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UAH TLT temperature is stubbornly resisting the post El Nino drop. Here are some trends of interest. 1st half: +0.14 C.decade-1 2nd half: +0.23 C.decade-1 Last 10 years: +0.41 C.decade-1 Last 15 years: +0.39 C.decade-1 Last 20 years: +0.30 C.decade-1 Last 25 years: +0.23 C.decade-1 Last 30 years: +0.17 C.decade-1 The acceleration is now at +0.03 C.decade-2.

AccuWeather increased their damage and economic loss estimate to $145-160 billion. https://www.accuweather.com/en/hurricane/helene-aftermath-dozens-dead-historic-flooding-millions-without-power-amid-catastrophic-destruction/1697545

AccuWeather is estimating the damage and economic losses at between 95 and 115 billion dollars. https://www.silive.com/weather/2024/09/hurricane-helene-accuweather-finds-storm-is-among-costliest-in-us-history.html

In this video at 3:04 we can see the Marathon gas station at 815 1st Ave in Steinhatchee, FL. Using Google Street view as a guide the water appears to be about 2 feet up the ice building on the property. Using detailed USGS topographic maps this property is about 10' above sea level. This puts the surge at about 12' at this point along the Steinhatchee River and at the time the video was made.

Helene surges are now breaking Idalia's records in Tampa Bay.

Yeah, that's...huh...concerning. If it is that bad down there then we may be about to see some eyebrow raising surges further north.

Wilma was small. Helene is big. IKE is a better predictor of storm surge. Helene is going to wreak some havoc in the surge department.

A dropsonde got 944 mb with a 23 kt wind about 20 minutes ago. I'm guessing that's good for 942'ish mb.

If you mean how does it stack up against other cyclones...Katrina was 127 TJ and Wilma was 17 TJ according to this calculator. Helene is basically top tier.

The P-Surge model is showing the possibility of a massive surge up the Suwannee River and into Fanning Springs, FL. That's almost 25 miles inland.

Based on the 5pm update Helene's IKE is near 100 TJ.

The RAMMB site has some useful products. https://rammb-data.cira.colostate.edu/tc_realtime/storm_experimental.asp?storm_identifier=al092024

Based on the latest update I calculate an IKE of 104 TJ. Helene is going to generate a substantial surge.

it is important to understand that the NHC cone is the 1σ uncertainty envelope based on track errors over the last 5 years. So we expect the actual track to fall outside the cone about 32% of time. It would also be the expectation that of all the models available to consider some would show tracks outside of the cone as well.

It was posted here a couple of years ago from someone with inside information that the NHC relies heavily on TVCN and IVCN for track and intensity forecasts respectively. For those that don't know these are the so called consensus ensemble suites. At least up through 2023 TVCN was comprised of GFS, ECMWF, UKMET, COAMPS, and HWRF while IVCN was comprised of SHIP, LGEM, COAMPS, HWRF, and HMON. I'm not sure if this has been updated for the 2024 season. Does anyone know if TVCN/IVCN have changed for the 2024 season?

And the AF plane just went through with 971 mb extrapolated. If we split the difference between NOAA and AF that's 972 mb. Maybe it's almost ready to intensify. Sent from my Pixel 5a using Tapatalk

The last pass through the eye was 973 mb extrapolated...no change in the last 80 minutes. The evidence still points to another round of intensification later tonight. It might be worth noting that although RI probabilities dropped on the 0Z cycle they are still high climatologically speaking. Sent from my Pixel 5a using Tapatalk

973 mb from the last dropsonde.

0Z SHIPS is out. There is a significant drop in forecasted intensity vs the 18Z cycle. For example 18Z-24 was 112 kts whereas 0Z-18 is now 94 kts. RI probabilities dropped as well. * GFS version * * ATLANTIC 2024 SHIPS INTENSITY FORECAST * * IR SAT DATA AVAILABLE, OHC AVAILABLE * * HELENE AL092024 09/26/24 00 UTC * TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120 132 144 156 168 V (KT) NO LAND 75 81 87 94 96 91 85 70 54 40 28 N/A N/A N/A N/A N/A N/A V (KT) LAND 75 81 87 94 96 48 33 29 28 27 27 N/A N/A N/A N/A N/A N/A V (KT) LGEM 75 81 88 94 97 49 33 29 28 27 27 N/A N/A N/A N/A N/A N/A Storm Type TROP TROP TROP TROP TROP TROP EXTP EXTP EXTP EXTP EXTP N/A N/A N/A N/A N/A N/A SHIPS Prob RI for 20kt/ 12hr RI threshold= 19% is 3.9 times climatological mean ( 4.9%) SHIPS Prob RI for 25kt/ 24hr RI threshold= 47% is 4.3 times climatological mean (10.9%) SHIPS Prob RI for 30kt/ 24hr RI threshold= 33% is 4.8 times climatological mean ( 6.8%) SHIPS Prob RI for 35kt/ 24hr RI threshold= 22% is 5.7 times climatological mean ( 3.9%) SHIPS Prob RI for 40kt/ 24hr RI threshold= 12% is 4.9 times climatological mean ( 2.4%) SHIPS Prob RI for 45kt/ 36hr RI threshold= 12% is 2.6 times climatological mean ( 4.6%) SHIPS Prob RI for 55kt/ 48hr RI threshold= 0% is 0.0 times climatological mean ( 4.7%) SHIPS Prob RI for 65kt/ 72hr RI threshold= 0% is 0.0 times climatological mean ( 5.3%) Matrix of RI probabilities ------------------------------------------------------------------------------ RI (kt / h) | 20/12 | 25/24 | 30/24 | 35/24 | 40/24 | 45/36 | 55/48 |65/72 ------------------------------------------------------------------------------ SHIPS-RII: 19.2% 47.0% 32.9% 22.2% 11.8% 12.2% 0.0% 0.0% Logistic: 21.0% 20.7% 21.1% 9.6% 1.4% 0.5% 0.0% 0.0% Bayesian: 14.6% 7.2% 3.3% 7.1% 3.0% 0.3% 0.0% 0.0% Consensus: 18.2% 24.9% 19.1% 13.0% 5.4% 4.3% 0.0% 0.0% DTOPS: 40.0% 43.0% 28.0% 21.0% 12.0% 0.0% 0.0% 1.0% SDCON: 29.1% 33.9% 23.5% 17.0% 8.7% 2.1% 0% .5%

The SHIPS RI probabilities were high at 18Z. We should have the 0Z coming out shortly. * GFS version * * ATLANTIC 2024 SHIPS INTENSITY FORECAST * * IR SAT DATA AVAILABLE, OHC AVAILABLE * * HELENE AL092024 09/25/24 18 UTC * TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120 132 144 156 168 V (KT) NO LAND 75 85 94 102 112 114 102 91 67 46 28 N/A N/A N/A N/A N/A N/A V (KT) LAND 75 85 94 102 112 71 41 31 28 28 27 N/A N/A N/A N/A N/A N/A V (KT) LGEM 75 85 95 104 112 73 41 31 28 28 27 N/A N/A N/A N/A N/A N/A Storm Type TROP TROP TROP TROP TROP TROP EXTP EXTP EXTP EXTP EXTP N/A N/A N/A N/A N/A N/A SHIPS Prob RI for 20kt/ 12hr RI threshold= 27% is 5.6 times climatological mean ( 4.9%) SHIPS Prob RI for 25kt/ 24hr RI threshold= 68% is 6.2 times climatological mean (10.9%) SHIPS Prob RI for 30kt/ 24hr RI threshold= 51% is 7.4 times climatological mean ( 6.8%) SHIPS Prob RI for 35kt/ 24hr RI threshold= 37% is 9.5 times climatological mean ( 3.9%) SHIPS Prob RI for 40kt/ 24hr RI threshold= 20% is 8.2 times climatological mean ( 2.4%) SHIPS Prob RI for 45kt/ 36hr RI threshold= 23% is 5.0 times climatological mean ( 4.6%) SHIPS Prob RI for 55kt/ 48hr RI threshold= 12% is 2.7 times climatological mean ( 4.7%) SHIPS Prob RI for 65kt/ 72hr RI threshold= 0% is 0.0 times climatological mean ( 5.3%) Matrix of RI probabilities ------------------------------------------------------------------------------ RI (kt / h) | 20/12 | 25/24 | 30/24 | 35/24 | 40/24 | 45/36 | 55/48 |65/72 ------------------------------------------------------------------------------ SHIPS-RII: 27.2% 67.8% 50.7% 37.2% 19.7% 23.1% 12.5% 0.0% Logistic: 35.0% 61.1% 50.3% 30.2% 9.7% 3.1% 0.1% 0.0% Bayesian: 47.5% 10.3% 15.3% 28.6% 14.4% 0.8% 0.0% 0.0% Consensus: 36.6% 46.4% 38.8% 32.0% 14.6% 9.0% 4.2% 0.0% DTOPS: 74.0% 99.0% 99.0% 91.0% 71.0% 2.0% 0.0% 1.0% SDCON: 55.3% 72.7% 68.9% 61.5% 42.8% 5.5% 2.1% .5%

SHIPS is now showing elevated RI probabilities. It's quick approach and land interaction may ultimately limit its potential though. * GFS version * * ATLANTIC 2024 SHIPS INTENSITY FORECAST * * IR SAT DATA AVAILABLE, OHC AVAILABLE * * HELENE AL092024 09/25/24 06 UTC * TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120 132 144 156 168 V (KT) NO LAND 55 63 72 82 91 109 109 92 78 54 38 N/A N/A N/A N/A N/A N/A V (KT) LAND 55 63 72 82 91 109 75 42 32 28 28 N/A N/A N/A N/A N/A N/A V (KT) LGEM 55 61 69 77 86 103 76 41 31 28 27 N/A N/A N/A N/A N/A N/A Storm Type TROP TROP TROP TROP TROP TROP TROP EXTP EXTP EXTP EXTP N/A N/A N/A N/A N/A N/A SHIPS Prob RI for 20kt/ 12hr RI threshold= 10% is 2.0 times climatological mean ( 4.9%) SHIPS Prob RI for 25kt/ 24hr RI threshold= 62% is 5.7 times climatological mean (10.9%) SHIPS Prob RI for 30kt/ 24hr RI threshold= 43% is 6.3 times climatological mean ( 6.8%) SHIPS Prob RI for 35kt/ 24hr RI threshold= 24% is 6.2 times climatological mean ( 3.9%) SHIPS Prob RI for 40kt/ 24hr RI threshold= 15% is 6.3 times climatological mean ( 2.4%) SHIPS Prob RI for 45kt/ 36hr RI threshold= 44% is 9.6 times climatological mean ( 4.6%) SHIPS Prob RI for 55kt/ 48hr RI threshold= 19% is 4.1 times climatological mean ( 4.7%) SHIPS Prob RI for 65kt/ 72hr RI threshold= 0% is 0.0 times climatological mean ( 5.3%) Matrix of RI probabilities ------------------------------------------------------------------------------ RI (kt / h) | 20/12 | 25/24 | 30/24 | 35/24 | 40/24 | 45/36 | 55/48 |65/72 ------------------------------------------------------------------------------ SHIPS-RII: 9.6% 62.4% 42.5% 24.3% 15.0% 44.1% 19.5% 0.0% Logistic: 11.4% 36.9% 18.8% 12.0% 4.8% 15.4% 3.0% 0.0% Bayesian: 23.7% 5.9% 2.8% 3.3% 0.3% 3.2% 0.5% 0.0% Consensus: 14.9% 35.0% 21.4% 13.2% 6.7% 20.9% 7.7% 0.0% DTOPS: 22.0% 92.0% 77.0% 55.0% 30.0% 99.0% 2.0% 1.0% SDCON: 18.4% 63.5% 49.2% 34.1% 18.3% 59.9% 4.8% .5%

Tomer Burg's super ensemble is focusing a possible landfall in the big bend area of Florida.

Landfall is expected around 96'ish hours. Tomer Burg's super ensemble probability density puts landfall near the Saint Joseph Bay and Saint Vincent Sound. This forecast is about 12 hours old now. I believe the UKMET is missing from the ensemble at least on this cycle, but the 12Z deterministic run is right now the center of the high probability corridor.

12z UKMET has a pretty large and weak circulation moving due north just east of the Yucatan at hour 168. Extrapolation is a skill I still struggle with, but it looks like it is going to miss the trough and loiter a bit after 168 at least according to the UKMET anyway. There might even be a bit of a Fujiwhara interaction with a closed low on the Pacific side.

Given that AI models generally tend to blur or smooth the forecasted fields [Bonavito 2024] the ECMW-AI looks really spicy.