raindancewx

We'll see. Even from 48 hours ago, there was nothing like this depicted on the models: When I did my outlook, it seemed like 12/10 would have been the time frame for a big December system, but we seem to be getting a lot of things that happened similarly in 2007 at time frames that are 2-3 weeks off. There were big drops in the SOI late Nov and Dec 2007, but not all of them preceded big systems. It's definitely a decent indicator for low passages but not as reliable for actually identifying storms with...moisture. In 2011, it actually got so cold down here that a couple systems missed northern New Mexico because they were too far south, some of the things I look at are somewhat similar to 2011, have to watch for that too.

I wanted to give an update on this idea because I consider it theoretical/experimental with so few years. It appears to be working. The low sea ice extent cold-ENSO years are much closer to November 2020 (another low-sea ice cold ENSO), and also much closer to the CFS idea for December 2020 and the +NAO November La Nina look for December than the higher sea ice years. The higher sea ice years are too cold in the East. The big area of very warm November conditions has appeared in the right spot (AZ to Michigan) at the right magnitude, with a cool spot by the NW. Not perfect, but close, and definitely closer than the higher sea ice years.

We've actually been getting pretty decent snowstorms this Fall, hopefully the big warm ups that have melted most of it are done for a while. My winter outlook had 20 inches of snowpack at Taos Powderhorn entering 12/1, we may actually beat that with the coming storms.

One year I've been looking at a lot lately in 1959. The NW Pacific is cold that year, but you have a very warm NE Pacific with a pretty cold ENSO event. If you blend in years to warm up the NW Pacific with 1959 it's not that hard to get a map resembling the oceans today but less extreme. More importantly though, early December 1959 is dead on to the CPC forecast. That map has issues for the La Nina intensity, and the far northern oceans are different. But the MJO / tropical zones are are in the correct spots, the little SE to NW warm zone from India to Australia west of a cool patch south of Indonesia is there, the cold ENSO and cold tropical Atlantic are there. The warm patch into the NE Pacific is too far SW, but the real issue is that cold spot in the NE Atlantic. If you try factor in the northern oceans, this probably a bit better with 2011 in there to fix the north Atlantic in particular (it has the same cold blotch by Greenland as 2020), while 2008 fixes the NW Pacific.

NAO in November looks like it finishes around +1, essentially splitting the difference between 2007 and 2011, in terms of recent +NAO Novembers. The designation used here is top third for 1950-2019 monthly readings in November. Positive NAO November La Ninas are pretty rare - but they look a lot like what the CFS is forecasting currently for December, but with less insane warmth everywhere. The right image is also close to the "lowest sea ice extent" cold ENSO composite of 2007, 2011, 2012, 2016. One thing I wanted to mention - and it could be a coincidence - the +NAO November La Nina all evolve to much warmer ENSO events the next winter including 1949-50 where I didn't have NAO data but matched the pattern. The neutral November NAO La Nina winters vary a lot with years like 1954 and 2017 both included, but overall look closer to a cooler version of the pattern on the right. March still fits the pattern of November being a good indicator too -

How did you all do in December 1959? The CPC outlook for week one of December is basically a spatial repeat of that week. Very snowy month here.

The subsurface reading for November 2020 should be around -1.1. If you blend in the subsurface reading for Sept-Nov, it looks just like November 2020. The right image is how December would look. I'm assuming a lot of the reds down here burn off with the cooler highs this week, and the map of 2020 moves toward the subsurface blend.

Back to the prior level after the hiccup last week. Nino 4 didn't change at all though. Nino 1.2 is now closer in 2010 than in 2007. Nino 4 is still pretty warm for cold the middle zones are currently. Nino 1.2 warmed up in 2007 rapidly in December and should come back as a better match than 2010. Right now, 2011 is closer than 2007 or 2010. Nino1+2 Nino3 Nino34 Nino4 Week SST SSTA SST SSTA SST SSTA SST SSTA 07OCT2020 19.5-1.2 23.4-1.5 25.5-1.2 27.8-0.8 14OCT2020 19.6-1.2 23.6-1.3 25.3-1.4 27.8-0.9 21OCT2020 19.9-1.1 23.8-1.2 25.3-1.4 27.8-0.8 28OCT2020 20.0-1.1 23.5-1.5 24.9-1.7 27.9-0.7 04NOV2020 20.3-1.0 23.6-1.3 25.1-1.5 27.8-0.8 11NOV2020 21.2-0.3 24.1-0.9 25.7-1.0 27.9-0.7 18NOV2020 21.0-0.7 23.6-1.4 25.2-1.5 27.9-0.7 10OCT2007 18.8-1.9 23.3-1.6 24.9-1.8 27.7-1.0 17OCT2007 18.6-2.2 23.5-1.4 25.3-1.4 27.9-0.7 24OCT2007 19.2-1.8 23.5-1.4 25.3-1.4 27.8-0.8 31OCT2007 19.7-1.5 23.2-1.8 25.2-1.5 27.8-0.8 07NOV2007 19.3-2.1 23.0-2.0 25.0-1.6 27.5-1.1 14NOV2007 19.2-2.3 23.2-1.7 25.2-1.5 27.3-1.3 21NOV2007 19.8-2.0 23.2-1.8 24.9-1.7 27.1-1.5 05OCT2011 19.8-0.8 24.1-0.8 25.7-1.0 27.7-0.9 12OCT2011 19.7-1.0 24.1-0.8 25.8-0.9 27.9-0.8 19OCT2011 20.0-0.9 23.9-1.1 25.8-0.8 28.1-0.6 26OCT2011 21.2 0.2 23.8-1.1 25.4-1.2 28.0-0.7 02NOV2011 20.5-0.8 23.9-1.1 25.6-1.0 27.9-0.8 09NOV2011 20.5-0.9 23.9-1.1 25.7-0.9 27.9-0.7 16NOV2011 20.5-1.1 23.8-1.1 25.6-1.0 27.9-0.7 06OCT2010 18.7-1.9 23.2-1.7 24.8-1.9 27.1-1.6 13OCT2010 18.9-1.9 23.0-2.0 25.1-1.6 27.1-1.6 20OCT2010 19.1-1.8 23.2-1.7 25.1-1.6 27.0-1.7 27OCT2010 19.8-1.3 23.6-1.4 25.2-1.5 27.0-1.6 03NOV2010 19.7-1.6 23.4-1.6 25.2-1.4 27.0-1.6 10NOV2010 19.5-1.9 23.5-1.5 25.2-1.4 27.2-1.5 17NOV2010 20.2-1.5 23.5-1.5 25.0-1.6 27.1-1.5 24NOV2010 20.6-1.3 23.3-1.7 24.9-1.7 26.9-1.7 To me it looks like the subsurface is continuing to warm too, as the warmth below the western zones has had some success moving east recently.

"La Ninas are warm and dry in the Southwest". Well... My analogs had 0.40" total precipitation in November, with a bit of snow. So it'd be nice if this verified. The timing/precip amounts look fairly similar to one of the late November storms in 2019. That doesn't really surprise me - in the records here heavy snow in November is highly clustered in short periods, and then it disappears for decades. So would not be shocked if we see a big snow storm. Still like the 12/1-12/3 period for a big storm too given the huge SOI crashes of late.

During the 2007-08 La Nina, you had several huge SOI crashes that preceded some big storms in the West. The crash recently is reminiscent of this period in 2007 particularly - although somewhat earlier. It's worth noting for those who like 2010, that La Nina had almost no -SOI readings at all from Sept-Dec, while this year has seen them semi-regularly, as in 2007. Think you have to assume the subtropical jet won't be super weak despite the La Nina strength. Date Tahiti (hPa) Darwin (hPa) Daily Contribution 30 day Av. SOI 90 day Av. SOI 23 Nov 2020 1010.25 1008.60 -7.83 6.36 7.89 22 Nov 2020 1010.60 1008.90 -7.51 6.66 7.94 21 Nov 2020 1011.63 1008.30 2.86 7.21 8.15 20 Nov 2020 1013.38 1007.85 16.86 7.44 8.23 19 Nov 2020 1014.15 1008.10 20.17 6.99 8.14 2007 325 1011.01 1007.15 6.23 2007 326 1010.69 1006.85 6.11 2007 327 1012.06 1005.65 22.46 2007 328 1014.19 1007.00 27.42 2007 329 1013.41 1009.25 8.14 2007 330 1012.05 1009.80 -4.01 2007 331 1011.34 1007.85 3.88 2007 332 1012.91 1006.95 19.59 2007 333 1013.66 1009.50 8.14 2007 334 1013.05 1010.90 -4.65 The 332 to 334 represents 33 to 31 days before the end of the year, i.e. 11/29 to 12/1. The rule for the SW is a storm will appear ten days after - so 12/10-12/11 2007 saw 150% of normal (monthly) precipitation for Albuquerque. Will be very curious to see if we see a major storm in the 12/1-12/3 period this year. The big drops that go positive to negative are usually the strongest storms out here.

The years that are similar to snow this Fall since 1930 have generally been good for the West after the Fall too. A blend of 1947/1996 looks a lot like 2007, which I think will be a decent analog for snow the rest of the way (it hasn't been so far). The three days ending November 23 have each seen big SOI crashes (10+ points) in a two period - have to watch 12/1-12/3 for a big system or systems.

Eyeballing past years, I'd say the top snowfall matches to Sept 1-Nov 20 2020 are 1946, 1947, and 1985, with 1996 and 2011 the best matches of the past 30 years. Those are some pretty good snow years out here, except for 1946.

My issue with the 1970s La Ninas, almost all of which were cold here and/or snowy here, is you have a much colder North Atlantic and North Pacific, and generally low ACE values. 1970 and 1975 are both very low ACE years particularly for a La Nina. Atlantic ACE is loosely correlated with the AMO so that makes sense. Outside the NW US, it really does seem like the Atlantic drives patterns in La Nina winters, unlike in El Ninos where the Pacific matters far more. I'm not a huge fan of 1999 either. I'm actually pretty curious to see how November finishes because it's pretty tough right now to get a good spatial match for it. The six years I mentioned as good matches through 11/15 are really not all good matches anymore. 1978 turned very cold by this point in the Northern & Western US as an example. Here is the same analysis but six days later. Here is a look at the unweighted six year blended highs - 1964, 1975, 1978, 1987, 2011, 2015 for ten US cities 11/1-11/21: Boston: 58.0F v. (54.0+63.9+54.5+53.8+59.0+58.6)/6 --> 57.3F Richmond: 67.2F v. (69.3+72.6+67.0+64.6+64.1+65.8)/6 --> 67.2F Jacksonville: 76.7 (76.4+76.3+75.2+73.2+74.0+80.2)/6 --> 75.9F Detroit: 58.7F (58.0+61.1+54.1+53.2+57.0+59.5)/6 --> 57.2F Chicago: 60.0F (58.3+62.0+55.8+54.4+54.5+57.9)/6 --> 57.2F St. Louis: 65.7F (63.4+64.7+60.0+61.0+62.8+63.5)/6 --> 62.6F Billings: 50.8F (46.4+51.2+33.7+54.0+42.0+48.3)/6 -->45.9F Albuquerque: 64.8F (57.1+63.4+62.0+60.0+57.7+57.6)/6 --> 59.6F San Diego: 73.3F (68.1+69.7+68.9+71.0+66.6+73.5)/6 --> 69.6F Seattle: 52.7F (46.5+52.0+48.2+55.8+49.4+51.4)/6 --> 50.6F The ten city average error jumped from 1.6 degrees to 2.2 degrees - pretty big increase for such a short period.

Date Tahiti (hPa) Darwin (hPa) Daily Contribution 30 day Av. SOI 90 day Av. SOI 22 Nov 2020 1010.60 1008.90 -7.51 6.66 7.94 21 Nov 2020 1011.63 1008.30 2.86 7.21 8.15 20 Nov 2020 1013.38 1007.85 16.86 7.44 8.23 19 Nov 2020 1014.15 1008.10 20.17 6.99 8.14 18 Nov 2020 1014.69 1008.65 20.10 6.27 8.18 Another pretty massive crash in the SOI. That 24 point crash 11/20 to 11/22 is probably going to be a big, cold low around 12/1-12/3 over the Southwest and/or Colorado/Utah. The mid-October SOI crash was similar in magnitude - and the storm came through the SW 10/25 to 10/28. 15 Oct 2020 1011.26 1009.50 -7.29 11.94 8.69 14 Oct 2020 1012.74 1010.20 -2.26 12.44 8.84 13 Oct 2020 1014.49 1010.00 10.31 12.58 8.77 I find anecdotally - I was starting to research this but I lost most of my non-essential research the other day when my computer died - the biggest, coldest, lows - the closed lows typically - tend to come after a big SOI crash that flips positive to negative. The crashes that go negative to more negative are usually super wet, and the crashes that go positive to less positive tend to be colder but moisture starved. It seems like the big crashes from positive to negative incorporate a big northern stream system that can tap into the subtropical jet essentially.

My July-June snow anomaly map looks OK so far. Canada border with Idaho/WA to NW NM/Western Colorado, Midwest, and Northern New England were favored zones.

This is smoothed out and not particularly precise, but the Midwest Regional Climate Center has a pretty snowy fall to date for the US. It's kind of weird since it is also a pretty warm Fall overall, and not particularly wet. I had about 8.5 inches of snow in October (it was 7.5" the first two days, and I had to rush out to work the third day it snowed before I could measure), so it's a bit high in Albuquerque. I had an area from Western CO and NW New Mexico to the WA/ID border with Canada snowier than average (like most La Ninas, but a bit SE), and then northern New England and the Midwest snowier than average. Looks OK so far. Not sure what is going on with the snow in the South that is shown. I'm expecting the system shown in a week or so on the European to be a better system than these weak/moisture starved systems moving through the next few days.

SOI crash verified - Date Tahiti (hPa) Darwin (hPa) Daily Contribution 30 day Av. SOI 90 day Av. SOI 21 Nov 2020 1011.63 1008.30 2.86 7.21 8.15 20 Nov 2020 1013.38 1007.85 16.86 7.44 8.23 19 Nov 2020 1014.15 1008.10 20.17 6.99 8.14 18 Nov 2020 1014.69 1008.65 20.10 6.27 8.18 17 Nov 2020 1014.71 1009.05 17.69 5.38 8.25 16 Nov 2020 1014.73 1010.05 11.45 4.53 8.37

The European has been showing a big precipitation event around 10 days from now. Would tie in well with the big time expected SOI crash today or tomorrow. The European has also been severely underestimating the current MJO wave. November 2000 has been very similar to the MJO wave this month. So we'll see if that continues. The big magnitude in phase 2 in 2000 was about two days earlier than this year, but it continued through phase 3 pretty easily.

This is what I get looking at non-El Nino Decembers following a November with a very positive NAO (top 1/3 +NAO for 1950-2019):

My idea for November has been that if we're to get a big storm it will be right at the end of the month. But it may actually be the first week of December. The European has been showing a pretty massive reversal in the SOI around 11/20. If we go from +10 or +20 to -10 or -20, you'll see something out here around Nov 30-Dec 2. Right now, there is a huge high by Tahiti, but it's going to be replaced by a pretty strong low. Tahiti going from being at the edge of a 1039 mb high to a good storm moving through in essentially two days. This may not actually be the peak of the transition but we'll see soon enough what the Australians come up with for the SOI.

The European has been showing a big SOI crash (big high by northern Australia, big low by Tahiti) around 11/20 that lasts for a days. Most recent SOI value was over 20 - the highest in a while - so we could see a 20-40 point crash in a short period that should shake everything up quite a bit around 12/1. The subsurface actually warmed this week too, it wasn't just a surface warming - still similar to 2007 in that regard which weakened in December from an earlier peak and then briefly rallied stronger in January. We're still not particularly close to the very highest Atlantic ACE seasons, but the composite at 180 ACE in a La Nina for 1931-2020 is not exactly a cold look. It's interesting though - four of the five "cold Neutral" years in the 140-220 range are still very much a like the 80-160 ACE La Nina composite. A lot of the years on the left also have extremely high solar activity, which we don't have this year. So if you take the cold-ENSO, low solar, similar ACE years, you get this look: Here are some strengths for the blend: 1932: Only other year on record with a category five hurricane in November in the Atlantic. (Cuba Hurricane of 1932). Snowed into the valleys of the Southwest in October. Fairly similar (but much colder) look to October (coldest Plains/Central). 1964: Delta was similar to Hilda in October, and the first half of November looks a lot like 1964 high temperatures nationally. Followed a weak El Nino like this La Nina is. 1996: Snowed into the valleys of the Southwest in October. Can't really think of any other particular similarities off the top of my head. This was actually the most recent "Major" snowstorm for Albuquerque in October, with several inches. Actually, the way the Jamstec depicts Summer next year in the tropical Pacific is very similar to how the 1997 El Nino developed - so that's another feature in favor of the year. 2008: Big Gulf of Mexico activity like this year, and some months have similar spatial patterns for temperatures (notably not great in Oct-Nov which were very cold in the SE). Pretty good QBO match. 2010: Bad match for the Gulf of Mexico hurricane activity. Similar QBO, followed an El Nino. Very different for blocking patterns and La Nina development. Not a fan of the year overall. 2016: Similar QBO, followed an El Nino. Main issue is the cold patch in the north Pacific (+PDO), and warm Nino 1.2. Also much weaker La Nina. Matthew was the first landfalling October hurricane in a while on the US mainland (Sandy was subtropical). The 1961-62 winter is a good QBO match, with similar types of Atlantic hurricane activity, and similar on NAO trends in the predictive periods for winter. But it had higher solar activity - but it looks almost identical to the six year composite. The six year blend actually looks a lot like November (although too cold).

Nino1+2 Nino3 Nino34 Nino4 Week SST SSTA SST SSTA SST SSTA SST SSTA 07OCT2020 19.5-1.2 23.4-1.5 25.5-1.2 27.8-0.8 14OCT2020 19.6-1.2 23.6-1.3 25.3-1.4 27.8-0.9 21OCT2020 19.9-1.1 23.8-1.2 25.3-1.4 27.8-0.8 28OCT2020 20.0-1.1 23.5-1.5 24.9-1.7 27.9-0.7 04NOV2020 20.3-1.0 23.6-1.3 25.1-1.5 27.8-0.8 11NOV2020 21.2-0.3 24.1-0.9 25.7-1.0 27.9-0.7 Pretty nice little warm up this week just about everywhere at the surface. Now well behind 2007 and 2010 for this week. Unlikely to last though. 10OCT2007 18.8-1.9 23.3-1.6 24.9-1.8 27.7-1.0 17OCT2007 18.6-2.2 23.5-1.4 25.3-1.4 27.9-0.7 24OCT2007 19.2-1.8 23.5-1.4 25.3-1.4 27.8-0.8 31OCT2007 19.7-1.5 23.2-1.8 25.2-1.5 27.8-0.8 07NOV2007 19.3-2.1 23.0-2.0 25.0-1.6 27.5-1.1 14NOV2007 19.2-2.3 23.2-1.7 25.2-1.5 27.3-1.3 06OCT2010 18.7-1.9 23.2-1.7 24.8-1.9 27.1-1.6 13OCT2010 18.9-1.9 23.0-2.0 25.1-1.6 27.1-1.6 20OCT2010 19.1-1.8 23.2-1.7 25.1-1.6 27.0-1.7 27OCT2010 19.8-1.3 23.6-1.4 25.2-1.5 27.0-1.6 03NOV2010 19.7-1.6 23.4-1.6 25.2-1.4 27.0-1.6 10NOV2010 19.5-1.9 23.5-1.5 25.2-1.4 27.2-1.5

The North Pacific actually looks like it is starting to respond to the La Nina with a lot of cooling in recent days. Would also say the PDO is trending toward a more normal looking negative phase. It looks to me like the centering of the La Nina will continue to slowly shift West for a while. Don't really expect eastern Nino 3 or Nino 1.2 to cool back down again for a while. One of the odder things about this even is how little the North Pacific has changed to date. I included 2019-20 as an analog almost solely because I suspected the little circled area would show up (presumably from high pressure persistence - I'd have to look).

A quick look at each Nov 1-15 from 1950-2019 shows that the current spatial look to November is fairly rare in that period. I only found six good matches nationally - 1964, 1975, 1978, 1987, 2011, and 2015. You're looking for something like this, but ideally warmer than 2011 was. The best match may be 1964 overall. Here is a look at the unweighted six year blended highs - 1964, 1975, 1978, 1987, 2011, 2015 for ten US cities 11/1-11/15: Boston: 59.9F v. (55.2+65.3+56.1+54.6+60.1+60.9)/6 --> 58.7F Richmond: 69.8F v. (70.2+72.9+68.7+66.6+65.0+66.1)/6 --> 68.3F Jacksonville: 78.7F v. (75.2+76.6+74.9+74.7+72.7+81.1)/6 --> 75.9F Detroit: 61.9F v. (64.0+61.3+58.7+55.3+59.4+60.9)/6 --> 59.9F Chicago: 62.9F v. (64.0+61.3+58.7+55.3+59.4+60.9)/6 --> 59.9F St. Louis: 67.3F v. (71.7+65.3+65.9+65.1+65.6+65.7)/6 --> 66.6F Billings: 51.0F v. (50.0+58.2+42.5+56.5+45.1+51.0)/6 --> 50.6F Albuquerque: 63.0F v. (61.1+66.7+63.7+61.9+56.9+58.7)/6 --> 61.5F San Diego: 72.7F v. (70.3+70.9+69.3+70.3+67.9+73.1)/6 --> 70.3F Seattle: 52.7F v. (48.3+53.7+50.3+56.5+51.2+52.3)/6 --> 52.1F The blend has a cold West look to December as a composite. The ten city average "error" for the Nov 1-15 blend is about 1.6 degrees. I find blends that close over a large area of the US usually hold for a little bit - but we'll see.

Cold morning lows have been a bit ahead of the analog schedule (black v. brown) so far for Albuquerque. Still behind last year though. It's a shame we didn't hit 100 lows <=32F last year with how cold in got in Oct-Nov. But we had super warm lows in March and barely any lows <=32F in Spring.