bluewave

The coldest departures so far went south of the Great Lakes this month. You can see the moderating effect of flow across the Great Lakes in conjunction with the warmth in Eastern Canada keeping the Northeast warmer than areas to the south relative to the means. While we will finish below average here this month due to the cold next week, coldest departures will remain south when the month finishes.

The average highs from 1-16 to 1-31 have been holding the line much better at ISP than 01-01 to 01-15 over the last 60 years. It will match up with the coldest temperatures of January coming in next week. Probably related to the mid portion of winter holding onto the cold better than December and February. It also lines up with the forecast moderation in temperatures for early February.

Even so, it’s been tough for NYC to dip under 5° with westerly flow Arctic outbreaks last 30 years. All the really cold days under 5° like the 3° on 2-3-23 had N to NW flow down the Hudson Valley. The Great Lakes often had a large coverage of ice back in the 70s to early 90s. So NYC went to 0° or lower multiple times with westerly flow.

Relative to the means, Florida had been having much more impressive cold than our area. While our area has been -0.4° during the first half of January, Northern Florida has been -5° to -8°. The Canadian warmth with the delayed freeze-up on Hudson Bay and near record Great Lakes temperatures and low ice has kept the Northeast much milder relative to the means. You could make the case that it has actually felt much colder in a place like Gainesville, Florida to the locals when they dropped from 75° to 26° within a few days earlier this month. Cold always seems to feel more pronounced when it’s closer to a much warmer day.

The GFS raw 2m low temps have been verifying closer than the Euro for NYC in recent years with these Arctic outbreaks. NYC usually needs a N to NW flow to drop under 5°. This was the case in early February 2023 when NYC made it down to 3°. The GFS has upper single digits to near 10° for NYC. Even if we blend the guidance it’s been tough for NYC to dip under 5° with westerly flow Arctic outbreaks.

That’s true. It will be interesting to see how close we can come to January 2022 cold levels when the month finishes. With enough cold it’s possible that spots like Newark could have a rare month under 30° like in 2022. The cold in the forecast for next week is much more impressive than anything we have seen so far this month and winter to date. Especially for areas that missed out on the great radiational cooling that arrived right before Christmas.

Getting annoyed by certain types of weather is a different topic than what types of patterns are average now vs in the past.

I get what you are saying since January is our coldest month of the year. So it’s always going to feel cold when we have the first half of January near normal. Especially with such strong winds like we have been getting. But the 8 station average is only -0.4 and 32.5° for the 1981-2010 warmest climate normals period. In earlier eras this would have been a warmer than average January so far. Plus after the last 2 Januaries this one feels much colder since it has been. The other issue is that it looks like the tree growth has created some cooling at Central Park since it has the coldest departure out of any of the stations. This effect has been more prominent when the trees have been fully leafed out. New Brunswick….0.0…32.2° EWR…-0.2…33.0° NYC…-2.1…32.1° LGA….-1.8…33.2° JFK….+0.9…34.4° HPN….+0.2…30.5° BDR……0.0…32.0° ISP……-0.1…..32.1° AVG….-0.4….32.5°

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I was discussing back in late October how the early MJO indicator was pointing toward a La Niña mismatch December with a +PNA like 2020 and 2017. So the fact that December into January was colder than the model forecasts from October into early November wasn’t that much of a surprise to me. But as I mentioned back then, other factors weren’t lining up the way they were in 2017 and 2020. Mainly that the Northern Stream of the Pacific Jet hasn’t relaxed this winter yet like 2020 and 2017 did. So we have much less snowfall by mid-January than those two mismatch Decembers into January did.

The very fast Northern Stream was forced south under the +PNA -AO block carving out a very deep 50/50 low.

We could actually use a little more of a Southeast Ridge since the storm track has been so suppressed this month.

This has been a one of a kind January so far in terms of the high vs low temperature departure divergence. We started out with some of the warmest Great Lakes SSTs and lowest ice cover for this time of year. Plus the record warmth around Hudson Bay and delayed freeze-up. So the strong winds crossing the Great Lakes have resulted in the cloudiest January so far on record in Buffalo. The stronger winds and clouds have resulted in the minimum departures running much higher than the maximums. https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=45&network=NY_ASOS&zstation=BUF&hour=12&year=2025&month=1&_r=t&dpi=100&_fmt=png

NYC will have a shot at the first single digits of the season next week. Models starting to more of a W to WSW flow which moves south of the Great Lakes. But if the flow is too much from the SW then NYC may struggle to get much under 10°. So the wind direction will play a big role in how cold we get since the Great Lakes are still so warm. The Great Lakes were so cold and Erie was often frozen over in the 1970s to early 1990s that NYC could go below 0° with flow across the Great Lakes. These days NYC generally needs a N to NW flow down the Hudson Valley for its coldest readings. It’s interesting how 22-23 was one of our warmest winters but NYC was still able to get down to 3° in early February since the N to NW flow avoided the warm Great Lakes. Same went for another warmest winter in 15-16 when NYC went below 0° on a NNW cold air drain down the Hudson Valley. So it will be funny if the NYC low ends up higher than in February 2023 even though this winter has been a colder one than that one through mid to late January.

Boston had more snow in one month back in 2015 than all the snow since December 2021. Maximum 30-Day Total Snowfall for Boston Area, MA (ThreadEx) Click column heading to sort ascending, click again to sort descending. 1 94.4 2015-02-22 0 Time Series Summary for Boston Area, MA (ThreadEx) - Oct through Sep Click column heading to sort ascending, click again to sort descending. 2024-2025 7.5 2023-2024 9.8 0 2022-2023 12.4 0 2021-2022 54.0 0 2020-2021 38.6 0 2019-2020 15.8 0 2018-2019 27.4 0

19-20 to 20-24 was the first time that the Boston 5 year moving average snowfall dipped down to only 25.1”. The lowest of the 1980s was 31.1”. So the persistent cutter, hugger, and suppressed Southern Stream storm tracks since 18-19 is really being felt across the region. We will need a return of the KU BM storm tracks before 28-29 in order to avoid the least snowiest decade on record for spots across the region.

Having the 1st half of winter finish closer to average across the Northeast feels much colder given the record warmth last few winters plus the very windy conditions this month.

The long term snowfall in the South is declining. But since the bar is lower for average there, it’s easier for an event or two to reach average. So if you average less than 10” annually, it doesn’t take much to have an occasional average to above average season. This is like what happened during May 2020 in NYC. All it took was a T to tie the previous snowiest May on record in 1977. May 2020 was the only month in NYC since 2018-2019 with a new snowiest month or tie of a previous snowiest month.

Philly is similar to our area since the 90s in needing KU storms that pass within a certain distance of the BM in order to reach 20” on the season. Before the 90s seasons could get either KUs or more moderate events and still reach 20”. So with all the cutter, hugger, and suppressed Southern Stream storm tracks since 18-19, only 20-21 made it over 20” with the great KU storm tracks that winter. 2022 was a little too wide of the BM to the south and east which favored ACY. So the lack of BM KU events in recent years where some part of the region gets a 10”+ jackpots has resulted in the 2020s starting off as the least snowiest decade in several spots. So we will need to see a big storm track improvement back to the BM going forward for the 19-20 to 20-29 to avoid becoming the least snowiest decade across the region.

The record warmth in December 2015. Monthly Mean Min Temperature for JFK INTERNATIONAL AIRPORT, NY Click column heading to sort ascending, click again to sort descending. 2015-2016 44.2 27.6 30.1 34.0

11-12 got pushed further back in the pack after all the warmth since then. Time Series Summary for JFK INTERNATIONAL AIRPORT, NY Click column heading to sort ascending, click again to sort descending average winter low temperature 1 2015-2016 34.0 0 2 2001-2002 33.5 0 3 2016-2017 33.2 0 4 2023-2024 33.0 0 - 1997-1998 33.0 0 5 2011-2012 32.7 0 6 1982-1983 32.6 0 7 2022-2023 32.5 0 8 1974-1975 32.2 0 - 1952-1953 32.2 0 9 2019-2020 32.1 0

14-15 was the only season with so many days having 1” OTG following a top 5 warmest Christmas high temperature. Data for December 25 - JFK INTERNATIONAL AIRPORT, NY Click column heading to sort ascending, click again to sort descending. 2015-12-25 64 52 0.10 0.0 0 2020-12-25 60 29 0.59 0.0 0 1982-12-25 58 42 0.01 0.0 0 2014-12-25 57 42 0.06 0.0 0 2008-12-25 57 32 0.06 0.0 0 1994-12-25 57 41 T 0.0 0 1964-12-25 56 42 0.02 0.0 0

Anything at or above 32 days for JFK qualifies for the 10 highest number of days with 1” of snow OTG. Time Series Summary for JFK INTERNATIONAL AIRPORT, NY - Oct through Sep Click column heading to sort ascending, click again to sort descending. 1 1995-1996 50 0 2 2014-2015 48 0 3 1977-1978 44 0 4 2002-2003 43 0 - 1960-1961 43 1 5 2010-2011 41 0 6 1976-1977 38 0 7 2004-2005 36 0 8 2000-2001 35 0 9 2013-2014 34 0 - 1963-1964 34 0 10 1993-1994 32 0

The nighttime temperatures in NW New Jersey have been warmer for average for January so far. The one time they got really cold was right before Christmas. That was when we had the great radiational cooling with the record high pressure. So there was no flow across the Great Lakes.

So far the Northeast temperatures have been running near average since the beginning of December. Slightly below average temperatures in December and a little above average for January so far. The cold coming in from the 20th to 25th will result in the December 1st through January 25th average temperature departure running below average. The Northeast has had numerous years that were much colder than this since the 90s through the first half of winter. So whether this winter will be the first colder one in the Northeast in 10 years will depend on the February departure. The combination of record warmth in Canada leading to the delayed freeze-up on Hudson Bay and record Great Lakes warmth has lead to the Northeast departures running warmer than the Mid-Atlantic. Plus this is against the warmest 1991-2020 climate normals. If we were using 1981-2010 climate normals then the Northeast would be warmer than average for the 1st half of the winter. So depending on February the Northeast could finish the winter below average using 1991-2020 climate normals and above average vs 1981-2010 normals. But if the February temperature departures are wam enough, then the Northeast will finish above average again.