GaWx

For the 2nd run in a row, the UKMET has Oscar get down to its lowest SLP yet (low enough to support a H) later this week after threatening Bermuda: TROPICAL STORM OSCAR ANALYSED POSITION : 20.3N 75.2W ATCF IDENTIFIER : AL162024 LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 21.10.2024 0 20.3N 75.2W 1004 33 0000UTC 22.10.2024 12 21.5N 75.0W 1003 31 1200UTC 22.10.2024 24 23.1N 73.9W 1004 33 0000UTC 23.10.2024 36 25.2N 71.3W 1000 38 1200UTC 23.10.2024 48 28.2N 68.0W 997 45 0000UTC 24.10.2024 60 33.4N 65.2W 990 46 1200UTC 24.10.2024 72 35.6N 64.0W 980 55 0000UTC 25.10.2024 84 38.8N 59.3W 983 48 1200UTC 25.10.2024 96 45.3N 53.2W 984 53 0000UTC 26.10.2024 108 51.9N 44.8W 995 41 1200UTC 26.10.2024 120 POST-TROPICAL

Hoping the CONUS, especially S FL, won’t have any more to worry about. Regardless, Oscar is far from done. Bermuda could be impacted. Also, the chances of an upcoming TCG in the W Caribbean are high.

Don/others, Compare this to WxBell’s 10 day avg for DJF (see image below)(apples to apples): WxBell is significantly too cold in the E 2/3 of the US! In the NE for example, WxBell averages ~-1C/-1.8F vs CPC’s ~+0.75C/+1.35F. So, WB is ~3F too cold! Another ex: Atlanta is ~2F too cold on WB. This is further proof that WB CFS maps tend to be significantly too cold in the E US. In addition note once again on the WB CFS map that everpresent cold spot in S Lake Michigan and warm spot just 250 miles N in N Lake Michigan/N Michigan: **Edit: Also, WB’s climo base is 1981-2010, which would make their maps even warmer than going against 1991-2020. In other words, if WB were to change the climo to 1991-2020, their maps would be even colder. So, WxBell may actually even be further off vs CPC than what I stated above!

Today’s AO: +3.4 A new record obliterating high AO peak for Oct is still on track over the next two days with high +4s to near +5 still progged by GEFS. Current record +3.754 set 10/24/2008 (Oct records have been late in the month more often than early, which is intuitive to me). This new record will also be higher than the Nov record of +4.544 (11/2/1978).

@bluewave Added mins for RONI, which I feel is a superior metric to ONI, and MEI: October 2022…Phase 6 peak +2.177....ONI….-1.0..RONI….-1.1….MEI….-1.7 October 2021….Phase 5 peak +2.087….ONI….-1.0….RONI….-1.2….MEI….-1.5 October 2020…Phase 5 peak +2.818….ONI…..-1.3….RONI….-1.5….MEI….-1.2 October 2017….Phase 6 peak +3.353….ONI….-1.0….RONI….-1.3….MEI….-0.8 October 2016….Phase 5 peak +1.800….ONI….-0.7….RONI….-1.1….MEI….-0.5 October 2011….Phase 6 peak +1.674….ONI….-1.1….RONI….-1.1….MEI….-1.3 October 2010….Phase 5 peak +2.880…ONI…..-1.6….RONI….-1.7….MEI….-2.4 MEI: https://psl.noaa.gov/enso/mei/#datacomp RONI: https://www.cpc.ncep.noaa.gov/data/indices/RONI.ascii.txt

Chris and others, What do you think about comparing RONI instead of ONI?

The rest of October through Nov 2nd is forecasted by the latest Euro ensemble mean to have near record low US pop weighted HDDs for the period (on left) <1/2 the normal. That means for CDDs (on right) near record high levels for the same period (3 times the normal). To put it into a different perspective, normally HDDs are 8 times as high as CDDs for this period, but they’re forecasted to be only 1.25 times as high! The purple line is based on the 12Z Euro ensemble mean (yellow was the 0Z). The dashed green lines are normals:

-The year was referring to Oct but same idea as your assumption. -I’d love a 1989-90 repeat as Dec gave us down here the first major winter storm in 17 winters! The next one wasn’t for another 28 winters! Since 1900, this area has had a major winter storm about once every 20 winters on average. But there are a good number more lighter measurable events along with an even higher number of trace events. But not even a trace of wintry precip here since 1/2018….7 winters is a new record long period w/o even a T! This one was from an offshore SE coastal storm which was windy and one of the coldest ever (snowing with low 20s….can you believe that way down here and close to the coast?!?)

Do I see a correlation between Octobers with a 3+ AO peak and the following winter’s mean AO during La Niña? No although the sample size is small: Niña Octobers with a 3+ AO peak: -1954: moderate -AO winter -0.7 -1983: weak +AO winter +0.3 -1989: strong +AO winter +1.2 -2008: weak +AO winter +0.3 -2022: moderate -AO winter -0.6 AVG winter AO: +0.1 (neutral)

Thanks for mentioning this. Because of what you said I was curious enough to go through the dailies. The upcoming ~10/23 peak won’t be just one of the strongest +AOs on record in Oct. It will be THE strongest Oct +AO peak on record and by a large margin: The current strongest Oct on record (back to 1950) is the 3.754 of 10/24/2008, which is about to be exceeded by ~1+! Strongest Oct +AO peaks back to 1950: 3.754 10/24/2008 3.560 10/6/1994 3.425 10/27/2003 3.379 10/10/2022 3.371 10/30/1983 3.294 10/31/1978 3.184 10/24/1989 3.078 10/20/1954 3.037 10/10/2001 3.009 10/17/1986 Since 1950, the only AO peaks exceeding +4.75 have been during Dec-March: 5.078 1/20/1957 4.917 3/16/1968 5.040 12/2/1979 4.800 12/5/1979 5.582 1/14/1989 5.147 2/9/1990 5.991 2/26/1990 5.245 1/14/1993 4.909 1/21/1993 5.588 3/8/2015 5.910 2/10/2020 6.073 2/21/2020 5.536 3/11/2021 (Note that the very highest peaks (6 of them at 5.5+) were almost all within Feb 10th-Mar 11th.) So with all of the +4.75+ peaks back to 1950 in Dec-Mar up til now, this is even more evidence of how anomalous the upcoming +AO peak will be! Even Nov has yet to have one at +4.75+ with its highest being the +4.544 of 11/2/1978. (Only Novs with a peak of +4+ were 1978, 1994, and 2013.)

That’s it! Thank you! I’m saving this as a bookmark this time. I have many bookmarks but for whatever reason I hadn’t saved that one and had instead always gotten that link easily via Googling “MJO historical data”. Recently when I’ve been Googling that, that exact link no longer was appearing.

Do you know where to find these? I’ve searched and searched and can no longer find a link to these great charts. I’ve been using them for at least a decade. Fortunately I have some saved here like this one, but those are all I can see now. They were copyrighted by Australia’s Bureau of Meteorology. If nobody knows here, I may try to email the BoM when I get a chance if I can find a good email.

What are the implications of a strengthening MJO wave in Oct?

The Oct 1-18 WCS version of the PDO is averaging ~0.2 lower than its Sept PDO, which was ~-2.55 vs NOAA’s -3.54. Depending on how Oct 19-31 ends up, Oct of 2024 will have a chance to break the -3.65 NOAA record low (set in both April 1859 and July 1950). More significantly, Jan-Oct of 2024 is headed for ~-2.57 which would be a new record low that barely beat’s 1894’s -2.55. Even more impressive is that April-Oct of 2024 is headed toward ~-3.03, easily the lowest April-Oct on record currently held by 1894’s -2.67 followed by 1950’s -2.66 and 2024’s -2.60. https://www.ncei.noaa.gov/pub/data/cmb/ersst/v5/index/ersst.v5.pdo.dat

Bump to show that as far back as this 0Z 10/14 (Sun evening) run, the UKMET (ignore strength because strength this far out is not a strength of the UK) was only just over 100 miles ENE of the actual 0Z 10/20 position. Also, the ICON has been fairly good with a storm in the general area as far back as the 0Z 10/13 run. The NHC didn’t have its best with Oscar’s genesis. It had only a 10% chance in yesterdays 8AM EDT TWO! Not good. To compare I thought they did very well with Milton overall but not good with Helene’s projected track into GA as they kept the center in W GA instead of E GA like most of the main globals had. Up and down recently for them although they usually do well imo. This year I feel like they’ve been extra conservative in recognizing TCG.

Yesterday’s Euro Weeklies have a 90 percentile ACEwise for Nov 4-10 with a whopping 4 x climo or ~9, which is norm for 1st week in Oct. The last time that week had 9+ was 2008 (Paloma). The MJO fcasts are supportive with mod left side at start. Ensembles have it active in W Car then.

I was among those closely following the 2014 SAI and was deeply disappointed. This 11/1/14 post from cfbaggett sums up well the excitement many of us had in the annual fall snowcover thread: And so October ends… Amazing month. The slope, as I calculate it, was 295,000 km^2/day. Thus, it appears we can predict with reasonable confidence a strongly negative AO winter. After this major fail, the SAI never regained its former luster. 2014-5’s AO was the most + since 07-08!

Euro Weeklies today upped 11/4-11/10 to 3.7 of climo:

That’s the way I’ve always felt down here about wintry precip and much more to the extreme. It is so rare that I don’t even expect a T in any one winter. Most winters don’t even get a T. Thus, just a T here is a big deal. Last one was nearly 7 yrs ago! For me winter mainly means up and down temps (with some wild swings) with much colder and drier air overall vs rest of year and a few nasty cold rains. That’s plenty enough to make it my favorite season. Wintry precip, even just a T, is never expected but always a hope as a rare bonus.

I realize that. But just about every WB CFS control run has a similar SSTa pattern with that large cold area that doesn’t show up on any other CFS maps anywhere and a strong moderation of the marine heatwave, both pure BS. So, an avg of 12 of them would usually be similar. The true CFS output isn’t showing anything of the sort. Thus, it’s essentially fake. For example, here are the last 5 for April:

I sure hope that these flawed CFS maps are not due to intentional manipulation like you’re saying! I’ve not been assuming that. Wouldn’t that be illegal? Why would a company take that chance?

Actually, CANSIPS has also been showing a strong -PDO. The only maps I’ve seen not showing a strong -PDO this winter are the heavily flawed WxBell CFS maps, which have on several occasions already been shown to be garbage and are far different from other versions of the same model! They were even showing a +PDO for this winter, which was getting JB excited and posting them. However, they’ve since backed down to neutral (though that’s still WAY off) as we’ve gotten closer due to the partial correction of the flawed maps. That’s why JB has recently not been as vocal about a possible +PDO this winter. However, WB CFS still show a +PDO but now not til spring (WPAC marine heatwave gone lmao) while TT CFS show no such thing. The flawed WB algorithms won’t allow the entire runs to avoid getting rid of the marine heatwave and showing a +PDO: WB CFS for Apr 2025: WPAC marine heatwave magically gone with fake strongly BN blue/green area covering much of WPAC: TT CFS for Apr 2025: WPAC marine heatwave intact and AN where WB has strong BN on the SAME model with similar base climo: @donsutherland1

Unless I missed others, the -3.54 of Sept is the 2nd lowest PDO since 1854 with only 7/1950’s -3.65 lower! There’s a strong correlation between a very strongly -PDO in Sep (-1.5-) and a strongly -PDO in winter (-1.0-) during La Niña with exceptions being: - 1892-3: Sep -2.5 vs DJF of -0.8 - 1924-5: Sep -1.7 vs DJF of -0.6 - 1933-4: Sep -3.0 vs DJF of -0.3

1. On RONI basis (relative ONI that takes into account the very warm global tropical SST anomalies overall) La Niña is very likely already bordering moderate. 2. Blocking in summer/fall has very little or no correlation to that in winter. Plus NAO was positive in August and has returned to positive. 3. PDO remains near record strong negative due to W Pacific marine heatwave. 4. That in combo with La Niña and all models showing a mild SE/good SE ridging (warmest of the E US in many cases) makes me pretty confident that this winter will be warmer than 23-24, which was NN to slightly AN, in SE. 5. This would be good news for W NC folks still then without shelter/heat. 6. Regarding the next potential chilly winter in the SE, I’m already looking forward to 25-26 potential due to a possible Modoki El Niño per the last two CANSIPS runs. 7. Regardless of how mild is this winter, winter is normally my favorite seasonas temperatures are near guaranteed to be 25+ colder than summer and RHs lower, great for walking!

With all due respect: if JB said that, he likely misquoted it. Besides, Dec is already in winter: “There’s an old saying I’ve heard over the years: ‘what happens in November, the winter will remember!’” from this link: https://whnt.com/weather/valleywx-blog/will-winter-remember-november/amp/