bluewave

After midnight highs today. This happens quite a bit with Arctic fronts. Some of the great Arctic outbreaks from 77 to 94 would have had lower daily maxes if the front was just a little faster. SXUS51 KOKX 080557 OSOOKX New York City Metropolitan Area Weather Roundup National Weather Service New York NY 100 AM EST MON DEC 08 2025 CITY SKY/WX TMP DP RH WIND PRES REMARKS Central Park PTCLDY 38 24 57 VRB7 30.05R WCI 33 LaGuardia Arpt PTCLDY 40 21 46 W16G23 30.03R WCI 31 Kennedy Intl PTCLDY 37 27 67 W9 30.05R WCI 30 Newark Liberty PTCLDY 37 25 61 W8 30.04S WCI 31 Teterboro Arpt PTCLDY 36 25 64 W7 30.03S WCI 30 Bronx Lehman C N/A 37 27 65 W6 N/A WCI 33 Queens College N/A 39 27 60 W9 N/A WCI 33 Breezy Point N/A 37 N/A N/A W12 N/A WCI 30 Brooklyn Coll N/A 39 28 65 W10 N/A WCI 32 Staten Island N/A 36 28 75 W6 N/A WCI 31

This has been due to the inability of the models to resolve the split forcing pattern which has been in place this month so far. So the first 16 days of the month will verify significantly colder than the long range forecasts were indicating back in late November. La Nina’s often had colder patterns in December so this isn’t that much of a surprise. The interference pattern has created a cold MJO 6 type and not the canonical MJO 8 pattern and storm track. This is due to the forcing near the MJO 4-6 regions with the standing wave. So now that the models have a consolidation of forcing there as the forcing weakens over the Western Hemisphere, they are showing the seasonal moderation in temperatures we often see beginning in mid-December. The last few days have been the first time in a while that they are actually raising heights more than in earlier runs. So the ridge coming east faster is a function of the big Jet extension and MJO 4-6 forcing. Remember last early December how the models underestimated the mid to late December Jet extension and lower Pacific heights. New run faster Pacific Jet lowering heights more over Western North America and raising heights in the East

These charts below do a good job showing the current burst of stronger forcing in the MJO 4-6 areas. I suspect it’s one of the reasons we aren’t getting the canonical MJO 8 even with the RMMS in that space. This is why I like to look at the total forcing when they are out of alignment with the RMMS. Notice that the Pacific Jet hasn’t relaxed and we have a dominant northern stream. So even though we are experiencing a colder pattern since late November, the warmer storm track of the last 7 years hasn’t varied. This was the case during some of the colder intervals last winter also. Models are beginning to come into better agreement for the relaxation of the cold as the falling AAM and MJO 4-6 forcing supports a broad ridge across the U.S. mid to late month. This is a seasonal shift that we have seen frequently approaching mid to late December over the last decade. We had a big jet extension last December at this time also when the temperatures moderated.

The current standing wave in MJO 4-6 will consolidate the forcing there leading to a jet extension in around 10 days and the ridge getting pushed east with the falling AAM.

The runoff is leading to higher salt content in the drinking water supply for areas around NYC and NJ. https://apnews.com/article/new-york-city-reservoirs-salt-c5d67e6c626878d0993974498c4629b6 The suburban reservoirs that supply 10% of New York City’s vaunted drinking water are getting saltier due to decades of road salt being spread near the system — and they will eventually have to be abandoned if nothing is done to reverse the trend, city officials warn. https://patch.com/new-jersey/bridgewater/salty-taste-nj-drinking-water-linked-use-salt-brine-roads NEW JERSEY — Have you noticed a salty taste in your water recently? New Jersey American Water said it is due to the use of salt and brine for public safety during the recent extreme winter weather and ongoing drought conditions. The water company shared a notice with customers about the change in taste on Friday.

Has been a common theme in recent years with the heavy road salting especially behind the 18-wheelers.

Some reservoirs in NNJ dipping under 50% with the below normal rainfall since the fall of 2024. https://dep.nj.gov/drought/current-conditions/#reservoir-levels

Yeah, the combination of the warmest SSTs on record for the month of November across sections of the WPAC are boosting the Pacific Jet due to the thermal gradient with the Asia. Plus the record SST warmth around Australia and the Maritime Continent keeping the forcing going in the MJO 4-7 regions also contribute to a faster Pacific Jet. It looks like the long range EPS retrogrades the ridge back to the Aleutians while the ridge is still in the West. Eventually, a jet extension will probably push that ridge further east at least for a time. We also have the falling AAM lag which will lower heights near Greenland later in the month. EPS Strong MJO 4-7 forcing into mid-December

That long duration event helped Newark to reach the 6th snowiest calendar year since the 1840s. Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Jan through Dec top 10 highest calendar year snowfall Click column heading to sort ascending, click again to sort descending. 1 1907 73.1 123 2 1867 72.0 0 3 1868 68.8 0 4 1978 65.8 0 5 1961 63.5 0 6 2003 63.3 0 7 1854 62.8 0 8 1916 62.7 31 9 1996 62.6 0 - 1862 62.6 0 10 1896 61.4 2

It’s the largest and deepest of the Great Lakes so it can absorb much more heat than the smaller and shallower lakes. So it’s still near record levels of warmth. Part of this is also related to Superior being closest to the record warmth this fall centered in Canada than the other lakes were. So this is an amazing set up for the near record snows that they experienced in November.

Lake Superior is still the 2nd warmest on record since 1995 for December 5th. https://apps.glerl.noaa.gov/coastwatch/webdata/statistic/pdf/all_year_glsea_avg_s.pdf

Places like Marquette are the big snowfall winner with this overpowering Pacific Jet and trough over the Great Lakes and Northeast with cold air flowing over the record warm Lakes. https://www.wpr.org/news/great-lakes-seeing-near-record-warm-waters-this-fall The Great Lakes are seeing near-record warm water temperatures right now, which means there’s a higher chance for lake effect snow when the weather turns cold.As of Thursday, all five of the lakes were around 4 to 5.5 degrees Fahrenheit warmer than their long-term average for the last three decades. That’s according to data from the Great Lakes Environmental Research Lab operated by the National Oceanic and Atmospheric Administration, or NOAA.

This was the 6th coldest December 5th low in NYC and 7th coldest max. Data for December 5 - NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. 1926-12-05 24 11 1.03 7.9 8 1886-12-05 22 13 0.37 5.3 M 1871-12-05 29 14 0.00 0.0 M 1935-12-05 37 15 0.00 0.0 0 1911-12-05 38 19 0.00 0.0 M 1901-12-05 27 19 0.00 0.0 M 2025-12-05 32 20 0.00 0.0 Data for December 5 - NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. 1886-12-05 22 13 0.37 5.3 M 1926-12-05 24 11 1.03 7.9 8 1901-12-05 27 19 0.00 0.0 M 1893-12-05 28 20 0.16 1.5 M 1871-12-05 29 14 0.00 0.0 M 1895-12-05 30 25 0.00 T M 2002-12-05 31 26 0.35 6.0 M 2025-12-05 32 20 0.00 0.0 0 1989-12-05 32 23 T T 0

That was some of my highest snow drifting in Long Beach since February 78.

If we had slightly weaker blocking in 09-10, then NYC could have challenged 95-96. During 10-11 we had over 60” at Newark from 12-26 to 1-27. But the pattern quickly reversed on February putting 95-96 out of reach. I am really grateful that I got to experience 10-11 as my last full winter living in Long Beach.

NYC and LGA continue their record under 4” daily streak while BOS moves into 2nd place for longest daily streak under 6”. Philly is getting closer to their longest daily under 5” streak. DC is currently at their 3rd longest run with no daily 12” amounts. State College is only a few weeks away from their new longest daily under 6” streak. Number of Consecutive Days Snowfall < 4 for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. 1 1405 0 2025-12-04 2 1394 0 1932-12-16 3 1063 0 1952-01-27 4 1051 0 1963-12-22 5 794 0 1956-03-15 Number of Consecutive Days Snowfall < 4 for LAGUARDIA AIRPORT, NY Click column heading to sort ascending, click again to sort descending. 1 1405 1 2025-12-04 2 1051 0 1963-12-22 3 761 0 2020-12-15 4 746 0 1952-02-29 5 744 0 1981-03-04 Number of Consecutive Days Snowfall < 6 for Boston Area, MA (ThreadEx) Click column heading to sort ascending, click again to sort descending. 1 1772 0 1992-12-11 2 1378 0 2025-12-04 3 1373 0 1981-12-05 4 1369 0 1987-12-28 5 1054 0 1909-12-25 Number of Consecutive Days Snowfall < 5 for Philadelphia Area, PA (ThreadEx) Click column heading to sort ascending, click again to sort descending. 1 1440 0 1987-01-21 2 1438 0 2000-01-24 3 1433 0 1896-12-15 4 1423 0 1970-12-31 5 1409 0 1945-01-15 6 1405 0 2025-12-04 Number of Consecutive Days Snowfall < 12 for Washington Area, DC (ThreadEx) Click column heading to sort ascending, click again to sort descending. 1 8383 0 1922-01-27 2 8043 0 1958-02-14 3 5829 0 2025-12-04 4 5122 0 1936-02-06 5 4768 0 1979-02-18 Number of Consecutive Days Snowfall < 6 for STATE COLLEGE, PA Click column heading to sort ascending, click again to sort descending. 1 1434 0 1990-12-27 2 1418 1 2025-12-05 3 997 0 2009-12-08 4 835 4 1932-03-27 5 816 4 1956-02-01

Some degree of moderation in the East after the 16th fits December climatology since 1991. But exactly how much of a relaxation remains to be seen. A 10 to 15 day lag following the current AAM reversal would indicate some degree of moderation by near or after the 20th.

It’s interesting that the rapid warming of the North Pacific could be contributing to the 2012 minimum not being surpassed due to a weakening of the AD since then. Article Open access Published: 18 November 2025 Decelerated Arctic Sea ice loss triggered by accelerated North Pacific warming over the past decade https://www.nature.com/articles/s43247-025-02882-1 This study offers fresh insights into the mechanisms behind the decelerating decline of Arctic sea ice from 2007 to 2024. We demonstrate that an SST trend in the North Pacific excites a Rossby wavetrain that propagates into the Arctic, driving a downward trend in the summertime Arctic Dipole (AD) index (−0.1 year⁻¹, p < 0.02). This shift induces anomalous surface wind patterns and colder air temperatures, fostering sea ice increases in the central Arctic Ocean near 180 °W (region 1) and the Canadian Arctic Archipelago (region 2), with trends of 0.4% year−¹ and 1.1% year−¹, respectively. These regional gains offset losses elsewhere, contributing to the observed slowdown in overall Arctic sea ice decline. Previous studies have documented the upward trend in September Arctic sea ice extent since 200734,35,36, yet its underlying cause remains unresolved. Our findings complement prior research on sea ice outflow11 and ocean heat transport13, while not diminishing their importance. For instance, southerly wind anomalies linked to increased sea ice in regions 1 and 2 (Fig. 2c, d) may reduce outflow through the Fram Strait, while northerly winds near the North Pole transport ice into region 1, enhancing its growth. Contrary to reports of an increasing AD index over the 2007–2024 period relative to the 1992–2006 period13, we attribute the deceleration to a declining summertime AD index, driven by North Pacific SST warming, which agrees with previous studies37,38. This warming, potentially tied to rising greenhouse gas emissions, merits further investigation to pinpoint its origins.

Colder start to December fits within the long term trend since 1991. NYC average temperatures have only risen +0.7° in NYC from December 1st to 16th. But the December 17th to 31st average temperatures over the same period have increased by +4.6°. This matches the streak of 55°+ days every year since 2011 around NYC from the 17th to 25th. So my guess is that the warmest departures we see this month will occur after the 16th. Time Series Summary for NY CITY CENTRAL PARK, NY highest temperature December 17th through 25th since 2011 Click column heading to sort ascending, click again to sort descending. 2024-12-25 59 0 2023-12-25 62 0 2022-12-25 58 0 2021-12-25 60 0 2020-12-25 61 0 2019-12-25 57 0 2018-12-25 61 0 2017-12-25 55 0 2016-12-25 58 0 2015-12-25 72 0 2014-12-25 62 0 2013-12-25 71 0 2012-12-25 56 0 2011-12-25 62 0

Yeah, the number of 1” snowcover days at ISP the last 7 seasons has been roughly half that of the colder and snowier 70s and 80s at 11 days vs 21 days. Monthly Number of Days Snow Depth >= 1 for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Mean 0 0 2 3 6 0 0 11 2024-2025 0 0 1 7 5 0 0 13 2023-2024 0 0 0 5 6 0 0 11 2022-2023 0 0 0 0 1 1 0 2 2021-2022 0 0 0 6 9 0 0 15 2020-2021 0 0 7 0 23 0 0 30 2019-2020 0 0 3 0 0 0 0 3 2018-2019 0 0 0 1 1 2 0 4 Monthly Number of Days Snow Depth >= 1 for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Mean 0 0 2 10 6 2 0 21 1988-1989 0 0 7 2 3 3 0 15 1987-1988 0 1 3 15 0 2 0 21 1986-1987 0 0 1 12 10 1 0 24 1985-1986 0 0 3 4 13 0 0 20 1984-1985 0 0 1 13 10 0 0 24 1983-1984 0 0 1 15 0 6 0 22 1982-1983 0 0 4 3 8 0 1 16 1981-1982 0 0 0 19 0 0 4 23 1980-1981 0 0 1 22 0 2 0 25 1979-1980 0 0 1 3 1 1 0 6 1978-1979 0 0 0 3 14 0 0 17 1977-1978 0 0 0 13 22 18 0 53 1976-1977 0 0 6 23 7 0 0 36 1975-1976 0 0 5 8 7 2 0 22 1974-1975 0 0 0 1 5 1 0 7 1973-1974 0 0 0 14 10 1 0 25 1972-1973 0 0 0 0 2 0 0 2 1971-1972 0 0 0 3 8 1 0 12 1970-1971 0 0 5 11 1 0 1 18 1969-1970 0 0 7 19 6 2 0 34

Earliest 20° reading in NYC since the 2007-2008 La Niña. But the snowfall outcome was lower this time around. We finally got some cold into Eastern Canada which has been lacking in recent years. Dec 5, 6:51 am 21 2 43 11 ENE 9 10.00 CLR 1027.20 30.18 30.35 24 20 Climatological Data for NY CITY CENTRAL PARK, NY - December 2007 Click column heading to sort ascending, click again to sort descending. 2007-12-01 38 25 31.5 -11.7 33 0 0.00 0.0 0 2007-12-02 36 20 28.0 -14.9 37 0 0.33 1.4 0 2007-12-03 47 32 39.5 -3.1 25 0 0.31 T 0 2007-12-04 34 28 31.0 -11.3 34 0 0.00 0.0 0 2007-12-05 33 28 30.5 -11.5 34 0 0.02 0.3 0 2007-12-06 33 21 27.0 -14.7 38 0 0.00 0.0 T 2007-12-07 35 28 31.5 -9.9 33 0 T T 0

This source shows the strongest tendency decline in months. Makes sense since we are seeing a big reversal from all the +PNA warmth last December which was a mismatch to the La Niña background state. The more robust La Niña background states can feature strong gradient patterns in December with a cold Canada and Northern Tier. Especially when the pattern matches up so closely with the December MJO 6 composite. The forcing in the MJO 6 region is driving the U.S. Western ridge and colder Eastern trough pattern which will dominate December 1st through the 16th. The stronger blocking near Greenland is a result of the other area of the forcing in the Western Hemisphere and the recent +AAM spike in late November. So a bit of a hybrid composite with the split forcing. Split forcing pattern

Strengthening La Niña background state with the falling AAM heading into mid-December leading to the very amplified Aleutian Ridge and -PNA trough in Western Canada.

During the 1970s and 1980s NYC averaged around 6.2”more of snow than we have over the last 7 seasons and ISP 8.0” more. We didn’t have to rely exclusively on KU NESIS events back then like we do now to get over 20” of snow on the season. We used to get snowy clippers and SWFEs. Plus the colder climate allowed for heavier snows on the front end before mixing became an issue. We never experienced a climate before that was so challenging to get over 20” from EWR to NYC and ISP. Monthly Total Snowfall for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Mean 0.0 0.9 2.3 3.7 6.4 1.6 T 14.9 2024-2025 0.0 0.0 2.8 3.0 7.1 0.0 0.0 12.9 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 2018-2019 0.0 6.4 T 1.1 2.6 10.4 0.0 20.5 Monthly Total Snowfall for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Mean T 0.2 2.2 7.9 7.6 2.7 0.6 21.1 1988-1989 0.0 0.0 0.3 5.0 0.3 2.5 0.0 8.1 1987-1988 0.0 1.1 2.6 13.9 1.5 T 0.0 19.1 1986-1987 0.0 T 0.6 13.6 7.0 1.9 0.0 23.1 1985-1986 0.0 T 0.9 2.2 9.9 T T 13.0 1984-1985 0.0 T 5.5 8.4 10.0 0.2 T 24.1 1983-1984 0.0 T 1.6 11.7 0.2 11.9 0.0 25.4 1982-1983 0.0 0.0 3.0 1.9 21.5 T 0.8 27.2 1981-1982 0.0 0.0 2.1 11.8 0.4 0.7 9.6 24.6 1980-1981 0.0 T 2.8 8.0 T 8.6 0.0 19.4 1979-1980 T 0.0 3.5 2.0 2.7 4.6 T 12.8 1978-1979 0.0 2.2 0.5 6.6 20.1 T T 29.4 1977-1978 0.0 0.2 0.4 20.3 23.0 6.8 T 50.7 1976-1977 0.0 T 5.1 13.0 5.8 0.6 T 24.5 1975-1976 0.0 T 2.3 5.6 5.0 4.4 T 17.3 1974-1975 0.0 0.1 0.1 2.0 10.6 0.3 T 13.1 1973-1974 0.0 0.0 2.8 7.8 9.4 3.2 0.3 23.5 1972-1973 T T T 1.8 0.8 0.2 T 2.8 1971-1972 0.0 T T 2.8 17.8 2.3 T 22.9 1970-1971 0.0 0.0 2.4 11.4 T 1.3 0.4 15.5 1969-1970 0.0 T 6.8 8.4 6.4 4.0 T 25.6 Monthly Total Snowfall for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Mean T 0.6 2.1 6.0 7.1 1.0 T 16.8 2024-2025 0.0 0.0 2.1 2.7 6.9 0.0 0.0 11.7 2023-2024 0.0 T T 3.1 7.8 0.0 0.0 10.9 2022-2023 0.0 0.0 0.4 T 3.0 1.6 0.0 5.0 2021-2022 0.0 T 0.3 31.8 3.3 1.6 0.0 37.0 2020-2021 T 0.0 7.5 1.1 24.9 T T 33.5 2019-2020 0.0 0.1 4.2 2.5 0.0 T T 6.8 2018-2019 0.0 4.3 T 0.9 3.5 4.1 T 12.8 Monthly Total Snowfall for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Mean T 0.3 3.3 8.8 8.5 3.0 1.0 24.8 1988-1989 0.0 0.0 10.4 4.4 1.2 3.0 T 19.0 1987-1988 0.0 1.1 4.2 10.7 0.1 3.4 0.0 19.5 1986-1987 0.0 T 3.4 8.8 8.6 1.7 0.0 22.5 1985-1986 0.0 T 2.1 2.6 10.4 0.1 T 15.2 1984-1985 0.0 T 4.7 13.5 8.7 T T 26.9 1983-1984 0.0 T 2.6 11.9 T 13.0 0.0 27.5 1982-1983 0.0 0.0 3.2 1.5 26.1 T 1.1 31.9 1981-1982 0.0 0.0 1.0 18.1 0.3 T 16.0 35.4 1980-1981 0.0 T 0.5 13.2 T 7.1 0.0 20.8 1979-1980 T 0.0 1.5 4.0 1.5 2.0 0.0 9.0 1978-1979 0.0 4.0 T 6.9 17.2 T T 28.1 1977-1978 0.0 0.8 0.2 27.7 28.9 10.4 T 68.0 1976-1977 0.0 T 6.2 11.2 6.6 4.0 0.0 28.0 1975-1976 0.0 T 11.0 7.8 7.5 3.9 0.0 30.2 1974-1975 0.0 0.5 T 1.8 11.0 1.2 T 14.5 1973-1974 0.0 0.0 T 9.0 17.0 8.0 T 34.0 1972-1973 T 0.0 T 1.5 3.0 T T 4.5 1971-1972 0.0 T T 2.1 12.5 1.0 T 15.6 1970-1971 0.0 0.0 2.1 11.3 2.0 1.0 2.5 18.9 1969-1970 0.0 T 12.0 7.0 7.0 1.0 T 27.0

The fast Pacific flow and lack of blocking didn’t allow the cold high to stay anchored over New England. The WAR flexed just enough so the thermal gradient got pushed north of NYC. So these features negated the usual colder influence we see with lows tracking south of Long Island. Plus the low was strung out on a N-S axis without enough deepening near the benchmark to allow the cold air to wrap in behind the storm.