bluewave

Just the late May patterns in recent years as May 1st through 20th has been the warmest on record for spots like JFK and ISP at +5.1° and +5.0° These briefly cooler patterns are a nice reprieve from the wall to wall warmth we usually experience. The warm rebound following the cool periods has usually been more impressive. So we could quickly shift back to warm in early June with the first 90° potential of the season at the warm spots. Time Series Summary for JFK INTERNATIONAL AIRPORT, NY Click column heading to sort ascending, click again to sort descending. 1 2025-05-20 64.0 0 2 2015-05-20 63.1 0 3 1979-05-20 63.0 0 4 1991-05-20 62.4 0 5 1982-05-20 62.2 0 6 2001-05-20 62.0 0 7 2018-05-20 61.8 0 - 2004-05-20 61.8 0 - 2000-05-20 61.8 0 - 1993-05-20 61.8 0 - 1949-05-20 61.8 0 8 1964-05-20 61.6 0 9 2014-05-20 61.5 0 - 1985-05-20 61.5 0 10 1960-05-20 61.2 1 - 1953-05-20 61.2 0 Time Series Summary for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. 1 2025-05-20 62.9 0 2 2015-05-20 61.7 0 3 2018-05-20 60.8 0 - 2014-05-20 60.8 0 5 2001-05-20 60.7 0 6 1993-05-20 60.6 0 7 1975-05-20 60.5 1 8 2000-05-20 60.3 0 9 1991-05-20 59.9 0 - 1979-05-20 59.9 0 10 2004-05-20 59.8 0 11 1982-05-20 59.6 0

Probably the last higher elevation snow potential for the season.

This end of May cool down has become a repeating feature over the last 10-15 years.

Yeah, in the old days I would have agreed with you. But after we saw how the WPAC completely overpowered that weak El Niño in 2018 -2019, I have my doubts that a weak El Niño could work with this Pacific SST configuration. At least January 2019 was nice for the cold fans in the Midwest with the record cold near Chicago. But DJF was a real dud for snowfall around NYC with the La Niña background pattern and nearly no snowfall over those 3 months. Plus the weak modoki El Niño signature in 2019-2020 that was overshadowed by the record IOD supercharging the SPV. But at least we got some El Niño backloading with the record May snows. Unfortunately, we needed that storm track much earlier in the spring in order to really produce.

You have to wonder how much the EPAC needs to warm in order to offset the warming in the WPAC. While 2023-2024 was the warmest winter on record across the CONUS, at least we had that great record breaking STJ in February with the El Niño. That was a nice snowstorm in a narrow zone between NYC and Philly. Unfortunately, it didn’t extend very far from this region since it was more of a mesoscale IVT feature. My attitude is that I would much rather roll the dice with a strong El Niño and STJ influence no matter how warm to just get the storm track further south. Heck, even in March 1998 we had a better snowstorm than we have seen in recent years even though it was also a very mild winter. This persistent Niña background since 2018-2019 has shifted the storm track too far north for many of us. Monthly Data for March 1998 for Upton NY NWS CWA Click column heading to sort ascending, click again to sort descending. NY YORKTOWN HEIGHTS 1W COOP 9.0 NJ GREENWOOD LAKE COOP 8.5 NY WEST POINT COOP 8.0 NY WALDEN 1 ESE COOP 6.5 NY PORT JERVIS COOP 6.1 NJ CHARLOTTEBURG RESERVOIR COOP 6.0 NY NY CITY CENTRAL PARK WBAN 5.0 NJ WANAQUE RAYMOND DAM COOP 4.8 NJ RINGWOOD COOP 4.8 NY LAGUARDIA AIRPORT WBAN 4.7 NJ CANOE BROOK COOP 4.5 NJ HARRISON COOP 4.5 NY WEST NYACK COOP 4.5 NY MINEOLA 1 NE COOP 4.2 NJ MIDLAND PARK COOP 4.0 CT DANBURY COOP 4.0

Nothing is about to eat us…LOL. Most people off these forums like milder and less snowy winters. This is why most people are moving to the sunbelt instead of to the cooler and snowier spots like Marquette and Caribou. I point out the changes in the Pacific Jet for the very reason that I enjoy colder and snowier weather. So in order to understand how we could potentially change up this pattern is key for winter weather fans. We have to change the Pacific side and Southeast Ridge trends in order to bring back some great winter weather here. I grew up in the 70s and had to wait at the bus stop during those little ice age throwback winters. Also fond memories of the Great 1980s into early 1990s Arctic outbreaks. So I am more a fan of cooler climates than ones that have become much warmer. I have been trying to think how we could change up the Pacific in order to bring back more of a STJ influence. Would probably involve a very potent El Niño that would be very warm. But I am fine with winter warmth provided there are great snowstorms like in 15-16, 16-17, 17-18, and 20-21.

I agree with you that the 500 mb pattern in February was actually -PNA. But it was also -PNA in February 2014 with lower heights in the PNA region when we had around 30” inches of snow that month in NYC. The main difference was that the Southeast Ridge and Pacific Jet weren’t factors back in 2014 like they have become today. That big jet extension east of Japan coupled with a Southeast Ridge keeps the storm tracks through the Great Lakes.

Cold pool clouds and pop up convection for Saturday and pop up clouds on Sunday but not much actual rain.

But similar patterns with great -AO blocks over 90N didn’t have any issues producing KU snowstorms in February 2014 and January 2016. So we can’t blame the +NAO either since the vortex near Iceland was much stronger those two months than this February. It comes back to the overpowering Northern Stream of the Pacific Jet which was much weaker in February 2014 and January 2016.

The big cutoff low which has become a familiar late May repeating pattern over the last 10 to 15 years.

We can’t blame the WPO for last winter since there was a decent -WPO interval during the Feb 1 to Feb 21 with a solid block in the Bering Sea.This also coincided with a -5 daily -AO which reliably produced KU snowstorms in the past. Very difficult to pull off with such a powerful Northern Stream of the Pacific Jet which gave us a potent Great Lakes cutter at the some time the -AO was down near -5. So another Southeast Ridge link up with Greenland to Iceland blocking. https://www.ncei.noaa.gov/access/monitoring/monthly-report/synoptic/202502

The WPAC warm pool seems to be driving the very potent La Niña background this spring. Notice how we continue to see the Aleutian Ridge displaced further west than usual. Looks like the very strong IO into WPAC forcing wants to gradually shift east as we head into early June. Perhaps an attempt for some WWB activity which could weaken the trades a bit from the strong present levels. Whether the ENSO regions register -0.5 or +0.5 in the coming months may not matter as much as how warm the WPAC is which would drive the La Niña background even if the ENSO regions are technically neutral.

The record low maxes for the 22nd should be in play. EWR…56°…..2003 NYC….54°…..1894 LGA…..57°…..2003 JFK…..55°……1967 ISP……54°……2003

Chalk it up to the shrinking Northern Hemisphere winter cold pool over the decades. The rankings I provided are for the entire CONUS. The rankings go from 1895 to the present. So it’s impressive that the coldest winter for the CONUS was 1978-1979. But there were probably colder winters prior to 1895 before the entire CONUS rankings began. You can see how the geographic footprint and magnitude of the cold has been getting smaller. So it’s not unusual for a winter like 13-14 to have its cold focused into a smaller regional area and not having the coverage of earlier decades. There has such limited cold relative to the past in the 2020s, that this recent cooler winter wasn’t anything like colder winters even in the 2010s.

These strong winds have been the common denominator this year. We set the new record for strongest average daily wind gusts since January. Nearly 35 mph which is a first for the winter into spring. https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=140&network=NY_ASOS&station=LGA&syear=1900&sday=0101&eday=0519&varname=avg_wind_gust&w=none&thres=1&year=2025&_r=t&dpi=100&_fmt=png

Not on the geographic footprint size and the magnitude of the cold across the CONUS. January 1994 and 2004 were focused in the Northeast ranking as the 5th and 11th coldest Januaries for the Northeast. But they weren’t high ranking cold Januaries for the CONUS. The 1970s were the last top 10 coldest winters for the entire CONUS. Those Arctic outbreaks were widespread across North America and the Northern Hemisphere. The last top 20 cold for the CONUS was in the 1980s. The last top 30 cold for the CONUS was in 2009-2010 which ranked as the 21st coldest winter. The last top 40 coldest winter was in 2013-2014 with a CONUS ranking as 32nd coldest. All the noteworthy high ranking winters since 2012 were for top warmest. Including the new 1st place warmest in 2023-2024 and 6 other top 30 warmest winters. Top 21 coldest and warmest winters in the CONUS since the 1970s Coldest #1…..1978-1979 #7…..1977-1978 #12…1976-1977 #14…1983-1984 #19…1984-1985 #21…2009-2010 Warmest #1….2023-2024 #2….2015-2016 #5….2011-2012 #7….2019-2020 #9….2016-2017 #18…2022-2023 #21….2021-2022

No doubt that in modern times February 2015 was a very cold month from the Great Lakes into the Northeast. But it came up short of being a February benchmark for cold like 1875 was in a place like Detroit and 1934 was in NYC. March 2012 established the new March benchmark for warmth in a spot like Detroit. March 2012 in Detroit set a new warmest monthly average temperature of 50.7° which was +2.8° warmer than the previous warmest March of 47.9° in 1945. The monthly high of 86° was +4° warmer than the previous March monthly high which was 82° in 1945. February 2015 Detroit the monthly average of 14.1°while significant, was +1.9° warmer than the coldest February in 1875 at 12.2°. So a very respectable 2nd place finish for coldest. The monthly low of -13° was very impressive also. But it was +6° warmer than the -20° record low in 1875.

But the magnitude of the March 2012 warmth both regionally and nationally far exceeded the local and regional cold in a month like February 2015. The aerial coverage of the +10 areas in March 2012 was significantly greater than coverage of sites which experienced the -10s and lower in February 2015. Plus the records for March 2012 absolute warmth in its warmest zones far exceeded the coldest minimums in February 2015. While the average cold for February 2015 was impressive, it was nowhere near the February 1934 benchmark cold when NYC dropped to -15 and many locations in the Northeast set all-time records for cold.

It’s going to take a major volcanic eruption in order to see a short term return to something resembling cold winters on a national basis for the CONUS. But these types of events have been lacking since Tambora. Would be an extremely disruptive event if it were to occur. https://bsky.app/profile/hausfath.bsky.social/post/3loqtpd5t6q2k Large volcanic eruptions have a major climate cooling effect. But the eruptions we've had in the past 170 years have been relatively mild compared to those in the more distant past. Here are climate model simulations of major eruptions since 1750 using FaIR:

The average high temperatures have been impressively warm also. JFK is currently 2nd highest for spring high temperatures nearly tied with 2010. But the absolute max is way back in the pack at only 82° for spring. This was due to some many spring 70° days. It would be the equivalent to a high number of summer 85° days at JFK but a low number of 90° or 95° days. This is why JFK hasn’t seen a 100° day since 2013. Time Series Summary for JFK INTERNATIONAL AIRPORT, NY spring average high tempersrures Click column heading to sort ascending, click again to sort descending. 1 2010-05-18 61.8 0 2 2025-05-18 61.7 0 3 2012-05-18 61.0 0 4 1985-05-18 60.7 0 5 2024-05-18 59.3 0 - 1973-05-18 59.3 0 Time Series Summary for JFK INTERNATIONAL AIRPORT, NY Highest spring temperature Click column heading to sort ascending, click again to sort descending. 1 1969-05-31 99 0 2 1996-05-31 95 0 - 1987-05-31 95 0 3 2022-05-31 94 0 - 2021-05-31 94 0 - 1992-05-31 94 0 4 2017-05-31 92 0 - 1988-05-31 92 0 5 2010-05-31 91 0 - 1991-05-31 91 0 - 1986-05-31 91 0 - 1965-05-31 91 0 - 1962-05-31 91 0 6 2002-05-31 90 0 - 1979-05-31 90 0 - 1977-05-31 90 0 - 1956-05-31 90 0 7 1998-05-31 89 0 - 1980-05-31 89 0 - 1976-05-31 89 0 - 1974-05-31 89 0 - 1964-05-31 89 0 8 2007-05-31 88 0 - 1960-05-31 88 1 - 1959-05-31 88 0 9 2016-05-31 87 0 - 2015-05-31 87 0 - 2011-05-31 87 0 - 2001-05-31 87 0 - 2000-05-31 87 0 - 1973-05-31 87 0 - 1970-05-31 87 0 - 1949-05-31 87 0 10 2019-05-31 86 0 - 2013-05-31 86 0 - 2009-05-31 86 0 - 2003-05-31 86 0 - 1999-05-31 86 0 - 1994-05-31 86 0 - 1985-05-31 86 0 11 2024-05-31 85 0 - 2023-05-31 85 0 - 2014-05-31 85 0 - 2012-05-31 85 0 - 1993-05-31 85 0 - 1990-05-31 85 0 - 1975-05-31 85 0 - 1963-05-31 85 0 - 1955-05-31 85 1 12 2018-05-31 84 0 - 2006-05-31 84 0 - 1995-05-31 84 0 - 1978-05-31 84 0 - 1957-05-31 84 0 - 1954-05-31 84 0 13 2020-05-31 83 0 - 1989-05-31 83 0 - 1981-05-31 83 0 - 1953-05-31 83 0 - 1952-05-31 83 0 14 2025-05-31 82 13

I never fails how in recent years we reliably get these cool and wet cutoff lows this time of year. The upper bowling ball is really going to take its time clearing the area this week. Just look at how many top 3 low max readings a place like LGA has had since 2011 from late May into early June. I have bolded all the top 3 coldest years since 2011. This late May into early June cool down is almost as reliable as the warm up every December around the solstice. New York-LGA Area, NYPeriod of record: 1939-10-07 through 2025-05-18DateLowest maximum temperatures (degrees F)Top Record 2nd Record 3rd Record 5/21 51 in 1990 56 in 2000 56 in 1967 5/22 57 in 2003 58 in 2011 59 in 1982 5/23 55 in 1982 56 in 2003 58 in 1940 5/24 54 in 1982 56 in 2003 60 in 1951+ 5/25 47 in 1967 55 in 2005 56 in 2013 5/26 55 in 1967 57 in 2003 58 in 1973 5/27 48 in 1961 55 in 1974 57 in 1973 5/28 58 in 1968 59 in 2009 60 in 2014 5/29 52 in 2021 58 in 1950 59 in 1967 5/30 52 in 2021 57 in 1953 61 in 1971 5/31 60 in 1984 62 in 1953 63 in 1966+ 6/1 58 in 2015 58 in 1945 60 in 1964 6/2 53 in 1946 56 in 2015 59 in 1942

February 2015 was impressively cold on a regional basis here in the Northeast ranking as our only top 10 coldest month in the Northeast since 2010. While there have been over 50 top 10 warmest months since then. February 2015 was the 2nd coldest on record in the Northeast. But nationally it was only the 52nd coldest since the geographic footprint of the cold was very small. Back in the old days these Arctic outbreaks covered much more real estate and weren’t limited to localized geographic regions. February 1979 was the 3rd coldest on record in the Northeast and was also the 7th coldest nationally.

While it has been a warm spring for average temperatures, this will be only the 3rd spring since 2010 with no 90° heat. Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Mar through May Click column heading to sort ascending, click again to sort descending. 2025 88 14 2024 90 0 2023 93 0 2022 98 0 2021 96 0 2020 86 0 2019 90 0 2018 94 0 2017 94 0 2016 96 0 2015 91 0 2014 88 0 2013 94 0 2012 92 0 2011 92 0 2010 95 0

2010 to 2018 wasn’t natural variability since the reason the snow increased was due to the warmer atmosphere holding more moisture while the storm tracks remained cold.

That Midwest warmth in March 2012 was more historic than the cold in 2015 was. The few months with -10 or more departures the CONUS since 2015 have been few and far between compared to the months over +10. This is a CONUS wide phenomenon and not just limited to one region. You can see how getting a +10 month nearly every winter since the 2015 higher temperature reset has become the norm while extreme cold is very isolated to places like Montana. Plus our Arctic outbreaks have shrunk the geographic footprint. So an Arctic outbreak into the Plains doesn’t extend all the way to the coast like it did as recently as the 1990s. Dec…2015….NYC….+13.3 JAN…2017….BTV…..+11.0 FEB….2017….ORD….+10.3 FEB…..2018…ATL….+10.6 FEB….2019…MGM….+10.5 JAN….2020…YAM….+9.8 DEC….2021….DFW….+13.2 JAN….2023….DXR….+12.3 FEB….2023…..SSI…..+9.8 DEC….2023….INL…..+15.8 FEB…..2024….FAR…..+17.5 DEC….2024…..LND…..+11.3