GaWx

For the first time like the GFS/CMC, the Euro (12Z) has this NW Gulf low (1011 mb now). It then drifts S (similarly to ICON/UK/others) while getting stronger. It doesn’t reach peak strength til Saturday, when it gets down to 1003 mb at 27N. Keep in mind that the Euro like the GFS/CMC is playing catch-up. Rumor (i.e., unconfirmed) from an outside source is that this is now Invest 90L. ICON has been amazing with this although the 12Z Euro may have been the main deciding factor.

As you know I’ve been hoping to see actual research papers backing up the idea of a connection of very high sunspot numbers and the recent quiet in the Atlantic basin to supplement my own analysis of the actual numbers and your confidence. Fortunately, I just became aware of a good number of papers thanks to @jconsorwritten dating back to 2008 suggesting a partial negative correlation between sunspots and hurricane activity. The idea is (as we’ve already suspected) that when the sun has an increasing level of sunspots, the upper troposphere and lower stratosphere immediately get warmer (more of a rise than lower down) thus increasing atmospheric stability in a general sense. Of course proving this relationship isn’t easy due to other variables. But the authors discuss this and seem to have done well taking these other variables into account. (I was first made aware of a possible direct connection only last week by Joe D’Aleo and seconded by Bastardi.) The August SSN of 215 is the highest of the active era for any August. And August had only two NS (even though both were hurricanes). Furthermore, since Ernesto it has been exceedingly quiet relative to climo. In light of the following papers, this is probably a major contributor to the quiet: https://agupubs.onlinelibrary.wiley.com/doi/pdfdirect/10.1029/2008GL034431 https://myweb.fsu.edu/jelsner/PDF/Research/HodgesElsner2010.pdf http://myweb.fsu.edu/jelsner/temp/PDF/Research/ElsnerJaggerHodges2010.pdf https://onlinelibrary.wiley.com/doi/pdf/10.5402/2012/517962 https://sci-hub.ru/10.1016/j.jastp.2009.09.012 https://ephyslab.uvigo.es/publica/documents/file_358JASTP_2015.pdf @snowman19 Edit: though not as high as most of August, sunspots are still quite high with an avg of 184 so far this month. The dailies will be worthwhile to monitor throughout the month to see whether a significant drop occurs: 2024 09 01 2024.668 180 16.2 26 33 2024 09 02 2024.671 197 19.4 24 31 2024 09 03 2024.673 180 22.4 19 22 2024 09 04 2024.676 179 29.7 19 23 2024 09 05 2024.679 180 13.7 13 16

Fwiw, I added ENSO as per Webb’s table: 1874-75: 2nd coldest weak Nina 1875-76: 19th warmest neutral 1876-77: 19th coldest weak Nino 1877-78: 16th warmest Super Nino 1878-79: 14th coldest cold neutral 1879-80: 12th warmest weak Niña 1880-81: 13th coldest weak Nino 1881-82: 1st warmest. neutral

Regarding NW Gulf: Latest UKMET (12Z) now has TCG at hour 6, much sooner than the hour 60 of the 0Z run. It then drifts S through the weekend: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 6 HOURS FORECAST POSITION AT T+ 6 : 27.9N 95.1W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 0000UTC 06.09.2024 12 28.1N 94.9W 1008 23 1200UTC 06.09.2024 24 28.3N 94.3W 1006 27 0000UTC 07.09.2024 36 27.7N 94.3W 1005 34 1200UTC 07.09.2024 48 25.3N 94.5W 1004 32 0000UTC 08.09.2024 60 24.2N 93.9W 1003 35 1200UTC 08.09.2024 72 CEASED TRACKING

The NW Gulf notwithstanding, there very well may be a connection between very high sunspot numbers and the recent quiet in the Atlantic basin. I just became aware of a good number of papers thanks to @jconsorwritten dating back to 2008 suggesting a partial negative correlation between sunspots and hurricane activity. The idea is that when the sun has an increasing level of sunspots, the upper troposphere and lower stratosphere immediately get warmer thus increasing atmospheric stability in a general sense. Of course proving this relationship isn’t easy due to other variables. But the authors discuss this and seem to have done well taking these other variables into account. I was first made aware of a possible connection only last week by Joe D’Aleo and seconded by Bastardi. But I didn’t feel comfortable depending on them saying this and thus wanted to see some actual studies. Well, now that I have seen the papers, I feel more confident that there really is something to this. The August SSN of 215 is the highest of the active era for any August. And August had only two NS (even though both were hurricanes). But since Ernesto it has been exceedingly quiet relative to climo. In light of the following papers, this may be a major contributor to the quiet. https://agupubs.onlinelibrary.wiley.com/doi/pdfdirect/10.1029/2008GL034431 https://myweb.fsu.edu/jelsner/PDF/Research/HodgesElsner2010.pdf http://myweb.fsu.edu/jelsner/temp/PDF/Research/ElsnerJaggerHodges2010.pdf https://onlinelibrary.wiley.com/doi/pdf/10.5402/2012/517962 https://sci-hub.ru/10.1016/j.jastp.2009.09.012 https://ephyslab.uvigo.es/publica/documents/file_358JASTP_2015.pdf

Kudos to @salbersbut also kudos to the ICON. No other model has even been close as far as consistently showing a closed surface low getting going around now in the NW Gulf. Folks can see it for themselves by looking at old runs going back many days right now at TT. That model has also been showing it move south toward the Bay of Campeche and getting stronger through the weekend. A few runs of the UKMET have had something but the ICON looks like the easy winner.

Thanks. I have no idea why the Arctic is shown as being cooler than the 1991-2020 normal on this weathermodels.com map.

Thank you. From your link per Joe D.: “The only year since 1998 since I have been doing this which has significantly departed for the seasons was 2001/02 winter when a strong second solar max in terms of solar flux and UV warmed low and mioddle latitude atmospheres and shrunk the polar vortex. I presented this at NWS regional winter workshops in the fall of 2002 and was invited the present that to CPC in Maryland. High ultraviolet produces warming through ozone chemistry, a finding that was speculated by Labitzke and van Loon (1997) and confirmed by Hansen's super modeler Drew Shindell (1999) who included ozone chemistry and flux/UV in a special climate model and got improved verficiation retrospectively..They all found a tendency for the warmth to work its way down from the high atmosphere where to the middle troposphere where it affected the jet stream and flow patterns. The peak in flux/UV in 2001/02 winter was very clear (from September 2001 to March 2002. The resultant warming in the low and middle latiudes was likewise very clear. This is the 500mb height in February. This looks more like the southern hemispehre with a tight polar vortec in blue - trapping real cold air in the polarregions and a warm ring in low and middle latitudes.” My concern is that he is showing only one period, the 2001-2 winter. For statistical credibility reasons, I’d like to see other years/analogs.

But Phil has yet to say that the high solar is even a possible factor in the upper atmospheric warming. I had hoped he would in yesterday’s update. Not even a mention of solar. To their credit the two Joes at WxBell have been. I’m open to that possibility, especially about the idea of a theoretical lowered ceiling on ACE during very high solar seasons based on my own analysis, but would also like to see peer reviewed studies to either back it up or else refute it. I don’t want to depend on WxBell just saying it. I’m open minded. I had never heard of this possible connection til last week thanks to Joe D.

It isn’t pointless because the NHC handles both tropical and subtropical. So, it is their responsibility. Don’t forget that ST storms get named, too.

The point I’m making in showing the progression of the last 6 is to see what the trend of the difference is going toward winter. The difference is important because the models only project ONI. I take those modeled ONIs and adjust them downward based on what I expect RONI-ONI to be. The last 6 have been -0.63, -0.62, -0.64, -0.61, -0.54, and -0.49. It looks like they’re finally starting to trend less negative. Based on that, I feel the difference could be near -0.40 by, say, SON.

This has been on the UKMET, Euro, and others for several days. I’ve been wondering whether or not it would be T, ST, or ET.

Let me restate as I wrote it wrong. I said JJA ONI-RONI was -0.49. I meant to say RONI-ONI was -0.49. RONI was -0.44 and ONI was +0.05. -0.44 - 0.05 = -0.49.

Would you please provide a link to this Arctic SST anomaly plot? I guess I’m not looking in the right place.

The complete data is in here: https://tropical.colostate.edu/archive.html Regarding how they did each year, go here for what actually occurred: https://en.m.wikipedia.org/wiki/Accumulated_cyclone_energy And go here for even more: https://www.nhc.noaa.gov/data/ I’m looking forward to your report!

CSU doesn’t consistently overestimate. Rather, they tend to overestimate only when they predict extremely active seasons. That’s why I was referring only to the 5 highest April ACE predictions rather than all of them. If you look at how they have done overall, I believe it is fairly balanced with some close, some missing too high (especially their most active progs), and some missing too low. As I said back in April, betting CSU is going to be too high tends to be a good bet when they’re going very high. That’s why I said I’d short their 4/24 progs of ACE, HDs, etc. But if they weren’t going super active, I wouldn’t make the same bet. I feel that CSU does as good a job as just about any organization and thus am thankful they make these freely available predictions. I like to hear their thoughts. But clearly they, just like all, are far from perfect and have had some very bad predictions. One thing I like about them a lot is that I feel that they neither are weenies nor are downplayers.

I sincerely hope your optimism is on the right path about any EC LF, but unfortunately it’s way too early imho to feel comfy about this, especially with the cold neutral to weak La Niña ENSO. Patterns, even persistent ones, often change after a few weeks. For example, in the 2016 Niña, Savannah in early Oct. had its worst H (Matthew) since way back in 1979 (David). Furthermore, seasons have become more backloaded overall as I recently posted about, likely related to CC. Many storms still would recurve safely, but having more activity increases the risk. In addition, a place like the NC OB that sticks way out remains vulnerable late despite increased chances for troughing. Lastly regarding outside of the E coast, FL’s Gulf coast is most at risk in Oct due to increased tendency toward troughing. Related to that, fast moving Gulf landfalls of strong storms often have major impacts well inland.

The JJA ONI-RONI came in at -0.49. The last 6: -0.63, -0.62, -0.64, -0.61, -0.54, and -0.49.

It’s good that you took that Twitter source saying nearly +20 with a grain as it not surprisingly ended up way off. The record high back to 1948 is only +15.62. August came in modestly higher than July’s +6.91. It was +8.61. There’s almost no way it has peaked as it hasn’t peaked below +9 since way back in 1973, which covers ~23 cycles. It has peaked within 5-13 months after the prior low point every time on this chart with an avg of ~8-9 months. So, my educated guess is that the peak will come during fall or winter (likely no earlier than Oct). https://psl.noaa.gov/data/correlation/qbo.data

If you’re talking about the monthly NAO table that goes back to 1950 and had July at +1.46 (see link below), that won’t be anywhere close to a record high. Based on the dailies, I expect it will most likely be near the +0.4 to +0.6 range with a small chance to be as high as +0.7 to +0.75 or so. It still isn’t out at this very late hour but it could be released later today. Even if it hits the upper end +0.75, that would be only the 17th highest of 74 August NAOs since 1950. The record high is the +1.97 of 2018. https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.nao.monthly.b5001.current.ascii.table I looked at August NAOs >+1 when JAS RONI wasn’t at a moderate or stronger Nino level: 1) 1955 (Niña) +1.07: Aug very active with 3H incl MH Connie; Sep also very active with 5H incl 3MH 2) 1967 +1.44: Aug very quiet but Sept active with 3H including MH Beulah 3) 1971 +1.55: Aug moderate activity; Sep very active including 4H, with one MH 4) 1976 +1.92: Aug very active with 4H including MH Belle; Sep active with 3H including 1 MH 5) 1983 +1.76: Aug active with 2H including MH Alicia; Sep pretty quiet 6) 1984 +1.15: Aug quiet; Sep active with 2H including MH Diana 7) 1991 +1.23: Aug only 1 NS but it was MH Bob; Sep 3 NS including MH Claudette 8) 1996 +1.02: Aug active with 3H including MH Edouard; Sep very active with 4 MH 9) 2018 +1.97: Aug quiet; Sep active with 3H including MH Florence 10) 2022 (Niña) +1.47: Aug very quiet (no NS); Sep very active with 4H including 2 MH —————— So for these 10 seasons with strong Aug +NAO: -Aug: 4 were quiet, 2 had moderate activity, and 4 were active. So, Aug was balanced as compared to climo. -Sep: only one was quiet (1983), one had moderate activity (1991), and 8 were active. -In summary regarding the 10 seasons with a strong Aug +NAO: none were shut down in both Aug and Sep, Aug was balanced between quiet and active, and Sep was mainly active. Thus, I see no discernible correlation between a +NAO in August and reduced hurricane activity. Are -NAOs more common in Aug during La Niña? Here’s the Aug NAO when JAS RONI was -0.50 or colder: 1954: -1.90 1955: +1.07 1964: -1.77 1970: +0.10 1973: -0.06 1975: -0.26 1988: +0.04 1995: -0.69 1998: -0.02 1999: +0.39 2007: -0.14 2010: -1.22 2016: -1.65 2020: +0.12 2021: -0.28 2022: +1.47 So, tally for RONI based Niña JAS since 1950: 7 -NAO, 6 neutral, 3 +NAO; AVG NAO -0.3 For RONI based El Niño JAS: 1951: -0.22 1953: -0.71 1957: -0.55 1963: -0.64 1965: +0.45 1968: -0.66 1972: +1.32 1976: +1.92 1977: -0.28 1982: +0.26 1986: -1.09 1987: -0.83 1991: +1.23 1994: +0.38 1997: +0.83 2002: +0.38 2004: -0.48 2015: -0.76 2023: -1.16 So, tally for RONI based Niño JAS since 1950: 10 -NAO, 1 neutral NAO, 8 +NAO AVG NAO 0.0

The Euro Weeklies’ ACE climo base is 2004-2023 (running 20 year). What I discovered is interesting for 2004-23 vs 1991-2020 climo for ACE: - 8/26-9/1: decreased ~1/8 - 9/2-9/8: little change (tiny increase) - 9/9-15: little change/still peak week - 9/16-9/22: increased ~1/7; now as active as 9/2-8; old climo was 1/10 less active than 9/2-8 - 9/23-29: increased 28%; slightly more active than 8/26-9/1; used to be just over 1/4 less active than 8/26-9/1 - 9/30-10/6: increased 1/4 So, peak day for ACE appears to be ~2 days later. With a drop in late Aug and a rise last 1/2 of Sep through early Oct, the season is significantly more backloaded ACEwise 2004-23 vs 1991-2020. Total seasonal ACE is 131 vs 122.

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.