GaWx

Thanks as I missed those 60s dewpoints at KSAV Mon afternoon. So, I need to retract what I said about no dewpoints below the low 70s since June. Where I live is closer to the coast and thus typically has higher dewpoints, but not that much higher. Thus I just edited my earlier post for this correction. My point was that the bulk of the cool, dry airmasses of earlier August didn't reach down here. That I’m still saying has been the case.

1. Erin will end up with ~33-4 ACE, which you didn’t forecast. Currently, 2024 has sharply risen to 15th of the last 75 years and it will rise several positions from there before Erin winds down, when total ACE should be ~36-38: 2. It does appear quiet ~8/24-9/7 on the ensembles/Euro Weeklies and there could easily be below normal ACE through that period. But even if so and allowing for ~5 added ACE by 9/7, ACE would still be near normal (in the 40s). 3. The Euro Weeklies have then been showing an increase in activity (likely MJO related), especially during 9/15-21: 9/8-14: 10-11 ACE 9/15-21: 13-15 ACE If these verify well, ACE would then be in the 60s. 4. The tendency in recent years, especially during cold ENSO has been for a more active late Sept through Nov. 2024 had its most active period late Sept-mid Oct. If that occurs again, 2025 would end up as another active season.

For the record, the NHC/model consensus were significantly too far east as recently as 96 hours out. For example, this is from the 11PM Fri 8/15 NHC discussion:FORECAST POSITIONS AND MAX WINDSINIT 16/0300Z 19.5N 59.5W 85 KT 100 MPH12H 16/1200Z 20.2N 61.6W 100 KT 115 MPH24H 17/0000Z 20.9N 64.2W 115 KT 130 MPH36H 17/1200Z 21.7N 66.3W 125 KT 145 MPH48H 18/0000Z 22.9N 67.9W 120 KT 140 MPH60H 18/1200Z 24.0N 68.9W 115 KT 130 MPH72H 19/0000Z 25.6N 69.8W 110 KT 125 MPH96H 20/0000Z 28.9N 70.5W 105 KT 120 MPH120H 21/0000Z 33.5N 69.0W 100 KT 115 MPHLink: Hurricane ERIN Erin’s center ended up going 180 miles west of 70.5W as it went to 73.7W! So, later at its closest pass, the center ended up ~half the distance from the OBs vs what was forecasted early last weekend. Had this 70.5W furthest W forecast verified well, there wouldn’t have been TS conditions on the OBs.

The Outer Banks had sustained TS force winds overnight through 8AM despite the center being 200 miles to the SE/ESE/E! 1. From 2AM NHC advisory: “A sustained wind of 40 mph (65 km/h) and a gust to 46 mph (74 km/h) were recently reported at the U.S. Coast Guard Station Hatteras.” 2. From 5AM NHC advisory: “A WeatherFlow station at Jennette's Pier in Nags Head, North Carolina, recently measured a sustained wind of 41 mph (67 km/h) and a gust to 49 mph (80 km/h).” 3. From 8AM NHC advisory: “A WeatherFlow station at Jennette's Pier in Nags Head, North Carolina, recently measured a sustained wind of 45 mph (72 km/h) and a gust to 54 mph (87 km/h).”

It would be nice if it would also get down here for a change. We still have had no dewpoints below the lower 70s since June. **8/21/25 Edit for correction: I totally missed that KSAV had hourly dewpoints as low as 62 during the afternoon of August 18th in between the morning and evening/overnight 70s. So, technically, I’m wrong despite my dewpoints often being a few degrees higher due to being closer to the coast than KSAV.

Barry, I agree because that’s me.

Hurricane Erin Intermediate Advisory Number 37A NWS National Hurricane Center Miami FL AL052025 200 PM EDT Wed Aug 20 2025 SUMMARY OF 200 PM EDT...1800 UTC...INFORMATION ---------------------------------------------- LOCATION...30.6N 73.6W ABOUT 530 MI...855 KM W OF BERMUDA ABOUT 335 MI...540 KM SSE OF CAPE HATTERAS NORTH CAROLINA MAXIMUM SUSTAINED WINDS...110 MPH...175 KM/H PRESENT MOVEMENT...N OR 360 DEGREES AT 13 MPH...20 KM/H MINIMUM CENTRAL PRESSURE...943 MB...27.85 INCHES Some strengthening is expected during the next day or so, and Erin could become a major hurricane again by tonight. Weakening is likely to begin by Friday, but Erin is forecast to remain a hurricane into the weekend. Erin is a large hurricane. Hurricane-force winds extend outward up to 105 miles (165 km) from the center and tropical-storm-force winds extend outward up to 265 miles (425 km).

You need to delete the portion after the “?”.

Thanks. I just found it. This is what I posted on 5/21/24 and thus this analysis doesn’t include what happened in 2024, a really bad year with it scoring 5G/0E. 2024’s ASO RONI was -0.75: ————————— I just did an analysis of CONUS landfalls for RONI ASO -0.50 to -1.00 vs sub -1.00. E = east coast and G = Gulf coast including FL Keys; if storm landfalled on both as a H, I counted it as 1/2 E and 1/2 G (1995’s Erin and 2022’s Ian) ASO RONI -0.50 to -1.00: every season at least 1 1954: 3 (3E) 1955: 2 (2E) 1964: 4 (2E, 2G) 1970: 1 (1G) 1983: 1 (1G) 1995: 2 (0.5E, 1.5G) 1999: 3 (1E, 2G) 2011: 1 (1E) 2017: 3 (3G) 2021: 2 (2G) AVG: 2.20 (0.95E, 1.25G) ASO RONI sub -1.00: less active avg despite 2020 1973: 0 1975: 1 (1G) 1988: 1 (1G) 1998: 3 (1E, 2G) 2007: 1 (1G) 2010: 0 2016: 2 (1E, 1G) 2020: 6 (1E, 5G) 2022: 2 (1.5E, 0.5G) AVG: 1.78 (0.50E, 1.28G) Analysis of ASO RONI wk vs mod+: -sig. more CONUS H landfalls (100%/70% had 1+/2+) -sig. more E coast landfalls (60%/30% had 1+/2+) -slightly fewer G coast landfalls due to 2020 being active -E being nearly as active as G for wk is relatively high for E -2020 ASO is mod+ per RONI but is only wk per ONI H tracks: https://www.nhc.noaa.gov/data/ RONI: https://www.cpc.ncep.noaa.gov/data/indices/RONI.ascii.txt

I’ll try to find it with a search on “RONI”.

Look at how well yesterday’s 0Z UKMET did with the general direction of pressures going both up and down: -0Z 8/19 initialization 943 vs actual of 947 -12Z 8/19 963 vs actual of 958 -12Z 8/20 942 vs actual of 948 then and actual at 14Z ~942 HURRICANE ERIN ANALYSED POSITION : 23.9N 71.5WATCF IDENTIFIER : AL052025LEAD CENTRAL MAXIMUM WINDVERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)-------------- ---- -------- ------------- -------------0000UTC 19.08.2025 0 23.9N 71.5W 943 841200UTC 19.08.2025 12 25.2N 72.6W 963 750000UTC 20.08.2025 24 26.9N 73.1W 953 791200UTC 20.08.2025 36 28.9N 74.3W 942 89

As shown on the image below, one can see how rapidly 2025’s ACE has increased in relation to others since 1951: it’s now 16th highest of the last 75

The minimum SLP has dropped as the models predicted. It’s down to 948 mb SUMMARY OF 800 AM EDT...1200 UTC...INFORMATION ---------------------------------------------- LOCATION...29.6N 73.7W ABOUT 560 MI...900 KM WSW OF BERMUDA ABOUT 400 MI...645 KM SSE OF CAPE HATTERAS NORTH CAROLINA MAXIMUM SUSTAINED WINDS...100 MPH...155 KM/H PRESENT MOVEMENT...NNW OR 345 DEGREES AT 13 MPH...20 KM/H MINIMUM CENTRAL PRESSURE...948 MB...28.00 INCHES Erin is a large hurricane. Hurricane-force winds extend outward up to 90 miles (150 km) from the center and tropical-storm-force winds extend outward up to 265 miles (425 km). The minimum central pressure reported by the Air Force Hurricane Hunter aircraft is 948 mb (28.00 inches).

Today’s Euro Weeklies have the 3rd week in Sept (9/15-21) for the first time and it is as Barry’s image above shows near the 2005-24 ACE avg. Regarding progged ACE in Sept from today’s run: after a well BN 1st week and a moderately BN week 2, week 3 (near normal) is significantly more active and actually has the most ACE of any of the 4 weeks by a good margin starting with the final week of August. This is giving me flashbacks to 2024 as this is at least hinting at a Sept resembling last Sept, which had a much more active 2nd half than first half. I’m guessing that this prog of relative quiet in week 1 transitioning to normal active in week 3 is MJO related. Here are today’s EW ACE forecasts: 8/25-31: 9-10 9/1-7: 5-6 9/8-14: 8-10 9/15-21: 13-15

This is a good illustration of a hurricane transferring warmth from the tropics to higher latitudes, the role of hurricanes. Otherwise, the tropical waters would be even hotter.

But look how much it cooled due to the energy transfer to Erin as potential energy in form of ocean warmth was converted to kinetic energy.

This apparent restrengthening is as predicted by the Euro, UKMET, Icon and possibly others.

Chris, Don and I have had discussions about the UHI portion of the warming at Phoenix over the last 30-40+ years due to the tremendous population growth. We agreed that the UHI portion isn’t at all insignificant if I’m recalling this correctly. @donsutherland1

I see nothing notable on the 12Z Euro regarding 99L. I don’t see any TC through at least 240 hours.

12Z Euro hour 24 isn’t nearly as strong as the 919 mb of the 6Z as this run gets it down “only” to 945 and is WNW of the 6Z.

I’m not sure but am thinking this 12Z UKMET might be for 99L: E of Bermuda moving NNE at the end: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 114 HOURS FORECAST POSITION AT T+114 : 25.7N 64.2W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 24.08.2025 120 26.9N 63.9W 1012 34 0000UTC 25.08.2025 132 29.9N 63.3W 1012 30 1200UTC 25.08.2025 144 32.0N 62.6W 1012 28 0000UTC 26.08.2025 156 34.8N 61.8W 1013 28 1200UTC 26.08.2025 168 37.5N 60.9W 1013 29

12Z UKMET: like the 0Z this run restrengthens Erin to a peak Thu evening off NC, but by not as much as it gets down to 947 vs 928 on the 0Z: HURRICANE ERIN ANALYSED POSITION : 25.3N 72.1W ATCF IDENTIFIER : AL052025 LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 19.08.2025 0 25.3N 72.1W 961 79 0000UTC 20.08.2025 12 27.0N 73.1W 960 71 1200UTC 20.08.2025 24 29.0N 73.8W 954 83 0000UTC 21.08.2025 36 31.7N 74.0W 950 84 1200UTC 21.08.2025 48 34.1N 73.1W 949 81 0000UTC 22.08.2025 60 36.1N 70.7W 947 76

Even if 22-23 is a good analog winter, that’s only one analog, which has little statistical weight on its own.

Regarding restrengthening potential: I just noticed this on the 0Z UKMET: it initialized it at 943 as of 8PM EDT last evening, then weakened it all the way down to 963 as of 12Z/8AM EDT this morning, and then restrengthens her starting today all the way down to 928 mb Thursday at 8PM EDT: HURRICANE ERIN ANALYSED POSITION : 23.9N 71.5W ATCF IDENTIFIER : AL052025 LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 0000UTC 19.08.2025 0 23.9N 71.5W 943 84 1200UTC 19.08.2025 12 25.2N 72.6W 963 75 0000UTC 20.08.2025 24 26.9N 73.1W 953 79 1200UTC 20.08.2025 36 28.9N 74.3W 942 89 0000UTC 21.08.2025 48 31.6N 74.3W 936 100 1200UTC 21.08.2025 60 34.0N 73.3W 935 96 0000UTC 22.08.2025 72 36.2N 70.8W 928 94