bluewave

March and November are the few months of the year that bucked the big warming trend since 2010.

This was the 2nd most backloaded DJF period on Long Island since 2010. Only Nemo in 2013 featured a more lopsided February snowfall total relative to December and January. 09-10 was more a bookend winter on Long Island. Monthly Total Snowfall for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Year Dec Jan Feb Season 2012-2013 0.6 3.3 31.4 35.3 2020-2021 7.5 1.1 24.9 33.5 2013-2014 8.1 25.2 24.5 57.8 2009-2010 25.3 6.4 21.7 53.4 2016-2017 3.2 14.0 14.7 31.9 2014-2015 0.4 30.2 13.4 44.0 2015-2016 T 24.8 13.2 38.0 2010-2011 14.9 34.4 3.9 53.2 2018-2019 T 0.9 3.5 4.4 2017-2018 6.0 22.0 1.4 29.4 2011-2012 T 3.8 0.6 4.4 2019-2020 4.2 2.5 0.0 6.7

We were as backloaded as Glasgow was frontloaded.

More confirmation of the GFS cold bias fix.

The AO reversal in February continues to set records. This is the first February with a daily -5 reading and only a monthly -1 average. The previous -5 drops in 2010, 1978, and 1969 all had -3 and lower monthly averages. https://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.ao.index.b500101.current.ascii https://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/monthly.ao.index.b50.current.ascii.table 2021 -2.484 -1.191 2010 -2.587 -4.266 1978 -0.347 -3.014 1969 -2.967 -3.114

The lack of multi-year ice has finally allowed the 1st transit of the Northern Sea Route in February.

The more slowly warming spring temperatures relative to the other seasons is reflected in the new 1991-2020 climate normals.

The spring of 2010 was a real outlier. Spring is the slowest warming season for us since 1981. So our springs usually feature a back and forth between warm and cool. But the warmer temperatures still have won out. Just not as lopsided as the other seasons. https://www.ncdc.noaa.gov/cag/divisional/time-series/3004/tavg/3/5/1981-2021?trend=true&trend_base=10&begtrendyear=1981&endtrendyear=2020 Seasonal warming for our area since 1981 DJF.........+0.8° F per decade MAM......+0.4°F JJA........+0.7°F SON.......+0.8°F

Euro coming in even warmer now for next week. Has the first 60s of the year by next Tuesday. Then it has a chance for some of the warmer spots to reach 70° by later next week. Looks like the big AO rise will really amp up the SE Ridge for a while.

That 1995 event was near the start of high dewpoint era. Matches the steep increase in minimum temperatures. 110°+ heat indices have occurred in 1993,1995, 1999, 2010, 2011, and 2019.

Yeah, the minimums are rising quickly at both urban and rural sites. POU has fewer July lows in the 40s. While the NYC lows in the 50s have been harder to come by.

The NYC years since the 1990s would be much warmer than the 1950s to 1980s if the sensor wasn’t blocked by the thick vegetation. The warmest 30 day periods at EWR and LGA were in more recent times. So we can add a few degrees to the more recent NYC warmest 30 day periods. warmest 30 day periods LGA 83.8...2010 83.3...2020 82.9....2005 82.8....2016 82.7....2006 82.5....2013 82.4....1999 81.9....1995 81.7....2019 81.8....1966 81.6....2012 81.5....1980....1955 EWR 83.6....1993 83.4....2011 83.1....1988 82.9....2010 82.6....2013 82.2....1994 82.0.....2005 81.9.....1999 81.6.....2012 81.4.....1980 81.3.....2016 81.2.....2020 81.1.....1955 80.6.....1966...1979 80.5.....1973

Yeah, the two most memorable heatwaves of the 1970s were late August into early September 1973 and mid-July 1977. The brief heatwave around 7-4-74 was also memorable since is was in the mid 90s for the July 4th celebrations. The 70s heatwaves usually didn’t last too long. Even the famous 1977 heatwave dropped into the 50s a few days later. NYC when the sensor was in the shade under thick foliage 1977-07-13 93 73 83.0 6.4 0 18 0.00 0.0 0 1977-07-14 92 73 82.5 5.8 0 18 0.00 0.0 0 1977-07-15 96 72 84.0 7.3 0 19 0.00 0.0 0 1977-07-16 98 75 86.5 9.8 0 22 T 0.0 0 1977-07-17 97 78 87.5 10.7 0 23 T 0.0 0 1977-07-18 100 78 89.0 12.2 0 24 0.00 0.0 0 1977-07-19 102 78 90.0 13.2 0 25 0.00 0.0 0 1977-07-20 92 75 83.5 6.7 0 19 0.06 0.0 0 1977-07-21 104 78 91.0 14.2 0 26 0.00 0.0 0 1977-07-22 88 68 78.0 1.2 0 13 0.00 0.0 0 1977-07-23 87 62 74.5 -2.3 0 10 0.00 0.0 0 1977-07-24 90 70 80.0 3.2 0 15 0.00 0.0 0 1977-07-25 78 70 74.0 -2.8 0 9 0.48 0.0 0 1977-07-26 82 62 72.0 -4.7 0 7 0.00 0.0 0 1977-07-27 81 58 69.5 -7.2 0 5 0.00 0.0 0

Looks like the new GFS upgrade will be on March 17th. It seems to have fixed the cold and suppressed bias. It did much better than the v15 with the December snowstorm. https://www.weather.gov/media/notification/pdf2/scn21-20gfs_v16.0.pdf Subject: Upgrade of NCEP Global Forecast Systems (GFS) to v16 Effective March 17, 2021 Effective on or about March 17, 2021, beginning with the 1200 Coordinated Universal Time (UTC) run, the National Centers for Environmental Prediction (NCEP) will upgrade the GFS and Global Data Assimilation System (GDAS) from version 15.3 to 16.0. NCEP also will roll in the operational standalone https://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/

With a NYC average of temperature of 75.0°, it wasn’t really a hot summer by recent standards. But it was the only July in NYC during the 1970s with 3 days reaching 100°. The sensor was in the open sunlight back then. 100° is a struggle now since all the foliage growing over the site keeps it cooler. Newark only had 2 days reach 100° with no 100s at LGA and JFK.

The only slightly cooler summers since 2010 were 2014 and 2017. From 2010 to 2013, we had drier heat with more westerly flow. The big ridges and droughts over the Plains allowed more 100° days. 2015 to 2020 was all about moist heat with more onshore flow. High numbers of 90°+ maxes and 70+mins with record numbers of days with 75°+ dewpoints. So the heat indices above 100° made it feel like we had numerous 100° days. We usually have to wait until the summer starts to see where the primary ridges that dictate the wind direction set up.

While these SST patterns can shift again before the summer, this is the lowest February PMM value since 2012. It’s an interesting development considering how this winter was so different from La Niña expectations.If this pattern can hold into the summer, then it may allow the WAR to link up with a ridge over the Plains. Recent summers featured more of a WAR pattern with lower heights over the Plains. This allowed large numbers of 90° highs and 70° lows with high humidity and onshore flow. But the numerous 100° days from 2010 to 2013 were absent. So the WAR linking up with the Plains ridge could allow a chance of 100° days to join the higher dewpoints of recent years. So we‘ll have to see how the pattern evolves. https://www.aos.wisc.edu/~dvimont/MModes/RealTime/PMM.txt 2021 2 -2.64 2012 2 -4.34

The key at this point is probably to keep expectations low for any snowfall amounts near the coast later in the month.The first week of March will feature a cold suppressed storm track pattern. Next week we will get our first early spring warm up. So we will go through the first few weeks of the month without any significant snowfall near the coast. Since 2010, the lower snowfall first half didn’t have that much snow during the second part. The snowiest late Marches featured at least 3” in NYC by March 15th. Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Ending Date Total Snowfall Mar 1 to Mar 15 Mar 16 to Mar 31 2020-03-15 0.0 T 2019-03-15 10.4 0 2018-03-15 3.2 8.4 2017-03-15 9.7 T 2016-03-15 0.4 0.5 2015-03-15 14.1 4.5 2014-03-15 0.1 T 2013-03-15 4.0 3.3 2012-03-15 0.0 0 2011-03-15 0.0 1.0 2010-03-15 T 0

That’s for sure. This will be the first time that both Dec 24th and 25th reached 60° with no 60° days until March. The big warm up around the solstice has become the new normal for us. This is currently the 3rd longest streak at Newark under 60° since 2010. Data for December 24 - 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 2015-12-24 71 59 0.03 0.0 0 1990-12-24 64 30 0.45 0.0 0 1996-12-24 63 38 0.37 0.0 0 2020-12-24 60 37 0.43 0.0 0 1941-12-24 60 47 0.46 0.0 0 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 1964-12-25 69 44 0.01 0.0 0 1982-12-25 68 40 0.02 0.0 0 2014-12-25 64 41 0.10 0.0 0 2015-12-25 63 54 0.03 0.0 0 2020-12-25 62 28 0.66 0.0 0 1940-12-25 61 32 0.00 0.0 0 1994-12-25 60 41 T 0.0 0 Number of Consecutive Days Max Temperature < 60 for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Rank Run Length Ending Date 1 75 2015-03-10 2 74 2011-02-13 3 66 2021-03-01 4 65 2010-03-06 5 58 2014-03-10

Yeah, it looks like the EPS, GEFS, and GEPS get us our first 60°+ of the year during the 2nd week of March. But we still have time for some measurable snow before the month is over. The last average measurable snowfall date since 2013 has been March 23rd. I left off last year since the polar vortex was on steroids from December through March. 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. Year Last Value First Value Difference Minimum 03-10 (2019) 11-15 (2018) 223 Mean 03-23 12-05 256 Maximum 04-16 (2014) 12-28 (2015) 281 2019 03-10 (2019) 0.2 12-01 (2019) 0.1 265 2018 04-02 (2018) 5.0 11-15 (2018) 6.4 226 2017 03-14 (2017) 6.9 12-09 (2017) 4.3 269 2016 03-20 (2016) 0.2 12-11 (2016) 0.3 265 2015 03-21 (2015) 0.3 12-28 (2015) 0.1 281 2014 04-16 (2014) 0.1 11-26 (2014) 1.4 223 2013 03-18 (2013) 2.1 12-08 (2013) 0.8 264

We’ll need one of the cutters during the 2nd week of March to produce another wave breaking event. That may be the best shot at NYC reaching 40” of snowfall in late March. Maybe the -AO can drop again after St.Patrick’s day with the way it has been bouncing around recently. EPS March 15-22

Unfortunately, the long range models don’t handle TPV splits and wave breaks very well. New run Old run

The TPV driving the wind and cold this morning is one of the strongest to dive into Northern New England in early March. This is a 5 SD event for the Canadian Maritimes. So it becomes a supercharged 50/50 low that suppresses the storm track this week.