bluewave

The 53.1° average November temperature in NYC is normal for South Carolina. Monthly Climate Normals (1981-2010) - GRNVL SPART INTL AP, SC November 52.4

The most impressive ridge during early December won’t be the +PNA. The models are indicating a +4.5 SD ridge to the east of New England. A 588 dm ridge in that area may be close to the early December record. This would be a continuation of the record ridges that we have been seeing out there recently. So early December should start like the last few winters with the dominant cutter and hugger storm tracks that pump the ridge in this location. Since the polar vortex is so strong, the wave breaks probably won’t be able to turn the NAO negative for longer than a brief period. By mid-December, both the EPS and GEPS retrograde that ridge back to New England. We have seen this retrogression numerous times in recent years. A very persistent pattern.

This is the first late November in a few years without any virtual snow showing up in the models.

NYC currently in the lead for the warmest January through November on record. This is the 5th top 10 warmest January through November since 2010. 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 Jan 1 to Nov 30 Missing Count 1 2020-11-30 59.1 4 2 2016-11-30 59.0 0 - 2010-11-30 59.0 0 3 1991-11-30 58.9 0 4 2012-11-30 58.8 0 5 1990-11-30 58.7 0 6 1953-11-30 58.6 0 - 1949-11-30 58.6 0 7 1998-11-30 58.5 0 8 2017-11-30 58.4 0 - 2002-11-30 58.4 0 9 2006-11-30 58.1 0 - 1999-11-30 58.1 0 10 1983-11-30 58.0 0

Recent years have shown how straight ENSO expectations can vary at times based on the increasingly active MJO. https://journals.ametsoc.org/jcli/article-abstract/33/11/4621/345274/How-MJO-Teleconnections-and-ENSO-Interference The results from this study show that during a particular phase of an active MJO, the extratropical response can considerably enhance or mask the interannual ENSO signal in the United States, potentially resulting in anomalies of the opposite sign than that expected during a specific ENSO phase. Analyses of specific MJO events during an El Niño or La Niña episode reveal significant contributions to extreme events via constructive and destructive interference of the MJO and ENSO signals.

Very warm end to November should allow NYC to finish near the top of the warmest Novembers list. KNYC GFSX MOS GUIDANCE 11/27/2020 0000 UTC FHR 24| 36 48| 60 72| 84 96|108 120|132 144|156 168|180 192 FRI 27| SAT 28| SUN 29| MON 30| TUE 01| WED 02| THU 03| FRI 04 CLIMO X/N 60| 46 58| 42 57| 48 60| 50 54| 36 45| 38 47| 39 46 34 47 Time Series Summary for NY CITY CENTRAL PARK, NY - Month of Nov Click column heading to sort ascending, click again to sort descending. Rank Year Mean Avg Temperature Missing Count 1 2020 53.0 4 2 2015 52.8 0 3 2001 52.7 0 4 1979 52.5 0 5 1948 52.4 0 6 1975 52.3 0 7 2011 51.9 0 - 2006 51.9 0 - 1994 51.9 0 - 1931 51.9 0 8 1902 51.4 0 9 2009 51.1 0 10 1999 50.8 0

Much more of an El Niño-like pattern to start December than La Niña. So the Northern Tier across to the Northeast is warmer than you would expect from a La Niña December. These Niño-like +AAM spikes have been occurring since earlier in the fall. This is why we didn’t get a textbook fall La Niña pattern. Probably related to the more Niño-like warmth in the IO and off equator warmer than normal SSTs for a La Niña. The MJO moving slowly toward the Maritime Continent is also a milder influence down the road for the area.

The 12-05 snow date is mostly a result of 2002 and 2003. This was within the historically snowy December streak that ran from 2000 to 2010. It was the 1st and 3rd snowiest 12-05 on record in NYC. That 11 year period was when NYC averaged 8.9” of snow in December. Since the Boxing Day Blizzard, NYC only averages 2.6” of snow each December. Data for December 5 - NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Date Max Temperature Min Temperature Precipitation Snowfall Snow Depth 2003-12-05 37 25 0.53 8.0 0 1926-12-05 24 11 1.03 7.9 8 2002-12-05 31 26 0.35 6.0 M 1886-12-05 22 13 0.37 5.3 M 1904-12-05 36 26 0.31 4.0 M Monthly Total Snowfall for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Year Dec Season Mean 8.9 8.9 2010 20.1 20.1 2009 12.4 12.4 2008 6.0 6.0 2007 2.9 2.9 2006 0.0 0.0 2005 9.7 9.7 2004 3.0 3.0 2003 19.8 19.8 2002 11.0 11.0 2001 T T 2000 13.4 13.4 Monthly Total Snowfall for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Year Dec Season Mean 2.6 2.6 2019 2.5 2.5 2018 T T 2017 7.7 7.7 2016 3.2 3.2 2015 T T 2014 1.0 1.0 2013 8.6 8.6 2012 0.4 0.4 2011 0.0 0.0

Not really since it was part of the general pattern of warmer departures during the 2nd half of December. 7 out of the last 9 years in NYC fit this pattern. The 2nd half warmer relative to the 1st was more exaggerated than 2015 during 2019,2018,2016,2014, and 2013. Year....12/1-12/15 departure...12/16-12/31 departure 2019....-1.2....+2.4 2018....-1.3....+6.3 2017...-1.1......-3.7 2016....-0.7.....+2.6 2015....+12.1....+14.4 2014....-0.3.....+6.1 2013....-2.1.....+4.0 2012....+5.1.....+2.9 2011....+5.0.....+6.5

I only posted the temperature progression since it matches the the NYC pattern since 1980. Relatively flat early December temperatures followed by rapid warming mid to late month. The MJO moving east across the Maritime continent would also match the pattern.

Since the Boxing Day Blizzard in 2010, the 2nd week of December has been the snowiest of the month in NYC. 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 7 Missing Count 2019-12-07 1.6 0 2018-12-07 0.0 0 2017-12-07 0.0 0 2016-12-07 0.0 0 2015-12-07 0.0 0 2014-12-07 0.0 0 2013-12-07 T 0 2012-12-07 0.0 0 2011-12-07 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 8 to Dec 14 Missing Count 2019-12-14 0.2 0 2018-12-14 T 0 2017-12-14 5.8 0 2016-12-14 0.4 0 2015-12-14 0.0 0 2014-12-14 1.0 0 2013-12-14 7.1 0 2012-12-14 0.0 0 2011-12-14 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 15 to Dec 21 Missing Count 2019-12-21 0.7 0 2018-12-21 T 0 2017-12-21 1.2 0 2016-12-21 2.8 0 2015-12-21 0.0 0 2014-12-21 T 0 2013-12-21 1.5 0 2012-12-21 0.0 0 2011-12-21 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 22 to Dec 31 Missing Count 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 0.0 0 2013-12-31 T 0 2012-12-31 0.4 0 2011-12-31 0.0 0

The latest EPS weeklies are on the MJO progression east across the Maritime Continent train. First week of December temperatures averaging slightly above normal in the Northeast. Second week closer to normal. As others have mentioned, maybe we can put some snow points on the board during the second week. This is followed by our annual warm up approaching the solstice and through the holiday period.

Looks like LGA tied the record high of 67°. This is a normal Thanksgiving for Charleston, SC. So another example of the subtropical climate zone shifting north. https://www.wrh.noaa.gov/mesowest/getobext.php?sid=KLGA&table=1&num=168&banner=off Almanac for LAGUARDIA AIRPORT, NY November 26, 2020 Daily Data Observed Normal Record Highest Record Lowest Max Temperature 67 51 67 in 1946 34 in 1974 Almanac for Charleston Area, SC (ThreadEx) November 26, 2020 Daily Data Observed Normal Record Highest Record Lowest Max Temperature M 67 82 in 1973 41 in 1938

65° at Newark. Getting close to the record high of 68° set back in 2011. Newark Liberty PTSUNNY 65 59 81 SW16 29.95F Almanac for NEWARK LIBERTY INTL AP, NJ November 26, 2020 Daily Data Observed Normal Record Highest Record Lowest Max Temperature M 51 68 in 2011 29 in 1938

This month the very strong IO MJO combined with a near record polar vortex for November record warmth. So it really enhanced the upper ridge over the area. The closest MJO composite match for November was a phase 3. You can see the dominant VP anomalies focused near that part of the IO.