GaWx

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.

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”.

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

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

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

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

Thanks. I was going by snowfall because that’s about all many here seem to care about. La Guardia had 33.2” and Kennedy had 30.9”. But good point about the sharp cutoff S of NYC. If I were to throw out 2016-7 due to the sharp cutoff, it would still be 35% of NYC winters with 30”+ vs 39% of all meaning only barely lower.

Based on NYC 30”+ snowfall, a Niña wasn’t a winter killer in: 2020-1, 17-18, 16-17, 10-11, 05-06, 00-01, 95-6, 55-6, 38-9, 33-4, 17-8, 16-7, 03-4, 1893-4, 86-7, 72-3 So, out of 43 La Niña winters including the unofficial 2024-5, 16 of them (37%) had 30”+ of snow at NYC. Edit: Compare 37% to 61 of 156 (39%) of all winters since 1869-70 having had 30”+ there. So, virtually the same %.

To add to the above post: Of the 22 listed years, including the three 2025 is projected to be just ahead of as of August 23rd, only 2007 ended up with a BN total season ACE (averages based on their era). Of the other 21, all ended up the season well AN (based on their era’s average).

NATL ACE has risen to 23.6, which is the 16th highest of the last 75 for the date. Based on the latest NHC prog, ACE would be ~42 as of late Aug 23. If that verifies, 2025 would move up to 9th or 10th of the last 75. It would also move up to ~19th or 20th of the last 175 years (~89th percentile). The only ones higher than 2025 as of Aug 23rd would be these: 2024, 2008, near tie with 2007, 2005, 1995, 1980, 1969, 1955, 1951, 1950, 1933, 1926, 1916, 1899, 1893, 1887, 1886, 1880, and 1871. 2025 would be just ahead of 2004, 1966, and 1915. @mitchnick@snowman19@PhiEaglesfan712

NATL ACE has risen to 23.6, which is suddenly the 16th highest of the last 75 for the date. Based on the latest NHC prog, ACE would be ~42 as of late Aug 23. If that verifies, 2025 would move up to 9th or 10th of the last 75. It would also move up to ~19th or 20th of the last 175 years (~89th percentile). The only ones higher than 2025 as of Aug 23rd would be these: 2024, 2008, near tie with 2007, 2005, 1995, 1980, 1969, 1955, 1951, 1950, 1933, 1926, 1916, 1899, 1893, 1887, 1886, 1880, and 1871. 2025 would be just ahead of 2004, 1966, and 1915.

Similar to yesterday earlier in the afternoon, thunderstorms with some heavy rains have just popped up including here along the seabreeze. Rain starting and just heard thunder. Edit: I ended up with ~0.80”, which brings me to ~14.4” Aug 1-17!

1. It’s a weak to very weak correlation at best regarding AN ACE to 35”+ NYC snow. Furthermore, correlation doesn’t necessarily mean causation. 2. If either of the two possibilities were to be the case even in a weak manner, I’d go with your 2nd option. 3. I’ve seen no indication about an even very weak correlation of recurving hurricanes and 35”+ NYC snow. 4. If anything, there may be a very weak correlation to seasons with 2+ US H hits and not the other way around. That sort of seems like the opposite 5. Regardless, how does one quantify the relationship of “recurving hurricanes” to 35”+ snowfall? That seems kind of vague/not very concrete.

Thanks, Don. I want to make sure I’m following you. You’re saying that the NYC snow/ACE coefficient of determination is only 1.4%? That’s next to no correlation. I thought it might have been closer to 10%/weak. Fwiw: opinions about this? ACE 160+ (20 years): NYC snow (avg is 28.1”) 1878: 35.8” 1886: 31.9” 1893: 45.5” 1906: 53.2” 1926: 22.3” 1932: 27.0” 1933: 52.0” 1950: 9.3” 1961: 18.1” 1995: 75.6” 1996: 10.0” 1998: 12.7” 1999: 16.3” 2003: 42.6” 2004: 41.0” 2005: 40.0” 2010: 61.9” 2017: 40.9” 2020: 38.6” 2024: 12.9” So, 11 of 21 (52%) of 160+ ACE seasons were followed by 35”+ at NYC vs only 44 of 156 (28%) of all seasons having 35”+ suggesting a possible weak correlation of 160+ ACE to 35”+ NYC snow. However, 11 of those 20 160+ ACE years were since only 1995! And as @bluewavesuggested, CC is probably a more significant predictive factor on high snowfall seasons than 160+ ACE. There have been 6 50”+ seasons just since 1993-4 or 19% of the last 32 winters. Prior to 1993-4, there were only 12 of 124 seasons (10%) with 50”+ snow. @snowman19

NYC was also very low with snow in 1950-1. Regardless, one season, alone, doesn’t destroy the theory because these correlations are not only not even close to 100%, they’re weak. If I instead had claimed it was a 100% perfect correlation, then that idea could be destroyed by just one season.

Due to curiosity about whether or not there likely is a connection between ACE and/or # of CONUS H hits with NE snowfall the following winter, I decided to research NE US AN winters and crunch the #s. I chose a central point with a very long history, NYC. I chose 35” as the breakpoint for AN: Hurr. seasons preceding NYC AN snow (35”+): 44 of last 156 seasons (top 28%): -AN ACE*, AN H hits (2+)**: 2020/17/05/04/03/1995/66/33/16/15/06/1898/96/93/87/80/78 -BN ACE/BN H hits (0 or 1): 2014/13/09/02/1993/77/22/19/1874 -NN ACE/AN H hits: 1960/59/48/47/38/1882/76 -NN ACE/BN H hits: 2000/57/1895/83/72 -AN ACE/BN H hits: 2010/1963/1892 -BN ACE/AN H hits: 1940/13/04 Summary of 44 H seasons preceding AN NYC snow: ACE/# of H hits: 1. AN/AN: 39% (17 seasons) preceding AN snow vs 26% of all H seasons being AN/AN 2. BN/BN: 20% (9) vs 28% 3. NN/AN 16% (7) vs 15% 4. NN/BN 11% (5) vs 13% 5. AN/BN 7% (3) vs 6% 6. BN/AN 7% (3) vs 11% ————— -AN ACE: 45% (20) vs 33% -NN ACE: 27% (12) vs 28% -BN ACE: 27% (12) vs 39% —————— -AN H hits: 61% (27) vs 52% -BN H hits: 39% (17) vs 48% ————— Conclusions -There appears to be a weak but noticeable correlation between ACE and the chance for >35” NYC snow -There appears to be a very weak but noticeable correlation between # of US H hits and the chance for >35” NYC snow -Combining these two factors, a season with both AN ACE and AN H hits, appears to give the strongest chance for >35” NYC snow with it possibly being as much as twice as high as the chance for >35” after BN ACE/BN H hits —————— *ACE norms adjusted for avg ACE of each era **Avg US H hits 1.8 1851-2024 Sources: -NYC snowfall: https://www.weather.gov/wrh/Climate?wfo=okx -ATL ACE: https://en.m.wikipedia.org/wiki/Accumulated_cyclone_energy -# of CONUS H hits: https://www.aoml.noaa.gov/hrd/hurdat/All_U.S._Hurricanes.html @PhiEaglesfan712@snowman19@donsutherland1@BlizzardWx

Thunderstorms that popped up along the seabreeze have resulted in moderate to heavy rain here since 1:45. I’m >1” and adding to that. So, I’m >13” for MTD! Edit: I ended up with ~1.6” on 8/16. That gets me to a whopping ~13.6” for Aug 1-16! Some in the county got as much as ~3” around the Windsor Forest area.

1. 2024 (161 ACE) didn’t get 2nd major til late Sep. 2. 2023 (146) didn’t have 1st MH til 8/20. 3. 2021 (146) 1st MH 8/20. 4. 2020 (180) 8/26 5. 2019 (132) 8/30 6. 2018 (133) 9/10 7. 2017 (225) 8/25 8. 2016 (141) 8/30 ——— 2025 got 1st MH on 8/16. Seasons with 1st MH by 8/16: 2024, 2008, 2005, 2004, 2000, 1996, 1995…only 7 of last 30 (23%).

1. 2024 (161 ACE) didn’t get 2nd major til late Sep. 2. 2023 (146) didn’t have 1st MH til 8/20. 3. 2021 (146) 1st MH 8/20. 4. 2020 (180) 8/26 5. 2019 (132) 8/30 6. 2018 (133) 9/10 7. 2017 (225) 8/25 8. 2016 (141) 8/30 ——— 2025 got 1st MH on 8/16. Seasons with 1st MH by 8/16: 2024, 2008, 2005, 2004, 2000, 1996, 1995…only 7 of last 30 (23%). Edit: We don’t need another storm even near Erin’s incredible strength to end up with an AN ACE season. @snowman19

Due to Erin ACE is now rapidly rising with 2025 about to cross median for the date (of last 75) and should cross mean tomorrow. 2025 should reach top 20 for the date by Mon and top 15 or higher by Tue or Wed. @snowman19@mitchnick

0Z UK is similar to the 12Z with a TS N of the Leewards moving WNW:NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 132 HOURSFORECAST POSITION AT T+132 : 15.6N 56.6WLEAD CENTRAL MAXIMUM WINDVERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)-------------- ---- -------- ------------- -------------1200UTC 21.08.2025 132 15.6N 56.6W 1009 260000UTC 22.08.2025 144 16.3N 58.8W 1007 321200UTC 22.08.2025 156 18.1N 60.9W 1006 370000UTC 23.08.2025 168 19.4N 63.3W 1005 38

Any chance his idea is the right one?