GaWx

Even though the rain isn't finished at the end of the run, one can see that the drier air is up through 120 hours holding back the extremely heavy amounts on the 18Z ICON to just offshore GA/far S SC vs the 12Z, which though a weaker storm had much heavier rainfall due to a further west track barely inland that allowed for less influence from the Canadian air. Hoping the center would stay just offshore to reduce the chance for extreme flooding in SE GA/far S SC.

A strong convective burst has developed near and just west of the center. This is the strongest convection I can recall anytime recently near the center. With the increased organization today quite evident on the visible loop, we'll see whether or not this leads to significant strengthening by DMAX late tonight.

I agree. Indeed, flooding, especially Brunswick south into much of FL where the higher dewpoint air looks to be, is a huge threat as of now. I'm just saying that the lower the dewpoints can get from the dry Canadian high to the north, the lower the potential for extreme rainfall amounts due to lower PWATs since there's a strong correlation between heavier rainfall potential and higher dewpoint air. I'm thinking mainly about north of FL, where the lower dewpoints would have a higher chance to mix in better.

On the east coast, the biggest flooding risk from rainfall as of now (subject to change) appears to be from areas near Daytona Beach to Jacksonville to Brunswick based on extremely slow motion on many model runs. If it plays out like some models show, it could be pretty devastating for some low lying areas. This is shown well in the WPC map above that has ~10-12" there.

That's likely if it moves that slowly and when also considering the much lower dewpoint air mixing in from the big high to the north. The biggest concern for especially NE FL and far SE GA with that is the potential for major flooding from rains though hopefully enough of the drier air from the Canadian high mixes in to keep rain totals down somewhat.

I agree as it looks the most organized (most stacked) yet imho. Thus, this could be on the verge of intensifying rapidly. This is my first comment on its organization since it got into the Caribbean.

12Z UKMET initialized one degree further north (15.3 N at 8AM EDT vs 14.3 N at same time on 0Z run). It ends up ~20 miles north of the Port Charlotte 0Z landfall point, which is Venice (~60 miles south of Tampa Bay). Another difference vs 0Z is that it never goes offshore N FL/S GA as it stays a little inland: MET OFFICE TROPICAL CYCLONE GUIDANCE FOR NORTH-EAST PACIFIC AND ATLANTIC GLOBAL MODEL DATA TIME 1200UTC 25.09.2022 TROPICAL STORM IAN ANALYSED POSITION : 15.3N 79.2W ATCF IDENTIFIER : AL092022 LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 25.09.2022 0 15.3N 79.2W 1003 29 0000UTC 26.09.2022 12 16.7N 80.8W 1001 31 1200UTC 26.09.2022 24 18.7N 82.8W 998 35 0000UTC 27.09.2022 36 20.8N 83.9W 995 38 1200UTC 27.09.2022 48 22.9N 84.4W 994 40 0000UTC 28.09.2022 60 24.7N 84.1W 992 45 1200UTC 28.09.2022 72 26.2N 83.7W 989 55 0000UTC 29.09.2022 84 26.9N 82.9W 990 53 1200UTC 29.09.2022 96 26.9N 82.7W 991 49 0000UTC 30.09.2022 108 27.5N 82.1W 993 42 1200UTC 30.09.2022 120 29.1N 82.5W 991 42 0000UTC 01.10.2022 132 30.1N 81.8W 993 36 1200UTC 01.10.2022 144 32.8N 81.3W 996 35

The 12Z GFS is the furthest east run since at least yesterday's 6Z run.

This map shows 7-8" in the SAV-CHS corridor, which if actually occurred would obviously imply a serious flood risk especially due to much of that area having had well above normal rainfall July through early Sept. leading to high water tables. I experienced that bigtime. But one small saving grace if that were to occur is that there's been very little rain the past two weeks. Also, there's hope that enough low dewpoint air would interact to keep rainfall down from what this map shows.

12Z ICON: goes to Jacksonville, FL, which is 100+ miles east of the 6Z and 0Z runs.

12Z ICON 102 near Daytona Beach vs 6Z's 108 still near west coast north of Tampa. This run earlier passed just SE of Tampa Bay vs north of there on the 6Z.

12Z ICON hour 51 ~50 miles NE of 6Z at 57, which implies to me a further south landfall on FL vs prior run, which went just west of Tampa and then had landfall north of there, which would be potentially a really bad scenario for Tampa. Perhaps this run will landfall south of there, which wouldn't be nearly as bad.

0Z UKMET landfalls near Port Charlotte vs near or just north of Tampa on runs of 12 and 24 hours ago. So, this is 75+ miles south of those runs.

0Z UKMET significantly south of the last two full runs with it landfalling FL now well south of Tampa: MET OFFICE TROPICAL CYCLONE GUIDANCE FOR NORTH-EAST PACIFIC AND ATLANTIC GLOBAL MODEL DATA TIME 0000UTC 25.09.2022 TROPICAL STORM IAN ANALYSED POSITION : 14.7N 76.9W ATCF IDENTIFIER : AL092022 LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 0000UTC 25.09.2022 0 14.7N 76.9W 1006 28 1200UTC 25.09.2022 12 14.3N 79.4W 1004 25 0000UTC 26.09.2022 24 15.7N 80.6W 1001 31 1200UTC 26.09.2022 36 17.5N 82.2W 1000 33 0000UTC 27.09.2022 48 19.6N 83.0W 998 37 1200UTC 27.09.2022 60 21.8N 83.7W 995 36 0000UTC 28.09.2022 72 23.9N 83.9W 994 41 1200UTC 28.09.2022 84 25.4N 83.5W 992 49 0000UTC 29.09.2022 96 26.1N 83.2W 991 54 1200UTC 29.09.2022 108 26.6N 82.7W 991 49 0000UTC 30.09.2022 120 27.4N 82.0W 990 49 1200UTC 30.09.2022 132 28.6N 81.6W 990 43 0000UTC 01.10.2022 144 30.2N 81.0W 989 44

0Z GFS 114 very close to 18Z GFS 120 and not quite as strong in N GOM.

Regarding the 18Z EPS 144, I don't see much change vs 12Z EPS 150 other than perhaps the spread being a little narrower

I don't know if anyone posted it, but the 12Z JMA landfalls near Tampa at 120. So, that is similar to the Euro and UKMET at 12Z.

For those who don't realize it, the "UKM2" on here that goes to 168 is the 12Z UKMET (18Z goes out only about 60 hours I think). But I think that the "AVNI" is the 18Z GFS.

The entire September average ACE 1991-2020 was 56. This September's MTD ACE is already 58 with lots more to come from Ian if he hits the forecasted strength. If so, a Sept of 70+ would occur with even a shot at 75, which would be 34% above the 30 year average. The 30 year average ACE for Sept 16-30 is 24.5. If it gets to 75 as of Sept 30, that would mean an actual ACE of 43 for 9/16-30, which would be 75% above the 30 year average! A 75 in Sept would give us 78 season to date vs the 30 year average of 94 STD. An active Oct/Nov would make it possible to get close to the entire season average of 123.

Right shift on 18Z ICON vs 12Z with Ft Myers to Daytona track

12Z EPS sizable W shift vs 6Z with densest concentration near and west of Tampa

UKMET is also near Tampa

This 12 Euro 72 is barely NW of 6Z at 78. Essentially the same location as 6Z run then. Headed for Tampa?

12Z Euro 48 only very slightly SW of 6Z run at 54

12Z Euro 24 slightly SW of 6Z at 30