GaWx

0Z Icon is coming in well to the east of recent runs with the upper low well to the east of prior runs.

Wow, Don, until you posted this I wasn’t even aware of the extreme Sep -NAO about to occur. According to the latest GEFS based NAO forecast (see below), it is expected to bottom out way down near -2.7 at some point during 9/23-5! That would easily exceed the record lowest Sep daily NAO as the current record low is -2.371, set on 9/12/1971. The only other Sep with any sub -2 daily was 1986. The record low for any month is -3.254, set on 10/21/2002. 9/22/24 GEFS based NAO forecast:

18Z GEFS mean: even further west near Pensacola, which is 50 miles W of 12Z, and then N into AL

This 18Z Icon is well E of the 12Z, showing that there’s still (not surprisingly) a lot of uncertainty.

Moderate to low end strong as best as I can tell per DJF.

Who’s dismissing Webb? You’re probably not talking about me, but in case you are I take him with a grain due to several bad misses but I’m not dismissing him. If I did, I wouldn’t have quoted him to bring him into the discussion. Taking with a grain and dismissing are two different things (at least the way I define them). I assume you agree. I take many seasonal forecasts with a grain due to the difficulty in making winter forecasts, especially early.

12Z EPS: mean landfall Thu night near Apalachicola and then it moves N fairly close to GA/AL border; many either W half of lower GA or E half of lower AL; mean a bit E of 6Z, which was in E AL and perhaps very slightly E of 0Z

12Z Euro 982 Thu evening in vicinity of Apalachicola; Atlanta Fri AM at 992

GEFS: 12Z mean has a significant shift NW vs prior runs with many more going through AL vs earlier runs

Fortunately Icon, CMC, and UKMET are much weaker though UKMET often is too weak this far out. 12Z UKMET: ~12 hours earlier landfall (Thu night) than and ~75 miles W of 0Z pretty close to Apalachicola at ~987 mb vs ~993 mb on 0Z: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 42 HOURS FORECAST POSITION AT T+ 42 : 17.9N 85.5W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 24.09.2024 48 18.0N 86.0W 1003 29 0000UTC 25.09.2024 60 18.2N 85.5W 1002 30 1200UTC 25.09.2024 72 20.3N 86.2W 998 40 0000UTC 26.09.2024 84 21.7N 86.2W 995 39 1200UTC 26.09.2024 96 24.0N 86.0W 992 44 0000UTC 27.09.2024 108 27.4N 85.1W 989 56 1200UTC 27.09.2024 120 31.3N 84.7W 987 39 0000UTC 28.09.2024 132 36.4N 84.7W 992 21 1200UTC 28.09.2024 144 40.5N 87.2W 996 34 0000UTC 29.09.2024 156 42.3N 91.4W 1000 21 1200UTC 29.09.2024 168 39.0N 94.3W 1004 13

TT 12Z GFS SLPs ~8 mb lower than my source

12Z GFS just slightly E of 6Z but well NW of 0Z with ~942 mb near Panama City moving N

What do you think about this from Eric Webb about what he calls very warm water centered on 150E? @bluewave@snowman19and others. Eric has had big busts before in winter forecasts though. So, I take him with a grain like I do most. “Why is the warmth ~150°E in the Tropical West Pacific important? Anomalous Tropical West Pacific warmth normally favors more frequent high-latitude blocking (-EPO/-WPO) over the North Pacific rim during the winter.”

The 12Z Icon is much quicker than its prior runs and is now much closer to the timing of the consensus. Although much further E early, this much quicker movement allows it to be captured by the cutoff H5 low and it then moves N to near Panama City at 984 mb late Thu night followed by a NNW move through AL.

It is not finished, but the 12Z Icon is much faster and well E of its prior runs with it missing the Yucatan to the E for the first time. It look like it is going to be similar to the 0Z Euro.

6Z Euro-AI shifted ~50 miles NW of its 0Z with it coming in to the middle of the Big Bend vs the far rt portion of it on the 0Z

6Z EPS mean shifted slightly W of its 0Z run mean (now a little W of AL/GA border vs about on that border)

0Z EPS: follows the faster and further E 0Z Euro but it is like the Euro still NW of the GFS suite with tracks centered on Apalachicola that then go N near the GA/AL line before curling back NNW. It is similar to the 0Z GEPS.

0Z Euro: east trend in this model too; similar strength to UKMET/CMC (989) with landfall Apalachicola Thu night (much closer to GFS’ Thu evening and UK’s Fri afternoon than Icon’s Sun morning). Gives 3-7” of rainfall to most of NW FL, GA, AL, TN as it moves N through W GA and TN

0Z GEFS is still another pretty ominous run for Pensacola to Tampa and inland NE from there. Fortunately most members are much weaker than the operational but still this isn’t a good sign.

Even though the Icon and GFS have similar landfall locations/strengths, the GFS landfall is a whopping 60 hours earlier (Thu evening) vs Icon (Sun morning).

0Z UKMET: significantly stronger at landfall (993 vs 1000 on 12Z run) and 150 miles east of 12Z with a landfall late afternoon Friday in the FL Big Bend moving NNE; thankfully not nearly as strong as Icon/GFS but UK is notorious for being conservatively weak this far out, especially with winds but also with SLP and the trend is worrying: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 84 HOURS FORECAST POSITION AT T+ 84 : 18.6N 85.7W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 25.09.2024 84 18.6N 85.7W 1003 34 0000UTC 26.09.2024 96 21.3N 85.1W 1001 34 1200UTC 26.09.2024 108 22.5N 85.8W 998 42 0000UTC 27.09.2024 120 25.0N 84.6W 995 40 1200UTC 27.09.2024 132 27.2N 84.3W 992 42 0000UTC 28.09.2024 144 31.1N 83.0W 995 41 1200UTC 28.09.2024 156 36.3N 82.7W 1000 23 0000UTC 29.09.2024 168 39.6N 82.7W 1005 27

If this storm were to actually take a similar path with that strength moving at that speed, that would likely be very damaging well inland (including in my area and well beyond). Hope nothing like this happens. I’d much prefer the slop.

18Z: GEFS: centered on FL Big Bend EPS: centered on Pensacola