bluewave

Euro and UKMET pretty much identical to the CanSIPS and JMA for the summer. Strongest heat over the Western US with wet and humid conditions in the East. Also notice the heavy precipitation with the IO standing wave.

There could be a very sharp cutoff between who gets the heaviest rains and doesn’t.

We get our brief warm up followed by about a week of easterly flow. Rainfall amounts will probably be determined in the short term. Looks like models are struggling with the placement of a PRE. Often happens with a subtropical or tropical systems to our SE.

We had 2 recent winters with the La Niña background state and an El Niño that couldn’t really develop. The MJO remained in the unfavorable phases. Models are hinting at a -IOD for next winter. This would mean more warm SST’s north of Australia near the Maritime Continent. So unfavorable MJO phases could be a player again. But the coupled La Niña in 16-17 and 17-18 had to deal with this . We were able to sneak in snowy intervals during those winters which alternated with record warmth. The last few winters the snowy intervals never materialized. So it will be interesting to see if a more coupled La Niña next winter resembles 16-17 and 17-18. Or has more in common with 18-19 and 19-20.

The CanSIPS has the same summer pattern. The IO has had a big influence on our weather since the record +IOD last fall.

The latest JMA summer forecast has a big IO standing wave pattern. It places the strongest ridging and warmest temperatures over the Western US. But there looks like a weak WAR keeping our temperature departures a little above normal. Pattern also looks wet and humid.

Very unusual 1800’s style April maximum temperature and May minimum temperature. Even more out of place following the 4th warmest December through March. So there are no analogs for this type of extreme pattern reversal. Time Series Summary for NY CITY CENTRAL PARK, NY - Month of Apr Click column heading to sort ascending, click again to sort descending. Rank Year Highest Max Temperature Missing Count 1 1874 64 0 - 1873 64 0 2 1940 67 0 - 1875 67 0 3 2020 68 0 - 1883 68 0 Time Series Summary for NY CITY CENTRAL PARK, NY - Month of May Click column heading to sort ascending, click again to sort descending. Rank Year Lowest Min Temperature Missing Count 1 1891 32 0 2 1874 33 0 3 2020 34 19 4 1947 35 0 - 1880 35 0 5 1977 36 0 - 1966 36 0 - 1913 36 0 - 1876 36 0 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 Dec 1 to Mar 31 Missing Count 1 2012-03-31 43.1 0 2 2016-03-31 43.0 0 3 2002-03-31 42.2 0 4 2020-03-31 41.4 0 5 1998-03-31 41.1 0 6 1991-03-31 40.5 0

It has been the 7th coldest so far. 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 Apr 15 to May 12 Missing Count 1 1875-05-12 47.2 0 2 1874-05-12 47.6 0 3 1873-05-12 49.3 0 4 1917-05-12 50.0 0 5 1893-05-12 50.2 0 6 1967-05-12 50.5 0 7 2020-05-12 51.0 0 - 1882-05-12 51.0 0

NYC is at -5.3 for May through the 12th. April finished at -2.7. The last time NYC had a cold April and May was in 2003. So it will be interesting to see if the cool onshore pattern coming up is enough for May to finish below normal. The April average temperature in NYC is 53.0 and 62.4 in May Monthly Mean Avg Temperature for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Year Apr May Season 2020 50.4 54.4 52.4 2019 55.5 62.2 58.9 2018 49.5 66.9 58.2 2017 57.2 61.1 59.2 2016 53.3 62.8 58.1 2015 54.3 68.5 61.4 2014 52.3 64.0 58.2 2013 53.0 62.8 57.9 2012 54.8 65.1 60.0 2011 54.3 64.5 59.4 2010 57.9 65.3 61.6 2009 54.5 62.5 58.5 2008 55.0 60.1 57.6 2007 50.3 65.2 57.8 2006 55.7 63.1 59.4 2005 55.1 58.9 57.0 2004 53.6 65.2 59.4 2003 49.8 58.7 54.3

Euro and EPS moving to more of an extended UL pattern along the East Coast starting with the backdoor on Sunday. The big warm up that the models were showing during this period will have to wait. The strongest ridging will remain to our west. So it looks like the 80+ on Friday will be our warmest day for a while. New run Old run

Euro and GFS agree on the backdoor and cool easterly for Sunday. But Monday and Tuesday depend on how far north the UL and subtropical system get. Euro is warmer for us Monday and Tuesday with the system staying suppressed. While the GFS is further north with cooler onshore flow lingering.

That’s tough to do this time of year. Looks like 80+ for the warm spots on Friday before the backdoor on Sunday.

There was some impressive May heat in the 1990’s. Years like 92 and 96 also had some of the coolest summers of the decade. But we had had plenty of April May record heat since 2010. Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Month of May Click column heading to sort ascending, click again to sort descending. Rank Year Highest Max Temperature Missing Count 1 1996 99 0 2 1992 98 0 - 1987 98 0

March has been the only consistently cooler spring month in recent times. The cold this year from mid April into May has been a big outlier. Seems like the usual March blocking and cold got delayed a bit this year. Could be a function of the record winter polar vortex taking longer to break down. 1981-2019 monthly temperature trends per decade for the OKX forecast zones Jan...+0.9°F/decade Feb....+0.2 Mar...+0.2 Apr...+0.6 May..+0.5 Jun..+0.4 Jul...+0.7 Aug...+0.7 Sep...+1.1 Oct...+1.0 Nov...+0.1 Dec...+0.9

We usually find a way to make a run on 90 in late May if we can verify a 588 DM ridge in the East. But there will probably be a backdoor nearby between the warm surges. Newark usually reaches 90 degrees between May 20th to 31st. Time Series Summary for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Ending Date Highest Max Temperature May 20 to May 31 Missing Count 2019-05-31 90 0 2018-05-31 92 0 2017-05-31 80 0 2016-05-31 96 0 2015-05-31 91 0 2014-05-31 88 0 2013-05-31 94 0 2012-05-31 92 0 2011-05-31 92 0 2010-05-31 95 0

That was the 3 day May record for NYC. These graphs only use hourly readings. Looks like the NYC high was 93 that day between hours. So a 55 degree rise.

Newark had a low of 34 on Saturday. If Newark can reach 84 degrees on Friday, then it would be a 50 degree temperature rise. The 6 day record for May was 50 degrees set back in 1996. NYC needs to reach 81 to tie its 47 degree record also set in 1996. https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=169&network=NJ_ASOS&zstation=EWR&hours=150&month=may&dir=warm&dpi=100&_fmt=png

Same thing before the 11-12 winter. Also the earliest 6” snowstorm in November 2018 before a nearly snowless DJF. RECORD EVENT REPORT NATIONAL WEATHER SERVICE NEW YORK NY 220 PM EDT FRI OCT 29 2011 ...RECORD OCTOBER SNOWFALL AMOUNT SET FOR CENTRAL PARK NY... AS OF 2 PM TODAY...CENTRAL PARK RECORDED 1.3 INCHES OF SNOWFALL. SINCE SNOWFALL RECORDS BEGAN IN 1869...AN INCH OF SNOWFALL HAS NEVER BEEN RECORDED IN THE MONTH OF OCTOBER. THE LAST TWO TIMES THAT MEASURABLE SNOW FELL IN THE MONTH OF OCTOBER WAS...OCTOBER 21 1952 WITH 0.5 INCHES AND OCTOBER 30 1925 WITH 0.8 INCHES. THEREFORE...THIS BREAKS THE DAILY RECORD FOR SNOWFALL IN OCTOBER AND THE MOST SNOWFALL EVER RECORDED IN THE MONTH OF OCTOBER. RECORD EVENT REPORT NATIONAL WEATHER SERVICE NEW YORK NY 0125 AM EST FRI NOV 16 2018 ...RECORD DAILY MAXIMUM SNOWFALL SET AT CENTRAL PARK NY... A RECORD SNOWFALL OF 6.4 INCH(ES) WAS SET AT CENTRAL PARK NY YESTERDAY. THIS BREAKS THE OLD RECORD OF 1 SET IN 1906. Time Series Summary for NY CITY CENTRAL PARK, NY - Dec through Feb Click column heading to sort ascending, click again to sort descending. Rank Season Total Snowfall Missing Count 1 1997-1998 0.5 0 2 1918-1919 1.1 0 3 1972-1973 2.6 0 4 1931-1932 2.7 0 5 1991-1992 3.2 0 6 2001-2002 3.5 0 7 2018-2019 3.7 0 8 2011-2012 4.5 0 9 2019-2020 4.8 0

Looks like Philly will have one of their latest first 80 degree days on record. First/Last Summary for PHILADELPHIA INTL AP, PA 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 1984 05-20 (1984) 81 10-28 (1984) 81 160 1997 05-19 (1997) 88 10-10 (1997) 84 143 1971 05-18 (1971) 81 09-29 (1971) 80 133 1988 05-13 (1988) 81 09-28 (1988) 82 137 1975 05-12 (1975) 80 11-05 (1975) 80 176 1987 05-10 (1987) 87 09-29 (1987) 80 141

Looks like 80 or warmer by later in the week as the extreme blocking pattern relaxes. This will allow more of a SE Ridge to develop. Be interesting to see if we can sneak in a first 90 by the last week of the month. The only year since 2010 that Newark didn’t reach 90 by the end of May was 2014. 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 First Value Last Value Difference 2019 05-26 (2019) 90 10-02 (2019) 96 128 2018 05-02 (2018) 90 09-06 (2018) 98 126 2017 05-17 (2017) 92 09-25 (2017) 90 130 2016 05-25 (2016) 91 09-23 (2016) 90 120 2015 05-25 (2015) 90 09-09 (2015) 91 106 2014 06-17 (2014) 91 09-06 (2014) 95 80 2013 05-30 (2013) 93 09-11 (2013) 96 103 2012 05-28 (2012) 91 09-07 (2012) 90 101 2011 05-30 (2011) 92 08-08 (2011) 93 69 2010 04-07 (2010) 92 09-25 (2010) 90 170

This was the first top 3 coldest monthly minimum temperature in NYC since August 1986. Top 3 warmest monthly maximums have been much more common. The most recent events were in January and October. Just before that was the warmest February reading on record in NYC during February 2018. Time Series Summary for NY CITY CENTRAL PARK, NY - Month of May Click column heading to sort ascending, click again to sort descending. Rank Year Lowest Min Temperature Missing Count 1 1891 32 0 2 1874 33 0 3 2020 34 22 Time Series Summary for NY CITY CENTRAL PARK, NY - Month of Aug Click column heading to sort ascending, click again to sort descending. Rank Year Lowest Min Temperature Missing Count 1 1986 50 0 - 1982 50 0 - 1976 50 0 - 1965 50 0 - 1885 50 0 Time Series Summary for NY CITY CENTRAL PARK, NY - Month of Jan Click column heading to sort ascending, click again to sort descending. Rank Year Highest Max Temperature Missing Count 1 2007 72 0 - 1950 72 0 2 1932 70 0 3 2020 69 0 - 2002 69 0 - 1916 69 0 Time Series Summary for NY CITY CENTRAL PARK, NY - Month of Oct Click column heading to sort ascending, click again to sort descending. Rank Year Highest Max Temperature Missing Count 1 1941 94 0 2 2019 93 0 3 1939 91 0 Time Series Summary for NY CITY CENTRAL PARK, NY - Month of Feb Click column heading to sort ascending, click again to sort descending. Rank Year Highest Max Temperature Missing Count 1 2018 78 0 2 1985 75 0 - 1930 75 0 4 1949 73 0

Flurries now in SW Suffolk.

This would be a nice snow squall by winter standards. Wonder if there is some graupel mixing in or it’s all snow?

It must be a function of our warming climate. But why it specifically manifests in this way would make a great research topic. Maybe a combination of declining Arctic sea ice, warming subtropical SST’s, warming tropical SST’s, rising land temperatures, and changing 500 mb and jet stream patterns. 1981-2019 monthly temperature trends per decade for the OKX forecast zones Jan...+0.9°F/decade Feb....+0.2 Mar...+0.2 Apr...+0.6 May..+0.5 Jun..+0.4 Jul...+0.7 Aug...+0.7 Sep...+1.1 Oct...+1.0 Nov...+0.1 Dec...+0.9

It actually looks more typical for May by later next week. We get a warm up followed by a backdoor cold front.