bluewave

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

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.

We saw something like this during the 15-16 winter. December went +13 and then NYC dropped below zero in February for the first time since 1994. Extreme blocking seems to be the common denominator.

Models have temperatures very close to record lows early Saturday. EWR...33 NYC....35 LGA....37 JFK....38 ISP......36 BDR....37

The record warmth took a break that May. It was the 5th latest 41 or lower reading on record in NYC. The temperatures rebounded again in July after a close to average June. 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 Last Value First Value Difference 1961 05-27 (1961) 41 10-28 (1961) 40 153 1925 05-25 (1925) 41 10-10 (1925) 36 137 1963 05-24 (1963) 39 09-24 (1963) 40 122 1907 05-21 (1907) 40 10-19 (1907) 39 150 2002 05-19 (2002) 41 10-15 (2002) 41 148 1976 05-19 (1976) 38 10-18 (1976) 38 151

Today was the 8th -10 departure in NYC since April 17th. There were only 2 days with a -10 departure in NYC for all of December through March. TEMPERATURE (F) TODAY MAXIMUM 52 1113 AM 92 1986 68 -16 74 1949 MINIMUM 48 253 PM 32 1891 51 -3 51 AVERAGE 50 60 -10 63

I believe that 5-22-02 was the latest freeze for the coldest spots on Long Island. Frost/Freeze Summary for WESTHAMPTON GABRESKI 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 2002 05-22 (2002) 32 10-15 (2002) 31 145 2016 05-20 (2016) 32 10-11 (2016) 31 143 2008 05-20 (2008) 31 10-07 (2008) 31 139 2003 05-19 (2003) 32 10-03 (2003) 29 136 2000 05-16 (2000) 30 10-09 (2000) 32 145 2013 05-15 (2013) 32 10-19 (2013) 32 156 1999 05-15 (1999) 31 10-06 (1999) 31 143

This may be a new surface to 500 mb steep lapse rate record for our area on Saturday.

Euro has some the lowest May 850 mb temperatures on record for Saturday. So it looks like NYC has a good chance to dip below 40 for the first time in May since the 1970’s. NYC may not get out of the 40’s for a high on Saturday. There also could be some wet snowflakes mixed in during the morning. That would tie 1977 for the latest trace of snow on record in NYC. The NYC record low is 35 and low max 44. Record Lowest Max Temperature M 69 94 in 1979 44 in 1977 Min Temperature M 52 74 in 2000 35 in 1947

18z NAM with a rare late season interior snow. Maybe some flakes to the coast behind the storm. Models really struggling with the TPV storm details.

Models continuing with record low May 500 mb heights this weekend. The Euro has a -5 SD event with the TPV. So maybe we can see some flurries if the precipitation coincides with the lowest temperatures in the morning. Would be a tie with 1977 for the latest trace of snow at the coast.

Euro hinting at possibly the lowest 500mb heights on record for May next weekend. The TPV drops into the Northeast with a -4 to -5 SD departure. TPV related storm details can be difficult beyond 120 hrs. But portions of the Northeast can see late season snow along with impressive May cold for most.

Euro continuing with the late freeze idea for next weekend N and W of NYC. Be interesting to see if NYC can actually drop below 40 degrees. Sometimes the OP Euro is too cool for NYC beyond 5 days out. But with the TPV dipping into New England, maybe NYC can pull off 37 to 39 degrees. Frost/Freeze Summary for SUSSEX AIRPORT, 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 Season Length Minimum 04-17 (2016) 10-05 (2019) 151 Mean 04-30 10-16 167 Maximum 05-14 (2013) 10-28 (2011) 188 2019 04-29 (2019) 28 10-05 (2019) 30 158 2018 05-01 (2018) 32 10-18 (2018) 31 169 2017 05-04 (2017) 32 10-17 (2017) 30 165 2016 04-17 (2016) 31 - - - 2015 04-26 (2015) 28 10-17 (2015) 27 173 2014 04-25 (2014) 30 10-20 (2014) 32 177 2013 05-14 (2013) 29 10-21 (2013) 32 159 2012 04-30 (2012) 27 10-12 (2012) 29 164 2011 04-22 (2011) 26 10-28 (2011) 32 188 2010 05-11 (2010) 28 10-10 (2010) 30 151

Newark made it to 80 with the warm downslope flow. Newark Liberty PTSUNNY 80 52 37 W15G22

We get our transient warm up this weekend. But one of the coldest 6-10 forecasts we see this time of year. The blocking pattern right across the pole is as strong as it gets for May.