got hit by like an EF2 tornado or something during one of the tropical events couple years back. Stay safe!

[GaWx]

12Z UKMET: about same as 0Z with landfall NW part of FL Big Bend moving NNE followed by turn to NE/ENE going through south central and then SE GA. Then it goes offshore near CHS, SC:

TROPICAL DEPRESSION 10L        ANALYSED POSITION : 19.8N  86.1W

     ATCF IDENTIFIER : AL102023

                        LEAD                 CENTRAL     MAXIMUM WIND
      VERIFYING TIME    TIME   POSITION   PRESSURE (MB)  SPEED (KNOTS)
      --------------    ----   --------   -------------  -------------
    1200UTC 27.08.2023    0  19.8N  86.1W     1003            24
    0000UTC 28.08.2023   12  20.4N  85.3W     1001            29
    1200UTC 28.08.2023   24  21.4N  85.5W     1001            33
    0000UTC 29.08.2023   36  22.6N  85.8W     1001            36
    1200UTC 29.08.2023   48  24.2N  86.1W     1000            34
    0000UTC 30.08.2023   60  25.8N  85.5W      999            38
    1200UTC 30.08.2023   72  28.6N  84.6W      995            49
    0000UTC 31.08.2023   84  31.2N  82.7W      993            39
    1200UTC 31.08.2023   96  33.2N  78.8W      993            43
    0000UTC 01.09.2023  108  33.4N  75.0W      995            48
    1200UTC 01.09.2023  120  33.8N  72.0W      999            46
    0000UTC 02.09.2023  132  33.2N  69.2W     1001            43
    1200UTC 02.09.2023  144  32.8N  68.4W     1003            37
    0000UTC 03.09.2023  156  33.6N  65.9W     1003            35
    1200UTC 03.09.2023  168  33.6N  64.5W      999            47

[Normandy]

The center drop is suggestive of a very healthy circulation despite being exposed right now.  I would expect a big convective burst soon.

[TheGhostOfJohnBolaris]

Is the 12z HAFS using any of the recon data? Strong start..

[Seminole]

The 12Z GFS is another trend toward the Euro solution. The timing of the trough that picks up Idalia will be crucial to whether this is a Forgotten Coast or Nature Coast strike. 

[MattPetrulli]

20 minutes ago, TheGhostOfJohnBolaris said:

Is the 12z HAFS using any of the recon data? Strong start..

If it is or isn't, it initializes about 6 mb too high

[WxWatcher007]

I’d probably wait until the 00z suite because the models will have data on not just right now but how Idalia evolved over the course of the day. 

[WxWatcher007]

FWIW, Euro is stronger and maybe a touch east? Definitely stronger as the low heads toward the FL/GA coast. 989mb at Savannah at 78.

[GaWx]

Euro landfalls in SE portion of Big Bend near 980 mb. It is significantly stronger and a bit further SE than recent runs. It then goes offshore 50 miles S of Savannah (mid-GA coast).