bluewave

Atmosphere trying to shift into El Niño mode as near record WWBs continue over the EPAC.

Last February was a much snowier one for spots like New Brunswick even though it was 5° warmer. The Northern Stream of the Pacific Jet was able to relax for 5 days when we had the record STJ with the El Niño. But the part of the area that really did well was pretty limited. Climatological Data for New Brunswick Area, NJ (ThreadEx) - February 2025 Click column heading to sort ascending, click again to sort descending. Sum 793 497 - - 651 0 3.00 4.1 - Average 39.7 24.9 32.3 -0.3 - - - - 0.3 Normal 42.0 23.3 32.6 - 648 0 2.09 6.9 2025-02-01 49 34 41.5 10.2 23 0 0.12 0.0 0 2025-02-02 38 17 27.5 -3.9 37 0 0.00 0.0 0 2025-02-03 32 18 25.0 -6.5 40 0 T T 0 2025-02-04 51 26 38.5 6.9 26 0 0.00 0.0 0 2025-02-05 49 27 38.0 6.3 27 0 0.00 0.0 0 2025-02-06 37 27 32.0 0.1 33 0 0.26 0.2 T 2025-02-07 40 33 36.5 4.5 28 0 0.15 0.0 0 2025-02-08 44 23 33.5 1.4 31 0 0.00 0.0 0 2025-02-09 35 27 31.0 -1.3 34 0 0.67 1.2 2 2025-02-10 37 27 32.0 -0.4 33 0 0.03 0.0 1 2025-02-11 39 20 29.5 -3.1 35 0 0.00 0.0 0 2025-02-12 36 25 30.5 -2.3 34 0 0.23 1.7 2 2025-02-13 39 31 35.0 2.1 30 0 0.20 0.0 0 2025-02-14 47 29 38.0 4.9 27 0 0.00 0.0 0 2025-02-15 37 24 30.5 -2.8 34 0 0.00 0.0 0 2025-02-16 37 31 34.0 0.5 31 0 0.74 1.0 0 2025-02-17 47 29 38.0 4.3 27 0 0.60 0.0 0 2025-02-18 37 19 28.0 -5.9 37 0 0.00 0.0 0 2025-02-19 29 15 22.0 -12.1 43 0 0.00 0.0 0 2025-02-20 33 15 24.0 -10.3 41 0 0.00 0.0 0 2025-02-21 M M M M M M M M M 2025-02-22 M M M M M M M M M 2025-02-23 M M M M M M M M M 2025-02-24 M M M M M M M M M 2025-02-25 M M M M M M M M M 2025-02-26 M M M M M M M M M 2025-02-27 M M M M M M M M M 2025-02-28 M M M M M M M M M Climatological Data for New Brunswick Area, NJ (ThreadEx) - February 2024 Click column heading to sort ascending, click again to sort descending. Sum 1381 820 - - 777 0 1.90 16.0 - Average 47.6 28.3 37.9 4.5 - - - - 0.9 Normal 42.8 24.0 33.4 - 885 0 2.97 9.3 2024-02-01 40 29 34.5 3.2 30 0 0.00 0.0 0 2024-02-02 48 30 39.0 7.6 26 0 0.12 0.0 0 2024-02-03 44 32 38.0 6.5 27 0 0.08 0.0 0 2024-02-04 47 27 37.0 5.4 28 0 0.00 0.0 0 2024-02-05 49 25 37.0 5.3 28 0 0.00 0.0 0 2024-02-06 48 23 35.5 3.6 29 0 0.00 0.0 0 2024-02-07 45 24 34.5 2.5 30 0 0.00 0.0 0 2024-02-08 49 26 37.5 5.4 27 0 0.00 0.0 0 2024-02-09 56 30 43.0 10.7 22 0 0.00 0.0 0 2024-02-10 60 37 48.5 16.1 16 0 0.00 0.0 0 2024-02-11 59 41 50.0 17.4 15 0 0.00 0.0 0 2024-02-12 48 33 40.5 7.7 24 0 0.00 0.0 0 2024-02-13 48 32 40.0 7.1 25 0 0.62 4.0 4 2024-02-14 43 30 36.5 3.4 28 0 0.14 1.0 2 2024-02-15 38 23 30.5 -2.8 34 0 0.00 0.0 2 2024-02-16 42 26 34.0 0.5 31 0 0.00 0.0 1 2024-02-17 44 30 37.0 3.3 28 0 0.38 11.0 11 2024-02-18 37 18 27.5 -6.4 37 0 T T 3 2024-02-19 42 24 33.0 -1.1 32 0 0.00 0.0 2 2024-02-20 43 23 33.0 -1.3 32 0 0.00 0.0 1 2024-02-21 41 20 30.5 -4.0 34 0 0.00 0.0 0 2024-02-22 43 23 33.0 -1.7 32 0 0.00 0.0 0 2024-02-23 50 29 39.5 4.5 25 0 0.14 0.0 0 2024-02-24 48 36 42.0 6.8 23 0 0.01 0.0 0 2024-02-25 45 20 32.5 -2.9 32 0 0.00 0.0 0 2024-02-26 42 25 33.5 -2.2 31 0 0.00 0.0 0 2024-02-27 56 32 44.0 8.1 21 0 0.00 0.0 0 2024-02-28 63 42 52.5 16.3 12 0 0.21 0.0 0 2024-02-29 63 30 46.5 10.2 18 0 0.20 0.0 0

Boston only had 3 seasons with below 10” of snow. So far they have had 3 top 10 lowest snowfall seasons during the 2020s. They had less snow the last 4 seasons combined than in 14-15. Time Series Summary for Boston Area, MA (ThreadEx) - Oct through Sep Click column heading to sort ascending, click again to sort descending. 1 1936-1937 9.0 0 2 2011-2012 9.3 0 3 2023-2024 9.8 0 4 1972-1973 10.3 0 5 2022-2023 12.4 0 6 1979-1980 12.7 0 7 1994-1995 14.9 0 8 2001-2002 15.1 0 9 1988-1989 15.5 0 10 2019-2020 15.8 0

This turned out to be a reversion to the 2020s snowfall mean from Philly up to Boston. So this season was very close to average for the 2020s. A big win for spots like Philly that avoided another under 1” season. NYC was able to miss having another season under 10”. And Boston got close to 30” instead of matching some of the lower under 15” seasons in recent years. Monthly Total Snowfall for Philadelphia Area, PA (ThreadEx) Click column heading to sort ascending, click again to sort descending. Mean T T 1.2 4.7 3.6 0.1 0.0 9.4 2024-2025 0.0 T 0.3 4.6 3.1 M M 8.0 2023-2024 0.0 T T 8.0 3.2 0.0 0.0 11.2 2022-2023 T 0.0 T T 0.3 T 0.0 0.3 2021-2022 0.0 0.0 T 12.1 0.4 0.4 0.0 12.9 2020-2021 0.0 0.0 6.6 3.0 14.3 0.0 0.0 23.9 2019-2020 0.0 T 0.1 0.2 T 0.0 0.0 0.3 Monthly Total Snowfall for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Mean 0.0 T 2.7 4.2 7.0 0.1 T 13.9 2024-2025 0.0 0.0 2.8 3.0 6.7 M M 12.5 2023-2024 0.0 T T 2.3 5.2 T 0.0 7.5 2022-2023 0.0 0.0 T T 2.2 0.1 0.0 2.3 2021-2022 0.0 T 0.2 15.3 2.0 0.4 0.0 17.9 2020-2021 0.0 0.0 10.5 2.1 26.0 T 0.0 38.6 2019-2020 0.0 0.0 2.5 2.3 T T T 4.8 Monthly Total Snowfall for Boston Area, MA (ThreadEx) Click column heading to sort ascending, click again to sort descending. Mean 0.7 T 5.3 11.5 8.2 0.6 0.2 26.5 2024-2025 0.0 0.0 5.7 8.2 14.2 M M 28.1 2023-2024 0.0 T 0.2 9.0 0.5 T 0.1 9.8 2022-2023 0.0 T 1.0 6.9 3.6 0.9 0.0 12.4 2021-2022 0.0 T 0.4 36.2 15.3 2.1 T 54.0 2020-2021 4.3 T 13.0 5.8 15.3 0.1 0.1 38.6 2019-2020 0.0 T 11.5 3.1 0.5 T 0.7 15.8

Yeah, the variability has become more extreme. Just look at the wild swings in the AO index. And that is just one area of the world. The new variation of getting a 970 mb cutter during a -5 -AO linking up with the Southeast Ridge was a new type of pattern variability. This variation has become more common during the 2020s.

What seems to have become permanent since around 2010 has been these stuck weather patterns for extended periods of time. But the variability that you mention can perhaps be related to interactions with other underlying patterns. So that we have been varying which patterns have been getting stuck and for how long before shifting to a new stuck pattern. One of the most impressive stuck weather patterns from the 09-10 winter through March 2018 was the phenomenal benchmark KU snowstorm pattern. With numerous snowfall records being set over the 9 year period. Our new warmer summer pattern emerged in 2010 leading to to 12 out of 15 warmer to record warm summers. The shift to warmer winters began in 15-16 with 9 out of the last 10 winters here running warmer to record warm. While this was our first colder winter using the new 91-20 climate normals, it really wasn’t that cold compared to winters like 13-14, 14-15, 10-11, and 02-03. So we can say this probably would have been a much colder winter in an earlier era. The faster Northern Stream of the Pacific Jet emerged back in 18-19 and continues to this day with the record cutter, hugger, and suppressed Southern Stream storm tracks. I have a ton of respect for the variability you mention since I have no idea how much longer this most recent stuck storm track pattern will persist. But it could take a shift in the marine heatwave configuration in coming years to ultimately attempt to shift back to at least an occasional benchmark snowstorm track. But it will be interesting to see how things turn out.

There has been an interesting phenomenon happening with the modeling since 18-19. Some models have been showing unrealistic snowfall outcomes longer range given the jet dynamics which have been in place. But the storm tracks once under 120 and 72 hrs conformed to the cutter, hugger, and suppressed Southern Stream storm tracks. So my guess is that the new model bias is showing too little Pacific interference or disruption longer range which becomes evident once the storm comes into closer range. A faster Northern Stream of the Pacific Jet can lead to shortwave spacing issues like we have this week. So the shorter term models will be able to see the shortwave behind acting as a kicker. But this distinction isn’t clear longer range leading to false positive snowfall outcomes. Then when we do have enough wavelength spacing like this past weekend, a suppressed or hugger initial long range forecast can become a cutter in the short range. Other times we had snowier long range forecast outcomes which had a slightly stronger Southeast Ridge like models were snowing earlier this month. This is why the EPS 240 to 360 hr snow means kept showing double digit totals for NYC which didn’t verify. The gradient drifted about 30 to 50 miles further north over time since the faster flow and warm water feedback off the East Coast worked in tandem. This has been a pretty big departure from the modeling from 2010 to 2018. Now we all know that there were false positive long range snowfall outcomes during this era. But there were also several successful long range modeling events. We can all remember the Euro control run from a week out nailing the 950mb benchmark blizzard in January 2018. And there were other examples of the models correctly forecasting longer range snowstorms. The Pacific Jet was much weaker and we had we had a well established benchmark storm track for the better part of 9 seasons. So these days it’s pretty much become the norm that the benchmark storm tracks only show up days 6-10 and 11-15 but don’t make it into the under 120 hr range once the full impact of the Pacific Jet comes into better focus. So models showing benchmark tracks beyond 120 hrs need to be taken with a grain of salt. But if this multiyear storm tracks is to end, it will have to occur in the short range in order to be believed.

The issue has been the storm tracks which have been favoring the higher elevations and LES zones.

Those were better periods for snowfall around NYC Metro than the last 7 season stretch here. We are currently on pace for a new 10 year snowfall low average across the area if we don’t get a big increase over the next 3 seasons. This current 7 year lower running snowfall average began in 18-19. The past slumps were followed by 50” seasons boosting the totals back up in the following years. But reaching such heavy totals in recent years has been a significant challenge. So we are going to need a big shift back to benchmark storm tracks in the coming seasons in order to avoid the least snowy calendar decade and 10 year running mean. Lowest 10 year averages and ending year and current 7 year average since 18-19 EWR…..1977……19.4”…….2025….17.3” NYC…..1993……18.8”…….2025….14.9” LGA…..1977…….17.7”……..2025….16.0” JFK…..1993….…18.0”…….2025…..14.5” ISP……1995…….19.3”……..2025…..16.8”

Those pattern specifics were are direct outcome of the record air and SSTs this winter across the globe. I understand that you are using a linear approach in your analysis of the winter pattern across the Northern Hemisphere. But when SST thresholds are crossed we can see non-linear outcomes. Such that a few tenths of a of degree temperature shift in one SST area can cause a regional shift of a much greater magnitude in other areas. Changing the structure of the 500mb pattern by what seems like a small amount along with a faster Northern Stream of the Pacific Jet can lead to non-linear outcomes. Such that it can shift what would have been a 25” to 50”or greater snowfall season in NYC to one under 20” on the season. So your marginal impact on snowfall statement could work under a linear understanding but not if we have experienced threshold effects acting as a force multiplier. This is an interesting conversation and I can see how you came to your description and understanding. It could be a small SST difference in a region like the WPAC east of Japan accelerated the Pacific Jet just enough to prevent a benchmark storm track from emerging and lead to the cutter, hugger, and suppressed Southern Stream storm tracks. That right there is the difference between a 25” to 50” season and one with under 20” of snowfall. The same can be said for the temperatures. By warming the global temperatures by just a few degrees, our local winter average temperatures could have been 3-5 degrees colder under a similar winter pattern from the 1970s into early 1990s. This would have also meant that the 10° low this winter in NYC could have been a 0 to -2 in that colder era. My take on snowfall averages and distribution is that we have seen a marked shift since the 1960s. The first colder winter regime from the 1960s into early 1990s featured a very stable distribution near the middle of the snowfall range. So that many seasons were in the 19” to 30” range around NYC and the coast. Very few seasons under 15” and over 31”. This all changed since the 1990s with very few 19-30” seasons and many more under 15” and over 31”. So the great outcomes from 09-10 to 17-18 were masking this shift as the climate has continued to warm. Since 18-19 we have been in a much faster Northern Stream of the Pacific regime leading to only one snowy season in spots like NYC in the last 7 seasons. This is directly a function of the warmer winters combined with the lack of benchmark storm tracks. So cutter, hugger, and suppressed Southern Stream storm tracks have dominated. From the 60s into the early 90s we had multiple ways to reach the 19” to 30” snowfall range around NYC. So we didn’t have to exclusively rely on benchmark storm tracks like we have since the 90s. The lack of benchmark storm tracks has resulted in the NYC and other local sites 7 year snowfall averages dropping into the 14” to 18” range. We are going to need a return to BM tracks next several winters for our area to avoid its least snowy decade so soon after our snowiest one during the 2010s. So I am open to possible changes in the Northern Stream of the Pacific Jet in coming winters. But if there isn’t a big shift away from this regime over the next 3-5 winters, then it’s possible it will become permanent or at least semi permanent. So 40/70 is mischaracterizing my position on the future. As I am always open to new data should it present itself in the future. I for one hope we can at least introduce some degree of a return to benchmark tracks in the future if only a weaker reflection of the 09-10 to 17-18 era.

I think part of your resistance to seeing the new reality of our 2020s climate is that you really enjoyed the winters during the much colder climate area. We both share the same sentiment. But not seeing the new parameters of the situation will hurt you forecast abilities in the long range by not adjusting to current regime.

This winter was nothing like 1979-1980. As I pointed out in the La Niña thread back in October, there were early indications that this would be a La Niña mismatch winter. So the near record +PNA from December into a January wasn’t a surprise to me. But I also said that there were differences between this year and other La Niña +PNA mismatches. This turned out to be a correct observation since the snowfall was dramatically below the La Niña +PNA mismatches we experienced in 20-21, 17-18, 10-11, 05-06, 00-01, and 95-96. The difference this winter was that the Pacific Jet didn’t relax enough to allow the benchmark track to lock in like it did during those La Niña winters. My guess is that this could be related to features like the ongoing record marine heatwave east of Japan leading to the frequent jet extensions when interacting with the Siberian air masses exiting the Asian continent. So we continued with the cutter, hugger, and suppressed Southern Stream storm tracks which have dominated since 18-19. We even had a -5 -AO which used to be associated with much snowier Februaries like 2021, 2010, 1978, and 1969. So now even great +PNAs and -AO patterns during La Ninas can’t produce the 25-50” or even 50” outcomes in this new climate state of the 2020s. Plus there were several posts on twitter back in December that we were on track for some type of 13-14 and 14-15 outcome based on the early December pattern. So those were both 50”+ seasons here. But I pointed out in the December threads that the Pacific Jet wasn’t following the weakening script necessary to produce those outcomes for cold and snow in spots like the NYC Metro region. The cold also didn’t approach the magnitude of the cold we saw back in 13-14 and 14-15 in the northeast.

It’s pretty simple actually. The competing marine heatwaves and warmer background conditions shift the storm tracks and lead to less cold and snowy outcomes. This winter would have been an easy 25-50” snowfall season around NYC and several degrees colder just a little over a decade ago.

These record swings in a short period time have become the new normal as the Arctic has rapidly warmed. We just experienced one back in October. Then our last -5 back in 2021 also experienced a steep rise. So these -AOs don’t lock in for longer periods like they used to in the past. Greatest AO swings on record in around a month or less since 1950 and the date on which the maximum difference from low to high or high to low occurred with the numerical value of the swing https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.daily.ao.nao.pna.aao.gdas.120days.csv https://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.ao.index.b500101.current.ascii #1……+10.790……3-11-21 #2…...+9.401…….1-16-16 #3……+9.256……3-2-56 #4……+9.039……4-21-13 #5……+8.522……1-25-05 #6…...+8.462…..1-15-77 #7…….+8.268….3-16-68 #8…….+7.793….2-25-01 #9…….+7.731….3-23-86 #10……+7.720…2-4-11 #11……+7.641…..3-5-70 #12…..+7.502…..1-19-85 #13……+7.387….3-20-78 #14……+7.240….10-23-24 #15……+7117……1-23-52 #16…..+7.066…1-24-08 #17……+7.043…3-19-15 #18……+7.038…2-10-76

While the departures will be cooling off, the coldest anomalies will stay west. Then the temperatures will moderate next week. So nothing too cold by past February standards. But compared to all the +5 Februaries in recent years it will feel cold especially with the stronger winds.

10”+ daily snowfalls at State College have become few and far between after 03-04 with the storm track shift for that part of the country. Maximum 1-Day Total Snowfall for STATE COLLEGE, PA Click column heading to sort ascending, click again to sort descending. Period of record: 1893-01-01 to 2025-02-17 1 26.6 1994-03-03 2 25.0 1993-03-14 3 17.6 1964-01-13 4 17.5 1942-03-30 - 17.5 1902-03-05 5 17.3 1928-04-28 6 16.5 1961-02-04 7 16.2 1996-01-08 8 15.1 1995-11-15 - 15.1 1965-03-06 9 15.0 2020-12-17 - 15.0 1922-01-11 10 14.8 1928-03-18 11 14.5 1925-01-29 12 14.0 2003-02-17 - 14.0 1936-01-19 13 13.8 1968-11-13 14 13.5 2010-02-06 15 13.0 2002-01-07 - 13.0 1942-03-29 - 13.0 1914-01-04 - 13.0 1894-04-11 16 12.8 1967-03-07 17 12.6 1966-01-23 18 12.5 1992-12-11 - 12.5 1971-03-04 - 12.5 1932-03-28 - 12.5 1923-01-14 19 12.2 1942-03-03 20 11.8 1935-02-22 21 11.7 1940-02-14 22 11.5 2018-11-16 - 11.5 1947-02-21 - 11.5 1920-02-04 23 11.3 2004-02-04 24 11.0 1921-02-20 - 11.0 1915-01-12 25 10.8 1969-12-26 26 10.5 1998-02-24 - 10.5 1978-01-18 - 10.5 1914-02-14 - 10.5 1908-02-19 - 10.5 1908-02-01 - 10.5 1901-04-03 27 10.2 1970-03-13

Another piece of the puzzle as to why global temperatures have been rising so quickly recently.

The first 16 days of the month have been +0.4°. EWR…+0.7 NYC….-0.7° LGA…..-0.4° JFK….+3.1° HPN….-0.5° BDR…..-0.4° ISP……+1.1°

Against the last several winters this one definitely feels more wintery in terms of temperatures ,extended snowcover, and windchills. This is the most snowcover days we have seen for so little seasonal snowfall. December wasn’t really that cold since the small cold departure was only due to the much warmer 91-20 normals. January was a little below average but the winds made it feel more like -5°. This month so far is running a little warmer than average but the stronger winds are making it feel colder.

It just shows how sensitive our snowfall has become to benchmark snowstorms since the 1990s. So we’ll need to see a return of these during the rest of the decade in order to see the snowfall averages areawide go back to the 20-30” range. Something similar happened to State College when they lost the big Appalachian snowstorms over 20 years ago. Their snowfall hasn’t been the same without the major Central PA snowstorms storm tracks which were common up to the early 2000s.

Another big EPAC WWB like we have been seeing in recent years boosted Nino 1+2 back above +1 again.

We are currently on pace for a new 10 year snowfall low average across the area if we don’t get a big increase over the next 3 seasons. This current 7 year lower running snowfall average began in 18-19. The past slumps were followed by 50” seasons boosting the totals back up in the following years. But reaching such heavy totals in recent years has been a significant challenge. Lowest 10 year averages and ending year and current 7 year average since 18-19 EWR…..1977……19.4”…….2025….17.3” NYC…..1993……18.8”…….2025….14.9” LGA…..1977…….17.7”……..2025….16.0” JFK…..1993….…18.0”…….2025…..14.5” ISP……1995…….19.3”……..2025…..16.8”

This is the first time that the combined 3 year snowfall average at EWR, NYC, JFK, LGA, and ISP dipped under 10”. The current 3 year mean is at 8.9”. The old record low from 96-97 to 98-99 was 10.5”.

This very strong westerly flow had been a persistent feature this winter.

One aspect of a fast Northern Stream of the Pacific Jet is shortwaves too close together like we are seeing this week leading to a suppressed outcome. So when you have lows coming into the West at the same time as one is trying to amplify along the East Coast it acts as a kicker low or trough. The next pattern is a hugger track. These were the string of small snows around NYC this month. Too much amplitude on the Southeast Ridge so we get the lows riding too far north leading to mixed precipitation events. And then this weekend was a record setting cutter for an -AO below -5 and a Greenland Block of +500 meters. In the old days we wouldn’t have had a Southeast Ridge link up with such an intense Greenland Block. My guess is that warm water feedback from the record Atlantic SSTs are combining with the faster Pacific to create this pattern. I posted composites a while back showing how in the 1950s to early 1970s when we had troughs in the West and a -AO there would often be a trough in the East instead of a Southeast Ridge. So in this case a little too much spacing between lows leading to one amplifying too much. So we have been seeing multiple ways not to get the benchmark track which has been a prerequisite since the 1990s for seasons in the 20-30” range and above. This has been a frequent occurrence since the 18-19 winter. It’s possible that this is related to competing marine heatwaves in the Pacific and Atlantic Basins. Could even be the IO marine heatwaves also. But we would probably need a research effort in order to confirm why the Pacific Jet has been following this type of pattern.