bluewave

The long range models have a pretty wide spread by the first week of December. The EPS is the only model to have a more favorable Pacific pattern. It is showing height rises along the West Coast which is different from the typical La Niña. The GEFS and GEPS maintain a La Niña trough near the west coast. So we probably need to wait for the models to settle down before buying into any scenario. This is especially true with how much the models have been jumping from run to run with the storm for Friday that got pushed back to Sunday. So if the models can’t even handle a 5 day forecast, then a week 2 forecast may not be very accurate either.

We can always get +PNA intervals during a La Niña winter. This was the case through much of the 20-21 winter and January 22. But last winter we had the record -PNA reversal from December to January and the NAO didn’t play ball. So Long Island cashed in with record snows while the flow was too progressive west of NYC.

The CMC went from a 959 mb low in New England on Saturday to a suppressed system and no storm in one run. Similar reversal on the GFS. The Euro seems to be slowly backing away from the stronger solution at 6z as the southern stream low lags behind. So this could be one of the worst model performances of the year so far.

I can’t remember the last time that all 3 models were so different at 5 days out. The CMC and GFS squash the southern stream with no wave break to pump the -NAO into early December. The Euro and EPS have a more amplified southern stream storm resulting in a wave break and stronger -NAO into early December. There was a strong storm at the end of November 2020 causing a wave break which flipped the -NAO going into December with 60-70 mph gusts on Long Island.

The 0z Euro is the only model that has a big storm now for Friday into Saturday. The CMC and GFS keep the streams separate with a weaker northern stream low crossing the lakes. So they don’t have a wave break following the low. This looks like why the EPS has stronger blocking in early December and the other guidance is weaker. The blocking in early December may come down to how strong a storm we get later in the week. Very low skill forecast at this point.

All our major snows since 2011 in November and December have been during the first 20 days of both months. Plus we can throw in 2011 for the record snow in late October. There haven’t been any major snow events from 11-21 to 11-30 and 12-21 to 12-31. Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Ending Date Total Snowfall Oct 28 to Nov 20 Missing Count 2021-11-20 T 0 2020-11-20 0.0 0 2019-11-20 0.0 0 2018-11-20 6.4 0 2017-11-20 T 0 2016-11-20 T 0 2015-11-20 0.0 0 2014-11-20 T 0 2013-11-20 T 0 2012-11-20 4.7 0 2011-11-20 2.9 0 Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Ending Date Total Snowfall Nov 21 to Nov 30 Missing Count 2021-11-30 T 0 2020-11-30 0.0 0 2019-11-30 0.0 0 2018-11-30 T 0 2017-11-30 0.0 0 2016-11-30 0.0 0 2015-11-30 0.0 0 2014-11-30 0.2 0 2013-11-30 T 0 2012-11-30 T 0 2011-11-30 0.0 0 Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Ending Date Total Snowfall Dec 1 to Dec 20 Missing Count 2021-12-20 T 0 2020-12-20 10.5 0 2019-12-20 2.5 0 2018-12-20 T 0 2017-12-20 7.0 0 2016-12-20 3.2 0 2015-12-20 0.0 0 2014-12-20 1.0 0 2013-12-20 8.6 0 2012-12-20 0.0 0 2011-12-20 0.0 0 Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Ending Date Total Snowfall Dec 21 to Dec 31 Missing Count 2021-12-31 0.2 0 2020-12-31 0.0 0 2019-12-31 T 0 2018-12-31 T 0 2017-12-31 0.7 0 2016-12-31 T 0 2015-12-31 T 0 2014-12-31 T 0 2013-12-31 T 0 2012-12-31 0.4 0 2011-12-31 0.0 0

The strong winds broke the radiational cooling inversion so BNL jumped 10°+ in under 30 minutes.

I believe the only lower reading was the -504 EPO around Christmas 1983.

Looks like the -428 EPO was one of the most negative readings for any time of the year. https://downloads.psl.noaa.gov/Public/map/teleconnections/epo.reanalysis.t10trunc.1948-present.txt

Report of some graupel mixing in with the heavier snow squalls. Serious flurries & BIG graupel outside Marksboro, Warren Co., NJ. Never saw graupel almost the size of peas!

First snow squall warning of the day in Central PA as the bands take shape and head for our area this evening.

Around 38° may be the magic number for getting snow showers this evening across the area. Could be some localized heavy snow bursts with the mesos indicating surface based cape. WSW flow could add some ocean enhancement to the snow across parts of LI that are away from the warmer immediate beaches which could stay as rain at 40°. Simulated radar loops looking unusually convective for late November. So a few rumbles of thunder will be possible. http://www.meteo.psu.edu/fxg1/HRRRNE_CUR/rloop.html http://www.meteo.psu.edu/fxg1/NAMSFC4_12z/rloop.html

The storm track in about a week will probably come down to how amplified the system is. The OP Euro was more amplified so the low cuts to our west and goes negative tilt. The ensemble mean was more positive tilt with the trough so the low takes more of a coastal track. Sometimes the ensembles smooth things out too much longer range. So we still don’t know if this will be cutter, hugger, or coastal track. The other possibility is that we get a primary crossing the lakes and the secondary gets going too late and favors New England.

I think the OP run was holding the energy back too long in the SW so it squashed the southern stream. The EPS had a bunch of nice coastal hits among the 50 members as the low ejects faster than the OP. Looks similar to the GEPS. We just don’t want such a quick ejection that the the low ends up hugging the coast like the GFS or cuts like the OP GEM. But a genuine storm signal of some type is there.

Pretty good coastal signal on the day 8-9 EPS.

First snow showers/squalls of the season here Friday evening.

December will probably come down to how the WP warm pool influences the MJO. The cold pattern coming up and record -EPO is a rough match for MJO 6 in November. We need the MJO to continue into 7 to maintain that -EPO into December. The EPS now gets us to phase 7 in early December. The duration of the -NAO this time of year is tricky since it can depend on wave breaks to keep it going. Those are outside the range of the longer range guidance. So we want to keep the Pacific as favorable as possible since it’s has such a big influence on our weather.

It’s very extreme to get a 581 dm ridge in Alaska during November.

The strongest full Novembers for -EPO blocking at the 500 mb level were 2019, 2018, 2014, 2013, 1996, and 1978.

This is probably the biggest day 6-10 full EPS mean shift in one run in a long time. Much more Pacific blocking holds on after this record -EPO. So it’s not just one of these overamped OP runs with no ensemble support. 0z 12z

One of our greatest snowstorms of all time in January 2016 occurred after the +13.3 December. This was followed by the snowiest March on record for Long Island in 2018 following the 80° at Newark in February. The 16-17 winter had record 60s warmth the day before the February blizzard. Last winter ACY was in the 60s the day before their record January snowfall. So warm winters can be great for snow if the blocking decides to show up between the record warmth. But we can always strikeout in the snowfall department like in 18-19 and 19-20 if there is no blocking. But even both those years had record November and May snows.

Yeah, we have entered a semi permanent La Niña background state since the super El Niño in 15-16 with giant La Niña ridges south of Alaska and along the East Coast. So the last 7 winters have all been warmer to record warm across the area. Snowfall has been modulated by how much blocking we get.

The rapid expansion of the Western Pacific warm pool has been slowing the MJO in phases 5-7. Here we show that rapid warming over the tropical oceans during 1981–2018 has warped the MJO life cycle, with its residence time decreasing over the Indian Ocean by 3–4 days, and increasing over the Indo-Pacific Maritime Continent by 5–6 days. We find that these changes in the MJO life cycle are associated with a twofold expansion of the Indo-Pacific warm pool, the largest expanse of the warmest ocean temperatures on Earth. The warm pool has been expanding on average by 2.3 × 105 km2 (the size of Washington State) per year during 1900–2018 and at an accelerated average rate of 4 × 105 km2(the size of California) per year during 1981–2018

I believe the 65” in 2014 was the greatest November event for east of Lake Erie. They have pure rocket fuel this time with the record 55° lake temperatures from the recent record warmth. The lake should be in the upper 40s by now. So it will just come down to how long the band stalls in any given location.

It was 12-17-83 at JFK and yesterday at ISP. Frost/Freeze Summary for JFK INTERNATIONAL AIRPORT, 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 1983 03-30 (1983) 31 12-17 (1983) 31 261 1998 03-25 (1998) 31 12-14 (1998) 31 263 2016 04-10 (2016) 31 12-09 (2016) 31 242 2009 03-25 (2009) 31 12-07 (2009) 31 256 2006 04-05 (2006) 32 12-04 (2006) 31 242 Frost/Freeze Summary for ISLIP-LI MACARTHUR AP, 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 2022 03-30 (2022) 25 11-15 (2022) 29 229 1984 04-10 (1984) 30 11-15 (1984) 29 218 2016 04-10 (2016) 32 11-14 (2016) 32 217 1994 04-23 (1994) 32 11-12 (1994) 32 202 1981 04-22 (1981) 32 11-12 (1981) 31 203 1977 04-11 (1977) 32 11-12 (1977) 32 214