ATL: IDALIA - Models

[LarryWx]

Below is a copy of a post I did 10/1/22 detailing Ian FL LF progs for 5 main op models starting from 0Z 9/25 runs, which were then 85 hours out from the Port Charlotte LF. As of 0Z today, Idalia was only ~60 hours from landfall. So, that would about correspond to the 0Z 9/26 runs for Ian.

 So, one can see from this that:

A. -Top performing UKMET <50 miles from actual Ian LF all runs within 85 hours. ~Spot on for runs that were 85, 61, 49, and 13 hours out with little net bias.

-2nd best ICON even had Tampa (70 miles too far left) just 49 hours out

-CMC was still way too far left just 25 hrs out!

-GFS not close til 25 hrs out

-Euro not close til 37 hrs out

B. Per 0Z 9/26 Ian runs, which correspond to ~how far from LF is Idalia as of 0Z today (~60 hours):

1) UKMET was spot on and ICON only 25 miles too far left

2) CMC and GFS were way up at Apalachee Bay, a whopping 250 miles too far left

3) Euro was up at Cedar Key, 160 miles too far left

4) So, non-UKMET models were all too far left with GFS, CMC, and Euro a whopping 160-250 miles too far left

5) For Idalia, models are way closer together for LF at ~60 hour point (0Z 8/28 runs):

-GFS/CMC furthest left near Perry

-ICON furthest right ~10 miles SE of Cedar Key

-So, range is only 75 miles vs 250 miles for Ian at same time from LF! GFS/CMC are furthest left like for Ian but not nearly by as much

-UKMET/Euro right in middle ~30 miles NW of Cedar Key

-Based on this, I'm guessing that 0Z GFS/CMC at Perry will verify too far left

-My best guess is to go close to 0Z UKMET/Euro, which were ~30 miles NW of Cedar Key and ~40 miles NW of 0Z ICON



---------------------------------

Here's the Ian FL landfall model performance post I made last year:


"Looking back to the 0Z 9/25 runs at where the models had FL landfalls:

0Z 9/25:
ICON Venice
CMC Cedar Key
GFS Destin
Euro Sarasota
UKMET Port Charlotte

12Z 9/25:
ICON Sarasota
CMC Apalachee Bay
GFS Apalachee Bay
Euro Tampa
UKMET Venice

0Z 9/26:
ICON Venice
CMC Apalachee Bay
GFS Apalachee Bay
Euro Cedar Key
UKMET Port Charlotte

12Z 9/26:
ICON Tampa
CMC Apalachicola
GFS Tampa
Euro Big Bend
UKMET Port Charlotte

0Z 9/27:
ICON Venice
CMC Big Bend
GFS Sarasota
Euro Venice
UKMET just N of Ft Myers

12Z 9/27:
ICON Port Charlotte
CMC Tampa
GFS just N of Port Charlotte
Euro Port Charlotte
UKMET 20 miles S of Ft. Myers

0Z 9/28:
ICON 15 miles S of Port Charlotte
CMC Venice
GFS Port Charlotte
Euro Port Charlotte
UKMET Port Charlotte

 My grades on FL landfall only (i.e., excluding SC landfall) for 9/25-8 runs:

UKMET A-
ICON B
Euro C-
GFS D
CMC F"

[Blown Away]

12z ICON

[tolakram]

ICON sticking extremely close to the same landfall position.

[SouthFLTropics]

Obviously the immediate concern is for the Florida Gulf Coast. Based on some of the recent model runs though, I'm beginning to be concerned about the possibility of Idalia getting trapped off of the SE US coastline. GFS has shown this for two runs in a row now and the Euro ensembles had many members showing her looping south.

[IcyTundra]

GFS has the remnants of Idalia pulling an Ivan and looping back SW once it comes off the coast of the Carolinas.

[chris_fit]

IF I'm reading this right.... UKMET with a pretty large shift to the West.

MET OFFICE TROPICAL CYCLONE GUIDANCE FOR NORTH-EAST PACIFIC

AND ATLANTIC

GLOBAL MODEL DATA TIME 12UTC 28.08.2023

TROPICAL STORM IDALIA ANALYSED POSITION : 20.6N 85.4W

ATCF IDENTIFIER : AL102023

VERIFYING TIME POSITION STRENGTH TENDENCY
-------------- -------- -------- --------
12UTC 28.08.2023 20.6N 85.4W MODERATE
00UTC 29.08.2023 21.5N 85.4W MODERATE LITTLE CHANGE
12UTC 29.08.2023 23.3N 85.8W MODERATE LITTLE CHANGE
00UTC 30.08.2023 25.3N 86.0W MODERATE LITTLE CHANGE
12UTC 30.08.2023 27.7N 85.3W MODERATE LITTLE CHANGE
00UTC 31.08.2023 30.2N 84.1W MODERATE INTENSIFYING SLIGHTLY
12UTC 31.08.2023 32.6N 81.8W MODERATE WEAKENING SLIGHTLY
00UTC 01.09.2023 33.6N 78.7W MODERATE WEAKENING SLIGHTLY
12UTC 01.09.2023 34.5N 75.3W WEAK LITTLE CHANGE
00UTC 02.09.2023 34.0N 72.7W WEAK LITTLE CHANGE
12UTC 02.09.2023 34.9N 70.4W WEAK LITTLE CHANGE
00UTC 03.09.2023 37.0N 66.5W WEAK LITTLE CHANGE
12UTC 03.09.2023 36.8N 64.9W WEAK LITTLE CHANGE
00UTC 04.09.2023 37.2N 62.1W MODERATE INTENSIFYING SLIGHTLY
12UTC 04.09.2023 38.9N 59.8W MODERATE INTENSIFYING SLIGHTLY

[SunnyThoughts]

Obviously the immediate concern is for the Florida Gulf Coast. Based on some of the recent model runs though, I'm beginning to be concerned about the possibility of Idalia getting trapped off of the SE US coastline. GFS has shown this for two runs in a row now and the Euro ensembles had many members showing her looping south.

Yes, I'm watching the GFS run now...at hour 162, the remnants of Idalia sitting right off the coast on the Atlantic side of Florida peninsula, after circling around. Interesting.

[LandoWill]

IF I'm reading this right.... UKMET with a pretty large shift to the West.

MET OFFICE TROPICAL CYCLONE GUIDANCE FOR NORTH-EAST PACIFIC

AND ATLANTIC

GLOBAL MODEL DATA TIME 12UTC 28.08.2023

TROPICAL STORM IDALIA ANALYSED POSITION : 20.6N 85.4W

ATCF IDENTIFIER : AL102023

VERIFYING TIME POSITION STRENGTH TENDENCY
-------------- -------- -------- --------
12UTC 28.08.2023 20.6N 85.4W MODERATE
00UTC 29.08.2023 21.5N 85.4W MODERATE LITTLE CHANGE
12UTC 29.08.2023 23.3N 85.8W MODERATE LITTLE CHANGE
00UTC 30.08.2023 25.3N 86.0W MODERATE LITTLE CHANGE
12UTC 30.08.2023 27.7N 85.3W MODERATE LITTLE CHANGE
00UTC 31.08.2023 30.2N 84.1W MODERATE INTENSIFYING SLIGHTLY
12UTC 31.08.2023 32.6N 81.8W MODERATE WEAKENING SLIGHTLY
00UTC 01.09.2023 33.6N 78.7W MODERATE WEAKENING SLIGHTLY
12UTC 01.09.2023 34.5N 75.3W WEAK LITTLE CHANGE
00UTC 02.09.2023 34.0N 72.7W WEAK LITTLE CHANGE
12UTC 02.09.2023 34.9N 70.4W WEAK LITTLE CHANGE
00UTC 03.09.2023 37.0N 66.5W WEAK LITTLE CHANGE
12UTC 03.09.2023 36.8N 64.9W WEAK LITTLE CHANGE
00UTC 04.09.2023 37.2N 62.1W MODERATE INTENSIFYING SLIGHTLY
12UTC 04.09.2023 38.9N 59.8W MODERATE INTENSIFYING SLIGHTLY

That's a huge change. I've said panhandle/western cedar key all along, nhc came back to me today we'll see at 5 and 11pm

[tallywx]

00UTC 31.08.2023 30.2N 84.1W MODERATE INTENSIFYING SLIGHTLY

Oof that's right at the St. Marks lighthouse. Apex of Apalachee Bay. No major hurricane has thread the needle to that location.

IF I'm reading this right.... UKMET with a pretty large shift to the West.

MET OFFICE TROPICAL CYCLONE GUIDANCE FOR NORTH-EAST PACIFIC

AND ATLANTIC

GLOBAL MODEL DATA TIME 12UTC 28.08.2023

TROPICAL STORM IDALIA ANALYSED POSITION : 20.6N 85.4W

ATCF IDENTIFIER : AL102023

VERIFYING TIME POSITION STRENGTH TENDENCY
-------------- -------- -------- --------
12UTC 28.08.2023 20.6N 85.4W MODERATE
00UTC 29.08.2023 21.5N 85.4W MODERATE LITTLE CHANGE
12UTC 29.08.2023 23.3N 85.8W MODERATE LITTLE CHANGE
00UTC 30.08.2023 25.3N 86.0W MODERATE LITTLE CHANGE
12UTC 30.08.2023 27.7N 85.3W MODERATE LITTLE CHANGE
00UTC 31.08.2023 30.2N 84.1W MODERATE INTENSIFYING SLIGHTLY
12UTC 31.08.2023 32.6N 81.8W MODERATE WEAKENING SLIGHTLY
00UTC 01.09.2023 33.6N 78.7W MODERATE WEAKENING SLIGHTLY
12UTC 01.09.2023 34.5N 75.3W WEAK LITTLE CHANGE
00UTC 02.09.2023 34.0N 72.7W WEAK LITTLE CHANGE
12UTC 02.09.2023 34.9N 70.4W WEAK LITTLE CHANGE
00UTC 03.09.2023 37.0N 66.5W WEAK LITTLE CHANGE
12UTC 03.09.2023 36.8N 64.9W WEAK LITTLE CHANGE
00UTC 04.09.2023 37.2N 62.1W MODERATE INTENSIFYING SLIGHTLY
12UTC 04.09.2023 38.9N 59.8W MODERATE INTENSIFYING SLIGHTLY

[LarryWx]

00UTC 31.08.2023 30.2N 84.1W MODERATE INTENSIFYING SLIGHTLY

Oof that's right at the St. Marks lighthouse. Apex of Apalachee Bay. No major hurricane has thread the needle to that location.

IF I'm reading this right.... UKMET with a pretty large shift to the West.

MET OFFICE TROPICAL CYCLONE GUIDANCE FOR NORTH-EAST PACIFIC

AND ATLANTIC

GLOBAL MODEL DATA TIME 12UTC 28.08.2023

TROPICAL STORM IDALIA ANALYSED POSITION : 20.6N 85.4W

ATCF IDENTIFIER : AL102023

VERIFYING TIME POSITION STRENGTH TENDENCY
-------------- -------- -------- --------
12UTC 28.08.2023 20.6N 85.4W MODERATE
00UTC 29.08.2023 21.5N 85.4W MODERATE LITTLE CHANGE
12UTC 29.08.2023 23.3N 85.8W MODERATE LITTLE CHANGE
00UTC 30.08.2023 25.3N 86.0W MODERATE LITTLE CHANGE
12UTC 30.08.2023 27.7N 85.3W MODERATE LITTLE CHANGE
00UTC 31.08.2023 30.2N 84.1W MODERATE INTENSIFYING SLIGHTLY
12UTC 31.08.2023 32.6N 81.8W MODERATE WEAKENING SLIGHTLY
00UTC 01.09.2023 33.6N 78.7W MODERATE WEAKENING SLIGHTLY
12UTC 01.09.2023 34.5N 75.3W WEAK LITTLE CHANGE
00UTC 02.09.2023 34.0N 72.7W WEAK LITTLE CHANGE
12UTC 02.09.2023 34.9N 70.4W WEAK LITTLE CHANGE
00UTC 03.09.2023 37.0N 66.5W WEAK LITTLE CHANGE
12UTC 03.09.2023 36.8N 64.9W WEAK LITTLE CHANGE
00UTC 04.09.2023 37.2N 62.1W MODERATE INTENSIFYING SLIGHTLY
12UTC 04.09.2023 38.9N 59.8W MODERATE INTENSIFYING SLIGHTLY

Indeed, the 12Z UKMET landfalls ~65 miles to the NW (at Apalachee Bay) of 0Z, which was ~30 miles NW of Cedar Key

[SouthFLTropics]

If the GFS is correct, we are going to be dealing with Idalia or her remnants well into next week. Talk about adding insult to injury.

[chris_fit]

She's not supposed to cross 85W until tomorrow at about this time.... something to monitor to see which side of that (or spot on) she's on.

[chris_fit]

Hurricane Models starting to run - Let's see if the W trends continue...

HAFS-A and HAFS-B starting up....

[SFLcane]

If the GFS is correct, we are going to be dealing with Idalia or her remnants well into next week. Talk about adding insult to injury.

Yup, lets do it again this time for the eastcoast.

[LarryWx]

With 12Z Euro still remaining, three 12Z runs shifted left vs their respective 0Z runs (UKMET, ICON, and the already tied for most left at 0Z run GFS) and one shifted right (the tied for furthest left at 0Z run CMC).

[IcyTundra]

Ridge building in east of Florida could block Idalia's exit once she leaves the Carolinas.

[FLLurker32]

She's not supposed to cross 85W until tomorrow at about this time.... something to monitor to see which side of that (or spot on) she's on.

I was just looking at that. 25N 85W is a big plot to watch in the angle it takes.

[SFLcane]

 https://twitter.com/ZachCoveyTV/status/1696203060316455178

[Ianswfl]

Ridge building in east of Florida could block Idalia's exit once she leaves the Carolinas.

Maybe this is like Ivan in 2004? Loops around and it will hit SEFL and go back into the Gulf eventually??

[SouthFLTropics]

12z HAFS-B bombing out, sub 930 into Upper big bend area.