raindancewx

https://www.americanwx.com/bb/topic/53528-winter-2020-21-discussion/page/34/?tab=comments#comment-5679938 I don't have a way to visualize it overall, but the Octobers that see unusually far South snowfall in the West and Plains are actually pretty good for one-two cold storms pretty deep into the SE, even in La Ninas. This is an example off the top of my head - but I'd still bet against a lot of snow for the coastal NE/SE outside New England. My comment above in late October in the Mid Atlantic winter thread about the likelihood of higher than normal snow in the South aged pretty well. .

Some research out lately comparing the Australian wildfires in 2019-20 to a volcanic eruption. Not sure if the California fires last fall are comparable in magnitude, but there is a strong signal here for unusual early snow in volcanic winters. Typically Sept-Nov depending on elevation, like in the past two years. The volcanic eruption in the Caribbean this month seems to have sent material into the stratosphere. Worth watching. For my purposes, the 2020-21 La Nina was only a weak event in winter. SSTs finished above 25.5C in winter in Nino 3.4, and 26.5C is average for 1951-2010. The 25.57C winter 2020-21 reading is far more likely to warm than it is to cool by historical standards. We generally have cold and/or wet winters in the Southwest if the year over year trend in Nino 3.4 is warming. Years like 1974, 2000, 2011 all come to mind as warmer La Ninas following a much stronger prior La Nina winter. Solar activity will still likely be below 55 sunspots per year for 2021-22. Long and the short of it is, if we have another La Nina with an active hurricane season, I'd expect near-above average snow totals for New England in a slightly to very warm winter. But an El Nino at this point in the solar cycle, especially if the PDO stays negative, would be a pretty interesting winter. I find there is some correlation between Nino 4 in the prior winter and the NAO in February. So when Nino 4 is very warm or so in a winter you don't ever get a -NAO the following February (1981-2010 basis). The past winter was cold in Nino 4. So I could see a pretty cold February for the first time in a while for the East in an El Nino with the -NAO in February. You guys missed out on the fun of the severe cold in February 2019 and February 2021. Also pretty sure there will be two very cold winters nationally in the next five years just based on animating trends in national winter patterns over the past 100 years, but we'll see.

Nino1+2 Nino3 Nino34 Nino4 Week SST SSTA SST SSTA SST SSTA SST SSTA 06JAN2021 23.1-0.8 24.7-0.8 25.5-1.1 27.1-1.3 13JAN2021 24.0-0.3 24.7-0.9 25.4-1.2 27.0-1.3 20JAN2021 23.9-0.8 25.2-0.6 25.5-1.1 26.9-1.4 27JAN2021 24.6-0.5 25.7-0.2 25.9-0.7 27.1-1.1 03FEB2021 25.3-0.2 25.8-0.3 26.0-0.7 27.2-1.1 10FEB2021 25.4-0.5 25.4-0.9 25.5-1.2 27.0-1.2 17FEB2021 25.7-0.5 26.2-0.3 26.0-0.7 27.2-1.0 24FEB2021 25.2-1.1 25.7-0.9 25.7-1.2 27.2-1.0 03MAR2021 26.6 0.2 26.5-0.4 26.3-0.7 27.4-0.8 10MAR2021 27.4 0.9 27.1 0.1 26.9-0.3 27.7-0.5 17MAR2021 27.1 0.5 27.0-0.2 26.8-0.5 27.9-0.4 24MAR2021 25.4-0.9 26.6-0.7 26.8-0.6 27.8-0.6 31MAR2021 24.9-1.1 26.8-0.6 27.1-0.5 27.9-0.6 07APR2021 25.3-0.5 26.9-0.6 27.3-0.5 28.3-0.3 14APR2021 24.7-0.9 26.9-0.7 27.5-0.4 28.5-0.1 Pretty fast warm up in Nino 4 since the lowest reading in February.

January -0.16 February -0.54 March -1.17 New PDO value from Nate Mantua showed a big -PDO month.

Date Tahiti (hPa) Darwin (hPa) Daily Contribution 30 day Av. SOI 90 day Av. SOI 14 Apr 2021 1010.16 1010.50 -19.69 0.22 5.46 13 Apr 2021 1009.79 1010.95 -25.60 0.83 5.90 12 Apr 2021 1011.26 1010.15 -9.23 1.60 6.45 11 Apr 2021 1012.90 1009.25 9.08 1.52 6.74 Need to watch the period around 4/22-4/24 for some kind of major system. It's been years since we've had 35+ drop in two days in the SOI.

Date Tahiti (hPa) Darwin (hPa) Daily Contribution 30 day Av. SOI 90 day Av. SOI 13 Apr 2021 1009.79 1010.95 -25.60 0.83 5.90 12 Apr 2021 1011.26 1010.15 -9.23 1.60 6.45 11 Apr 2021 1012.90 1009.25 9.08 1.52 6.74 That's trouble.

Looks pretty promising for snow over the next four days down here. Only need 1.3" in the city to make it the snowiest cold season since 2006-07. Doubt we'll get much if any accumulating snow though. Oct, Dec, Jan, Feb, Mar, Apr snow at the airport would be six months with measurable snow. That's rare if it happens. Would be the the first cold season to see accumulating snow in six months since 1997-98.

3/26-3/27 +17 to 21 days....there it is. SOI crash was huge 4/7 too.

Nino1+2 Nino3 Nino34 Nino4 Week SST SSTA SST SSTA SST SSTA SST SSTA 06JAN2021 23.1-0.8 24.7-0.8 25.5-1.1 27.1-1.3 13JAN2021 24.0-0.3 24.7-0.9 25.4-1.2 27.0-1.3 20JAN2021 23.9-0.8 25.2-0.6 25.5-1.1 26.9-1.4 27JAN2021 24.6-0.5 25.7-0.2 25.9-0.7 27.1-1.1 03FEB2021 25.3-0.2 25.8-0.3 26.0-0.7 27.2-1.1 10FEB2021 25.4-0.5 25.4-0.9 25.5-1.2 27.0-1.2 17FEB2021 25.7-0.5 26.2-0.3 26.0-0.7 27.2-1.0 24FEB2021 25.2-1.1 25.7-0.9 25.7-1.2 27.2-1.0 03MAR2021 26.6 0.2 26.5-0.4 26.3-0.7 27.4-0.8 10MAR2021 27.4 0.9 27.1 0.1 26.9-0.3 27.7-0.5 17MAR2021 27.1 0.5 27.0-0.2 26.8-0.5 27.9-0.4 24MAR2021 25.4-0.9 26.6-0.7 26.8-0.6 27.8-0.6 31MAR2021 24.9-1.1 26.8-0.6 27.1-0.5 27.9-0.6 07APR2021 25.3-0.5 26.9-0.6 27.3-0.5 28.3-0.3 Will be curious to see how various features evolve later in the year. PDO is still pretty negative even as the subsurface warms. The pattern for fall-spring will probably remain to some extent in Summer nationally. Predominantly warm with some brief periods of severe cold. That volcanic eruption in the Caribbean is a bit of a wild card, it's listed as a VEI 4 eruption on Wikipedia and could maybe change some forcing in the tropical Atlantic or even the far eastern tropical Pacific.

We haven't really had a wet month here since June 2020, so I'll buy more into El Nino conditions when we start seeing consistent wetter than average months across the Southwest. It is weird to say that though, since places like Santa Fe will end up with snow every month from September-March, and probably April too this cold season.

The intense western cold and eastern cold are both thinning, but the map is definitely shifting to warmth pretty rapidly from where it was in February.

Huge SOI crash in recent days also supports a big low in the time frame of the Kamchatka low now. Around 4/16 in all likelihood. Date Tahiti (hPa) Darwin (hPa) Daily Contribution 30 day Av. SOI 90 day Av. SOI 7 Apr 2021 1010.87 1009.55 -7.72 0.47 6.90 6 Apr 2021 1011.66 1009.35 -0.58 0.59 7.27 5 Apr 2021 1011.76 1007.60 12.76 0.49 7.57 4 Apr 2021 1009.21 1006.20 4.47 -0.02 7.65 3 Apr 2021 1008.30 1007.75 -13.27 -0.41 7.88

Cyclically, this is the warm part of the pattern of the repeating 46-day cycle that's been in place since July. There has been consistent +10 degree warmth down here in each prior cycle (first half of February was quite warm as an example). I do think there is one pretty major cold shot later in the month though, going by the timing of the prior cold shots. You guys probably aren't completely done with snow just yet.

The record +WPO in March really helped extend winter a bit out here. These correlation maps show r. So the purple spots are up to 0.5 r-squared for the WPO in March. Pretty interesting distribution of total snow compared to average so far. Will run an analysis of my snow forecast from last fall in another week or two after the final major western systems move through.

Nino1+2 Nino3 Nino34 Nino4 Week SST SSTA SST SSTA SST SSTA SST SSTA 03MAR2021 26.6 0.2 26.5-0.4 26.3-0.7 27.4-0.8 10MAR2021 27.4 0.9 27.1 0.1 26.9-0.3 27.7-0.5 17MAR2021 27.1 0.5 27.0-0.2 26.8-0.5 27.9-0.4 24MAR2021 25.4-0.9 26.6-0.7 26.8-0.6 27.8-0.6 31MAR2021 24.9-1.1 26.8-0.6 27.1-0.5 27.9-0.6 CPC reported -0.94C for JFM ONI using 1991-2020 as the baseline. Would be -0.8C against 1951-2010 averages. On the stable 1951-2010 averages I like to use, I get these figures for March: Nino 1.2: 25.66C (-0.49C) Nino 3 : 26.49C (-0.51C) Nino 3.4: 26.47C (-0.66C) Nino 4 : 27.62C (-0.45C) Here are the recent similar transitions in Jan-March in Nino 3.4. The years within 0.2C in all three months are 1996 and 1968. I would blend those two in with 2018, which is remarkably close in January & March. 2021: 25.55 / 25.71 / 26.47 2018: 25.57 / 25.97 / 26.48 2012: 25.67 / 26.08 / 26.67 2009: 25.66 / 25.96 / 26.59 2006: 25.63 / 26.08 / 26.57 1996: 25.69 / 25.89 / 26.67 1985: 25.38 / 26.03 / 26.50 1968: 25.69 / 25.68 / 26.33 1956: 25.34 / 25.76 / 26.46 1955: 25.61 / 25.81 / 26.22

My sense is there is blocking next winter too. But if it is an El Nino, it will probably be focused Feb-Mar, not Dec-Jan focused like this winter. I would like another El Nino. The El Ninos after La Ninas are cool to very cold out here, pretty reliably, and the jump to even a weak El Nino from a ~25.57C La Nina in winter would be one of the larger jumps in the past 70 years, I think top ten for a year to year warm up. Solar activity is still rising, but it's going up fairly fast now. Next winter is probably the last "low solar" winter for a while. The relevant threshold nationally seems to be an average of 55 sunspots/month for a year from July-June. The subsurface in March was +0.28 down to 300m, from -0.82 in February. Huge jump. The trajectory Jan-Mar is still like some La Nina years (2011), but also now like some El Nino years (2006). https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ocean/index/heat_content_index.txt

New Canadian has cold-neutral conditions for Apr-Jun, warmer than the prior run.

Time frame to watch now is mid-April for a big system. Not sure if the position was right for the front range or west, but the 3/26 967 mb off Kamchatka should come through somewhere in the US as a major system.

SOI finished March at -0.46. As I mentioned a few weeks ago, since 1990, cold ENSO winters are 4/4 in going to El Ninos the next winter with a -SOI in March. The 1985-86 and 2008-09 cold ENSO winters both saw SOI values of 0 to -1 in March.

These maps are never particularly precise, but it's been interesting month for snow. Remarkably low totals for a lot of the East, and some solid storms in the West.

The rebound at the surface is a bit misleading given the destruction of the La Nina below.

Tropical Tidbits has shown cooling recently - the weeklies show it too now. Nino1+2 Nino3 Nino34 Nino4 Week SST SSTA SST SSTA SST SSTA SST SSTA 06JAN2021 23.1-0.8 24.7-0.8 25.5-1.1 27.1-1.3 13JAN2021 24.0-0.3 24.7-0.9 25.4-1.2 27.0-1.3 20JAN2021 23.9-0.8 25.2-0.6 25.5-1.1 26.9-1.4 27JAN2021 24.6-0.5 25.7-0.2 25.9-0.7 27.1-1.1 03FEB2021 25.3-0.2 25.8-0.3 26.0-0.7 27.2-1.1 10FEB2021 25.4-0.5 25.4-0.9 25.5-1.2 27.0-1.2 17FEB2021 25.7-0.5 26.2-0.3 26.0-0.7 27.2-1.0 24FEB2021 25.2-1.1 25.7-0.9 25.7-1.2 27.2-1.0 03MAR2021 26.6 0.2 26.5-0.4 26.3-0.7 27.4-0.8 10MAR2021 27.4 0.9 27.1 0.1 26.9-0.3 27.7-0.5 17MAR2021 27.1 0.5 27.0-0.2 26.8-0.5 27.9-0.4 24MAR2021 25.4-0.9 26.6-0.7 26.8-0.6 27.8-0.6

Edit: Oh wait, it is Sunday. No new update yet.

The SOI is negative for the past 30 days but has come up a lot in recent days after a persistent bout of negative days. It may not finish March negative. The 30 day reading is -2, it had been almost +17 as recently as December. The WPO was record positive in January, so maybe that's just a recurring part of the pattern for a while now. My research in my Spring Outlook implied a series of lows moving across the southern US in March based on the ~record +NAO in November (+2.54). It's been interesting seeing that play out. Southern US is definitely colder than the Northern US by anomalies this month. I had kind of assumed the correlation was due to a lot of +NAO Novembers in El Nino. But it seems to not be only that. https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.nao.monthly.b5001.current.ascii.table

What do you make of these ongoing super powered lows off Kamchatka? I don't remember seeing them this strong in the WPO region this late in the year. That's big trouble for somebody in the US if it translates to the US 4/12-4/16. I mean 967 mb on the old saffir simpson scale is like a borderline major hurricane.