bluewave

The flow around the block used to be much colder in the Northeast before Canada started getting so warm. The warmer Hudson Bay and Great Lakes are 100% due to Canada coming off its warmest year on record. Plus the 500 mb blocks are getting stronger and warmer leading to areas further north warming faster than to the south.

Cold departures don’t mean what they used to in such a rapidly warming climate. New Brunswick which has a record back to 1893 is currently at 28.6°. That’s a -3.1° departure so far against the warmest 1991-2020 climate normals. It would have been a run of the mill cold month during 1961 to 1990 with a departure around -0.4°. The actual temperature is close to January 2018. Having the 30th coldest January average temperature isn’t that big of a deal. But it feels colder relative to how warm the recent winters have been. Time Series Summary for New Brunswick Area, NJ (ThreadEx) - Month of Jan Click column heading to sort ascending, click again to sort descending. 1 1977 19.5 0 2 1918 20.2 0 3 1893 21.4 0 4 1912 21.9 0 5 1982 22.2 1 - 1940 22.2 0 6 1970 22.6 0 7 1981 22.7 0 8 1904 22.8 0 9 1994 23.6 2 10 1988 24.0 0 - 1920 24.0 0 11 2004 24.3 0 12 1948 24.4 0 13 1961 25.1 0 14 1945 25.2 0 15 2014 25.5 0 - 1984 25.5 0 16 1971 25.6 0 17 1985 25.9 0 18 1976 26.0 0 19 2003 26.5 0 20 2009 26.7 0 21 1978 26.8 0 22 2011 26.9 0 - 1936 26.9 0 23 1905 27.1 0 24 1925 27.2 0 25 2015 27.4 0 26 1968 27.5 0 27 1957 27.7 0 28 1965 28.1 0 - 1922 28.1 0 - 1895 28.1 0 1996 28.4 1 29 1969 28.5 0 - 1935 28.5 0 - 1914 28.5 0 30 2025 28.6 5 - 2018 28.6 0

The CAA into West Virginia which has been very impressive tracked south of the Great Lakes. So the airmass didn’t travel over the warmer Great Lakes with the much lower ice than normal. Plus Erie which is the closest Lake to them is one of the few with sufficient ice cover. Remember, the Great Lakes warmth is a result of the record warmth in Canada which had their warmest year on record. So it’s a symptom of the overall pattern and not the cause. Same goes for the delayed freeze-up on Hudson Bay. The Northeast being closer to this warmer region to the north is why the cold was muted this month in the Northeast relative to areas to our south. Past instances when West Virginia was so cold in January were significantly colder in the Northeast. This is the first time that parts of Northern Maine are +5 with West Virginia at -10. So this is something new for the Eastern US. In the old days it didn’t matter that the core of the cold went to our south. That PV lobe would have been far more expansive covering the Northeast and Eastern Canada. So as the climate continues to warm, the geographic footprint of these Arctic Outbreaks will continue to shrink. We saw a version of this smaller sized Arctic outbreak in February 2021 and January 2019. Much smaller areas of Arctic cold focusing into a smaller area than Arctic outbreaks of the past.

The reason for the delayed freeze-up on Hudson Bay plus the warmer lakes with less ice this winter is due to the lack of cold up in Canada. So the Northeast being closest to these influences muted the cold here this winter. In the old days Canada and the Northeast would have been much colder. A 7 station -2.6° average against the warmest 30 year climate normals would have been a run of the mill colder January before the 2020s. Same story as recent years with the coldest departures missing to our south and west. Canada warmth especially Hudson Bay and areas east January 2025 December 2024

They did a great job with quality control at Central Park while the NWS was still at 30 Rock into early 1993. The new ASOS was established around 1995 when the NWS was already out at Upton. So the deep shade issues artificially cooling the site didn’t emerge until the 1990s. The site was always open exposure like every other climate station before then. So the temperature and snowfall measurements were always very reliable before the NWS left NYC and they made sure that the there was a proper siting for the sensors. You can see how a spot like New Brunswick doesn’t have the sensors underneath the trees. But in a open clearing like the guidelines specify. 1920 2021 New Brunswick proper siting

It’s an accomplishment these days getting two colder winter months in a row even if the slightly colder December was a result of the much warmer averages. This December would have been warmer than average using 81-10 normals. The last time all of our climate sites had 3 consecutive colder winter months was way back in 02-03. During 09-10 some stations had a warmer January.

Yeah, the warmer flow from Eastern Canada crossing the Great Lakes kept the Northeast much warmer than areas to our south.

I never use the term torch when describing monthly temperature departures. My guess is that the February departure will be warmer than average across the 7 station average. Pretty typical for a Southeast Ridge pattern during February in a La Niña year. It’s a bit early for an exact warm departure number.

The trees are tall enough now close in to the sensors that the site can even get shade during the afternoon without any leaves on the trees.

-2.6° is the average. The NYC site has been consistently running too cold compared to the other stations across the area. So the increased tree growth is probably artificially suppressing the temperatures there during the day in the winter like during the warm season.

The cold has been more focused in other regions as the best we have been able to do for a 7 station average this month has only been -2.6°. It’s just remarkable how the coldest departures have been missing the Northeast since the 15-16 super El Niño. Even with the Southeast Ridge completely suppressed in January. So while I am not sure of the exact departure for February yet, it’s probably a good bet that the 7 station average will be warmer than the departures were in December and January as the Southeast Ridge returns. EWR..-2.7° NYC...-3.8° LGA….-3.3° JFK…..-1.1° HPN….-2.6° BDR….-2.3° ISP…...-2.6° AVG.…-2.6°

Yes. My guess is that the month will finish above average for temperatures. We don’t get cold months with a Southeast Ridge.

I don’t trust the EPS 2m temperatures as they have been running too cold all winter. Remember that they had that 10 day run of not getting above freezing for NYC in mid-January which never verified. Plus this week has been correcting warmer as we got closer. So probably a back and forth pattern into early February with the warmer departures eventually winning out as the month progresses.

We are seeing the classic La Niña progression with the Southeast ridge making a return as we approach February. That -EPO will west based allowing more of a -PNA. So any cooldown showing up days 6-10 will only last a few days before the next warm up arrives beyond the period you mentioned. West based -EPO allowing -PNA and Southeast Ridge

Models continuing to back off the colder pattern that they were showing for this week. New run Old run

JFK is in the same boat as all the other local stations. None of the models are showing a KU storm track anytime soon. So a continuation of the cutter, hugger, and suppressed Stream would signal a seasonal total under 20”. It’s still uncertain if JFK like our other stations can see another small or moderate event putting them over 10” on the season.

JFK had 3.1” by 1-26-12 at an average temperature of 39.5°. This year JFK has 5.5” with a 35.8” average. So the extra amount of cold wasn’t able to translate into significantly more snow due to how hostile the storm tracks have been.

Even if you remove the late October event, parts of the area had a better January snowstorm in 2012 than this year. Plus JFK had the same monthly low in 2012 than this month so far. Just goes to show how hostile the storm tracks have become for snow with even below average January temperatures. Monthly Data for January 2012 for CT COASTAL Climate Division Click column heading to sort ascending, click again to sort descending. WESTPORT 2.5 ENE CoCoRaHS 8.7 NEW HAVEN 1.7 NW CoCoRaHS 8.4 TRUMBULL COOP 7.5 IGOR I SIKORSKY MEMORIAL AIRPORT WBAN 7.4 GROTON COOP 7.0 MILFORD 2.9 ESE CoCoRaHS 7.0 Monthly Data for January 2012 for NY COASTAL Climate Division Click column heading to sort ascending, click again to sort descending. BAITING HOLLOW COOP 5.6 RIVERHEAD 1.3 SSE CoCoRaHS 5.6 SHOREHAM 1.8 SSE CoCoRaHS 5.5 BRIDGEHAMPTON COOP 5.0 DOBBS FERRY-ARDSLEY COOP 5.0 Time Series Summary for JFK INTERNATIONAL AIRPORT, NY - Month of Jan Click column heading to sort ascending, click again to sort descending. 2025 13 6 2024 18 0 2023 29 0 2022 9 0 2021 15 0 2020 19 0 2019 3 0 2018 4 0 2017 13 0 2016 12 0 2015 8 0 2014 3 0 2013 12 0 2012 13 0

Very strong Pacific blocking both years. But as we have seen this year, storm tracks have been more important than 500 mb teleconnections and temperatures for snow. We can’t get to average snowfall anymore without big KU events. The cutter, hugger, and suppressed Southern Stream tracks since 18-19 aren’t enough to get us over 20” even with marginally below average average temperatures this winter so far. Any winter month near or under 40° is cold enough for snow. But it becomes harder to get a big March once the averages get above 42° to 43° which is common for March as the climate warms. So while we had more cold and blocking than the 2011-2012 La Niña, that year was snowier for several spots near the coast through the end of January. So the storm tracks were even more hostile for snow in some spots around the region than 2011-2012. Snowfall by January 31st EWR…2025….7.2”…..2012….8.5” NYC….2025….5.8”…..2012….7.2” BDR…..2025….5.4”…..2012…11.4” ISP…….2025….4.8”…..2012….4..1”….close

Same story as 08-09. Much more snowfall both years through the end of January than this year. So March was a continuation of the seasonal pattern both La Niña years. 1-31-25….5.8” so far 1-31-09….15.0” 1-31-84….13.3”

08-09 was a much snowier winter through the end of January than this year was with 15.0” by the end of January while we are still in the single digits this year. So the favorable storm tracks for snow were already established by March. Plus Marches during the 2020s have been less snowy than the 2010s were. So even if this March can show improvement over the last 5 years, it’s unlikely we can count on March alone to get to average. Since most of those Marches had a great snowfall pattern in one prior month.

All I can say about the snowfall is that it doesn’t appear like any KU BM snowstorms are on the near horizon. So probably a continuation of the cutter, hugger, and suppressed Southern Stream storm tracks which have dominated since 18-19. The prerequisite for a 20s snowfall season in NYC since 93-94 has been KU BM events where somebody from EWR to Eastern LI records 10” to 12”+ in a single event. So my guess is that NYC will finish this season with under 20” of snow. The one unknown at this point before the season ends is if NYC can finish over 10” with a few smaller events of maybe even a moderate one.

Even though this La Niña was later to get going, the La Niña atmospheric response became very strong during October into November as per the CP OLR readings. But since it was a mismatch year, we got the +PNA from December into January. This has happened many times in the past also. These occurrences were also accompanied by some areas experiencing the coldest winter readings in mid to late January like we just did. Those other La Ninas also saw the Southeast Ridge and departures rebound for February. The Northern Stream of the Pacific Jet influence has been very strong this winter even by La Niña standards. Several locations actually had more snowfall by this time in the 2011-2012 La Niña. So even though spots like the CT Shoreline have had less snow so far than 2011-2012, this year was significantly colder. So this shows us that the La Niña can also manifest in a way that results in hostile storm tracks for snow even when it’s more than cold enough to snow. Pacific Jet actually less hostile for snow at some spots here in Southern CT back in 2011-2022 through the end of January like Bridgeport to New Haven. Data for October 1, 2011 through January 26, 2012 Click column heading to sort ascending, click again to sort descending. TRUMBULL COOP 11.5 IGOR I SIKORSKY MEMORIAL AIRPORT WBAN 11.4 NEW HAVEN 1.7 NW CoCoRaHS 11.2 WESTPORT 2.5 ENE CoCoRaHS 8.7 GROTON COOP 8.5 MILFORD 2.9 ESE CoCoRaHS 7.0 Data for October 1, 2024 through January 26, 2025 Click column heading to sort ascending, click again to sort descending. SHELTON 1.3 W CoCoRaHS 10.5 NEW CANAAN 3.8 N CoCoRaHS 10.5 NEW CANAAN 1.9 ENE CoCoRaHS 9.9 STAMFORD 1.0 S CoCoRaHS 8.2 NORWALK 2.9 NNW CoCoRaHS 8.1 NORTHFORD 0.8 SW CoCoRaHS 5.5 IGOR I SIKORSKY MEMORIAL AIRPORT WBAN 5.4 GUILFORD COOP 5.2 DARIEN 2.4 NW CoCoRaHS 5.2 STRATFORD 0.2 ESE CoCoRaHS 5.0 KILLINGWORTH 2.6 ESE CoCoRaHS 4.4 MADISON CENTER 1.3 N CoCoRaHS 3.9 GUILFORD CENTER 2.7 WSW CoCoRaHS 3.9 NORWALK 1.4 ENE CoCoRaHS 3.0

The La Niña progression has been right on track all winter. I was discussing back in October how this could be one of those mismatch La Ninas from December into January with a +PNA and the MJO warm phases influence muted. But unfortunately the Pacific Jet was never able to relax like the prior mismatch years. So our snowfall had been much lower than past years with these types of La Niña patterns. I mentioned how there were other factors due to the competing marine heatwaves in the Pacific. But we are still seeing the Southeast Ridge become a player again as we head into February which is typical for La Ninas. There have been several La Nina’s with a colder December and or January which had a warmer than average February departure.

Yes. We are on track for February having the warmest departure of the winter. It’s also possible the NYC departure this January currently at -4.1° will be the lowest monthly departure for all 12 calendar months of 2025. This has been the case since 2016 as these colder months below -3 have been few and far between. But NYC is a bit of an outlier this month as the other stations aren’t as cold. Could be related to the vegetation so close in near the sensors blocking the sunlight.