bluewave

We needed that Arctic outbreak about 10 days before the 3-22 snowstorm in NYC. The record 80s warmth didn’t occur until after the snow in March 1998.

Bradford was actually warmer than the winter of 01-02 for 2 years in a row now. Time Series Summary for BRADFORD REGIONAL AIRPORT, PA - Dec through Feb Click column heading to sort ascending, click again to sort descending. Rank Season Mean Avg Temperature Missing Count 1 2023-2024 32.7 7 2 2022-2023 32.0 0 3 2001-2002 30.9 0 4 1997-1998 30.2 8 5 2016-2017 29.3 0 - 2015-2016 29.3 0 6 2011-2012 29.2 0 7 2012-2013 28.9 0 8 2019-2020 28.8 0 9 2021-2022 27.4 1 10 1998-1999 27.3 0

Good question. Plus we may be dealing with non-linear changes involving threshold temperatures for deep convection. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022GL101499

We have had a Virginia winter temperature regime in place since the +13.3 December 2015. NYC has been at a new winter average of 38.5° lasting almost an entire decade. The previous 1981-2010 winter average was 35.1° So that is +3.4 warmer over a 9 winter period. Plus this is a regional event for the East and many other sites have made a shift like this in December 2015 and are at +3 to +4 over 1981-2010 climate normals. I am not aware of any other region of the country that has ever had nearly a decade at +3.4° above the previous 30 year climate normals. It’s seems like the frequent marine heatwaves in the Eastern IO to WPAC have loaded the dice for more forcing in these regions which is warm for us. I don’t really know what it would take to shift this pattern. Monthly Mean Avg Temperature for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Year Dec Jan Feb Season Mean 41.0 35.7 38.8 38.5 2023-2024 44.6 37.0 39.4 40.4 2022-2023 38.5 43.5 41.1 41.0 2021-2022 43.8 30.3 37.3 37.1 2020-2021 39.2 34.8 34.2 36.1 2019-2020 38.3 39.1 40.1 39.2 2018-2019 40.1 32.5 36.2 36.3 2017-2018 35.0 31.7 42.0 36.1 2016-2017 38.3 38.0 41.6 39.3 2015-2016 50.8 34.5 37.7 41.0

Looks like this will end up as a 10-15.6” winter for most closer to the coast. CT IGOR I SIKORSKY MEMORIAL AIRPORT WBAN 15.6 CT RIDGEFIELD 3.6 N CoCoRaHS 15.6 CT GUILFORD COOP 15.5 CT MIDDLEFIELD 1.4 W CoCoRaHS 15.5 CT DANBURY COOP 15.4 NY MOUNT SINAI COOP 15.3 NJ GLEN ROCK 0.7 SSE CoCoRaHS 15.2 NY HOWARD BEACH 0.4 NNW CoCoRaHS 15.2 NJ WAYNE TWP 0.8 SSW CoCoRaHS 14.9 CT NORWALK 2.9 NNW CoCoRaHS 14.7 CT NEW CANAAN 3.8 N CoCoRaHS 14.7 NJ NEW PROVIDENCE 0.8 ESE CoCoRaHS 14.7 NY RIDGE 1.5 SE CoCoRaHS 14.5 NJ CLARK TWP 1.3 ENE CoCoRaHS 14.3 NJ POMPTON LAKES 1.0 ENE CoCoRaHS 14.2 NY COMMACK 1.3 SW CoCoRaHS 14.1 NY PORT JEFFERSON STATION 0.3 SSW CoCoRaHS 13.9 CT NORWICH 5.4 SE CoCoRaHS 13.9 NY NESCONSET 1.4 SSW CoCoRaHS 13.7 NJ TENAFLY 1.3 W CoCoRaHS 13.6 NJ MONTCLAIR 0.7 N CoCoRaHS 13.5 CT HIGGANUM 0.8 NE CoCoRaHS 13.5 NJ HAWTHORNE 1.0 SSE CoCoRaHS 13.4 NY NEW HEMPSTEAD 0.6 SE CoCoRaHS 13.4 CT RIDGEFIELD 3.7 NNE CoCoRaHS 13.4 NY STATEN ISLAND 1.4 SE CoCoRaHS 13.4 NJ VERONA TWP 0.8 W CoCoRaHS 13.3 NJ FAIR LAWN 1.2 SE CoCoRaHS 13.2 NY BRIGHTWATERS 0.7 NNW CoCoRaHS 13.1 NY ST. JAMES COOP 13.0 NY JFK INTERNATIONAL AIRPORT WBAN 12.8 NY UPTON COOP - NWSFO NEW YORK COOP 12.7 NY MANHASSET HILLS 0.2 NNE CoCoRaHS 12.4 NJ HARRISON COOP 12.4 CT MYSTIC 3.4 NW CoCoRaHS 12.4 CT SEYMOUR 1.2 WSW CoCoRaHS 12.4 CT NORWICH 5.2 SE CoCoRaHS 12.3 NJ NEWARK LIBERTY INTL AP WBAN 12.2 CT KILLINGWORTH 2.6 ESE CoCoRaHS 12.2 NJ KEARNY 1.7 NNW CoCoRaHS 11.6 NJ MAPLEWOOD TWP 0.9 SE CoCoRaHS 11.2 CT NORWICH PUBLIC UTILITY PLANT COOP 11.1 NJ RIVER EDGE 0.4 NNE CoCoRaHS 11.0 CT ANSONIA 1 NE COOP 11.0 NY BELLMORE 0.9 SSE CoCoRaHS 10.9 NY ISLIP-LI MACARTHUR AP WBAN 10.9 CT STRATFORD 0.9 W CoCoRaHS 10.9 NY SYOSSET COOP 10.8 CT BETHEL 4.5 SSE CoCoRaHS 10.8 NY LITTLE NECK 0.3 SE CoCoRaHS 10.7 NY RIVERHEAD RESEARCH FARM COOP 10.7 NY LAGUARDIA AIRPORT WBAN 10.5 CT PAWCATUCK 1.8 SSE CoCoRaHS 10.3 NY WEST POINT COOP 10.2 NJ WEST CALDWELL TWP 1.3 NE CoCoRaHS 10.2 NJ WESTFIELD 0.8 WSW CoCoRaHS 10.2 CT WALLINGFORD CENTER 1.9 WNW CoCoRaHS 10.1 NY AMITYVILLE 0.6 NNE CoCoRaHS 10.0 NY REMSENBURG-SPEONK 0.9 NE CoCoRaHS 10.0

No surprise we are seeing this big warm up as these are some off the warmest SSTs ever recorded this time of year near the Maritime Continent driving the forcing there.

Pretty impressive for UCLA to establish the new all-time monthly rainfall record beating the 1998 El Niño.

The Pacific has been much more important for us than than anything happening with the stratosphere or the -NAO. Next week we’ll see our strongest -PNA trough since last spring. So it looks like a warm pattern for us from late February into early March. If a more -NAO pattern develops by mid-March, then it will come down to the Pacific again. If that -PNA trough dominates, then it will be warm like last March was with the -PNA -NAO.

This El Niño is finally fading as the models have the strongest -PNA drop since last spring. If the clouds end up dominating next week, then the highs will only max out in upper 50s to low 60s. But a slower frontal passage and more breaks of sun will allow the warm spots to make a run on 70°.

These more south based blocks could be related to the record Atlantic SSTs.

It think it may be related to these more frequent south based blocks in recent years not having the same staying power as the older ones which where located closer to the Arctic.

That was the only time NYC had a 5” snowstorm so close to a string of 80° days. Data for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Date Max Temperature Min Temperature Snowfall 1998-03-22 36 30 5.0 1998-03-23 47 32 0.0 1998-03-24 49 34 0.0 1998-03-25 50 34 0.0 1998-03-26 67 40 0.0 1998-03-27 83 56 0.0 1998-03-28 80 63 0.0 1998-03-29 81 62 0.0 1998-03-30 82 59 0.0 1998-03-31 86 66 0.0

Pretty impressive for Bradford,PA to beat the 01-02 winter warmth for two years in a row as the warmest departures missed just to our west. Time Series Summary for BRADFORD REGIONAL AIRPORT, PA - Dec through Feb Click column heading to sort ascending, click again to sort descending. Rank Season Mean Avg Temperature Missing Count 1 2023-2024 32.6 9 2 2022-2023 32.0 0 3 2001-2002 30.9 0 4 1997-1998 30.2 8 5 2016-2017 29.3 0 - 2015-2016 29.3 0 6 2011-2012 29.2 0 7 2012-2013 28.9 0 8 2019-2020 28.8 0 9 2021-2022 27.4 1 10 1998-1999 27.3 0 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 Mean Avg Temperature Missing Count 1 2001-2002 41.6 0 2 2022-2023 41.0 0 - 2015-2016 41.0 0 3 2023-2024 40.5 9 - 2011-2012 40.5 0 4 1931-1932 40.2 0 5 1997-1998 39.6 0 6 2016-2017 39.3 0 7 2019-2020 39.2 0 8 1990-1991 39.1 0 9 1998-1999 38.6 0 10 1948-1949 38.5 0 - 1889-1890 38.5 0

But the interior has been favored during recent Marches.

The MOS gets down to 19° but may be able to get closer to 17° again if the winds go calm faster.

Even Islip didn’t drop below 17° which is a first. Time Series Summary for ISLIP-LI MACARTHUR AP, NY - Dec through Feb Click column heading to sort ascending, click again to sort descending. Rank Season Lowest Min Temperature Missing Count 1 2023-2024 17 10 2 2001-2002 15 0 - 1997-1998 15 0 3 2020-2021 13 0 - 2019-2020 13 0 4 2009-2010 12 0 - 2005-2006 12 0 5 2011-2012 10 0 - 2007-2008 10 0

Criticism of these recent AMOC model studies from the leading experts in Sweden. Researchers: "Stop sounding the alarm about the Gulf Stream!" PUBLISHED FEBRUARY 17, 2024 Earlier alarms that the Gulf Stream may be about to collapse - with an extreme cooling in Sweden, among others as a result - are now being criticized by several of Sweden's leading experts in the field. - I was a bit shocked, says climate scientist Frederik Schenk. Last week there was a new Dutch study on the Gulf Stream that made big headlines around the world. It described what could happen if the large and important AMOC ocean current system, of which the Gulf Stream is a part, collapses. A collapse could have devastating consequences for the climate, and the Dutch researchers described an extreme and rapid cooling in Sweden. "Outright misleading" Now several of Sweden's leading researchers are criticizing some of the conclusions. Not least because the latest study is a model. - To hastily draw conclusions based on isolated observations, indirect reconstructions or model simulations is not only risky, it is downright misleading, says Léon Chafik, oceanographer and climate scientist at Stockholm University. His and his colleagues' research on the Nordic branch of the Gulf Stream instead shows that it is strengthened in a warmer world . - It may indicate a potential resilience of the Gulf Stream that has not been noticed before. "I was a little shocked" Frederik Schenk at the Bolin Center for Climate Research also reacted to the findings. - Not least the extreme temperature difference surprised. This is not what previous studies have shown. The researchers in Utrecht have not included global warming, which is likely to moderate cooling, in their model. And there are studies that indicate that the warming we have had and will have would likely completely trump a cooling in northern Europe in the long run. This does not mean that a systemic collapse of the ocean currents would not be serious. However, the Earth's southern hemisphere is not expected to cool down, but on the contrary to become significantly hotter, which could threaten both the Amazon and some of the world's most populous areas south of the equator in completely different ways.

My guess is that the unusually active MJO 2-7 for such a strong El Niño combined with the record Atlantic SSTs for a much stronger Eastern ridge than usual in an El Niño. Notice how much higher the heights were in the East compared to the Euro seasonal forecast. The -PDO background could also have given an assist.

The first 5 years of the 2020s are averaging less than half the snowfall of the 2010s. Monthly Total Snowfall for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Year Oct Nov Dec Jan Feb Mar Apr Season Mean T 0.0 3.3 4.7 8.8 0.4 T 17.1 2023-2024 0.0 T T 3.1 9.1 M M 12.2 2022-2023 0.0 T 0.1 T 2.0 0.6 0.0 2.7 2021-2022 0.0 0.1 0.1 14.6 2.3 0.8 0.0 17.9 2020-2021 T 0.0 11.9 3.2 30.6 T 0.0 45.7 2019-2020 0.0 T 4.2 2.7 T T T 6.9 Monthly Total Snowfall for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Year Oct Nov Dec Jan Feb Mar Apr Season Mean 1.0 1.3 9.8 12.9 15.7 2.2 0.1 43.1 2013-2014 0.0 T 9.4 20.8 30.3 0.2 0.4 61.1 2012-2013 0.0 6.6 1.9 1.4 10.8 8.8 0.0 29.5 2011-2012 5.2 0.0 0.0 3.3 0.3 0.0 0.0 8.8 2010-2011 0.0 T 24.5 37.4 4.1 2.2 T 68.2 2009-2010 0.0 0.0 13.3 1.7 32.9 T 0.0 47.9 Monthly Total Snowfall for IGOR I SIKORSKY MEMORIAL AIRPORT, CT Click column heading to sort ascending, click again to sort descending. Year Oct Nov Dec Jan Feb Mar Apr Season Mean T T 3.3 6.8 9.9 0.5 T 20.4 2023-2024 0.0 T T 5.5 10.1 M M 15.6 2022-2023 0.0 T 0.8 T 4.1 T 0.0 4.9 2021-2022 0.0 T 0.2 20.8 4.7 2.0 0.0 27.7 2020-2021 T T 10.0 3.1 30.7 0.0 0.0 43.8 2019-2020 0.0 T 5.5 4.6 T T T 10.1 Monthly Total Snowfall for IGOR I SIKORSKY MEMORIAL AIRPORT, CT Click column heading to sort ascending, click again to sort descending. Year Oct Nov Dec Jan Feb Mar Apr Season Mean 0.8 1.8 8.8 15.0 17.3 3.4 0.0 47.2 2013-2014 0.0 0.1 10.9 13.4 32.1 0.8 0.1 57.4 2012-2013 0.0 8.4 7.8 4.7 30.4 13.0 0.0 64.3 2011-2012 4.0 0.0 0.0 7.4 2.2 T T 13.6 2010-2011 0.0 0.4 12.0 42.0 5.0 3.2 T 62.6 2009-2010 T 0.0 13.4 7.7 16.9 0.1 T 38.1

The 50s and the 80s were much colder than the last 9 winter average temperatures. The years in that era with below average snowfall were mostly the result of drier winter patterns and unfavorable storm tracks. 72-73 was actually a colder than average winter by todays standards. But the storm tracks were very unfavorable for snow here. It was cold enough for portions of the Southeast into Mid-Atlantic to have one of their greatest snowstorms of all time that winter. The increase in moisture and amazing storm tracks actually boosted our winter snowfall from 02-03 to 17-18. Those two factors were masking the warming process that was continuing. So the snowier winters made people pay less attention to winters like 01-02, the first half of January 2005, the record warm January 2006, and 70° warmth in January 2007. Then we had the 11-12 winter followed by the very warm start to 12-13 sandwiched in between the phenomenal 09-10, 10-11, 13-14, and 14-15 cold and snowy winters. Now that the warming picked up after the historic December 15 +13.3 departure, it has resulted in 5 out of the last 6 winters with below average snowfall. We have been seeing more frequent combinations of both unfavorable tracks and warmth cutting down on our snowfall potential. When we do get finally get a favorable track like last week, we lost a portion of the snow potential to lower ratios and melting due to the warmth. You are correct that it will take a while to finally determine if a longer term snowfall decline is underway. But my guess is that the 2010s will mark the peak decadal snowfall for our modern era. And that the beginning of a snowfall decline commenced during the 18-19 season. Now this doesn’t mean we still won’t have above normal snowfall along the way in future winters like in the 20-21 season. But that over time into the future decades the seasonal snowfall averages will be on a down trend from the 2010s peak. At some point the warming will probably result in our new 30 year averages dipping below 20”. Instead of just reverting to the long term mean around 25” which was common before the 2010s.

The 50s and 80s were much colder than the present era. Less snowy winters in those years were still cold by todays standards. They were mostly the result of unfavorable storm tracks. This is the first time we are getting a combination of too warm for snow for numerous storm occasions plus unfavorable tracks.

It makes sense that the more southern areas have lost the most snow since they have passed warming thresholds faster for snowfall accumulation.

They would make the trip from 30 Rock over to Central Park to take the snowfall measurements before 1993. https://vlab.noaa.gov/web/nws-heritage/-/100-years-of-weather-observations-at-belvedere-castle-in-central-park#:~:text=On January 1%2C 1920 the,communications with the primary office. The lack of space for weather observing equipment in Rockefeller Plaza resulted in the decision to make the Central Park observing site the official NYC observation and, on January 1, 1961 it became such. References from this point out for climatological records in New York City referenced the Park, not the Weather Bureau office in Lower Manhattan. In addition, the observation was automated, with the exception of sky cover and snowfall, and remoted to a display at 30 Rockefeller Plaza. Snow observations were taken by staff from the Weather Bureau who made the trek through the snow to Central Park to measure it.

That’s why Lonnie Quinn got the intermediate measurement which was higher. Add this up over a complete season and we can see how the official totals at NYC are lower than the surrounding stations. It’s also how that artificial under 1” record ran so long only at NYC and not any other local stations. https://www.cbsnews.com/newyork/news/biggest-snow-accumulation-totals-around-n-y-n-j-and-conn/ Central Park: 3.2 inches officially, 3.9 inches as measured by CBS New York's Lonnie Quinn Number of Consecutive Days Snowfall < 1 for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Rank Run Length Ending Date 1 701 2024-01-15 2 383 1998-03-21 3 381 1955-02-01 Number of Consecutive Days Snowfall < 1 for LAGUARDIA AIRPORT, NY Click column heading to sort ascending, click again to sort descending. Rank Run Length Ending Date 1 642 1973-12-16 2 386 1992-03-18 3 383 1998-03-21 4 378 2023-02-26 Number of Consecutive Days Snowfall < 1 for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Rank Run Length Ending Date 1 661 1973-12-15 2 378 2023-02-26 3 363 1955-01-14 4 351 1992-02-12 Number of Consecutive Days Snowfall < 1 for JFK INTERNATIONAL AIRPORT, NY Click column heading to sort ascending, click again to sort descending. Rank Run Length Ending Date 1 660 1974-01-03 2 378 2023-02-26 3 363 1989-01-05

I am glad your area was able to really cash in on this jet stream assist creating a great left from exit region.