GaWx

If it doesn’t get more active that would be fine with me. And of course it may not. But the Euro weeklies have done well so far this season. They had very high activity in late June and early July. Also, they did very well with the recent quiet period. They’ve been calling for a substantial increase in late Sep for a full week. Of course even if it gets more active they could still mostly avoid land.

Today’s Euro Weeklies added a new week, Sep 30-Oct 6, and that week is quite active vs climo. In addition the week before is also progged to be active as has been the case on many runs. So this run suggests that activity will pick up markedly next week though would still be below avg. After a similar subsequent week, activity is suggested to pick up substantially in late Sep and continue into early Oct vs climo: 9/3/24 Euro Weeklies (EW) mean ACE projections as % of climo: 9/2-8: 20% per yest.’s run (meaning ACE of 3) 9/9-15: 60% (meaning ACE of 10)(climo peak week) 9/16-22: 70% (meaning ACE of 11) 9/23-29: 130% (meaning ACE of 17)(vs peak wk climo of 16) 9/30-10/6: 140% (new week)(meaning ACE of 13) So, today’s EW progs by week are 3-10-11-17-13 meaning two most active weeks are at the end despite climo having dropped off substantially from peak by then. That would get 2024 to ~110 ACE as of Oct 6.

The Euro Weeklies sort of agree. More later.

In April CSU predicted ACE of 210. Their prior highest April progs were 160-183 (five years). Of these five, all progs ended up too high with even the closest being 34 too high! (That day I predicted 176 ACE based on it being 34 under 210.) The five averaged a whopping 85 too high for ACE! So, if their April of 2024 forecasted ACE ends up 85 too high, it will end up at 125.

Looking more closely, this new CANSIPS is forecasting Aug of 2025’s Nino 3.4 to be ~+1.0C unadjusted or ~.+0.5C adjusted downward for surrounding warmth. It has Nino 3.4 warmest and Nino 4 2nd warmest (only modestly cooler). So, it literally has a Modoki Nino forming by late summer. Of course fwiw due to very low probability of being accurate that far out. I can see it now. @George001titles next year’s main ENSO forecast thread “2025-6 Modoki El Nino”.

COLORADO STATE UNIVERSITY FORECAST OF ATLANTIC HURRICANE ACTIVITY FROM SEPTEMBER 3–16, 2024 We believe that the most likely category for Atlantic hurricane activity in the next two weeks is below-normal (60%), with near-normal (30%) and above-normal (10%) being less likely. (as of 3 September 2024) https://tropical.colostate.edu/Forecast/2024-0903.pdf

12Z UKMET has a strong TS form well off the US E coast Wed night that then moves NE and hits Nova Scotia this weekend: @WxWatcher007 NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 66 HOURS FORECAST POSITION AT T+ 66 : 34.8N 70.6W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 06.09.2024 72 36.8N 68.9W 1010 34 0000UTC 07.09.2024 84 39.2N 66.8W 1005 45 1200UTC 07.09.2024 96 41.4N 64.9W 997 43 0000UTC 08.09.2024 108 44.0N 63.3W 998 39 1200UTC 08.09.2024 120 47.1N 62.3W 1003 32 0000UTC 09.09.2024 132 49.4N 60.9W 1007 25 1200UTC 09.09.2024 144 CEASED TRACKING

The ICON (12Z) still has not backed down and thus is once again slowly developing a LLC in the NW Gulf off TX late this week.

Fwiw, this CANSIPS map for Aug of 2025 implies a developing Modoki El Niño in time for ‘25-26. Opinions? @PhiEaglesfan712 @snowman19

Is there any peer reviewed study done that actually confirms that high solar warms the upper troposphere significantly and more than lower levels like Joe D’Aleo is implying? If so, please provide a link.

1. The last week has been during peak and has had these three AOIs all at or S of 15N. 2. La Niña not being near as robust as forecasted isn’t normally hostile to development like El Niño typically is. Even if we call it neutral ENSO, that in itself isn’t typically hostile.

1. There are three AOIs on the TWO that are between 12N and 15N, which are not north at all. Furthermore, they’ve been at 15N or further S since leaving Africa: 2. Nino 3.4 has been warmer than expected. But cold neutral isn’t typically hostile for activity. In addition, on a RONI basis we’re already near -0.7 (weak Niña). 3. Joe D’Aleo *fwiw* has recently been suspecting the current very active sun causing reduced instability in the atmosphere via a warming of the upper atmosphere. The August sunspot mean of 215 was the highest for August since 1991. There MAY be a partial correlation that puts a ceiling on ACE (i.e., perhaps making it very difficult to have a hyperactive season when sunspots are very high). The highest season’s ACE that has occurred with ASO sunspots of 175+ is the 149 of 1980 fwiw. With Aug at 215, there’s a high chance that ASO of 2024’s sunspots will be 175+: https://en.m.wikipedia.org/wiki/Accumulated_cyclone_energy

0Z 9/2/24 WB CFS control DJF in S Lake Michigan is as cold as 19 F BN (which obliterates the coldest winter back into the late 1800s) while far N Lake Michigan is right at normal : different run but same distribution of anomalies in that area yet again

My sources don’t show an August update yet. Are you talking raw number or anomaly? The anomalies were headed in that direction. But if that’s the raw, that would be a huge jump.

Since 1851 here are the 18 years with 10 or lower sunspot avg during ASO (10% of the years): (* means El Niño (including incoming) season) *1855: 18 1856: 49 1878: 181 *1888: 85 1901: 99 *1911: 34 1912: 57 *1913: 36 1933: 259 1954: 111 1964: 153 1996: 166 2007: 74 2008: 146 *2009: 53 *2018: 133 2019: 132 2020: 180 AVG ACE for 18 years of 10- ASO sunspots: 104 (significantly > longterm avg) AVG ACE for 12 non-Nino years of 10- ASO sunspots: 124 (much > longterm avg) So, analysis of this post and post just above this for non-El Niño seasons only: - avg ACE was 124 for the twelve 10- ASO sunspot seasons - avg ACE was 82 for the nineteen 175+ ASO sunspot seasons - Whereas none of the 15 non-El Nino seasons with 175+ ASO sunspots had 150+ ACE, five of the 13 non-El Nino (38%) 10- sunspot seasons had 150+ ACE. Conclusions from the analysis in my 3 sunspot/ACE -correlation related posts: -I think @40/70 Benchmark’s idea about the tendency for high ACE seasons to be near solar min has a lot of merit and is backed up pretty well with the above data. That may also mean it is going to be difficult for 2024 or a typical future year with ASO sunspots >175 to get to 175+ ACE (or maybe even just 150+ ACE) despite other very favorable factors like La Niña and near record warm Atlantic MDR SSTs. -I think the research that Joe D’Aleo mentioned about the tendency for a strong solar spike to hamper hurricane activity via a lowering of instability due to warming of the upper atmosphere should be investigated further as quite possibly being one of the main reasons for the recent quiet. I read elsewhere about it being quite warm. @snowman19 Sources of data: Sunspots: https://www.sidc.be/SILSO/DATA/SN_m_tot_V2.0.txt ACE: https://en.m.wikipedia.org/wiki/Accumulated_cyclone_energy ENSO pre 1950: https://www.webberweather.com/ensemble-oceanic-nino-index.html ENSO 1950+: https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php

Since 1851 here are the 19 years with 175+ sunspot avg during ASO (11% of the years), where 2024 is very likely headed, along with their respective ACE (* means El Niño (including incoming) season): 1859: 56 1860: 62 1870: 88 1917: 61 1937: 66 1947: 88 1948: 95 1949: 96 1956: 57 *1957: 79 *1958: 110 1959: 77 *1979: 93 1980: 149 1981: 100 1989: 135 1990: 97 *1991: 36 2001: 110 AVG ACE for ASO sunspots >175: 82 (near longterm avg)(same if throw out El Niño seasons) Highest ACE for ASO sunspots >175: 149

Thanks, Ray. Great point. I’m going to look more closely now to see if I can confirm your suspicions about hyper seasons tending to be near solar min. Here are the 13 ATL seasons with 180+ ACE along with ASO averaged monthly sunspots: 1878: 5 (min) 1887: 20 (quiet) 1893: 160 (max) 1926: 110 (1.5 yrs before max) 1933: 5 (min) 1950: 95 (halfway from max to min) 1961: 75 (halfway from max to min) 1995: 20 (nearing min) 1998: 110 (2 years after min) 2004: 65 (3 years after max) 2005: 35 (quiet/3 years before min) 2017: 30 (quiet/2 years before min) 2020: 10 (just after min) So, of the 13 180+ ACE seasons, 7 had low sunspots, 3 had near avg, and 3 had above avg. though only one of those 3 had well above avg (1893) like 2024. And 2024 has an excellent shot at exceeding the 160 of 1893 since Aug was 215. It could end up near 200 for all we know now. I’d say 175+ is pretty safe. The avg monthly of these 13 seasons’ ASO sunspots was only ~55, which is well under the 1900-2022 avg of ~85 for all months. When looking at ASO averaged monthly sunspots of 135+, the only other high ACE were the 166 of 1969 (ASO sunspots avg 135), the 149 of 1980 (ASO sunspots avg of 215), and the 177 of 1999 (ASO sunspot avg of 140). So, the highest ACE during a 200+ ASO (edit: actually 175+) sunspot avg was only 149 (1980). https://en.m.wikipedia.org/wiki/Accumulated_cyclone_energy https://www.sidc.be/SILSO/DATA/SN_m_tot_V2.0.txt

Do you think that the current very active sun could be one of the main factors (especially when considering lag) keeping the recent Atlantic tropics quiet? Aug of 2024 had a 216, the highest mean sunspots in Aug since 1991. That means that this Aug had the highest mean for Aug of the current active Atlantic tropics era so far. https://www.sidc.be/SILSO/DATA/SN_m_tot_V2.0.txt Per met. Joe D’Aleo: “We have mentioned the strong solar spike which research has shown can suppress hurricane activity.” “One negative may be the big spike in solar in cycle 25. Most cycles have had a dual max and recent ones had the second one higher. This warms the upper atmosphere and hampers development.”

Icon (12Z) has it again while CMC, GFS, and UKMET again don’t.

My educated guess is no because in a good portion of the central and E US, especially the Midwest, August of 2024 wasn’t as hot as Aug of 2021. In much of the C/E US, June was the hottest month anomaly-wise and in some cases even outright. Much of the Midwest as well as some of the Plains and mid-south had only near to only slightly warmer than the 1991-2020 normal for July-August, combined.

Happy met. autumn! Here’s to a relatively comfortable September as we start a new season.

I’m suspecting that one of the factors leading to the current quiet is the record warm E Atlantic from 30 to 45N. Any opinions about this?

Total here for August: 15.33”, with 10.9” from Debby 8/5-7 (which flooded parts of my garage). A thunderstorm on 8/20 caused some more water to flow into my garage but it wasn’t nearly as bad and I was on top of it. It has been at least several years since I had 15.33” in any month. The 15.33” combined with 12.25” in July gives me a two month total of a whopping 27.58”, which is just over double the normal! My JJA was ~31”. That is just under the 32.23” I got in the also very wet JJA of 2022. I got 20.9” just for the period 7/19-8/7! There’s been only traces since after the Aug 20th thunderstorm allowing the water table to drop back down some.

If this disturbance in the NW GOM were to become a TC eventually, the ICON will deserve major kudos. A whole bunch of runs in a row, including the 0Z, have shown this. I don’t recall any other global having a TC from this.