bluewave

NYC average DJF 30 year climate normals…. 1991-2020….2020s….36.2 1981-2010…..2010s….35.1 1971-2000…..2000s…34.7 1961-1990…..1990s….33.9 Cold departure winters bolded Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Season Mean Avg Temperature Missing Count 2020-2021 36.1 0 2019-2020 39.2 0 2018-2019 36.3 0 2017-2018 36.2 0 2016-2017 39.3 0 2015-2016 41.0 0 2014-2015 31.4 0 2013-2014 32.9 0 2012-2013 36.8 0 2011-2012 40.5 0 2010-2011 32.8 0 2009-2010 33.8 0 2008-2009 34.2 0 2007-2008 36.4 0 2006-2007 36.5 0 2005-2006 37.3 0 2004-2005 35.4 0 2003-2004 32.4 0 2002-2003 31.2 0 2001-2002 41.5 0 2000-2001 33.5 0 1999-2000 36.2 0 1998-1999 38.6 0 1997-1998 39.6 0 1996-1997 37.8 0 1995-1996 32.2 0 1994-1995 37.1 0 1993-1994 31.1 0 1992-1993 35.0 0 1991-1992 37.2 0 1990-1991 39.1 0

Yeah, those were the last cold winters since our snowier era began in 02-03. Colder than normal winters bolded Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Season Mean Avg Temperature Missing Count 2020-2021 36.1 0 2019-2020 39.2 0 2018-2019 36.3 0 2017-2018 36.2 0 2016-2017 39.3 0 2015-2016 41.0 0 2014-2015 31.4 0 2013-2014 32.9 0 2012-2013 36.8 0 2011-2012 40.5 0 2010-2011 32.8 0 2009-2010 33.8 0 2008-2009 34.2 0 2007-2008 36.4 0 2006-2007 36.5 0 2005-2006 37.3 0 2004-2005 35.4 0 2003-2004 32.4 0 2002-2003 31.2 0

We’ll have to wait and see what happens after the the colder period with blocking from late November into early December. The extended EPS goes -PNA by the 2nd week of December. But that is still way out there for the extended EPS accuracy. Nov 29-Dec 6 Dec 6-13

While we get a strong -NAO/-AO block next week, it’s becoming more south based than the models were indicating several days ago. A block approaching 588 dm south of Greenland is near record levels for this time of year. But like we have seen since last winter, these blocks extending south to New England aren’t as cold as the traditional Greenland blocks. New run Old run South based blocking dominating since last winter

The Southeast will have departures approaching -20 before Thanksgiving.

Continuation of the coldest departures going to our south on the latest extended EPS. Looks like the -AO and -NAO peak during the last week of November before weakening in early December. But the +EPO La Niña influence remains constant. November 22-29 Nov 29-Dec 6

The 72° at Newark so far is just 1° off the record high. Newark/Liberty MOSUNNY 72 48 42 S15 11/18 73 in 1963 72 in 1953 70 in 1931

Models will always struggle beyond the day 6-10 ensemble means. But the extreme nature of the Pacific Jet this year really stands out. One record storm after another along the West Coast. The storms have been so intense, that they dropped the -PDO to near record lows for this time of year.

You can see what the models are trying to do in the 11-14 day range by looking at the velocity potential charts. The La Niña standing wave is MJO 4-5. The forcing near Africa and South America closer to phase 1. So the RMM charts won’t be able to resolve all the forcing in multiple locations. This combination of phases in early December supports a +EPO and south based -AO -NAO extending to near the Canadian Maritimes. There is also a battle out West between a neutral to -PNA at times.

The near record warm ocean is more impressive. Long Island pushing 60° with a southerly wind. The SSTs are still near 60° in late November. Shirley CLEAR 59 51 75 S9

November continuing the post 2010 pattern of having the lowest monthly departure of fall. Station…..Nov…..Oct…..Sep EWR….+1.1….+6.9….+3.3 NYC….-0.5….+4.1…..+1.1 JFK…+0.8…..+5.8….+2.3 LGA…+1.4…..+5.1….+1.9 HPN…-0.5….+5.6….+1.3 ISP……-0.1….+5.5…..+2.7 BDR….+0.1….+4.7….+2.2

I know we had a 2-3” snow event around NYC at the end of November 1995. But the highest impact storm that month was the November 11th powerful cutter. I had 70-75 mph SSW gusts with a severe squall line that came through near midnight. Quite a few power outages around the area after that severe event.

It’s remarkable how that November 1995 pattern locked in right through April. That was an example of a stuck weather pattern from before the 2010s era. It will be interesting to see how low we can extend that 6-10 day +EPO, SW ridge, and -NAO.

The day 6-10 EPS 500 mb pattern is similar to November 1995. While it’s showing a more +EPO than 1995, the SW ridge near California and the -NAO block resembles 1995. It will be interesting to see how long we can hold that kind of a pattern.

Great illustration of how an extreme La Niña Pacific Jet can trigger a wave breaking event that pumps the -NAO -AO block.

All the guidance is correcting stronger with the -NAO -AO blocking for late November. This is what we want to see during La Ninas in November for winter blocking intervals and better snowfall chances.The individual storm details will probably have to wait until we get within the 120 hr range. New run Old run

We will need a strong enough storm Thanksgiving week for our first -10 departure of fall behind the cold front. Our last multi station average below -10 was the July 4th weekend. The only recent fall without one averaged for our climate division was the 2016 La Niña. https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=32&network=NYCLIMATE&station=NYC004&year=2021&var=high&gddbase=50&gddceil=86&how=diff&cmap=jet&_r=t&dpi=100&_fmt=png

Yeah, the warmest SSTs for the period of record during this time of year. https://mco.umaine.edu/gom_sst/

And these unusually potent late fall severe weather patterns in recent years. https://weather.com/storms/tornado/news/2018-10-04-pennsylvania-record-october-tornado-outbreak Tuesday's swarm of tornadoes in parts of the Northeast set an October record in Pennsylvania. It was the state's most tornadic day in over 20 years. https://www.washingtonpost.com/weather/2018/10/24/rare-late-october-tornado-outbreak-hit-massachusetts-rhode-island-tuesday/ October 24, 2018 Cape Cod is a fun summertime vacation destination, and the weather is usually turning increasingly wintry this time of year. Tuesday, the Cape looked more like Oklahoma than New England as several tornadoes tore through Massachusetts and Rhode Island. At least three tornadoes seem likely to have touched down. It’s a region that doesn’t see many twisters any time of year, and this is as late as they come in Southern New England.

Record number of tornado warnings issued from the NWS at OKX for October and November since 2018. https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=171&opt=wfo&station=OKX&state=NY&_ugc_state=NY&ugc=NYC059&phenomena=TO&significance=W&cmap=Greens&_r=t&dpi=100&_fmt=png

The December pattern will probably begin to set up during the last week of November. We need a strong cutter or hugger to pump the -NAO into December like last year. All our La Ninas that have near to above normal snows have a front loaded part when we put down snow at some point in December. This was true during our last La Niña Decembers in 2016 and 2017.

Partial collapse of the restaurant according to a report on twitter.

Small planes flipped at Brookhaven airport.

Damage at Chipotle in Suffolk.

This was the first time that I saw asperatus clouds ahead of severe storms on Long Island.