bluewave

Near 50° passes for close to normal over the last 10 years on Christmas. Data for December 25 - NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Date Max Temperature Min Temperature Precipitation Snowfall Snow Depth 2020-12-25 62 28 0.66 0.0 0 2019-12-25 48 27 0.00 0.0 0 2018-12-25 42 29 0.00 0.0 0 2017-12-25 38 28 0.20 0.1 0 2016-12-25 52 34 0.00 0.0 0 2015-12-25 63 54 0.03 0.0 0 2014-12-25 64 41 0.10 0.0 0 2013-12-25 30 19 0.00 0.0 0 2012-12-25 43 31 0.02 0.0 0 2011-12-25 48 25 0.00 0.0 0 Summary Maximum Temperature Maximum Average Minimum Percent of Years >=100° F >=90° F >=50° F <=32° F 64 49.0 30 0 0 40% 10%

Getting close to 50° now with breaks of sun.

The CPC commented on how unusual this type of MJO stall in the WPAC is. Dynamical model MJO index forecasts depict a fairly unusual setup, with a persistent West Pacific signal over the next couple of weeks suggesting the evolution of a lower-frequency mode than MJO.

New Aleutians ridge and -PNA record for this time of year.

Yeah, I can remember the discussion of this paper a while back. So it’s possible the QBO could be a piece of the puzzle. The +500 mb height anomaly south of the Aleutians driving the -PNA is on track to be the strongest on record for December. https://agupubs.onlinelibrary.wiley.com/action/downloadSupplement?doi=10.1002%2F2017GL076929&file=grl57089-sup-0001-2017GL076929-SI.docx https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017GL076929 Storm tracks, defined as the preferred regions of extratropical synoptic-scale disturbances, have remarkable impacts on global weather and climate systems. Causes of interannual storm track variation have been investigated mostly from a troposphere perspective. As shown in this study, Northern Hemisphere winter storm tracks are significantly modulated by the tropical stratosphere through the quasi-biennial oscillation (QBO). The North Pacific storm track shifts poleward during the easterly QBO winters associated with a dipole change in the eddy refraction and baroclinicity.

Another all-time highest temperature for December.

I was agreeing with the post that I was replying to. It can snow in warm winter patterns. We saw this with the 16-17 winter which had more DJF snow than 18-19 which was colder. The more favorable Pacific intervals in 16-17 made the difference.

The extreme of snow in November 2018 was a result of the very favorable Pacific and record -EPO. Your point about comparing two different months doesn’t change the fact the the average monthly temperatures were the same. So you are actually agreeing with me that’s it’s more about storm track and teleconnections than the temperatures.

Central Park 0.2 in 0700 AM 12/24 Official NWS Obs

Our snow amounts seem to be more a function of storm track and teleconnections than temperature. We just got a light snow event today with an average NYC December temperature of 44.1°. We had a much more favorable Pacific in November 2018 and NYC picked up 6.4” of snow with an average temperature of 44.4°. So favorable patterns can produce more snow than the same temperature in a less favorable pattern. The January average temperature in 2019 was 32.5° and NYC got 1.1” of snow. But a much warmer January 2012 picked up 4.3” with a 37.3° average temperature. The difference between the two years was that the pattern in 2012 allowed a better storm track for one day than the whole month of January 2019 got. But it’s easier for NYC to reach 50” of snow if they get extended cold like 14-15. We had close to a 40-40 winter for parts of area in 2016 and 2017. But the 40° winter in 11-12 only produced single digit seasonal snowfalls for many. Factors like storm track and Pacific favorability play a large role in snowfall amounts for us.

This was the fourth warmest first three weeks of December in NYC. 8 out of the 10 warmest average temperatures occurred since the late 90s. The most recent La Ninas this warm in December were 2011, 1998, and 1999. Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Mean Avg Temperature Dec 1 to Dec 21 Missing Count 1 2015-12-21 50.2 0 2 2001-12-21 48.9 0 3 1998-12-21 48.7 0 4 2021-12-21 44.8 0 5 2012-12-21 44.7 0 6 2011-12-21 43.9 0 7 1999-12-21 43.7 0 - 1984-12-21 43.7 0 8 2006-12-21 43.5 0 - 1923-12-21 43.5 0 9 1990-12-21 43.3 0 10 1956-12-21 43.2 0

Maybe we need another El Niño to change up the winter North Pacific pattern. The Super El Niño in 15-16 shifted the ridge axis west. It had been further east in 13-14 and 14-15. But the common denominator seems to be the record WPAC warm pool generating these giant stationary waves .

The record WPAC warm pool has turned into an extreme Rossby wave generating machine. Last summer it was the record ridge and heatwave over the PACNW. This month the record ridge is centered south of the Aleutians.

Sometimes a December signal is so strong, that the models correctly see it from months away. The Euro seasonal back in October had this very amplified Aleutians Ridge, -PNA, and SE Ridge pattern. But even for a La Niña, this will be our first with close to 3 sigma block centered just south of the Aleutians in December. December verification so far October Euro seasonal forecast

This is all part of the interference from the La Niña standing wave. These RMM charts by individual component show what’s going on. Notice how several components are hanging back closer to the Maritime continent.

Models continue in push back mode. The forecast colder pattern near the end of December is now warmer than the old run. This is the same thing that happened for Christmas from a week ago. It’s one of the problems with such a strong -PNA pattern. New run Old run

2021 was probably the first year that the NYC coldest daily temperature departure occurred on the Memorial Day weekend. The July 4th weekend was the last time this year that there was a -10 or lower departure. The one bright spot with the few -10 departure days is that we got some great snowstorms with them in early February. 2021 -10 departure days in NYC 1-21….-13.9 1-31…..-10.6 2-08…..-11.6 2-12…..-10.3 3-12……-12.0 3-15…..-10.8 4-22….-14.2 5-29….-17.7 5-30….-18.0 7-3…….-14.1

The VP anomaly forecast for this week is a blend of phase 6 and phase 7. The GEFS has been really struggling with this. Notice how poorly it did with its forecast from a week ago. So it looks like the signal is more like a La Niña standing wave. This is where we sometimes get these interference patterns which can make the RMM charts very noisy. New forecast for this week Old forecast from last week

The Euro seasonal had it.

The US is on track for the 2nd warmest December behind 2015.

It’s tough for the -AO to have the intended effect when it’s up against a 5 sigma Aleutians Ridge. This may be the strongest positive 500 mb height anomaly on record in that area for the month of December. So it results in the very deep -PNA trough over the Western US.

It actually feels cold for a change. NYC down to 25°. But this is the 8th latest 25° or lower in NYC. This is 15 days late for NYC with the average first day on December 5th since 2010. Frost/Freeze Summary for NY CITY CENTRAL PARK, NY Each section contains date and year of occurrence, value on that date. Click column heading to sort ascending, click again to sort descending. Year Last Value First Value Season Length 1974 03-25 (1974) 20 01-14 (1975) 20 294 2015 03-29 (2015) 25 01-04 (2016) 14 280 2012 03-06 (2012) 25 01-02 (2013) 22 301 2001 03-27 (2001) 24 12-30 (2001) 22 277 1990 03-08 (1990) 25 12-25 (1990) 22 291 1948 03-13 (1948) 17 12-24 (1948) 21 285 1998 03-13 (1998) 23 12-22 (1998) 22 283 1997 03-16 (1997) 25 12-22 (1997) 25 280 2021 03-22 (2021) 23 12-20 (2021) 25 272

I wonder if the new indoor ski model will gain in popularity? https://www.wsj.com/articles/how-skiing-can-survive-climate-change-11612969209 Downhill skiing could become an increasingly exotic proposition in a warming world. By midcentury, the U.S. could see 90 fewer days below freezing each year, according to a 2016 study published in the Journal of Climate and based on data from the federally funded North American Regional Climate Change Assessment Program. Nearly all ski areas in the U.S. are projected to have at least a 50% shorter season by 2050, according to a 2017 study funded by the Environmental Protection Agency and published in the Global Environmental Change journal. SHARE YOUR THOUGHTS What do you think the ski industry needs to do to adapt to a warmer world, if anything? Join the conversation below. Higher temperatures make snow more elusive on the slopes, cutting into revenues for ski areas. Low snow years between 1999 and 2010 already cost ski areas an estimated $1 billion in revenue, according to a 2012 analysis commissioned by the nonprofits Protect Our Winters and the Natural Resources Defense Council.

Maybe all you guys throwing weenies should try out for the Nathan’s hot dog eating contest.

Not a surprise given how the models have been unsuccessfully trying to weaken the La Niña standing wave near Australia. New run Old run