bluewave

While it’s always possible to eventually have a colder winter or series of winters again, the coldest winters have been steadily warming over time. None of our colder winters since the late 1970s can come close to a winter like 76-77 for the magnitude and duration of that cold. Our coldest recent winter in 14-15 had 60s on Christmas and NYC averaged 40.5° in December. The last top 10 coldest month in February 2015 was answered by over 30 top 10 warmest months around the region throughout the year since then.

31-32 was a warm outlier for that much colder era. Now we get 40° winter months or 40° average winters nearly every year around NYC. There is much more than background warming occurring when we have seen an historic 9 warmer to record winters in row. The area is more than +3° above any previous 30 year winter average temperature over nearly the last decade. Why is it so hard to believe that CO2 causes the planet to warm up? The first studies were done in the 1800s on this topic. NYC hasn’t had a winter average temperature below 30° since the 1970s. So the much warmer climate makes this an unlikely occurrence barring some major volcanic eruption. As winters have been steadily warming over time, our area has had more all or nothing type snowfall winters since the 1990s. Either above average or below average snowfall with almost no median seasons for places like Long Island. Those more average snowfall seasons were much more common before the 1990s. The risk with the all or nothing track we have been on since the 1990s is that the nothing will become a more common outcome with continued warming. But like we saw in 21-22, we can still score some more above average snowfall seasons along the way. Nearly every snowfall season on Long Island since the 90s has been under 15” or over 30”. The 20s season common before the 90s is almost non-existent at places like Islip.

We could have used these dewpoints in the single digits ahead of some our winter storms. East Hampton MOSUNNY 33 3

Looks like plenty of clouds and rain to go along with the warmer temperatures. We have a strong blocking signal getting met by an overpowering warm Pacific MJO signal. So flooding could eventually become a concern again like we saw before we dried out in February. Could also be more beach erosion with so much high pressure east of New England with easterly flow and lows undercutting. It’s very hard to do warm and dry in a transition month like March with so much volatility. That 80° warmth with dry conditions in early March 2016 after that super El Niño was a real rarity. Our warmest days this March through the first 10 days will probably be 50s and 60s. Maybe someone in the interior away from the marine influence can make a run on 70°. Data for March 10, 2016 through March 11, 2016 Click column heading to sort ascending, click again to sort descending. State Name Station Type Highest Max Temperature NJ CANOE BROOK COOP 82 NJ NEWARK LIBERTY INTL AP WBAN 81 NJ TETERBORO AIRPORT WBAN 81 NJ TETERBORO AIRPORT COOP 81 NJ HARRISON COOP 80 NY SHRUB OAK COOP 80 NY YORKTOWN HEIGHTS 1W COOP 80 NY PORT JERVIS COOP 79 NY NY CITY CENTRAL PARK WBAN 79 NJ CALDWELL ESSEX COUNTY AP WBAN 79 NJ CHARLOTTEBURG RESERVOIR COOP 79 NY WEST POINT COOP 79 NY MOUNT SINAI COOP 79 NY LAGUARDIA AIRPORT WBAN 78 CT SAUGATUCK RESERVOIR COOP 78 CT STAMFORD 5 N COOP 77 NY WESTCHESTER CO AP WBAN 77 NY BAITING HOLLOW COOP 77 NY CENTERPORT COOP 76 NY CARMEL 4N COOP 76 NY SETAUKET STRONG COOP 76 CT MERIDEN MARKHAM MUNICIPAL AP WBAN 75 CT PUTNAM LAKE COOP 75 CT NORWICH PUBLIC UTILITY PLANT COOP 75 NY RIVERHEAD RESEARCH FARM COOP 75 NY UPTON COOP - NWSFO NEW YORK COOP 75

High pressure will dominate east of New England in early March so plenty of easterly flow with clouds and rain potential. It looks like the kind of pattern where the warmer days are into the 50s to lower 60s around EWR and NYC but clouds and onshore flow limit the 70°+ potential for a while near the metro.

Looks like a warm and wet pattern going into March as this is another example of these south based blocks linking up with the Southeast ridge. March 4-11

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