bluewave

It’s interesting how blocking has less of a cooling influence as we move into the summer. In fact, our hottest summers since 2010 have had strong blocking patterns. The last 11 year summer composite has featured some of the strongest summer blocking on record. The period also featured our hottest summers on record. 9 out of 11 years recorded above average summer temperatures. Only 2014 and 2017 came in near or below average on the temperatures. But those summers had strong blocking like the warmer ones. The one difference is on the Pacific side. The warmer than average summers had the North Pacific ridge axis to the north of Hawaii. During the cooler 2014 and 2017 summers, this ridge was located over Western North America. So we need blocking to combine with a stronger ridge near the PACNW for more comfortable temperatures.

The summer maximums are rising nearly as fast as the minimums. The minimums are increasing only about a tenth of a degree per decade faster. Since 1981, the highs are increasing at +0.6°per decade vs +0.7° for the lows. Last summer was the 2nd warmest with numerous top 10s since 2015. We have also had numerous top 10 summers for 90° days away from the sea breeze. So the rising high temperatures have been driven by more 90° days while the 100°s have been fairly steady since 1981. 201006 - 201008 75.2°F 126 3.5°F 202006 - 202008 74.4°F 125 2.7°F 201606 - 201608 74.2°F 124 2.5°F 200506 - 200508 73.9°F 123 2.2°F 201106 - 201108 73.9°F 123 2.2°F 199906 - 199908 73.7°F 121 2.0°F 201206 - 201208 73.4°F 120 1.7°F 201806 - 201808 73.4°F 120 1.7°F 201906 - 201908 73.2°F 118 1.5°F 201506 - 201508 73.1°F 117 1.4°F 194906 - 194908 73.0°F 116 1.3°F Time Series Summary for LAGUARDIA AIRPORT, NY - Jan through Dec Click column heading to sort ascending, click again to sort descending. Rank Year Number of Days Max Temperature >= 90 Missing Count 1 2010 48 0 2 2018 38 0 3 2002 35 0 4 2020 34 0 - 1991 34 0 5 2016 32 0 6 1983 31 0 7 2005 30 0 - 1953 30 0 8 1955 29 0 - 1944 29 0 9 2012 28 0 - 1949 28 0 10 1959 27 0

The winter maximum temperatures have been more impressive than the summer maximums since the 2015-2016 super El Niño. Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Dec through Feb Click column heading to sort ascending, click again to sort descending. Rank Season Highest Max Temperature Missing Count 1 2017-2018 80 0 2 1998-1999 76 0 - 1948-1949 76 0 3 2016-2017 74 0 - 2001-2002 74 0 - 1996-1997 74 0 - 1953-1954 74 0 - 1949-1950 74 0 4 1984-1985 73 0 5 2006-2007 72 0 - 1982-1983 72 0 - 1946-1947 72 0 6 2015-2016 71 0 - 2013-2014 71 0 - 2010-2011 71 0 7 2019-2020 70 0 - 1997-1998 70 0 - 1978-1979 70 0 - 1938-1939 70 0 - 1931-1932 70 0 Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Jun through Aug Click column heading to sort ascending, click again to sort descending. Rank Year Highest Max Temperature Missing Count 1 2011 108 0 2 2001 105 0 - 1993 105 0 - 1966 105 0 - 1949 105 0 3 2012 104 0 - 1995 104 0 - 1936 104 0 4 2010 103 0 - 1999 103 0 - 1954 103 0 - 1948 103 0 5 2005 102 0 - 1994 102 0 - 1991 102 0 - 1977 102 0 - 1953 102 0 - 1952 102 0 - 1944 102 0 - 1943 102 0 6 2013 101 0 - 2006 101 0 - 1997 101 0 - 1988 101 0 - 1980 101 0 - 1957 101 0 - 1955 101 0 - 1933 101 0 7 2002 100 0 - 1986 100 0 - 1982 100 0 - 1973 100 0 - 1963 100 0 - 1959 100 0 - 1937 100 0 - 1934 100 0

The humid subtropical climate zone has expanded north into more of our area on the latest 1991-2020 climate normals.

Euro and EPS upgrade on Tuesday.

The weather swings from warm to cold were even more extreme in Europe this spring.

79 °to snow in a week during May. Data for BRADFORD REGIONAL AIRPORT, PA Click column heading to sort ascending, click again to sort descending. Date Max Temperature Min Temperature 2021-05-01 61 32 2021-05-02 79 51 2021-05-03 63 57 2021-05-04 71 57 2021-05-05 57 40 2021-05-06 55 32 2021-05-07 49 32 2021-05-08 49 30 2021-05-09 M M

If the wet snow in PA verifies later, then it will be the 2nd Mother’s Day weekend in a row for the Northeast.

The range between the high and low temperature at Newark from April 1st is one of the greatest since 2010. It’s part of the very strong blocking and highly amplified MJO activity. Models try to weaken the blocking in 8-10 days with more of.SE Ridge. So that will be our next warm up. 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 Apr 1 to May 9 Minimum Temperature 2021-05-09 89 28 2020-05-09 80 32 2019-05-09 80 32 2018-05-09 94 31 2017-05-09 87 36 2016-05-09 83 26 2015-05-09 87 33 2014-05-09 83 31 2013-05-09 85 31 2012-05-09 88 38 2011-05-09 87 37 2010-05-09 92 38

Strong -NAO and record MJO are producing quite a bit of high temperature volatility. Data for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Date Max Temperature Max Temperature Departure 2021-04-01 58 1.4 2021-04-02 40 -17.0 2021-04-03 54 -3.4 2021-04-04 67 9.1 2021-04-05 70 11.7 2021-04-06 71 12.3 2021-04-07 71 11.9 2021-04-08 68 8.4 2021-04-09 53 -7.0 2021-04-10 67 6.6 2021-04-11 58 -2.9 2021-04-12 50 -11.3 2021-04-13 66 4.3 2021-04-14 72 9.9 2021-04-15 58 -4.5 2021-04-16 55 -7.9 2021-04-17 54 -9.4 2021-04-18 63 -0.8 2021-04-19 68 3.8 2021-04-20 78 13.5 2021-04-21 75 10.1 2021-04-22 51 -14.3 2021-04-23 67 1.3 2021-04-24 72 5.9 2021-04-25 67 0.6 2021-04-26 64 -2.8 2021-04-27 63 -4.1 2021-04-28 89 21.5 2021-04-29 80 12.2 2021-04-30 73 4.9 2021-05-01 68 -0.4 2021-05-02 86 17.3 2021-05-03 71 2.0 2021-05-04 75 5.7 2021-05-05 64 -5.6 2021-05-06 69 -0.9 2021-05-07 66 -4.2 2021-05-08 55 -16.0

A waterspout to go with the hail today.

Getting pea size hail now on Staten Island.

If we can keep these record 700-500 mb lapse rates going into the summer, then it will be the case.

Heavier showers filling in more quickly just west of NYC than the models indicated yesterday. Impressive cold pool aloft with very steep mid-level lapse rates. So any stronger cells could produce some pea sized hail.

Models have pop up convection tomorrow under the deep upper low and cold pool. So it will be a hit or miss type affair during the day. Somebody could see the ground whitened with small hail under the steep mid-level lapse rates and low freezing level.

Unusual temperature pattern so far this May. Newark reached 86° during the first week of the month. Looks like our first time since 2010 with no May 8-15 follow up 80s in the forecast. Just goes to show how impressive a MJO event this was combined with lingering April blocking. 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 1 to May 7 May 8 to 15 2021-05-07 86 ? 2020-05-07 80 86 2019-05-07 78 79 2018-05-07 94 92 2017-05-07 76 71 2016-05-07 61 77 2015-05-07 87 88 2014-05-07 78 85 2013-05-07 72 81 2012-05-07 76 84 2011-05-07 73 76 2010-05-07 90 83

Our precipitation is increasing along with the temperatures. Rural, suburban, and urban sites are experiencing a faster minimum temperature rise than maximum. The maps below show the rate of change per decade. https://www.sciencedaily.com/releases/2020/09/200930194912.htm Days warmed more quickly in some locations, and nights did in others -- but the total area of disproportionately greater night-time warming was more than twice as large. The study shows this "warming asymmetry" has been driven primarily by changing levels of cloud cover. Increased cloud cover cools the surface during the day and retains the warmth during the night, leading to greater night-time warming. Whereas, decreasing cloud cover allows more warmth to reach the surface during the day, but that warmth is lost at night. https://www.ncdc.noaa.gov/temp-and-precip/us-trends/tmin/ann

I did a calculation of how much warmer the new 30 yr and 15yr climate normals are in NYC than 1981-2010. Month….30yr….15yr Dec.+1.6….+2.2 Jan..+1.1….+1.7 Feb…+0.6…+0.5 Mar..+0.3…+0.7 Apr…+0.7…+1.0 May…+0.8…+1.4 Jun….+0.5…+0.6 Jul….+1.0….+1.9 Aug….+0.9….+1.0 Sep….+1.2….+1.9 Oct….+1.0….+1.9 Nov…+0.3…+0.4

Same story in the Poconos. The summer minimums have been rising more quickly than the maximums. So this is a shared temperature pattern at rural, suburban, and urban stations.

The Euro has convection along the inverted trough with steep mid-level lapse rates on Saturday.

This will be our first cool stretch in a while. So it only took a record breaking MJO event to pull It off. Goes to the recent theme of needing something extreme to get cooler than average temperatures. KEWR GFSX MOS GUIDANCE 5/05/2021 0000 UTC FHR 24| 36 48| 60 72| 84 96|108 120|132 144|156 168|180 192 WED 05| THU 06| FRI 07| SAT 08| SUN 09| MON 10| TUE 11| WED 12 CLIMO X/N 65| 48 68| 47 63| 47 59| 45 62| 46 67| 47 66| 48 70 50 70 TMP 59| 51 61| 52 56| 51 53| 50 54| 50 60| 52 59| 53 63 DPT 45| 35 30| 35 37| 39 34| 37 36| 40 34| 35 32| 37 39 CLD OV| PC PC| CL OV| OV OV| PC OV| OV PC| CL PC| CL PC

The minimums are increasing faster than the maximums across the region. So the number of 70° minimums has doubled or tripled from 1981 to 2020. This is the case at urban,rural, and suburban stations. My guess is that this is related to the big increase in humidity and clouds at night as the climate warms. Since the Central Park station has become so overgrown with vegetation, POU to our north now has more 90° days than NYC. But the NYC nighttime minimums are increasing just as fast as other stations. So you can see it’s an artificial shading effect due to poor sensor sitting under the trees and bushes. Change in 90° highs and 70° lows ……….1981….90°…..70°…….2020…….90°……70° EWR…26/35….29/43 LGA….14/32….26/67 NYC….19/29…16/47 JFK…..11/29….11/40 ISP……..6/15……9/30 BDR……6/11……11/35 POU….12/3…..…19/9 BDL……14/6…….24/13 TTN…….18/17…..26/31

The fewest MJO winter phase 8-1 days followed by a new May phase 1 amplitude record. It’s tough to keep up with all these new weather extremes and swings. Back in February it was the historic AO/NAO reversal.

Classic spring backdoor day. Highs BDR…64° ISP…..65° LGA…69° JFK….71° EWR…75°

It’s good to see that we now have supplemental 15 year climate normals for the first time. The 15 year snowfall average at Islip of 36.3 is now similar to the old 1981-2010 normals for portions of New England. The December 15 year average temperature is now close to 40° in NYC. A 40° December is similar to the old 1981-2010 normals around Washington DC. The new 15 year July temperature around 80° at LGA and EWR is similar to the 1981-2010 average around DC. ISLIP LI MACARTHUR AP, NY Get this data as .csv | .pdf Season MAX TEMP (°F) MIN TEMP (°F) AVG TEMP (°F) PRECIP (IN) SNOW (IN) Annual 61.8 45.8 53.8 47.42 36.3 NEW YORK CNTRL PK TWR, NY Dec 45.0 34.4 39.7 4.88 4.6 NEW YORK LAGUARDIA AP, NY Jul 87.4 72.8 80.1 4.47 0.0 NEWARK INTL AP, NJ Jul 88.0 70.3 79.2 5.05 0.0 https://www.ncei.noaa.gov/access/us-climate-normals/ https://www.washingtonpost.com/weather/2021/05/04/noaa-new-climate-normals/ It used to be that the normals would give a great idea of what the climate has been like for someone’s 30-year career, so new resource managers could get up to speed quickly on how and why a more senior manager made the choices they did based on past climate,” McPherson said in an email. “Now we’re seeing enough change from one decade to the next that we need to prepare managers differently. They need to understand these are not static, so the direction of change is as important, or more important, as the values of the normals themselves.” NOAA has been experimenting with supplemental climate normals that may better reflect what to expect in the 2020s. Some researchers have argued that climatological periods shorter than 30 years could be more accurate for monthly temperature averages used in the near future. Thus, the new NOAA climate normals include a supplemental set of 15-year data for the period 2006-2020, a first for any climate-norms update.