bluewave

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

Could be the best Noreaster of 2025 this week. While the Euro may be overdone on the intensity, the gradient should be tight enough for easterly gusts over 40 and very rough surf and wind driven heavy rain potential. It’s possible that with the low clouds and easterly flow, that some spots may not get out of the 40s for afternoon highs. This is impressive cold for late May when the average daily high is 73°.

During transition periods from cold to warm like 2010 to 2018 ,we got amazing snows due to the way the pattern was shifting. First, the warming process loaded the atmosphere with more moisture. Second, the colder storm tracks to the south of the big cities had already been in place from 09-10, 10-11, 13-14, and 14-15. But the signs that this was getting ready to change were evident with the pattern during December to March 2011-2012. March near the Great Lakes was one of the most anomalously warm months there since the 1800s with +15° degree warm departures. The warmth continued into January 2013 and we had the Southeast Ridge briefly linking up with the -AO in December. Nemo in February was one of the greatest phasing blizzards with 50dBZ returns from snow which was a first for the Doppler radars which were installed back in the 1990s. Then it was winter cold and snow galore through March 2015. Then in December 2015 the Northeast experienced one of the most anomalously warm months warm winter months ever going over +13. But the lingering cold storm track in January resulted in the greatest snowstorm near 30” around NYC. 2016-2017 followed as one of the warmest winters on record but there were blizzards after days in the 60s with record warmth. Then 17-18 featured our greatest 14 days of cold and snow this century from after Christmas into early January with the amazing benchmark 950mb blizzard. Fast forward to February for our first 80° winter heat before the record snowy February. This continued into November 2018 with the record snowstorm. But the storm track became very warm that 2018-2019 winter with one cutter after another and nearly no snow during DJF. Since that 18-19 that warmer storm shift and much faster Pacific Jet, we have been getting more consistent record warmth a lower snowfall. So we were getting more extended warmth like 22-23 to 23-24 plus the very warm Northern Stream of the Pacific Jet. So the cold storm tracks have been absent even this past winter when we had average to slightly below average cold. It was still 41° with a strong Southeast Ridge in NYC on the days with .25 or more of precipitation. So the warmer storm tracks muted the influence of the cold and snowfall was well below average again. So the winter warming with first began to emerge in 11-12 has become more widespread. Then the warmer storm tracks with started in 18-19 have become more frequent. So when those 2 features become dominant it loads the dice for below normal to well below normal snow into the 2020s. it would be nice if we could get at least get a brief return to colder storm tracks and better snows during the 2nd half of the 2020s. But the climate has already significantly warmed. The strength of the Pacific Jet hasn’t allowed benchmark colder storm tracks during the winter. Instead, it has been all cutters, huggers and suppressed Southern Stream storm tracks. But most on here would be happy with a 16-17 repeat with record warmth and a few nice blizzards.

They have run the climate models pretty far out in time. The summer forecast through later in the century is for drier to our west and wet for our area. Plus an extensive ridge across North America allowing the Western Ridge to link up with the WAR . We have seen this pattern at times over the last decade like in June 2021 and other months. Though the trough which has been over the Ohio Valley between the WAR and Western Ridge has been stronger than what is indicated in the long range forecast. So it could eventually weaken in coming decades with the expansion of drought into the Plains. We see how it goes.

Yeah, areas further south will naturally see the declines in snowfall first since they were always more marginal to begin with. The further north lake effect zones and higher elevations of the Northeast will still do well since warmer storm tracks for the coast are good for snowfall in those areas. While we can’t completely rule out some major volcanic event which could temporarily cool the climate, those type of events have been pretty rare and aren’t easily predictable.

Newark isn’t the warmest location in NJ since the ASOS is right on the bay and is subject to cooling sea breezes. Several other locations in NJ have had more 90° days since the flow turned more onshore in recent years. There are 4 stations in NJ with more 90° days than Newark over the last 10 years. These sea breezes are why the areas east of the Hudson River in New York don’t have as many 90° days as NJ does. Data for January 1, 2015 through December 31, 2024 Click column heading to sort ascending, click again to sort descending. HIGHTSTOWN 2 W COOP 383 HARRISON COOP 376 FREEHOLD-MARLBORO COOP 351 CANOE BROOK COOP 348 NEWARK LIBERTY INTL AP WBAN 343 Newark Area ThreadEx 343 TETERBORO AIRPORT WBAN 310 ESTELL MANOR COOP 307 New Brunswick Area ThreadEx 304 NEW BRUNSWICK 3 SE COOP 304 Several other stations in NJ had an average high within a degree of Newark during the summer of 1993. Data for June 1, 1993 through August 31, 1993 Click column heading to sort ascending, click again to sort descending. WAYNE COOP 90.1 NEWARK LIBERTY INTL AP WBAN 88.9 Newark Area ThreadEx 88.9 MOORESTOWN 4 E COOP 88.1 LITTLE FALLS COOP 88.0 WOODSTOWN PITTSGROV 4E COOP 88.0

This wasn’t the case for many first order sites such as NYC. So recent snowfall measurements are inflated relative to the way snowfall was measured prior to the 1990s around NYC and to before 1950 in other locations. So boost pre-1950 snowfall totals by 15-20% and the majority of first order sites in the U.S. will show a steady decline since the late 1800s. Several stations already show a long term snowfall decline. So imagine how much steeper a decline we would have if the snowfall was measured as frequently as it is today. Plus places like NYC would use melted down gauge snow equivalents and not actual measurements like in the blizzard of 1888 using a simple 10:1 ratio which is very inaccurate when the 1800s were so cold with much higher ratios. https://news.ucar.edu/14009/snowfall-measurement-flaky-history As a hydrometeorological instructor in UCAR’s COMET program and a weather observer for the National Weather Service, I am keenly interested in weather trends. In this case, climate change is an important factor to explore, since we know that the heaviest precipitation events have intensified in many parts of the world (see related story: Torrents and droughts and twisters - oh my!). But when we turn to snowstorms in the Northeast, or elsewhere in the U.S., there is an additional factor at work when comparing modern numbers with historical ones. Quite simply, our measuring techniques have changed, and we are not necessarily comparing apples to apples. In fact, the apparent trend toward bigger snowfalls is at least partially the result of new—and more accurate—ways of measuring snowfall totals. Climate studies carefully select a subset of stations with consistent snow records, or avoid the snowfall variable altogether. Official measurement of snowfall these days uses a flat, usually white, surface called a snowboard (which pre-dates the popular winter sport equipment of the same name). The snowboard depth measurement is done ideally every 6 hours, but not more frequently, and the snow is cleared after each measurement. At the end of the snowfall, all of the measurements are added up for the storm total. NOAA’s cooperative climate observers and thousands of volunteers with the Community Collaborative Rain, Hail and Snow (CoCoRaHS), a nationwide observer network, are trained in this method. This practice first became standard at airports starting in the 1950s, but later at other official climate reporting sites, such as Manhattan’s Central Park, where 6-hourly measurements did not become routine until the 1990s. Earlier in our weather history, the standard practice was to record snowfall amounts less frequently, such as every 12 or 24 hours, or even to take just one measurement of depth on the ground at the end of the storm. You might think that one or two measurements per day should add up to pretty much the same as measurements taken every 6 hours during the storm. It’s a logical assumption, but you would be mistaken. Snow on the ground gets compacted as additional snow falls. Therefore, multiple measurements during a storm typically result in a higher total than if snowfall is derived from just one or two measurements per day. That can make quite a significant difference. It turns out that it’s not uncommon for the snow on the ground at the end of a storm to be 15 to 20 percent less than the total that would be derived from multiple snowboard measurements. As the cooperative climate observer for Boulder, Colorado, I examined the 15 biggest snowfalls of the last two decades, all measured at the NOAA campus in Boulder. The sum of the snowboard measurements averaged 17 percent greater than the maximum depth on the ground at the end of the storm. For a 20-inch snowfall, that would be a boost of 3.4 inches—enough to dethrone many close rivals on the top-10 snowstorm list that were not necessarily lesser storms! Another common practice at the cooperative observing stations prior to 1950 did not involve measuring snow at all, but instead took the liquid derived from the snow and applied a 10:1 ratio (every inch of liquid equals ten inches of snow). This is no longer the official practice and has become increasingly less common since 1950. But it too introduces a potential low bias in historic snowfalls because in most parts of the country (and in the recent blizzard in the Northeast) one inch of liquid produces more than 10 inches of snow. This means that many of the storms from the 1980s or earlier would probably appear in the record as bigger storms if the observers had used the currently accepted methodology. Now, for those of you northeasterners with aching backs from shoveling, I am not saying that your recent storm wasn’t big in places like Boston, Portland, or Long Island. But I am saying that some of the past greats—the February Blizzard of 1978, the Knickerbocker storm of January 1922, and the great Blizzard of March 1888—are probably underestimated. So keep in mind when viewing those lists of snowy greats: the older ones are not directly comparable with those in recent decades. It’s not as bad as comparing apples to oranges, but it may be like comparing apples to crabapples. Going forward, we can look for increasingly accurate snow totals. Researchers at NCAR and other organizations are studying new approaches for measuring snow more accurately (see related story: Snowfall, inch by inch). But we can’t apply those techniques to the past. For now, all we can say is that snowfall measurements taken more than about 20 or 30 years ago may be unsuitable for detecting trends – and perhaps snowfall records from the past should not be melting away quite as quickly as it appears. Update • January 29, 2015 | Thanks to thoughtful feedback by several colleagues, this article has been updated. Paragraph 3 now includes a description of how climate studies handle the data inconsistencies. Paragraph 9 was added to describe the pre-1950s practice, no longer in wide use, of recording liquid water content only, and not snow depth. Matt Kelsch is a hydrometeorologist in UCAR's COMET Program. He specializes in weather and climate events involving water, such as floods, droughts, rain, hail, or snow. Kelsch develops and delivers educational materials designed for both domestic and international groups including National Weather Service forecasters, the military, the World Meteorological Organization, university students and faculty, government agencies, and private industry.