bluewave

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.

This will be the first time since 2014 and 2015 that we had to with until March for the first 60°+ of the year. First/Last Summary for NY CITY CENTRAL PARK, 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 First Value Last Value Difference Minimum 01-11 (2020) 11-26 (2019) 275 Mean 02-08 12-19 313 Maximum 03-26 (2015) 12-28 (2018) 349 2021 - - - - - 2020 01-11 (2020) 69 12-25 (2020) 61 348 2019 02-04 (2019) 61 11-26 (2019) 61 294 2018 01-12 (2018) 61 12-28 (2018) 60 349 2017 01-12 (2017) 66 12-05 (2017) 61 326 2016 02-20 (2016) 61 12-27 (2016) 60 310 2015 03-26 (2015) 62 12-27 (2015) 61 275 2014 03-11 (2014) 66 12-25 (2014) 62 288

The AO has had a much bigger influence this winter than the MJO. We got our biggest snowstorm of the winter in early February when the MJO was in an amplified +2 phase 6. The AO was the more dominant force. Now that we are finally getting a MJO 8, the AO is spiking to +2 or +3 becoming the greater factor next week.

Yeah, the GEFS is coming in even stronger with the AO rise. So it looks like we have a shot at our first 60°+ of the year sometime during the 2nd week of March. The ridiculous AO volatility since the February record rise continues.

This is the summary from NOAA: https://www.ncei.noaa.gov/news/Upcoming-NOAA-2020-Climate- Calculating the New Climate Normals Palecki emphasized that NOAA’s Normals are rather complicated sets of calculations, not just simple averages. These calculations fill in missing data using surrounding weather stations and ensure that daily Normals match monthly Normals. They also remedy discrepancies that might arise when stations change locations. In this next round of Climate Normals, new things will be added—including several small changes to how NCEI calculates them. “Our main methodologies have not changed since the last Normals cycle,” Palecki said. “But minor improvements have been made in how we round numbers, calculate percentiles, count the numbers of days exceeding thresholds, and format output.” todayAlso, for the first time, this updated batch of Normals will include 15-year Normals for those needing a climatology representing a period closer to today. NOAA will also release high spatial resolution monthly Normals data for the conterminous U.S., as well as develop new tools and methods to access the data. These new Normals are a better baseline for today’s climate, helping inform activities in many economic sectors,” Palecki added. “Interestingly, this shift will result in there being fewer ‘above normal’ temperature days in most of the U.S. at the start of this decade compared to recent years that used the previous Normals cycle. Climate will continue to change in the U.S. during this decade, however, so we will need to do this again in 2031.” Once the new NOAA Normals are released in May 2021, they will be available to the public from NCEI.

Based on the raw numbers it’s this last decade. Looks like December will see the greatest temperature rise. But the exact numbers will have to wait until the raw data goes through quality control. https://www.ncdc.noaa.gov/data-access/land-based-station-data/land-based-datasets/climate-normals/1981-2010-normals-data Procedures are put in place to deal with missing and suspect data values. In addition, Climate Normals include quantities other than averages such as degree days, probabilities, standard deviations, etc. Climate Normals are a large suite of data products that provide users with many tools to understand typical climate conditions for thousands of locations across the United States.

The new 30 year climate normals are scheduled to come out this spring. It looks like the NYC 1981-2010 DJF average of 35.1° is set to rise closer to 36.0° for 1991-2020. But the NCDC has the final say since they look for any possible errors in the raw data.

It took an AO drop under -5 to get only the 4th colder winter month since December 2015. This was the first 6 winter stretch with an average temperature of 36.0° or warmer. So the warmer than average winter run since 15-16 continues. NYC Dec 15....+13.3 Jan 16....+1.9 Feb 16....+2.4 Dec 16....+0.8 Jan 17....+5.4 Feb 17....+6.3 Dec 17....-2.5 Jan 18.....-0.8 Feb 18....+6.7 Dec 18....+2.6 Jan 19....-0.1 Feb 19....+0.9 Dec 19....+0.8 Jan 20....+6.5 Feb 20....+4.8 Dec 20.....+1.7 Jan 21.....+2.2 Feb 21.....-1.1 Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Season Mean Avg Temperature Departure 2020-2021 36.1 +1.0 2019-2020 39.2 +4.1 2018-2019 36.3 +1.2 2017-2018 36.2 +1.1 2016-2017 39.3 +4.2 2015-2016 41.0 +5.9

We’ll probably see a warm up during the 2nd week of March as there is another big AO rise forecast.

Colder start to March on the 12z EPS.

This is also the first time that Allentown had nearly 25” more than Suffolk since the snowfall increase in 2002-2003. Islip snowfall 2010-2021 and BNL 2003-2009 Time Series Summary for Allentown Area, PA (ThreadEx) Click column heading to sort ascending, click again to sort descending. Ending Date Total Snowfall Oct 1 to Apr 30 ISP/BNL 2021-04-30 58.1 33.5 2020-04-30 5.3 6.8 2019-04-30 32.1 12.8 2018-04-30 49.9 65.9 2017-04-30 28.3 39.3 2016-04-30 36.2 41.4 2015-04-30 50.1 63.7 2014-04-30 68.1 63.7 2013-04-30 21.4 46.9 2012-04-30 12.0 4.7 2011-04-30 38.9 55.3 2010-04-30 59.8 53.8 2009-04-30 24.1 43.0 2008-04-30 21.2 11.5 2007-04-30 23.0 9.5 2006-04-30 32.5 30.5 2005-04-30 42.3 78.5 2004-04-30 39.3 66.2 2003-04-30 54.4 62.1

This was a really unusual winter with the strong blocking displaced so far south. You can see how much warmer the US average temperature was than the 09-10 winter which was the last time we had a -1 or lower AO for all 3 winter months. So that resulted in the more tucked in storm track with the ridging and record warm SSTs east of New England.

Yeah, this is our first snowy winter in a while when the heaviest snowstorms only had 990s mb pressures. Our last snowy winter in 17-18 featured the 950mb benchmark blizzard and other deep lows in March. Even 16-17 which was so warm , had the deeper MLSP blizzards mixed in.

Probably not since the easterly flow was so strong with that event.

Very unusual to get a snowy winter with such a tucked in storm track. This is only the 3rd time since 1996 that EWR had near 10” or more of snow than ISP or BNL. I use BNL before 2010 due to missing ISP snowfall data. This winter featured the record south based blocking and record warm SSTs east of New England. So this allowed the ridge to build east of New England with storm tracks very close to Southern NJ. Most other years we had more of a benchmark storm track further east favoring Suffolk over Newark. Time Series Summary for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Ending Date Islip Snowfall Newark Snowfall 2021-04-30 33.5 45.7 2020-04-30 6.8 6.9 2019-04-30 12.8 22.0 2018-04-30 65.9 39.4 2017-04-30 39.3 30.0 2016-04-30 41.4 32.8 2015-04-30 63.7 46.4 2014-04-30 63.7 61.1 2013-04-30 46.9 29.5 2012-04-30 4.7 8.8 2011-04-30 55.3 68.2 2010-04-30 53.8 47.9 Click column heading to sort ascending, click again to sort descending. Ending Date Newark Snowfall Oct 1 to Apr 30 BNL LI Snowfall 2009-04-30 27.1 43 2008-04-30 14.6 11.5 2007-04-30 16.5 9.5 2006-04-30 37.9 30.5 2005-04-30 43.4 78.5 2004-04-30 47.8 60.2 2003-04-30 53.1 62.1 2002-04-30 3.6 5.5 2001-04-30 39.3 51.2 2000-04-30 18.4 14.0 1999-04-30 12.8 23.0 1998-04-30 6.9 4.5 1997-04-30 16.3 18.0 1996-04-30 78.4 90.7

Yeah, looks like the TPV that gives us the brief Arctic outbreak Monday night into Tuesday acts to suppress the southern stream for a while.