raindancewx

Last year, the October pattern showed up again in February. Will it do the same thing this year? I suspect not, but will be interesting to see. -WPO October and -AO February kind of do the same thing spatially

The subsurface blotch of cold is moving up and east to the surface. This is consistent with my matches to Nino 1.2, 3, 3.4, and 4 for Jan-Sept which showed Nino 4 not cooling much after the Fall, unlike last year. Nino 1.2/3 will probably cool most at the surface at the surface (relatively). You can also see that the warm area is expanding east and by intensity.

I don't think you're completely wrong. My main issue for you guys this winter is just that I think the Nor'easters are going to time up to periods of weakening blocking rather than strengthening blocking. So you'll have a lot of Nor'easters, some pretty powerful ones in all likelihood, but they'll start cold with snow and go to rain a lot of the time. You guys have much better La Ninas for snow in periods of low-solar activity too. There is a real shot though that the annualized period (July-June) won't actually be low solar activity. I don't have a good method to predict solar - that part of my outlook is a pure guess. Nationally, the key threshold for solar changes on patterns seems to be 55-sunspots per year whenever I test it (i.e. the 12 month average is 55 from July-June). Solar activity is about ~26 sunspots/month for the past 12 months (11/2020-10/2021). In 2010, we were at ~22 sunspots/month (for 11/2009-10/2010), and then rose to 44 sunspots/month for July 2010-June 2011. We're running ahead of the 2010 solar trend, so it's possible we'll be in the "high solar" grouping below (say 60 sunspots). Way more common for Boston do get slammed with snow in a La Nina with lower solar (1933, 1995, 2008, 2010, 2017 all ~60"+, and all low solar La Ninas). Low Solar La Nina Boston Snow (<55 sunspots, July-June, 1762-2021 average is 85) Average is 49.5 inches 1933-34 (62.7" snow Boston) 1942 (23.9") 1954 (25.1") 1964 (50.4") 1973 (36.9") 1974 (27.6") 1975 (46.6") 1984 (26.6") 1995 (107.6") 2005 (39.9") 2007 (51.2") 2008 (65.9") 2010 (81.0") 2016 (47.6") 2017 (59.9") 2020 (38.6") High Solar La Nina (>55 sunspots). None over ~60" since at least the 1930s. Average is 37.8 inches for Boston. 1938 (37.6") 1949 (32.0") 1950 (29.7") 1955 (60.9") 1956 (52.0") 1970 (57.3") 1971 (47.5") 1983 (43.0") 1988 (15.5") 1998 (36.4") 1999 (24.4") 2000 (45.9") 2011 (9.3")

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It's interesting looking at the near term. Eyeballing it, the AO looks positive but the NAO is negative. We're in the weird La Nina transitional pattern now that happens in a lot of November. But even so, I'd expect that NAO/AO split to show up in the winter a couple times. For what it's worth, NDJ seems to oscillate in La Ninas from the SE or SW being hottest by how active the Atlantic hurricane season. These are the La Ninas since 1990 by ACE Index. Pretty obvious where the biggest impact is, but the West/Central heat has downwind impacts for the East too. Relatively inactive (<160). Highly active (>160)

I mentioned in my winter outlook that I expected November to feature two distinct patterns, with a flip mid-month. Modeled that after August. You can see that the CFS has one of the two patterns I mentioned, using August. You can see the core heat in the Northwest with the South cold, like in the one part of the August pattern. In August, the cold in the West showed up later. If you're like me and think the CFS is much better at seeing the early month look, then the late August cold push may still be in there, but not visible yet to the CFS. These were from page 38 of my outlook - you can see it in the other thread.

This is the period most correlated to ACE nationally in La Ninas - basically always warm in the West when 160 or higher. Last year certainly was warm in the West for NDJ. The white areas are more variable, so last year only is a decent match to the West. ACE 160+, NDJ, La Nina: ACE <160, NDJ, La Nina. The last year like this was 2016-17, and it certainly matches the hot Southeast US look, although again the rest of the US is variable.

In general, La Ninas with ACE under 160 in the Atlantic tend to feature wetter conditions in the West in October, and overall for the cold season. It's nice to see Western October precipitation looking like 1974, 1984, 2016, rather than 1995, 2017, 2020, just as some examples off the top of my head. My main analogs were 1974 and 2017 for the winter - mostly because I doubt we'll be as wet as 1974, or as hot as 2017 in the West. As a blend though it seems pretty realistic given how the other factors are going, and I had a few other years in there to smooth out the strangeness of the blend. Under 160: ACE over 160:

ACE is kind of a big deal in La Nina for precipitation patterns in the West, especially in Nov-Jan, but you can already see the template setup in October. Years like 1995 with the record early Fall snows in the Rockies, super -WPO, and super ACE tend to follow the super-dry West template, while the lesser ACE years, like say 1984, look much more like 2016 and 2021. I'm looking forward to seeing 3,000 forecasts that have the western drought worsening though even though there are a lot of signs that this not that type of winter. 140 ACE La Nina: 180 & 225 ACE La Ninas:

Euro and GFS are completely at odds with moisture over the West over the next week or so. I think the Euro makes more sense personally, but we'll see soon enough.

I'm a big believer in matching precipitation patterns nationally when selecting analogs. You can decide for yourself if this is a good match or not. Can already see the effect of the Atmospheric River event in California even over a six month period. Locally, the wetness in SE NM and SW AZ with dryness in between was damn hard to match.

This a good example of why I think it's dumb to use climate models for seasonal forecasting. This is a one day change over 600 miles for the upper high in the Northwest Pacific for Novemeber. It's literally 180W / 50N one day, 165E / 50N another. If it can show a key feature moving 600 miles in a day, who the hell knows what it will show 10/31 when it will actually have some skill for November.

Roughly day 7 or 8 at this point - but nice to see the GFS / Euro at least occasionally showing something in the SOI crash +10 day range.

Actually think the first half of November may be fairly active. That 28 point SOI drop is showing up for 11/2 as a system for NM or CO. Then the big low south of the last one by Kamchatka on 10/20 should be something 11/6-11/10, and then we've been seeing recurring precipitation every 45-days (with cold) for three cycles now. Last cycle time was 9/30. So next time is likely 11/15 or so.

It's very early, but the GFS & Euro both had storms in NM/CO depending on the run around 11/2 as the SOI drop implied. Also, the GFS has a stormy period for the 11/6-11/10 window already - in line with the more southerly track of the 10/20 Kamchatka low.

Nino1+2 Nino3 Nino34 Nino4 Week SST SSTA SST SSTA SST SSTA SST SSTA 08SEP2021 20.8 0.1 24.7-0.2 26.6-0.1 28.4-0.3 15SEP2021 20.7 0.0 24.7-0.2 26.4-0.3 28.1-0.5 22SEP2021 21.2 0.5 24.7-0.2 26.4-0.2 28.1-0.5 29SEP2021 21.2 0.5 24.9-0.1 26.3-0.4 28.0-0.6 06OCT2021 21.0 0.2 24.7-0.3 26.1-0.6 28.0-0.7 13OCT2021 20.7-0.2 24.4-0.7 26.0-0.8 28.1-0.5 20OCT2021 20.3-0.7 24.2-0.8 25.9-0.8 28.1-0.6 09SEP2020 19.9-0.8 24.0-0.9 26.1-0.6 28.3-0.3 16SEP2020 20.1-0.6 24.1-0.8 26.1-0.6 28.2-0.4 23SEP2020 20.1-0.6 24.1-0.8 25.9-0.7 28.1-0.5 30SEP2020 20.0-0.8 24.4-0.6 26.0-0.7 27.9-0.7 07OCT2020 20.1-0.7 24.1-0.9 25.8-0.9 27.9-0.7 14OCT2020 20.5-0.4 24.1-0.9 25.6-1.1 27.8-0.8 21OCT2020 20.5-0.6 24.2-0.9 25.5-1.3 27.8-0.8 Solid basin wide look on the weekly data. With apologies to CPC, 25.9C is more like -0.6C for mid-October long-term (1951-2010 or even 1981-2010). To me calling last year a moderate La Nina is still bs - the event dropped below 25.5C for three months. Meaningfully below for one month. There are like 15 stronger La Ninas than that by coldest reading or by duration just since 1950. The peak last year was 25.28C in November. We're barely edging below 26.0C in Nino 3.4 in late October. https://www.psl.noaa.gov/data/correlation/nina34.data I'd expect this month to come in around 25.95C in Nino 3.4 shown below, v. the 25.46 in bold last October. 2020 27.15 27.12 27.76 28.18 27.66 27.39 26.99 26.26 25.89 25.46 25.28 25.44 2021 25.54 25.75 26.49 27.10 27.48 27.45 26.91 26.35 26.21 CFS currently looks a bit like a 1974/2017 blend for November. Those were my main analogs, but not the weightings I used for November. CFS still looks off to me though. Subsurface looks like it will be around -1.6 for October. It looks like it may have stopped cooling, but no reversal just yet. That's pretty cold - but 1983, 1988, 1998, 2010 are colder. When I recreate the subsurface for a three month period, you usually can only get one outcome if you match on the numbers and the trend. For Aug-Oct, you can get a cold national November match (1983 & 1984 is very close) or a very warm November match depending on what you use. Will be very curious to see how things go. My gut is 2017 blended with stronger events will produce the correct result. But cold Aug-Oct matches 1983, 1988, 2007, 2011, 2017, 2020 among others, if you filter by dropping subsurface, and similar readings. You can get wildly different national outcomes depending on how those years are blended. The SOI looks like it will be around +9 or +10 for October. That supports a look about half way between what the CFS has (mild SE, hottest SW/Plains) and what I had (mild West Coast and TX, somewhat warm elsewhere) based on Aug-Oct matches from 1931-2020. SOI does look pretty positive the next week or so - have to see if it goes well over 10.

This is probably something big for early November - crashes over 10 points are rare for a single day. This is nearly 30.

The huge rains dumping into the West shortly remind me of January 2021. The temperature profile is similar too nationally, +WPO, -NAO, but still very warm nationally outside the West. Sometimes it seems like we're still in the pattern from last year, but timing is off by 3-months. Of course if we were to continue down that road, you'd see the nuclear cold dump into the Plains in Nov or Dec. But I don't think that will happen, if for no other reason than the cold hasn't had time to build yet.

It's likely the time of year means the lows won't be as far south as last year at the same position. But the later we get into the season with the more southerly tracks, the more similar the tracks should be to the Bering Sea Rule idealized spot. The -PDO may also support a northerly track deep relative to normal, but not sure about that yet.

Date Tahiti (hPa) Darwin (hPa) Daily Contribution 30 day Av. SOI 90 day Av. SOI 23 Oct 2021 1010.35 1010.90 -22.18 11.18 8.13 22 Oct 2021 1013.86 1010.00 6.25 11.58 8.55 21 Oct 2021 1014.88 1010.10 12.18 11.38 8.66 20 Oct 2021 1016.08 1012.15 6.70 11.41 8.73 Some fun for me coming. Been ages since we've have an almost 30 point daily SOI crash. Longer-term, the 90 day SOI is still at weak La Nina levels (+8 to +12)

This is probably the simplest way to explain why I'm not in the Modoki La Nina camp. Right now, it is much warmer than last year by Peru. Last year, the cold there shifted West. This year, the body of "less cold" should shift West. The cold below the surface should come up to the east though. In general, there is a big trend to much more -IOD conditions (warmer near Indonesia, colder east of East Africa), and the -PDO especially - 2-5C colder by the West Coast, warmer east of Japan where the warm tongue is for the -PDO.

Some interesting things happening in the background: -NAO with a +AO. That's not real common. Still think it's interesting that people think this event is going to catch up to last year at the surface. When is that going to happen? It's not early anymore. There are no big areas of purple like last year to spread out. The development is also opposite of last year, the western zones seem to be warming a bit this year, while they were cooling at this time last year. This is still a relatively basin wide event with a weakness in the middle to me (around 120W).

This month is a good example of how useless the teleconnections are in certain periods. The October temperature profile matches well to an idealized +WPO look in the Pacific, and nothing like a -NAO look in the Atlantic. My view is the WPO beats the NAO with a hammer in the Sept-Oct and also May as an indicator. We essentially have the La Nina version of the +WPO look this month.

Some of the -ENSO Novembers following a +WPO/-NAO October include years like 1960, 1998, 2005 which broadly look like November on the CFS at the moment.

I'm not a huge fan of the bucketing for periods as long as Dec-Mar. A lot of the stronger ENSO events start with one form and then migrate to another. I'm much more interested in the similar start and similar finish v. a similar average look. I liked 2007 last year because it was very cold by Peru initially and then it gradually shifted to become very cold by Nino 4 as the east warmed. If you just looked at the average of 2007-08 you would miss that transition. Nino 4 is a relevant precipitation indicator in February - it'll be interesting if it's much warmer than last year. For what it's worth, when Accuweather speaks of the "severe" January or whatever, I think they're going with the TNI tendency (Nino 1.2 v. Nino 4 for stronger warmth/cold). When the TNI is positive, the east tends to be warm in January. TNI was positive last January. The +TNI years are the Modoki La Nina / East El Nino years, while the -TNI years are the Modoki El Nino / East La Nina years. (+TNI January: 1998, 2012, 2021, -TNI January: 2010, 2014, 2018). Issue is the -TNI years are much more common in El Ninos, and so the -TNI eastern cold is really just dominated by the PDO signal when you have a -TNI with +PDO, since east La Ninas are less common than Modoki El Ninos. I think there are 10 meaningfully -TNI, cold ENSO Januaries (Jan 1968, 1979, 1981, 1982, 1986, 1997, 2002, 2013, 2014, 2018), and at least 20 in warm ENSO years since 1950, so even with a -TNI in January (which I expect), I don't buy the correlation map below. https://psl.noaa.gov/data/correlation/tni.data