bluewave

The snow cover is helping plus the airmass isn’t crossing the warmer Lakes and the delayed freeze-up on Hudson Bay which is keeping the Northeast warmer.

The 07-08 La Niña developed during the summer of 07 after a much weaker El Niño and lingered into 08-09. https://www.climate.gov/news-features/blogs/enso/january-2025-update-la-nina-here Why was La Niña so slow to develop? The short answer to this is “we don’t yet know.” The emergence of La Niña-like atmospheric conditions before substantial tropical Pacific Ocean surface cooling was unusual, though. The global oceans have been running much, much warmer than average for more than a year, which might have had a hand in La Niña’s delay. When we calculate the Niño-3.4 index but account for the temperature of the tropical oceans (the “Relative Niño-3.4 index”) we get an index that’s been in La Niña territory for months. Only this past year or so has the difference between the traditional and relative Niño-3.4 indexes been so large, and we’re still researching this new measurement and all the implications for ENSO development and impacts in a warmer world.

The delayed start from such a warm global background state and continued 1+2 warming makes this one of the more unusual La Niña events that we have seen. The equatorial Eastern Pacific off the South American coast has warmed in recent weeks *. The rains are felt in the entrance basins to #Poechos and #SanLorenzo where the 30% storage of the useful volume estimated by the operators has already been exceeded. It's raining again today, which will translate into higher income. *This does not mean that we are heading towards a #NiñoCostero just in case. But it helps tremendously to improve the contribution of humidity that is used, among other processes, for the formation of rain.

Yeah, the minimum departure is currently running +8.4 up in Caribou through the 8th. My guess is it’s a function of how warm Canada has been around Hudson Bay with the delayed freeze-up. Plus the lower pressures, very strong winds, and clouds limiting the overnight low potential. Climatological Data for Caribou Area, ME (ThreadEx) - January 2025 Click column heading to sort ascending, click again to sort descending. Sum 187 107 - - 371 0 1.03 8.0 - Average 23.4 13.4 18.4 4.8 - - - - 2.4 Normal 22.2 5.0 13.6 - 412 0 0.80 6.6 2025-01-01 39 31 35.0 20.5 30 0 0.47 0.2 0 2025-01-02 34 24 29.0 14.8 36 0 0.19 2.2 1 2025-01-03 24 13 18.5 4.6 46 0 0.07 1.5 3 2025-01-04 13 3 8.0 -5.7 57 0 0.01 0.2 3 2025-01-05 10 -3 3.5 -9.9 61 0 T T 3 2025-01-06 18 7 12.5 -0.7 52 0 T T 3 2025-01-07 25 15 20.0 7.1 45 0 0.06 0.8 3 2025-01-08 24 17 20.5 7.8 44 0 0.23 3.1 3 2025-01-09 M M M M M M M M M 2025-01-10 M M M M M M M M M 2025-01-11 M M M M M M M M M 2025-01-12 M M M M M M M M M 2025-01-13 M M M M M M M M M 2025-01-14 M M M M M M M M M 2025-01-15 M M M M M M M M M 2025-01-16 M M M M M M M M M 2025-01-17 M M M M M M M M M 2025-01-18 M M M M M M M M M 2025-01-19 M M M M M M M M M 2025-01-20 M M M M M M M M M 2025-01-21 M M M M M M M M M 2025-01-22 M M M M M M M M M 2025-01-23 M M M M M M M M M 2025-01-24 M M M M M M M M M 2025-01-25 M M M M M M M M M 2025-01-26 M M M M M M M M M 2025-01-27 M M M M M M M M M 2025-01-28 M M M M M M M M M 2025-01-29 M M M M M M M M M 2025-01-30 M M M M M M M M M 2025-01-31 M M M M M M M M M

The cold departures so far in January are being driven by the cooler maxes rather than the minimums. The strong winds blowing across the warm lakes along with the clouds are keeping the minimum temperatures up. This is why even interior spots around our area have been struggling to get into the single digits like they often do during colder patterns in early January. Time Series Summary for SUSSEX AIRPORT, NJ Click column heading to sort ascending, click again to sort descending January 1-8 minimum temperature 2025-01-08 17 1 2024-01-08 18 0 2023-01-08 25 0 2022-01-08 12 0 2021-01-08 17 0 2020-01-08 22 0 2019-01-08 20 0 2018-01-08 -4 2 2017-01-08 13 0 2016-01-08 4 0 2015-01-08 2 0 2014-01-08 -9 0 2013-01-08 8 0 2012-01-08 9 0 2011-01-08 0 0

I am hoping NYC can find a way to sneak in a 4”+ event during the PNA transition being forecast for later January. Maybe some type of overrunning once the Southeast Ridge starts flexing? But no guarantees with the way things have been going. Would want to see something within 120 hrs on all 3 models to be believable. Jan 20-27 Jan 27 to Feb 3

Yeah, the mismatch analogs I listed were December based. But I was uncertain how the actual process would turn out since this La Niña was so much weaker than the past mismatch instances. So the Northern Stream of the Pacific Jet was much stronger than the past mismatch Decembers leading to the cutter, hugger, and suppressed Southern Stream storm tracks. This has been the theme since the 2018-2019 winter which has continued into early January so far. It could be the same warm background SST state in the Pacific which slowed the La Niña SST response also being related somehow to the faster Northern Stream than past mismatch La Niña patterns.

The delayed freeze-up on Hudson Bay and warmer lakes really moderating the cold. https://sites.google.com/view/arctic-sea-ice/home/nsidc-arctic

Yeah, the 7 station average for January so far would be a little above average in 81-10 normals. We are currently running -0.6 in 91-20 averages. The warmth in Canada has worked down into the Northeast as Caribou is +4.8 so far. Same pattern as recent years with the coldest departures going to our west and south. EWR….-0.6 NYC….-2.4 JFK…..+0.5 LGA…..-2.2 HPN….+1.0 BDR….-0.4 ISP……-0.1

The wind has had more to do with how cold it has felt the last few days. Plus the first week of January is starting colder than the last two years. But it’s warm compared to how cold January 1st-7th in 2018 and 2014 were. Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending January 1-7 average temperature 2025-01-07 33.0 0 2024-01-07 36.2 0 2023-01-07 49.5 0 2022-01-07 37.6 0 2021-01-07 38.1 0 2020-01-07 41.2 0 2019-01-07 40.1 0 2018-01-07 16.4 0 2017-01-07 35.6 0 2016-01-07 32.9 0 2015-01-07 32.7 0 2014-01-07 24.0 0

New Brunswick went +4.5 last February with 16.5” of snow due to the record STJ and borderline super El Nino in mid-February allowing the Northern Stream to relax. So unless the monthly average temperature is above 40° in January and February, it’s always cold enough to snow this year. But December and March are different as +5 patterns will usually be too warm for snow. So for us storm tracks are more important than departures in January and February. 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

At this point the definition of a good season in NYC would be going over 10” and reverting to the 2020s decadal mean around 14.2”. Monthly Total Snowfall for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Mean 0.0 T 2.6 4.4 7.1 0.1 T 14.2 2019-2020 0.0 0.0 2.5 2.3 T T T 4.8 2020-2021 0.0 0.0 10.5 2.1 26.0 T 0.0 38.6 2021-2022 0.0 T 0.2 15.3 2.0 0.4 0.0 17.9 2022-2023 0.0 0.0 T T 2.2 0.1 0.0 2.3 2023-2024 0.0 T T 2.3 5.2 T 0.0 7.5

The Northern Stream of the Pacific Jet has just been too overpowering. So we have continued the cutter, hugger, and suppressed Southern Stream storm tracks. If this was an El Niño with a STJ further south near the Baja then we would probably all be in double digit snowfall by now. It would have carved out more of a trough near the Tennessee Valley. Hopefully, we can get some relaxation of this theme later this month.

NYC and surrounding areas are on the lower side of La Niña seasonal snowfall by January 10th since 1980. The best La Ninas are usually frontloaded by nature. We are behind 2022 but ahead of 2012. NYC La Niña snowfall by January 10th 2025…3.7” 2023…T 2022…6.0” 2021…10.5” 2018…17.5” 2017….9.5” 2012….2.9” 2011…21.8” 2009…7.0” 2008…2.9” 2006…9.7” 2001…15.2” 1999…4.5” 1996…37.2” 1989….5.3” 1986….0.9” 1985….7.0” 1984….5.4”

Yeah, a bunch of individual lows under the block feeding into the big gyre. It may take the transient Southeast Ridge in a little over 10 days to finally weaken it. Then it looks like we get a vortex consolidating closer to Hudson Bay out toward day 15.

One of the most expansive 50/50 lows that we have seen so far this decade with high pressure pressing in from the west.

Another day with the highs beating guidance with many spots getting above 32° today.

Yeah, hard to believe we got such an amazing 24 day stretch of winter following a December than was warmer than most Novembers. Maximum 24-Day Total Snowfall for JFK INTERNATIONAL AIRPORT, NY Click column heading to sort ascending, click again to sort descending. 1 40.8 1961-02-07 0 - 40.8 1961-02-06 0 - 40.8 1961-02-05 0 - 40.8 1961-02-04 0 2 39.8 1961-02-08 0 3 38.5 2016-02-15 0 Time Series Summary for JFK INTERNATIONAL AIRPORT, NY - Month of Feb Click column heading to sort ascending, click again to sort descending. 1 1963 -2 0 2 1961 -1 0 3 1967 0 0 4 2016 1 0 5 1979 2 0

It’s ironic that one of our greatest 24 day winter stretches occurred after the +13.3 December.

It was actually one of our most impressive 3 to 4 week winter periods of all-time with a 30” snowfall in spots and then another 10”+ in early February and then the first below 0° in NYC since 1994.

Much weaker Pacific Jet in 90-91 so we were still able to reach average snowfall even if it was a mild winter by the averages in those days. The pattern really flipped warmer in Janaury 1990 with the amped up MJO. December 1989 into January 1990 was one of the strongest MJO driven patterns of that era.

1990-1991 wasn’t too bad as it was of those more frequent near average winters for snowfall close to 25” following the previous 2 lower seasons.

We had multiple 3-6” events around our big 1980s Arctic Outbreaks. Even if NYC didn’t make it to exactly 6”, several spots around the area from NNJ out to Suffolk did. So the cold and dry during the 1980s was a bit of a misnomer. While it was true that the big 12”+ KU events were a rarity back then , we had multiple seasons with close to 25” average in the 70s and 80s without one. Since it was cold enough back then to get to average with a bunch of small to moderate events. With the warmer winters since the 1990s, a KU has been become a prerequisite for average snowfall. These days we just don’t have enough sustained cold to get to average with just small to moderate events.

We are coming up on the 40th anniversary of one of the greatest Arctic outbreaks of the late 20th Century. It was one the most impressive displays from the Long Beach Boardwalk of Arctic Seasmoke plus multiple steamnadoes over the ocean. I was out on the boardwalk with -2° temperatures and 40 to 50 mph gusts. One of the few times I got to experience a below 0° in morning and afternoon temperatures in the single digits. We had a 6” snowstorm a few days earlier with highs below freezing ratio fluff. Then another 6” with a few events a week later. So our 80s Arctic outbreaks usually had at least some snow and not cold and dry. https://www.wunderground.com/history/daily/us/ny/new-york-city/KJFK/date/1985-1-21

Back in October I was pointing out the potential PNA mismatch signal for December which worked out. But I also mentioned that other factors weren’t lining up like they did as recently as 2020 and 2017. As it turns out the Northern Stream of the Pacific was among the strongest we have ever seen with such a positive +PNA. So this lead to the warmer and less snowy outcome than most of the past +PNA La Niña Decembers. La Niña Decembers with strong +PNA patterns 2024…PNA…+1.70….NYC….avg temp…38.2°….snowfall…2.8” 2020…+1.58….39.2°….10.5” 2017….+0.89…35.0°…..7.7” 2005…+1.38….35.3…..9.7” 2000….+1.23…31.1°…..13.4” 1995…..+0.92…32.4°….11.5” 1985…..+1.39….34.2°….0.9” 1963……+1.77….31.2°….11.3”