bluewave

No problem. I think the reference to 72-73 came up in discussion about this being a rare case of a -PDO with such a strong El Niño. Not that the actual 500 mb and temperature pattern would be a carbon copy. We are even seeing changes with the -PDO due to so much warming in the entire Western Pacific Basin. In addition to the record tropical marine heatwaves in the warmer WPAC MJO phases for us, the ongoing marine heatwave near Japan has been a compounding warm factor also. I saw a great post recently on twitter on how this is a different flavor of -PDO than we used to see before.

I didn’t say 72-73 was a good match for this winter since that was a much colder winter than this one was across North America. We are in such a different global climate state now, that winter analogs before the 15-16 super El Niño are too different. I mostly focused on the record WPAC warm pool for such a strong El Niño presenting warmer risks to the winter computer model forecasts.

One of the strongest leap day cold fronts on record with 50+ mph gusts and heavy convection to possible snow squalls. Temps will quickly fall from the 60s to 20s.

This winter is a great example of the limitations of long range computer model forecasts beyond the 360 hr EPS and other models. All the EPS forecasts beyond 15 days defaulted to its seasonal forecast of -EPO -AO. My guess is this was based solely on the models simple structure of being able to detect the El Niño and not the long range MJO. Notice how the closer in we got to the late February into March period the more amplified the forcing became from the IO into WPAC. This has been the pattern all winter. Longer range models tried to weaken the convection in these areas only to see the stronger convection once within 2 weeks. I was discussing the record marine heatwave potential since last summer that I believed would occur once the -IOD rapidly reversed in December. This is why I had the warmer risks to the forecasts as the primary issue that I saw for the long range this winter. The EPS even had a cold bias for its first two weeks.

The Mineola COOP was active from 1938 to 2010. The guy who maintained the observations for all those years was the president of the Long Island Weather Observers. 2010 was the only year with over 50 days due to the unusual amount of heat combined with westerly flow. Time Series Summary for MINEOLA, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Number of Days Max Temperature >= 90 Mar 1 to Sep 30 Missing Count 1 2010-09-30 52 0 2 1988-09-30 34 0 3 2002-09-30 33 0 4 2005-09-30 32 1 5 1999-09-30 27 6 - 1991-09-30 27 0 https://www.nytimes.com/1990/01/07/nyregion/cold-snap-tests-service-agencies.html The average temperature on the Island in December was 25.9 degrees, 10.3 degrees below normal and the third coldest on record, according to Steve Thomas, a National Weather Service meteorologist for the New York region. The coldest December on record occurred in 1876, when temperatures averaged 24.9 degrees; the most recent record was 1976, when temperatures averaged 29.9 degrees. In Mineola, temperatures hit a low of 6 degrees on Dec. 23, according to Ed Lynt, president of the Long Island Weather Observers, a volunteer organization that provides data for the New York Regional Office of the National Weather Service and to local radio and television stations.

Mineola had 52 days reach 90° in 2010. Data for January 1, 2010 through December 31, 2010 Click column heading to sort ascending, click again to sort descending. State Name Station Type Number of Days Max Temperature >= 90 NJ CANOE BROOK COOP 59 NJ NEWARK LIBERTY INTL AP WBAN 54 NY MINEOLA COOP 52 NJ RINGWOOD COOP 51 NJ HARRISON COOP 50 NY LAGUARDIA AIRPORT WBAN 48 NJ CRANFORD COOP 46 NY BRONX COOP 45 NJ TETERBORO AIRPORT COOP 41 NJ TETERBORO AIRPORT WBAN 40 NY NY CITY CENTRAL PARK WBAN 37 CT DANBURY COOP 37 NY WANTAGH CEDAR CREEK COOP 35 NY DOBBS FERRY-ARDSLEY COOP 34 NY WEST POINT COOP 33 NY JFK INTERNATIONAL AIRPORT WBAN 32 NJ CALDWELL ESSEX COUNTY AP WBAN 31

I believe the old Mineola COOP holds the record for Long Island with 6 days reaching 100° in 2010. That’s a great spot for compressional heating along the sea breeze front. We would probably need a severe drought from the Midwest to East Coast to see 10 days reaching 100 around the region. NJ would probably have the best chance. As it’s been tough to sustain offshore flow near the coast with the big highs parking to the east of New England instead of to our SW. Plus extended droughts have been tough to come by in the much wetter recent era. for January 1, 2010 through December 31, 2010 Click column heading to sort ascending, click again to sort descending. State Name Station Type Number of Days Max Temperature >= 100 NY MINEOLA COOP 6 NJ NEWARK LIBERTY INTL AP WBAN 4 NJ HARRISON COOP 4 NY WANTAGH CEDAR CREEK COOP 4 NJ CANOE BROOK COOP 3 NJ RINGWOOD COOP 3 NY JFK INTERNATIONAL AIRPORT WBAN 3 CT DANBURY COOP 3 Data for January 1, 2010 through December 31, 2010 Click column heading to sort ascending, click again to sort descending. State Name Station Type Highest Max Temperature NY MINEOLA COOP 108 NJ CANOE BROOK COOP 107 NY WANTAGH CEDAR CREEK COOP 107 NJ HARRISON COOP 106 NJ RINGWOOD COOP 106

The summer of 2022 came close in NJ. Data for January 1, 2022 through December 31, 2022 Click column heading to sort ascending, click again to sort descending. Name Station Type Number of Days Max Temperature >= 100 Newark Area ThreadEx 6 NEWARK LIBERTY INTL AP WBAN 6 FREEHOLD-MARLBORO COOP 5 SOMERSET AIRPORT WBAN 5 CANOE BROOK COOP 4 HARRISON COOP 4

Guidance is confirming that the warmer and less snowy March pattern which began in 2020 will continue. March used to be a colder and snowier more winter-like month from 2013 to 2019. So March is much more like a an early spring month during the 2020s. Monthly Mean Avg Temperature for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Year Mar Season Mean 42.8 42.8 2023 41.8 41.8 2022 42.4 42.4 2021 42.4 42.4 2020 44.8 44.8 Monthly Total Snowfall for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Year Mar Season Mean 0.8 0.8 2023 1.6 1.6 2022 1.6 1.6 2021 T T 2020 T T Monthly Total Snowfall for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Year Mar Season Mean 11.3 11.3 2019 4.1 4.1 2018 31.9 31.9 2017 7.4 7.4 2016 3.2 3.2 2015 19.7 19.7 2014 5.4 5.4 2013 7.4 7.4 Monthly Mean Avg Temperature for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Year Mar Season Mean 38.4 38.4 2019 38.7 38.7 2018 38.0 38.0 2017 37.1 37.1 2016 45.5 45.5 2015 35.2 35.2 2014 35.8 35.8 2013 38.3 38.3

Very unusual. Many comments on the rare location of the dryline to our West. We could actually see dewpoints in the single digits on Thursday behind the front.

It will feel like quite a shift if some of those snow squalls can make it east of the Delaware Thursday morning with upper 20s.

The HRRR has some 70° potential today down around Philly.

February 2018 style all-time record warmth but to our west this time.

I noticed that the MJO 5-6 was much stronger in the Octobers ahead of our snowiest La Ninas since 2010. But two of our three snowiest La Niña winters were still warmer than average like the ones with the weaker October MJO 5-6 and less snowy winters. So not sure why this has worked out for us just since 2010. The 10-11 and 11-12 multiyear La Niña was snowier in 10-11. Then the 16-17 and 17-18 event was snowier in 17-18. This was followed by 20-21, 21-22, and 22-23 which was snowiest in 20-21. It was almost like 20-21 was a weaker and warmer reflection of the stronger -AO and snowy 10-11. 16-17 was less snowy and much warmer than 17-18. But still found a way to produce above average snow. February 2018 was the most extreme daily winter warmth record we ever saw when we hit 80° for the first time. Even if the winter into spring was so snowy.

Under 15” seasons in NYC before 1990 were usually the result of drier conditions or hostile storm tracks. These days it’s warmer conditions of 38.0° to 41.5° and hostile storm tracks which result in under 15” seasons. Having those two features working in tandem will eventually produce more frequent under 15” seasons. But we will still have opportunities for snowier seasons from time to time like 20-21. Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Total Snowfall Oct 1 to Apr 30 DJF Average Temperature 1 2023-04-30 2.3 41.0° 2 1973-04-30 2.8 35.5° 3 2002-04-30 3.5 41.5° 4 1919-04-30 3.8 36.6° 5 2020-04-30 4.8 39.2° 6 1901-04-30 5.1 31.7° 7 1932-04-30 5.3 40.1° 8 1998-04-30 5.5 39.6° 9 2012-04-30 7.4 40.5° 10 2024-04-30 7.5 40.3° 11 1989-04-30 8.1 35.9° - 1878-04-30 8.1 33.2° 12 1951-04-30 9.3 36.1° 13 1997-04-30 10.0 37.8° 14 1942-04-30 11.3 32.9° 15 1955-04-30 11.5 33.9° 16 1931-04-30 11.6 33.7° 17 1995-04-30 11.8 37.1° 18 2008-04-30 11.9 36.4° 19 1872-04-30 12.1 29.5° 20 2007-04-30 12.4 36.5° 21 1992-04-30 12.6 37.2° 22 1999-04-30 12.7 38.6° 23 1980-04-30 12.8 35.4° 24 1986-04-30 13.0 33.4° - 1959-04-30 13.0 30.8° 25 1975-04-30 13.1 37.5° 26 1990-04-30 13.4 35.7° 27 1930-04-30 13.6 35.4° - 1900-04-30 13.6 33.6° 28 1929-04-30 13.8 34.7° 29 1950-04-30 14.0 37.6°

The 95° days have also been increasing at the warm spots like Newark away from the sea breeze. But the days with the heat index of 95° have also been increasing due to the higher humidity. https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=161&network=NJ_ASOS&zstation=EWR&var=max_tmpf&dir=aoa&thres=95&month=all&year=2024&_r=t&dpi=100&_fmt=js

On track for another winter with 30 or more days reaching 50° at the warm spots away from the immediate shoreline.

If they measured the temperatures in Central Park the same way they did before the 1990s, then NYC would average closer to 29 days a year reaching 90° than the 19 days since the warmer summer era began in 2010. 1951-1980 average number of 90° days EWR….23 NYC….18 LGA…..15 2010-2023 warmer era EWR….33 NYC…..19…actual ..close to 29 LGA…..26

Taking the Central Park temperatures under the trees since the new ASOS was installed back in the 90s created an artificial cooling of daytime highs during the the warm season. When they measured the temperatures away from the trees prior to the 1990s, NYC had more 90° days than LGA. So the decline in 90° days from 30 years before and after the new ASOS was installed is an artifact of the poor sitting and not a reflection of the actual temperatures in Central Park which used to be warmer than LGA. All our other stations away from the sea breeze have seen a steep increase in 90° days over this period. https://www.nytimes.com/1977/07/22/archives/vandals-in-central-park-forcing-weather-service-to-seek-new-site.html When the devices at the castle are not functioning, the Weather Service substitutes readings from La Guardia Airport. But Mr. Gibson said those readings do not really reflect conditions in the city, because they may be several degrees cooler in summer or warmer in winter than those in Central Park. https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=74&network=NJCLIMATE&station=NJTNBR&season=all&dir=above&var=high&threshold=90&year=1960&_r=t&dpi=100&_fmt=png

We came close back in 2022. But notice all the 40 day years recently reaching 90°. 2011 and 2012 had a much lower number of 90° days. But noteworthy shorter record heatwaves centered in July. Time Series Summary for NEWARK LIBERTY INTL AP, NJ - 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 54 0 2 2022 49 0 - 1993 49 0 3 1988 43 0 4 2021 41 0 - 2002 41 0 - 1991 41 0 5 2016 40 0 - 1983 40 0 - 1959 40 0 6 1994 39 0 - 1944 39 0 7 2005 37 0 - 1987 37 0 8 2018 36 0 - 1949 36 0 9 2015 35 0 10 1961 34 0 11 2012 33 0 - 1999 33 0 - 1995 33 0 - 1966 33 0 12 1955 32 0 - 1953 32 0 - 1943 32 0 13 2020 31 0 - 2011 31 0 - 1973 31 0 - 1952 31 0

2010 is the only summer that the coastal stations stations haven’t been able to beat. The summers after 2011 did have the memorable 105-108° maxes. But the heat peaked during 30 day periods centered around July. Our recent summers have had extended warmth throughout the summer. Places like Newark have already surpassed 2010 in the last few years. The lack of westerly flow in recent years has favored the stations away from the shore for the most extreme heat. Time Series Summary for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Rank Year Mean Avg Temperature Missing Count 1 2010 74.7 0 2 2022 74.6 0 - 2020 74.6 0 3 1999 74.5 0 4 2016 74.4 0 5 2011 73.9 0 6 2019 73.8 0 7 2021 73.7 0 8 2018 73.5 0 - 2005 73.5 0 9 2013 73.4 0 10 2012 73.3 0 Time Series Summary for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Rank Year Mean Avg Temperature Missing Count 1 2022 79.2 0 - 1993 79.2 0 2 2010 78.7 0 3 1994 78.5 0 4 2021 78.3 0 5 2011 78.0 0 6 2005 77.8 0 7 1988 77.7 0 8 2020 77.6 0 - 2016 77.6 0 - 1973 77.6 0 9 1999 77.1 0 10 1995 77.0 0

Yeah, the El Niño releases the excess heat building up in the oceans as the climate warms. So the El Niño itself isn’t causing the warming. If we had a stable climate like in the late 1800s, the global temperatures would quickly drop in few years like after the super El Niño like in 1877-1878. But as the climate continues to warm, each El Niño year sees a new annual jump. So it’s mostly a modulator of which years set new global temperature records between the neutral or La Nina years. I guess we have been lucky that the pace of the summer warming since 2010 hasn’t been as high as the winter warming since 2015.

Each new El Niño boosts the temperatures to a higher baseline. The 09-10 El Niño marked the beginning of a much warmer summer pattern which continues to this day. The 15-16 El Niño coincided with a shift to much warmer winters. The winter warming shift was of a higher magnitude than we have seen relative to the previous means than the summers. Now the global temperature jump with the 23-24 El Niño was even higher than the 15-16 super El Niño even though it wasn’t as strong. So it will be interesting to see what happens to our temperatures and weather patterns in coming years at this even higher temperature baseline.

It was good to see how much we were able to dry out this month. Monthly Total Precipitation for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Year Dec Jan Feb Season 2023-2024 6.71 5.28 1.35 13.34

Very amplified -PNA Southeast ridge pattern coming up. The amount of rain will depend on whether something tries to cutoff underneath. If we can escape the cutoffs, then just the typical cuttters with showers and maybe some thunderstorms from time to time.