bluewave

It’s called xmACIS2. https://xmacis.rcc-acis.org

Yeah, the contrast between Siberia and the SSTs in the WPAC is the strongest on record for early October. It resulted in a 5 sigma jet streak out near the Aleutians recently. This has lead to the record warmth over North America from late September into early October.

That’s my point. It was easier back during the colder climate era to pull off a series of epic years like that. I agree that it was an amazing run even during that era. But the colder climate made it possible. I am sure the posters around Boston would be happy seeing a winter or two during the remainder of the 2020s bouncing back closer to the long term average in the low 40s.

Highs easily beating guidance today especially with the very dry conditions. Newark Liberty MOSUNNY 86 50 28

Yeah, areas west of the I-95 corridor are several degrees colder than NYC during the winter making it easier for them to average near or below freezing. But the rising winter temperature trend is the same at both locations. So unless this warming pattern stops, the areas just west of the I-95 corridor will also stop seeing 50”+ seasons in the coming decades.

The magnitude and the duration of the warm ups are usually more impressive than the cool downs even using the warmer climate normals.

We would need a much larger even than that once since the cooling effects only lasted into 1992 and the temperatures now are much warmer than back then. https://www.sciencedirect.com/science/article/abs/pii/S1364682624000154#:~:text=Highlights,may be worse than thought. Conclusions The cooling attributed to the Mt. Pinatubo eruption of 0.5 °C over 18 months in the literature mostly based on climate model predictions is overrated. Despite uncertainties remaining in the determination of the cooling and the duration, accounting for natural variability as described in this work by using a simple and intuitive approach reduces the cooling to up to 0.28 °C, on average 0.2 °C, and the duration is similarly reduced to 13 months. This result is consistent with other empirical

90°+ would be the warmer days during the summer. But past summers would have many days remaining in the 80s even during July. 2009 was our last cooler summer before the summers dramatically warmed since 2010. Only 1 day made it to 90° at the warm spots like Newark. Climatological Data for NEWARK LIBERTY INTL AP, NJ - July 2009 Click column heading to sort ascending, click again to sort descending. Sum 2577 2028 - - 0 293 6.60 T - Average 83.1 65.4 74.3 -3.9 - - - - 0.0 Normal 86.9 69.4 78.2 - 0 408 4.66 0.0 2009-07-01 81 66 73.5 -3.5 0 9 0.00 0.0 0 2009-07-02 79 68 73.5 -3.7 0 9 0.23 T 0 2009-07-03 81 65 73.0 -4.4 0 8 0.08 0.0 0 2009-07-04 83 65 74.0 -3.5 0 9 0.00 0.0 0 2009-07-05 81 63 72.0 -5.7 0 7 0.00 0.0 0 2009-07-06 86 60 73.0 -4.8 0 8 0.00 0.0 0 2009-07-07 82 64 73.0 -4.9 0 8 0.11 0.0 0 2009-07-08 80 59 69.5 -8.6 0 5 0.00 0.0 0 2009-07-09 74 62 68.0 -10.2 0 3 0.00 0.0 0 2009-07-10 77 58 67.5 -10.7 0 3 0.00 0.0 0 2009-07-11 79 62 70.5 -7.8 0 6 0.24 0.0 0 2009-07-12 84 64 74.0 -4.4 0 9 0.03 0.0 0 2009-07-13 83 61 72.0 -6.4 0 7 0.00 0.0 0 2009-07-14 83 60 71.5 -7.0 0 7 0.00 0.0 0 2009-07-15 87 62 74.5 -4.0 0 10 0.00 0.0 0 2009-07-16 91 71 81.0 2.5 0 16 0.00 0.0 0 2009-07-17 88 69 78.5 0.0 0 14 0.07 0.0 0 2009-07-18 86 70 78.0 -0.5 0 13 T 0.0 0 2009-07-19 85 63 74.0 -4.5 0 9 0.00 0.0 0 2009-07-20 83 67 75.0 -3.5 0 10 0.00 0.0 0 2009-07-21 73 65 69.0 -9.5 0 4 0.78 0.0 0 2009-07-22 82 65 73.5 -5.0 0 9 0.00 0.0 0 2009-07-23 79 65 72.0 -6.4 0 7 0.14 0.0 0 2009-07-24 83 65 74.0 -4.4 0 9 0.00 0.0 0 2009-07-25 84 64 74.0 -4.3 0 9 0.07 0.0 0 2009-07-26 87 69 78.0 -0.3 0 13 1.03 T 0 2009-07-27 86 69 77.5 -0.7 0 13 0.18 0.0 0 2009-07-28 87 72 79.5 1.3 0 15 T 0.0 0 2009-07-29 85 73 79.0 0.9 0 14 2.97 T 0 2009-07-30 89 73 81.0 2.9 0 16 0.00 0.0 0 2009-07-31 89 69 79.0 1.0 0 14 0.67 0.0 0

Yeah, the much warmer temperatures at places like Boston separates this record low 7 year run from previous well below average streaks. The 7 year period ending in 1992 was several degrees colder. So much of that periods lower snowfall was related to issues other than temperatures being too warm. This is why it’s unlikely that Boston will see 3 seasons before this decade is out with 83” to 107” snow. Since this much warmer climate would struggle to produce such high totals in quick succession like 1992-1993 to 1995-1996 did. This is why it will be more challenging for Boston and other l-95 cities to the south to end this current much lower snowfall period like they did back in the early to mid-90s without a major VEI 7 or larger volcanic eruption to cool the climate down temporarily. Boston average snowfall 2019-2025….26.6”……DJF average temperature….34.6° Boston average snowfall 1986-1992….29.9”……DJF average temperature….32.2° Outstanding seasons following that lower snowfall period which ended the 7 year low 1992-1993…..83.9”……31.4° 1993-1994…..96.3”……27.8° 1995-1996…..107.6”……30.9°

More summer-like than the Memorial Day weekend was. The Saturday to Monday highs were only in the upper 60s to mid 70s at the warm spots. The average high during that late May weekend is 75°. Models have 80°+ at the warm spots from Saturday through Tuesday. The average high this time of year is only 70°. Newark 2025-05-24 69 50 59.5 -6.0 5 0 0.02 0.0 0 2025-05-25 71 50 60.5 -5.3 4 0 T 0.0 0 2025-05-26 75 54 64.5 -1.6 0 0 0.00 0.0 0

2022 was the latest 80° and 2024 was the latest 82°. First/Last Summary for JFK INTERNATIONAL AIRPORT, NY Each section contains date and year of occurrence, value on that date. Click column heading to sort ascending, click again to sort descending. 2022 05-21 (2022) 87 11-07 (2022) 80 169 2024 04-29 (2024) 82 11-01 (2024) 82 185 1950 05-07 (1950) 81 11-01 (1950) 80 177 1971 05-11 (1971) 80 10-29 (1971) 80 170 2023 04-12 (2023) 84 10-28 (2023) 81 198 1963 04-18 (1963) 82 10-21 (1963) 81 185 1949 05-05 (1949) 83 10-21 (1949) 80 168 1969 04-26 (1969) 80 10-20 (1969) 81 176 2016 05-25 (2016) 87 10-19 (2016) 86 146 1975 05-20 (1975) 81 10-15 (1975) 82 147 2021 03-26 (2021) 81 10-14 (2021) 80 201 1990 03-13 (1990) 85 10-14 (1990) 82 214 1962 04-22 (1962) 81 10-12 (1962) 81 172

It’s more like a regression to the mean for what used to be average in past decades for locations to our south. So Boston has seen a reversion last 7 seasons for what was the old average closer to NYC. Then NYC has had a 7 year average closer to what used to be the old norm from DC to Philly.

NYC needs two things in order to have a 50” snowfall season. One is an average winter temperature close to 32°or colder. The other is a cold storm track out near the benchmark. NYC has been nowhere near achieving this combination since the winters shifted so much warmer since 2015-2016. First, the winters shifted warmer in 2015-2016 which was followed by a storm track warming since 2018-2019. NYC highest snowfall total over the last decade has only been 40.9”. The coldest winter average temperature has been 34.8°.

Why do you say that? Since I am only pointing out what the current climate is capable of producing. Absent a major volcanic event, it’s statistically unlikely for NYC to see a 50” season with how much the winters and the storm tracks have warmed.

2019 could be tough to beat for a while but JFK set their all-time November high last year at 82°. Time Series Summary for JFK INTERNATIONAL AIRPORT, NY - Month of Nov max high temperature Click column heading to sort ascending, click again to sort descending. 1 2024 82 0 2 2022 80 0 - 1950 80 1 3 1993 77 0 - 1982 77 0 - 1975 77 0 4 1974 76 0

But it’s still very rare for MSP to hit 90° in October since it has only happened three times before. Time Series Summary for Minneapolis-St Paul Area, MN (ThreadEx) - Month of Oct Click column heading to sort ascending, click again to sort descending. 1 2023 92 0 2 1997 90 0 - 1928 90 0 4 1953 89 0 - 1922 89 0 6 2011 88 0 - 1947 88 0

Those rebounds occurred back in a much colder climate. So previous snow droughts were a function of dry patterns and not too much warmth like we have seen in the last decade. DC has been experiencing a long term snowfall decline as the winters have been warming. So unless the winters stop warming, the long decline will continue. Hard to say if the next 9 years declines more, holds steady, or bounces a little off the current record lows. But it’s too warm now for a strong rebound like was the case for past 9 year lows with the 9 year means getting back above 20”. it would probably take VEI 7 eruption to cool the winters enough for a more significant rebound next 9 years. But long range volcanic forecasting is still very low skill. Plus the effects of large eruptions would only be temporary lasting several years. 9 year running mean snowfall is black line and the trend line is red

Statistically pretty unlikely since the warm spots like Newark haven’t stayed under 70° from 10-8 to 10-18 which is the end of the GFS run since 2002. Time Series Summary for NEWARK LIBERTY INTL AP, NJ max temp 10-8 to 10-18 Click column heading to sort ascending, click again to sort descending. 2024-10-18 78 0 2023-10-18 74 0 2022-10-18 71 0 2021-10-18 84 0 2020-10-18 77 0 2019-10-18 75 0 2018-10-18 81 0 2017-10-18 83 0 2016-10-18 85 0 2015-10-18 81 0 2014-10-18 79 0 2013-10-18 75 0 2012-10-18 73 0 2011-10-18 88 0 2010-10-18 79 0 2009-10-18 73 0 2008-10-18 79 0 2007-10-18 89 0 2006-10-18 80 0 2005-10-18 75 0 2004-10-18 76 0 2003-10-18 78 0 2002-10-18 65 0

Another over the top warm up this weekend with the record 90° heat forecast for MSP while we stay in the 80s.

Walpack was able to get their first freeze of the season yesterday. Pretty wild microclimate in that valley with an early morning low of 31° and high still near 70°. Had my coolest morning of the fall so far at 45°. ▼ Walpack NJ 2025-10-02 Mesonet 68 31

30 years averages will take longer to catch up with the shorter term changes. But DCA has only averaged 7.8” over the last 9 seasons. We’ll have to see if the next decade declines a bit more or holds closer to the 7.8” figure. They had been at 17.4”for the previous 9 season period. This is their first 9 year stretch with an average under 10”. Their highest 9 year run was 29.9” back in 1912. Monthly Total Snowfall for Washington Area, DC (ThreadEx) Click column heading to sort ascending, click again to sort descending. Mean 0.0 0.2 0.3 5.0 1.5 0.9 T 7.8 2024-2025 0.0 T 0.1 8.3 6.5 0.0 0.0 14.9 2023-2024 0.0 0.0 0.1 7.8 0.1 T T 8.0 2022-2023 0.0 0.0 T T 0.4 T T 0.4 2021-2022 0.0 0.0 0.0 12.3 T 0.9 0.0 13.2 2020-2021 0.0 0.0 T 2.6 2.8 0.0 0.0 5.4 2019-2020 0.0 0.0 0.4 0.2 T 0.0 0.0 0.6 2018-2019 0.0 1.4 0.0 11.5 3.7 0.3 0.0 16.9 2017-2018 0.0 0.0 1.9 1.2 0.2 4.5 T 7.8 2016-2017 0.0 0.0 T 1.4 T 2.0 0.0 3.4 Monthly Total Snowfall for Washington Area, DC (ThreadEx) Click column heading to sort ascending, click again to sort descending. Mean T T 2.6 5.5 6.5 2.8 T 17.4 2015-2016 0.0 0.0 0.0 18.8 3.1 0.3 T 22.2 2014-2015 0.0 T T 3.6 9.8 4.9 T 18.3 2013-2014 0.0 T 1.5 6.6 11.2 12.7 T 32.0 2012-2013 0.0 T 0.2 0.9 0.4 1.6 0.0 3.1 2011-2012 T 0.0 T 1.7 0.3 T 0.0 2.0 2010-2011 0.0 T 2.1 7.3 0.5 0.2 T 10.1 2009-2010 0.0 0.0 16.6 7.4 32.1 T 0.0 56.1 2008-2009 0.0 T T 1.9 0.1 5.5 0.0 7.5 2007-2008 0.0 0.0 2.6 1.3 1.0 0.0 0.0 4.9

Unfortunately, the jet max out near the Aleutians was one of the strongest on record for late September. Right along the northern gradient of that record SST pool. Looks like more of the same next few days with a daily 5 sigma jet max. We saw how this lead to the record warmth around our area in late September. It’s no surprise the models are so warm for early October with near 90° heat forecast in places like MSP. https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=AFDMPX&e=202510021750 These strong southerly winds will also usher in a very warm airmass, with highs both Friday and Saturday expected to be up around 90 west of I-35 and south of I-94 both days, which will put record highs in play both days for MSP and STC. The only saving grace when it comes to this heat is dewpoints won't be horrendous, mainly in the mid 50s to lower 60s. Still, when the Twin Cities has only seen the high meet or exceed 90 in October 3 times going back to 1872, this a rare airmass for us to see so late into the season.

It’s remarkable how reliable this warm up has been since 2011 from 12-17 to 12-25. Every year has seen at least a high of 55°. This period has had a large concentration of top 3 warmest temperatures. Time Series Summary for NEWARK LIBERTY INTL AP, NJ Max Temp 12-17 to 12-25 Click column heading to sort ascending, click again to sort descending. 2024-12-25 61 0 2023-12-25 64 0 2022-12-25 58 0 2021-12-25 62 0 2020-12-25 62 0 2019-12-25 57 0 2018-12-25 61 0 2017-12-25 57 0 2016-12-25 59 0 2015-12-25 71 0 2014-12-25 64 0 2013-12-25 71 0 2012-12-25 57 0 2011-12-25 62 0

Yeah, it was nice. But the 55+ warmup occurred right on schedule just before on the 17th and 18th. Then mid 60s warmth to close out the month. Sum 1396 953 - - 833 0 4.39 3.5 2024-12-17 61 46 53.5 15.9 11 0 0.02 0.0 0 2024-12-18 55 39 47.0 9.6 18 0 0.23 0.0 0 2024-12-19 47 36 41.5 4.4 23 0 0.04 0.0 0 2024-12-20 39 33 36.0 -0.9 29 0 0.05 0.3 0 2024-12-21 33 20 26.5 -10.1 38 0 0.08 2.2 2 2024-12-22 23 13 18.0 -18.4 47 0 0.00 0.0 1 2024-12-23 29 11 20.0 -16.2 45 0 0.00 0.0 1 2024-12-24 41 26 33.5 -2.4 31 0 0.07 1.0 T 2024-12-25 36 27 31.5 -4.2 33 0 0.00 0.0 T 2024-12-26 39 22 30.5 -5.0 34 0 0.00 0.0 0 2024-12-27 44 22 33.0 -2.3 32 0 0.00 0.0 0 2024-12-28 48 38 43.0 7.9 22 0 0.71 0.0 0 2024-12-29 65 46 55.5 20.6 9 0 0.19 0.0 0 2024-12-30 59 44 51.5 16.8 13 0 0.21 0.0 0 2024-12-31 54 38 46.0 11.5 19 0 0.71 0.0 0

It has become one of our most persistent annual climate patterns. For some reason the late December temperatures have been warming faster than during early December. So even if the models early in December aren’t showing a big warm up closer to the Solstice, they always play catch up as the period gets closer.