GaWx

A couple of us just yesterday were talking about how the NHC has been too slow this season to date in upgrading systems vs years like 2020 and possibly overreacting to criticism then. Example:

Oops, yes, 3-0-0. I think I was looking ahead at Franklin model projections to become a H down the road.

-With the upgrade of TD6 to Gert, August is already up to 3/1/0. -Gert now joins Arlene, Bret, Cindy, and Emily as names that go back at least to 1981 and which will return in the 2029 list. - Arlene at 12 times had already been the most frequently used Atlantic name through 2023. Now it will be back for at least #13.

I'm predicting Nino 3.4 will be +1.3 in tomorrow's weekly release, not too far from getting into the strong category. Yet, this hurricane season is now about as busy as can be in terms of number of features being followed south of 30N!

It looks to me that Las Vegas will dodge the proverbial bullet as model consensus suggested ~2" was quite possible for the Fri-Mon period, including the Fri monsoon. Right now they're near 0.70" with ~1" total for Fri-Mon, if that, looking much more likely than anything close to 2" total. So far, the only flash flooding was 4-5PM Fri from the monsoon, not Hilary.

A 5/2/2 August would not be a big shocker considering the # of features being followed/modeled as well as the very warm Atlantic. So, I'd say most likely anywhere from 3/1/0 to 5/2/2. As was just posted, Franklin becoming a MH wouldn't be that surprising. Ldub's highly successful career as a pure entertainer/troll stretches for two decades although even he/she can end up right at times due as much to luck as anything.

And at most wx forums, too. At this early stage, NE, especially SE MA/ME, is at some risk from this next week especially from the outer fringes per the 12Z ensembles. At higher risk in addition to the Caribbean are SE Canada, Bermuda, and the Bahamas.

Bell ringing day last year vs this year: Last year: very quiet despite moderate La Niña This year just about as many systems at one time as ever despite moderate El Niño:

Wow, OISST 1+2 anomaly cooled a whopping 0.5C in just 24 hours!!

Also, I should have specifically referred to this summer's warm bias of the BoM as having been in Nino 3.4, 3, and 4. I've never seen a BoM forecast for Nino 1+2.

Although the BoM has been much too warm this summer, it actually averaged a neutral bias the prior ten years with several significantly too warm but others significantly too cool to balance it out. So, despite the 10 year neutral bias, it might have a relatively high average error though I didn't calculate it and thus don't know how its error has been relative to other models.

With Emily, 2023 is at 6 storms to date. Regarding 1991-2020 averages: - 6th storm date 8/29: so ahead by 9 days despite El Niño - 2+ more storms are likely to be named by then, which would mean 8+ by 8/29. 8th storm average date isn't til 9/9. 9th not til 9/16. - 1st H forms 8/11 and 2nd forms 8/26. So, pretty close to average for that with a decent shot at the 2nd H of 2023 by 8/26. Invest 90L appears to be the best candidate for this right now. - 1st MH date 9/1. With the higher than normal # of systems for late August being monitored, there's a decent shot for the first MH by 9/1. Invest 90L may be the best candidate for this possibility, but we'll also need to see what the E MDR may produce. https://www.nhc.noaa.gov/climo/

The opposite was often said in years like 2020, naming too many. So, this may be an overreaction by the NHC to then.

Other than 4-5PM on Friday (due to monsoon, not Hilary), LV has had fairly light hourly rain rates for the most part to this point. Due to the continuous nature of the rain over many hours, rain amounts have been heavy for LV relative to climo. On Friday 8/18, they received 0.30". But that was due to the monsoon flow rather than Hilary. This was the third heaviest on record for the date (back to 1937). Looking more closely, it appears that they got ~0.26" 4-5PM on 8/18, which is quite heavy for just one hour. Edit: That is the heaviest hourly rainfall since at least 8/11/2022. Yesterday 8/19 they got 0.21", which was largely from Hilary and was a record for the date as the old record was 0.18" (2003). Also, their high was only 79, a record low high that was 24 BN. Old record was 81 (2003). So far today, they have received ~0.10", which already has broken the record for today. The old record had been 0.06" (1975). So, for the period since Friday, LV has already received ~0.61" due to a combo of the monsoon and Hilary (near even split) with quite a bit more expected today from Hilary. The three day period 8/18-20 averaged only 0.02" during the period 1937-2022.

-I have Aug JMA for DJF 22-23 -0.43 vs actual -0.67 for a miss of +0.24 -I have Aug JMA for DJF 21-22 -0.16 vs actual -0.97 for a miss of +0.81 (but admittedly still a big error) During last 10 years: -Avg Aug JMA miss when DJF <-0.5: +0.5 -Avg Aug JMA miss when DJF >-0.5: -0.2 If we were in/headed for another La Niña, I'd lean to this last JMA run being too warm. And it of course may be. But with it not La Niña and with all 7 major models now +2.0+, it is hard for me to lean that way considering the recent non-La Niña years as well as how earlier months this year have gone. So, I'm neutral on its latest of +2.18 for DJF, especially with it rising so much even with a much cooler OHC in July and only a tepid 3.4 SST rise in June/July.

-But those forecasts were made in April -August JMA forecast miss for DJF ONI last 10 years: avg +0.1; -average dynamic models Aug miss for DJF ONI last 10 years +0.3 -the same but for last 7 El Niños alone: JMA -0.1; avg dyn: 0

The Meteo-France has been similar to AUS on being much too warm. I expect they'll both verify significantly too warm for peak. That July Euro will clearly verify much too warm for Aug and it does have a warm bias. Their May forecasts for peak ONI (whether - or +) have not verified too cool since way back in 2004! The model run that has recently had the biggest impact is the JMA's warming from +1.76 to +2.2. The JMA had recently been lauded ITT as one that has done well. I then analyzed how it had done earlier this year and found it to not be warm biased and instead slightly cool with averaging a -0.1 miss for the subsequent month and a -0.3 miss for several months out.

I became curious about 19-20 after reading this. So, I checked the 19-20 threads and found that nearly every forecast ended up verifying much too cold. I'm placing some of the blame on some seasonal model forecasts that were much too cold. For example: -JAMSTEC (11/1/19) a pure disaster (I think it is cold biased in the E US because it has had cold forecasts there for a good # of winters that ended up mild) -But this C3S was actually not bad though it wasn't warm enough: -The CFS and CANSIPS maps were ~normal. -The forecasters largely went near normal to slightly colder than normal. The consensus among them was a neutral to -NAO, possibly influenced by the strong -NAO (-1.6) (second strongest -NAO on record) for May-Oct 2019. NAO ended up sharply reversing to strong +NAO all 3 of DJF. -Though even he verified too cold, Don Sutherland did the best of those that I saw with no BN anywhere in US. He had near normal Desert SW/Great Lakes/NE and slightly AN most other areas other than solidly AN SE. The key to him not missing by as much: he predicted a +NAO. -If Don were to go -NAO this winter, that would be quite encouraging because historical stats show no correlation of a -NAO summer to -NAO following winter.

The relatively cool OHC is the main thing keeping me from going higher than 70% chance for a +2.0+ ONI peak. But I don't think ENSO SST forecasts overall are showing "excessive momentum" because the latest major ones outside of the already very warm BoM and Meteo-France substantially warmed from the prior month despite a tepid June-July 3.4 warming/~neutral SOI/big OHC drop. Also, the JMA, CFS, CANSIPS, and UKMET all actually had cooled the prior month.

Also, 2.58" is the heaviest for any date of the year. And their second heaviest daily record for any date of the year occurred on the very next date, 8/22! (1.65") The record high two cal. day record is 2.59". That may be in danger.

Although I'm not saying they can't end up with a dangerous situation then, I'd say that the worry regarding the 12Z GFS would be the case for folks not realizing that the exact 10 day position on the GFS or really on any operational for that matter is of very limited forecasting value since they jump around a lot that far out from run to run. Regarding GFS runs over the last 5 days, only the 0Z 8/16 run has anything similar.

Those diagrams suggest a transition from east based in OND to a cross between east based and central based DJF.

Though it still has no GOM TC, the 12Z UKMET continues to have E MDR TCG from a non-tagged AEW next week: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 126 HOURS FORECAST POSITION AT T+126 : 14.5N 18.4W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 0000UTC 24.08.2023 132 14.7N 19.2W 1004 30 1200UTC 24.08.2023 144 15.8N 22.1W 1003 35 0000UTC 25.08.2023 156 17.0N 25.5W 1005 37 1200UTC 25.08.2023 168 17.6N 28.4W 1005 35

Per today's monthly summary of dynamic models: 1. Most recent CANSIPS is confirmed to be at +2.05 ONI peak OND vs +1.61 a month ago. 2. New UKMET now up to +2.00 NDJ. 3. The ONI peak from the average of all dynamic models has risen from +1.81 last month (OND) to +2.06 (NDJ). 4. DJF has risen from +1.50 to +1.91. 5. Based on the new UKMET also being super, I'm raising the chance for super ONI peak from 60% to 70%. It is still far from a lock largely because of OHC at last check only in the +0.80s though I expect it to rise substantially in the coming months. https://iri.columbia.edu/our-expertise/climate/forecasts/enso/current/?enso_tab=enso-sst_table

8/18/23 like night and day vs 8/18/22 in MDR: 8/18/22 2AM EDT TWO: 8/18/23 2AM EDT TWO: SEVEN features have significant activity on the 0Z EPS just through day 10! That almost has to be near a record: