raindancewx

The GFS run from Tuesday was honestly better for this time frame than runs of the recent days. This is the most recent five day period depiction on the GFS and the Canadian: The Canadian is probably too optimistic but I like to use it as a "bust up" ceiling for the high end of what is possible. A lot of this is Thursday-Saturday, so not exactly in la-la model land anymore, but the details are still going to change.

I'm a bit surprised there hasn't been more snow in the red circled area. That's my guess for the next area to fill in a lot.

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 25NOV2020 21.0-1.0 23.7-1.3 25.3-1.3 27.9-0.7 02DEC2020 21.8-0.5 24.4-0.7 25.5-1.1 27.6-1.0 We're going to a Modoki La Nina event if the structure of this week keeps up. You have Nino 4 likely to take over as the coldest zone by anomaly as soon as the next few weeks, as Nino 1.2/3/3.4 warm (probably aren't really as weak as this week on a monthly basis though). If you look at early Dec 1997, there is at least a passing resemblance to the early Dec 2020 look in the US, with Nino 1.2 much warmer (relatively) than the western zones.

GFS and Canadian are different, but the NAM looks like the Euro to some degree. The northern stream system is more of a mess at this point, but still expect some snow for Colorado.

You're the one who has been expecting an east-based La Nina. Good luck with that. Trends have been running opposite for weeks now. The plume moves from majority -0.5C or lower through March, to majority above -0.5C in April. That's the end of the La Nina on the Euro. Whether it's fast by a month, or slow by a month, doesn't really matter. I had the event peaking in Nov/Dec at the surface, Oct/Nov at the subsurface, that's still at least possible.

Once the system is over the waters west of Los Angeles and the models see how much moisture it has, I think you'll see rapid re-conciliation toward one solution. Curious to see what the Euro has in a few minutes though. The members above, 2,3,5,10,11,19 seem about right in terms of that "SOI rule" I use. Actually think the ICON has about the right idea on the last run, it goes to the Gulf of California, crosses SE Arizona, runs north north east, loses a lot of moisture, but western NM, SW Colorado get good moisture - rain and snow, southern NM gets rain. Then another system comes in with snow but less moisture.

From 1931-32 to 2019-20 there is no year in Philadelphia over 30 inches of snow (Oct-May basis) if it doesn't snow by 12/20. GFS currently has nothing through 12/20. The average for years with a first snow after 12/20 is 14.5 for Philadelphia. My outlook back in October assumed La Nina would peak in November or December - that still looks right to me. Nino 4 should be the coldest zone in January, given the warming forecast in 1.2, 3, 3.4 while Nino 4 cools longer. The model has essentially a Modoki La Nina for a brief period. A cold Nino 4 in January (say -1.0C) would be a strong wet signal for Ohio, Michigan, Kentucky and Indiana. Even though the south is strongly favored for warmth.

Euro says this La Nina ends in March in Nino 3.4. Nino 4 will continue to strengthen into January, but it thinks Nino 3.4 is done.

You jinxed it. One for me - One for Colorado. (I really think the models may try to phase these somewhere).

It looks like Logan has gone over to snow at 33 degrees in the past half hour or so.

Warm, wet and stormy has been the idea for December for a while now. Keep the snow mostly north of New York City like I had in my outlook, and I'll be happy. Further north you go, the more you get generally, not just overall, but relative to averages. That's been the idea for a while. NAO has gone negative btw -

The 12/10-12/12 periods needs to be watched. The GFS, Canadian, Euro all at least have precipitation for NM and CO in that time frame.

We've now had multiple instances since October where Boston and north do well for snow despite a generally warm pattern. That was one of the ideas in my outlook for the northeast. The 'normal' line for snow should remains between NYC & Boston if I did it right. I know in 2007-08, snow totals were not that good for NYC and Philly and south, but pretty solid for New England. All that said, Boston itself hasn't had a flake of snow just yet at the official site (as of 3 pm) with the current system. I'm sure parts of the Southwest will finish very dry for winter, but I'm still not convinced northern New Mexico, north TX, and southern Colorado will be that dry. The GFS has also been trending this feature north with subtropical origins. There were substantial SOI crashes around 12/1 which usually precedes a storm or subtropical impulse over the SW in 10 days. Some hint of a northern stream feature with some moisture in the 12/10 to 12/12 time frame too.

CPC really isn't that optimistic on a cold look for the northern United States through mid-month, and it's already warm in those areas generally. They have warmth building even into the South too. My outlook didn't have the NE that warm, and even in the Southeast I wasn't super hot in December, generally +2 to +4 South, and +1 to +3 north. Will be curious to see how these do.

2007 and 2020 have been very similar all year on the western side of the La Nina. Don't really see that changing anytime. The CPC had Nino 3.4 at 25.31C (-1.19C v. 1951-2010, but much colder for the last 30 years) and Nino 4 as 27.85C (-0.54C v. 1951-2010, but much colder for the last 30 years). The ( ) includes the 60-year anomaly in Nov with the recent stronger La Ninas since 2000. Nov 1.2 3 3.4 4 2007 19.92C (-1.51C) 23.48C (-1.37C) 25.17C (-1.32C) 27.61C (-0.78C) 2010 20.34C (-1.09C) 23.59C (-1.26C) 25.06C (-1.43C) 27.11C (-1.28C) 2011 21.09C (-0.34C) 23.98C (-0.87C) 25.52C (-0.97C) 27.80C (-0.59C) 2020 20.86C (-0.57C) 23.88C (-0.97C) 25.31C (-1.18C) 27.85C (-0.54C) A blend of 2007/2011 is pretty close for the four zones in November: 20.50C / 23.70C / 25.35C / 27.70C Both 2007/2011 had +NAO looks too. I'd call the November La Nina look "central" looking as opposed to basin-wide (2010), east based or west based since Nino 4 and Nino 1.2 are nothing special.

QBO rose to +11 in November. 2020 -2.51 -3.20 -4.36 -5.03 -4.86 -2.78 0.34 4.78 7.95 10.80 11.15 -999.00 Still think is the decent blend. The QBO really doesn't get much higher than it is now, but it misbehaved to get here (really should be negative), so maybe we'll bust through that +16 barrier this year. Doubt it though. Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov 1961 -5.47 -0.62 0.54 2.82 6.88 7.96 6.69 5.60 6.02 7.59 8.74 2010 -16.02 -16.98 -19.68 -23.57 -26.28 -25.05 -9.84 1.45 6.58 10.83 12.16 2016 9.34 6.77 3.16 0.64 2.37 3.86 6.25 10.07 10.48 12.83 14.16 2016 9.34 6.77 3.16 0.64 2.37 3.86 6.25 10.07 10.48 12.83 14.16 2016 9.34 6.77 3.16 0.64 2.37 3.86 6.25 10.07 10.48 12.83 14.16 Blend 1.31 0.54 -1.93 -3.77 -2.46 -1.10 3.12 7.45 8.81 11.38 12.68 2020 -2.51 -3.20 -4.36 -5.03 -4.86 -2.78 0.34 4.78 7.95 10.80 11.15 Trend down down down up up up up up up up Timing wise, 2016 is still a better match than 2010 in terms of the East (-)/West (+) QBO positioning and trend.

This is roughly how we're doing locally - A lot more snow for the northern and western areas of town today. I had a dusting, the official site had nothing. I was at 7.5 inches with the October snow before the final inch or so came in and I couldn't measure it since I had to drive to work. But probably close to 9 inches at my place this season. Average for this part of town is around 11 inches.

The northern oceans aren't a bad match to 2013, but there are still a lot of issues with that year. The La Nina, solar activity, the Summer/Fall progression for US weather, the two hurricane seasons are completely different, sea ice extent is far lower, and 2020 follows several warm ENSO years while 2013 follows several cold ENSO years. Can't really see blob similarities over riding all of those differences.

I'm aware of the research, but it's more of an Eastern New Mexico and east thing than for the Rio Grande Valley where I am. We do get a lot of surprisingly bad large hail events in New Mexico. I've had to get my roof and windshield fixed from hail damage several times in the past decade. The SOI crash from 10 days ago (11/21-11/23) more of less verified here with widespread light snow bands over Northern New Mexico. Missed the airport, but I had a dusting. Some areas of town had four inches or so. This is the West Side of Albuquerque. North of town in Rio Rancho A lot of the mountain ski resorts should be fine when they open. I know Taos and some of the other resorts have a good base of mostly natural snow. At 11,000 feet up, the Taos Powderhorn mountain observations showed 26 inches of snow pack today, very similar to the strong Fall starts in 2013, 2015, 2018 and 2019, all 25-29 inches. I mention the snow for a couple reasons. The La Nina snow signal is "bad" - usually in the entire Southwest. But just about all of New Mexico is running well above average. The West Side of Albuquerque had 8-14" in October, with 2-4" with this storm. They average less than the airport (9.6"), more like 6 inches. Where I am, it's more like 4-8" in October, 0-1" with the current system, and the average is closer to 12" or so. Santa Fe had 1" in September, 4-8" in October, 1-3" in November, and now 2-4" in December against 22" or so long-term. So a lot of places are already nearing their annual snow averages. In the mountainous areas, towns like Chama and Red River get well over 100 inches with good long-term records and are at least 30-35% of the way to their final averages already, even though they'll keep seeing snow into May most years. I find New Mexico does well in La Ninas when they stop developing or start to weaken, but also about 1/3 of La Ninas that are average to good for snow here: 1970, 1971, 1973, 1974, 1983, 1984, 1988, 2000, 2011, 2016. I'm looking at those years more lately, a lot more than the one third of very bad La Ninas out here (1933, 1950, 1955, 1975, 1995, 1999, 2005, 2008, 2017). The 1981-2010 baseline is ~26.75C, so the 1.4C depicted here implies 25.35 or so November. We'll see what the CPC reading is when ONI updates this week. For 1951-2010, the November average is 26.5C - so this event is still not that strong by historical standards. It's much more 2011 than 2010 right now. My winter forecast assumed a 25.5C La Nina overall for Dec-Feb, with Dec coldest of the three months by raw SSTs and Feb warmest. Looks OK so far. Generally, the La Ninas with a warmer Nino 1.2 relative to 3/3.4/4 are better here. So the depiction of the Canadian (shifting West) matches with the observations that this event is not really East based despite what DT and some of the other forecasts I've seen imply. The European initialization has even Nino 4 colder than Nino 1.2, for the actual winter, both were -0.8C for November. I've liked 2007 for a while because it started east-based in early Fall, but ended up coldest in Nino 4 for a while late winter and spring. You can compare the structure to 2017-18, when you had Nino 1.2 go near 0 to -1.5 in December - way colder than the other zones. The current event is far more likely to see additional cooling in Nino 4 while Nino 1.2 warms a lot.

The airport of course got literally nothing. But areas north and west of it in the metro did very well overnight. So that SOI crash from 11/21-11/23 did well here. I had a dusting.

Let's try this again: There was another big SOI crash today. As far out as it is, the three models I look at all have a day ten storm tapping subtropical moisture. Are they going to be right, or even close this far out? No. But...this is the first time they've all had something depicted that far out since the October storm. Date Tahiti (hPa) Darwin (hPa) Daily Contribution 30 day Av. SOI 90 day Av. SOI 2 Dec 2020 1014.81 1008.05 15.78 8.74 7.73 1 Dec 2020 1014.91 1007.10 21.23 8.99 7.70 30 Nov 2020 1013.51 1006.20 28.18 9.24 7.69 There was an associated SOI drop in this time frame in December 2007 ahead of a big storm. 2007 332 1012.91 1006.95 19.59 (Nov 28) 2007 333 1013.66 1009.50 8.14 (Nov 29) 2007 334 1013.05 1010.90 -4.65 (Nov 30)(-23 in two days) 2007 335 1012.80 1010.30 -6.33 (Dec 1) (-15 in two days) Ten days later in Albuquerque: Date Hi Lo Mean Dpt HDD CDD Precip Snow 2007-12-10 40 32 36.0 -0.7 29 0 0.49 T 0 2007-12-11 43 33 38.0 1.5 27 0 0.24 0.3 0 Too early to expect anything useful from the models, but it is rare to see something on all three so far out here. The GFS has actually had something around 12/11 for a while already...but I had been ignoring it.

The PDO is negative. It's not speculation. https://www.ncdc.noaa.gov/teleconnections/pdo/ 202001 -1.40 202002 -1.47 202003 -1.75 202004 -1.32 202005 -0.51 202006 -0.76 202007 -0.89 202008 -1.32 202009 -1.02 202010 -0.58 Warm North Pacific does not mean +PDO. The blob idea as a unique feature is the most over rated idea of seasonal forecasting in the past decade. Same orientation in the Fall last year and ended up with a very warm winter. The Fall pattern wasn't even that different overall despite completely different tropical patterns. The Fall this year was hot west/east, cold central. Last year had more cold West, but not that different and presumably a lot of that is how close the North Atlantic/North Pacific look.

These are likely the closest La Nina matches to November 2020 overall: Blend Nino 4 Nino 34 Nino 3 Nino 12 Match 1971 27.71 25.56 23.79 20.89 0.47 2011 27.80 25.52 23.98 21.09 0.49 1956 27.89 25.56 23.77 20.59 0.61 1962 27.90 25.75 23.98 20.78 0.75 1995 28.11 25.60 24.04 21.37 1.02 1984 27.79 25.52 24.11 21.52 1.06

I actually don't think that Euro storm is going to come back as depicted unfortunately. The GFS has had something similar a bit later though. The SOI thing I've mentioned - that's the systems now. The crash was 11/21-11/23, and the rule is you wait ten days. It more or less did work as it is snowing across our northern mountains pretty heavily (really squalls with low qpf snow). There is a low over the area in the correct time frame too. But the NAM and HRRR were hinting at snow even down here earlier today. There is a winter weather advisory out, and the local NWS learned their lesson this time, waiting for the snow to actually develop before issuing an advisory. I want to see how December goes, but I find replicating July-December precipitation patterns is a good predictor for Jan-June. So if this holds up, there is a pretty strong precipitation signal for January here. Each blue period is wetter than average. The 12/1-12/5 high for the city as currently forecast looks ~top 20 for cold for the past 100 years. So some cold and some snow isn't a terrible way to start of a La Nina down here. I'm much more concerned about the Spring than the Winter for moisture. December has a bunch of ways it can be wet regardless of the outcome the next ten days. MJO phase five is usually pretty good in December, La Nina rapidly weakening would be good, another SOI crash could help. I'm a little bit optimistic for March too, just because every year we've seen snow in October in the city has seen snow in March. The years with October snow have all seen storms come through in the time frames we've seen them this year. The weird pattern of a lot of early cold days is unusual too (highs <=55), but it has some similarities to 1936 when I looked.

When I looked at all the years after a strongly +NAO November for December, I think there were only 2/23 from 1950-2019 with a warm West / cold East look. The most common outcomes were warm everywhere, warm East/cold West, and then cold South/warm North was next most common. Some weird mixed up patterns in there too. If you look at the current CPC 6-10 and 8-14 analogs, a lot of the +NAO November years show up. Forgetting the model depictions, when I looked at Boston, Chicago, Minneapolis and Billings, temperatures looked generally +5 to +10 for 12/1-12/5. So the December 2000 and December 2010 looks for extensive and severe eastern cold are very unlikely. Boston was mid-60s today for instance. Even in the South though, this first five day period has some warmth - Jacksonville has some 70s. So it's not super hard to see how the models came in warm for the month if this is the cold part of the month.