bluewave

The snowfall volatility since 1993-1994 has been unprecedented in the climate record. Very few average seasons especially at spots like ISP which was the opposite of the 1960s through early 1990s.Well above snowfall during the 2010s and well below in the 2020s.

Yeah, NYC went from 37.9” in the 2010s to 14.2” in the 2020s. Monthly Total Snowfall for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Mean 0.3 1.1 5.3 12.9 11.8 6.0 0.6 37.9 2018-2019 0.0 6.4 T 1.1 2.6 10.4 0.0 20.5 2017-2018 0.0 T 7.7 11.2 4.9 11.6 5.5 40.9 2016-2017 0.0 T 3.2 7.9 9.4 9.7 0.0 30.2 2015-2016 0.0 0.0 T 27.9 4.0 0.9 T 32.8 2014-2015 0.0 0.2 1.0 16.9 13.6 18.6 0.0 50.3 2013-2014 0.0 T 8.6 19.7 29.0 0.1 T 57.4 2012-2013 0.0 4.7 0.4 1.5 12.2 7.3 0.0 26.1 2011-2012 2.9 0.0 0.0 4.3 0.2 0.0 0.0 7.4 2010-2011 0.0 T 20.1 36.0 4.8 1.0 T 61.9 2009-2010 0.0 0.0 12.4 2.1 36.9 T 0.0 51.4 Monthly Total Snowfall for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Mean 0.0 T 2.6 4.4 7.1 0.1 T 14.2 2023-2024 0.0 T T 2.3 5.2 T 0.0 7.5 2022-2023 0.0 0.0 T T 2.2 0.1 0.0 2.3 2021-2022 0.0 T 0.2 15.3 2.0 0.4 0.0 17.9 2020-2021 0.0 0.0 10.5 2.1 26.0 T 0.0 38.6 2019-2020 0.0 0.0 2.5 2.3 T T T 4.8

Coastal sections could see 40-50 mph gusts later with the steep low level lapse rates.

November 2018 was the end of the great snowfall pattern which began in December 2009 with only a brief interruption during 2011-2012. Even the 2011-2012 season featured the snowiest October on record. Epic run of record breaking benchmark snowstorms. The 2018-2019 DJF period with the big squall and the end of January being the main event was the beginning of the hostile Pacific pattern.

This is the new era of Greenland and Iceland blocks linking up with the Southeast Ridge.

The big model test may be where the best rainfall sets up with the cutoff later next week. Hopefully we don’t see too much suppression. But that has been the trend since late August we need to reverse.

I guess the million dollar question is how much longer the this 2023-2024 warming rate lasts which is probably beyond the scope of the study. https://climatereanalyzer.org/clim/t2_daily/?dm_id=world

This was the 3rd warmest start to November away from the sea breeze behind 2022 and 2015. While the milder pattern continues, the stronger blocking than originally forecast will prevent any more 80° record warmth. So more modest warm departures than we have experienced since the end of October. Time Series Summary for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. 1 2022-11-07 65.4 0 2 2015-11-07 61.3 0 3 2024-11-07 60.7 0 4 1994-11-07 60.5 0 5 1974-11-07 60.1 0

Volatility of the AO and NAO domains continues to be the main theme. We had the record October AO swing recently from low to high in the raw index. This was following the record 500mb low pressure in August. Now the area south of Iceland is approaching the positive 500 mb height record for November at near +4.6 SD for next week. The block is coming in a little more south based than usual so the raw indexes are missing the magnitude of the 500mb anomaly.

72-73 still stands as Phillys least snowy winter even though it was significantly colder than many recent winters which had more snow. Top 5 lowest snowfall seasons at Philly and DJF average temperature 72-73…..T……36.0° 22-23….0.3….41.3° 19-20….0.3…..39.5° 97-98….0.8….40.4° 49-50…2.0….38.7° 11-12…..4.0…..40.7° 01-02….4.0…..41.3°

72-73 had a great backloaded winter in the Southeast with a record breaking snowstorm in February. 82-83 had the famous February Northeast snowstorm. 97-98 didn’t have any cold or snowy periods for many. 15-16 started with historic warmth but the lingering +PDO from 13-14 and 14-15 helped produce the heaviest snowstorm in NYC history in January and the first below 0° since 94 in February. The La Niña background influence through the MJO and -PDO combined with the borderline super El Niño to create the warmest winter in record along the Northern Tier and Canada in 23-24.

While it still looks warmer than normal, it’s a little less warm than the earlier runs. New run Old run

The models are correcting stronger with the blocking next week. New run Old run

The one common denominator to many of our recent winters has been some feature of the December pattern repeating for part or the entire winter. Last December it was the record breaking ridge over Southern Canada which locked in for the whole winter. In December 22 it was the Western Trough and the lack of snow in December which carried through the whole winter. December 21 had the warm pattern which returned in February following the great MJO 8 in January. December 2020 began with the great +PNA mismatch which carried through into mid-January. But since this allowed a trough to set up near the mid-Atlantic, that trough carried through the whole winter even when the PNA shifted. The snowy December also carried through the entire winter. December 2019 featured the very strong polar vortex and +AO which ran the table that winter.

The sensible weather is derived from the dominant forcing and 500mb weather patterns. While last January was colder relative to the means than December and February, the mean 500 mb anomaly ridge remained over Southern Canada. So December 500mb ridge anomaly locked in for the entire winter which is very rare for an El Niño.

Those were the old days when North America used to get really cold during the winter. The 93-94 winter was the last time Canada had a top 10 coldest winter. Most recent years have been top 10 warmth.

It looks like today will probably be the last 80° potential of the season for the usual warm spots. While the models are still warmer than average going forward, the departures are forecast to be smaller than the last week. Even with all the record warmth in recent years, we haven’t been able to go over 80° after the first week of November. The last time we had mid-November 80° warmth was way back in 1993. It was also the last time we reached 100° after August. So those two records have been very tough to beat. Less warm is the new cool First/Last Summary for NEWARK LIBERTY INTL AP, NJ Each section contains date and year of occurrence, value on that date. Click column heading to sort ascending, click again to sort descending. 1993 04-20 (1993) 80 11-15 (1993) 80 208 2022 04-14 (2022) 88 11-07 (2022) 81 206 1948 05-10 (1948) 87 11-06 (1948) 80 179 2003 04-15 (2003) 81 11-03 (2003) 81 201 1982 04-25 (1982) 81 11-02 (1982) 80 190 1950 04-04 (1950) 82 11-02 (1950) 84 211 1974 04-22 (1974) 81 11-01 (1974) 81 192

The interesting thing about the recent +EPO pattern this fall is that the vortex near Alaska has been weaker than in past +EPO events. So there may very well be more neutral to negative episodes in the seasonal mix. But the +EPO ridge over North America has been as strong or stronger than when the Alaskan Vortex was deeper. I have noticed this pattern in recent years where the -PNA trough has been weaker than in the old days but the Southeast Ridge was stronger. This may be a function of 500mb heights increasing as the atmosphere warms. So the old one to one relationship with the magnitude of the troughs over the Pacific and corresponding ridges has been changing. So we don’t need as deep a trough anymore to get such strong to record breaking ridges and warmth over North America.

The state of the pattern at the start of December and the medium range forecasts at the time have spoken volumes about the winter patterns especially during La Ninas over the last decade. But sometimes we had to wait for periods which went against the La Niña and -PDO like Jan 22. Even last winter during an El Niño the winter pattern locked in early December which was rare for an El Niño. Before the last decade or so the weather patterns didn’t exhibit the pattern persistence that they have in recent times. It could be a feedback between the numerous marine heatwaves and 500mb patterns leading to these standing waves which have become the new normal.

The LES snowstorm details for the Great Lakes will probably come down to the state of the winter EPO. We haven had a +EPO dominant La Niña winter since 11-12. That resulted in a sharp LES gradient pattern. Buffalo finished in the top 5 lowest winters for snowfall while Marquette was only the 20th lowest. So improvement relative to the averages and absolutes the further north you went. Hopefully for your area this current +EPO isn’t a preview of the upcoming winter. We will probably have a better idea of more micro details like that once we get into the first week of December and see what the pattern and modeling indicates at that time.

Anything above a T would be a win at this point.

The Euro did much better with the winter temperature forecast in 21-22 than the last two winters. It had close to a +1C departure for parts of the Northeast which was fairly close. But it required the big MJO 8 in January to go against the La Niña and -PDO at least for one month. So I think the only way the Euro seasonal will end up being closer this winter is for at least one month to go against the -PDO and La Niña background enough.

It’s been a while since the models had measurable rain within about 120 hrs. Hopefully, the development of the Plains trough pays off for us. We’ll take what ever we can get and need to at least start putting some rainfall points on the board.

Seems to be closing the gap a bit between the DMI volume. But the DMI is still lower. The October temperatures above 80N were warmest on record by a wide margin.

For the 22-23 La Niña the Euro was too warm in the West and too cool in the East. So the Euro was too cool under where the La Niña SE Ridge set up. The +1C forecast in those areas verified closer to +3.5C.