GaWx

The dewpoints well down into the 60s along with pretty brisk NE winds and afternoon temps in the 80s here the last couple of days have been refreshing for summer!

QBO/solar 1950-1 slight E/moderate solar ~3 yrs after prior peak 1961-2 slight W/moderate solar ~4 hrs after prior peak

What do you mean by “a bit more aggressive”?

I don’t have much to go on though I did see this at another BB fwiw: “If I’m being honest, the only model I have much trust in right now is the AI-EURO. Mainly because it’s gotten every storm this season (was a bit slow with Debby but caught on) and caught on 10-14 days out.”

Followup showing that this WxBell CFS map was as expected significantly too cool at DC for 8/16-20: As the above WxBell map for 8/16-20 shows, it had DC and vicinity at 6.5 F BN. It ended up verifying at only 0.7/1.8 F BN at IAD/DCA, which is close to what the DCA NWS had predicted: 1. IAD: actual mean/1991-2020 normal mean 8/16: 75/76 8/17: 78.5/76 8/18: 80/76 8/19: 76/75.5 8/20: 66/75.5 So, 8/16-20: 75.1/75.8 Thus IAD verified at only 0.7 F BN vs WB forecasted ~6.5 F BN. https://kamala.cod.edu/offs/KLWX/2408170524.cdus41.IAD.html ————————— 2. DCA: actual mean/1991-2020 normal mean 8/16: 79.5/79.5 8/17: 79/79.5 8/18: 80/79.5 8/19: 80.5/79.5 8/20: 69.5/79.5 So, 8/16-20: 77.7/79.5 Thus IAD verified at only 1.8 F BN vs WB forecasted ~6.5 F BN. https://kamala.cod.edu/offs/KLWX/2408170524.cdus41.DCA.html This adds to the evidence that WxBell CFS maps have significant flaws in their map generating algorithms as TT CFS maps weren’t nearly as cool. @donsutherland1

The 6Z Euro-AIFS has a TC that originates from a TCG in the vicinity of the Leeward Islands ~Sept 2nd. This makes it the 17th run in a row with a TCG near the Leewards ~9/2. This goes all of the way back to the 6Z 8/19 run! You can still see all of these runs on Tropical Tidbits

I’d say the 18Z is about the most active GEFS for early Sep yet though not really that active for late Aug as there were a number of runs more active for then awhile back. **Corrected from 12Z to 18Z

The 12Z AI-Euro is the 14th run in a row with TCG near the Leewards ~9/2. It then recurves near 70W fwiw.

12Z Euro has no TC. But per last 13 Euro AIFS runs the crucial period for TCG may be centered around Sep 2nd, just beyond the 12Z Euro 240.

Long range GFS, whether active or not, has low statistical credibility. I prefer to look at GEFS/EPS for trends toward either more or less activity. Granted I did post about the late portion of the Euro-AIFS but that was because the last 13 runs have had a similar solution. Sort of its own 13 run ensemble in a sense.

Fwiw and for the record the 6Z Euro AIFS is the 13th run in a row (back to the 6Z 8/19 run) with a TCG in the vicinity of the Leeward Islands ~Sept 2nd.

Good question. My understanding is (or at least the way I use it) that the required +/- 0.5C for 5 consecutive trimonthly periods is just for whether or not an event is Nino, neutral, or Nina based on ONI. However, because RONI is a pretty new concept and has yet to be used for official classifications, it’s going to be hard (if not impossible) to find anything about requiring 5 consecutive RONI for classifying. But I think it makes perfect sense to use RONI that way. I don’t see why not.

Very well thought out! Thanks for posting this. With my being in a vulnerable location, I hope you’re wrong with the very active peak or if not that people aren’t too badly impacted during the peak. I’d love for the peak to be like 2010. This is a minor point but I do want to point out that 2024 is 3rd highest of satellite era with 1980 also being higher as of today. The graph you show goes back only to 1991. That’s why it shows 2024 as 2nd highest. But since you mentioned 2nd highest of satellite era, I thought I should mention this.

- I believe that Oct is the most dangerous month for a direct landfall on the Gulf coast of FL. - Up here in E GA, Matthew in Oct of 2016 was easily the worst since at least David (1979). - Hazel in Oct of 1954 was one of worst ever in NC/SC and then was a monster well inland in much of E US - Oct of 1898 was another really bad H (in GA and far N FL)

Strong thunderstorms have popped along the seabreeze front and are now over downtown as well as N into lower SC. I’ve heard a good bit of thunder but am not getting any rain at least as of yet. Edit 9:14 PM: The heavy rain has slowly slipped S and now it is falling here. I ended up with ~1”. I actually got a little bit of new flooding into my garage but I took care of that. I’ve been waiting for them to get out here to replace the garage door’s bottom seal. They’ve had a lot of calls due to Debby backing them up.

Euro weeklies mean ACE forecast update vs norm last 7 days (newest far right, which is 0Z of Tue): 8/26-9/1: 50%/60%/50%/50%/50%/30%/20%; Norm 14 9/2-8: 110%/110%/120%/100%/110%/70%/70%; norm 15 9/9-15: 90%/80%/90%/80%/100%/80%/90%; norm 16 9/16-22: 90%; norm 13 So, in today’s Euro Weeklies update regarding the 3 weeks I’ve been following, yesterday’s progged sharp mean ACE drop from 40 to 28 was maintained today. Also, todays added a new week (9/16-22) with a mean of 12 ACE. Thus, today’s Euro Weeklies mean ACE prediction for the 4 week period 8/26-9/22 is 40. This 40 compares to the 1991-2020 avg of 58. So, mean ACE prediction is significantly below the 1991-2020 avg mainly due to weeks 1-2 fwiw. Thoughts? https://charts.ecmwf.int/products/mofc_multi_tcyc_family_frequency/overview/base_time?base_time=202408200000&parameter=Accumulated cyclone energy&valid_time=202409020000

CSU outlook for next 2 weeks (8/20-9/2): most likely near normal with activity more concentrated in 2nd week as one would expect based on models; no surprises in this. They did well with their prior 2 week fcast, which verified mainly due to Ernesto with its favoring of above avg activity: https://tropical.colostate.edu/Forecast/2024-0820.pdf

12Z GEFS: another GEFS that looks rather active for first few days of Sept.

Well, Tahiti had 1019.15 yesterday, the highest daily SLP there since Sep of 2010 and only the 14th day of 1019+ since 1991. There look to be 3 more chances for a 1019+ through Aug 22. Then it will drop, but there are hints of another strong high passing to the S of Tahiti early next week that could easily raise them back above 1018 for a couple of days. These high Tahiti SLPs favor further development of La Niña.

It just missed being a MH during the window ending 9/1 by one day.

Probably not worth that much but fwiw the last 4 Euro-AIFS suggest the area around Puerto Rico may have to watch for a nearby TC ~Sep 3. Again, fwiw. Will be interesting to see what todays Euro weeklies show after yesterday’s sudden pretty sharp downturn (ACE fell to 28 from 40, which is about where it had been for 7 days) for 3 weeks ending mid Sep. So, it still had some activity but was BN. Was that just a blip? The 6Z GEFS is pretty active with many members having a TC in the W basin late.

Ernesto’s total ACE will end up ~15 or just under, which is near the 1991-2020 avg for a hurricane.

I’ve found that most, if not all, of the significant cooling from strong and/or large TCs tends to reverse within a few weeks during early to mid season.

I had just a shortlived shower ~4PM. Nothing measurable.

If the GFS/Euro end up verifying well, there could be as many as 4 straight Tahiti SLPs of 1019+ during Aug 19-22. I’d be very surprised if there isn’t at least one. Keep in mind that higher Tahiti pressure is favored during developing La Niña. There hasn’t been even a single day of 1019+ since 2010! Tahiti SLP 1019+ since 1991: 1019.55: 1994 (Aug) 1019.1, 1019.44: 1996 (June) 1019.3: 1998 (Aug) 1019.28: 1999 (Aug) 1019.24: 2010 (July) 1019.44, 1019.61, 1019.78, 1019.59, 1019.14: 2010 (Sep) 1019.05: 2010 (Sep) -So, there have been only 13 days of Tahiti SLP of 1019+ over the last 33 years with the record high being 1019.78 (Sep of 2010). - This shows there’s been only one time when there were more than two days in a row of that (Sep of 2010). That was during the longest streak on record, 5 days. - This shows that all were during June-Sep with a mean date of Aug. That makes sense because that’s during their winter, when sfc cold high pressures are at their highest SLP of the year. - There is a decent correlation between high Tahiti SLP periods and an active Atlantic tropics mainly 1-3 weeks afterward. That jibes well with the idea of an active Atlantic sometime between very late this month and mid Sep.