bluewave

I think NYC has a shot at a 5° or colder reading this Friday and Saturday. Temperatures this cold over the last decade have been few and far between. There have only been 5 days getting this cold over the period. The last time was back in early February 2023. The one feature all these very cold days had in common was a strong block north of Alaska. The current block is approaching records near -5 SD which will drive a lobe of the TPV into the Northeast. NYC 5° and colder days since 2016 2-4-23…..3° 1-31-19…..2° 1-21-19….4° 1-7-18……5° 2-14-16….-1° 500 mb composite of dates Current pattern and forecast

The unusually early SSW event leading to the disruption of SPV in late November was possibly caused by an interaction between the record low Arctic Sea ice near the Barents and Kara regions and the -QBO. This event seems to have caused key features of the November 500 mb pattern to lock in for the winter. It’s also unusual for some many elements of a November pattern to become amplified and persist into the winter. The current activation of the STJ and the recent largest snowstorm since January 2022 for spots in the Northeast is probably the result of the forcing finally shifting east of the Dateline. https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2025JD044403 one model, HadGEM3-GC31-MM, has a statistically significant equatorward shift in vortex latitude, deceleration of vortex winds, and increase in sudden stratospheric warmings. Its response is found to be highly state-dependent, significant only in the easterly phase of the quasi-biennial oscillation (QBO). Though we cannot comprehensively conclude why models simulate this range of responses, our analysis does highlight areas for consideration in future work to better constrain the stratospheric response to Arctic sea-ice loss. We explore the role of ensemble size, resolution and basic state, including zonal-mean winds in the polar and midlatitude stratosphere and upper troposphere, as well as the QBO. https://alaskaclimate.substack.com/p/december-2025-arctic-climate-summary For the second December in a row, the Arctic-wide average sea ice extent was the lowest on record in all of the major sea ice analyses. In the National Snow and Ice Data Center analysis, the December 2025 average extent was 11.22 million km², which is about 15 percent lower than the late 20th century December average. The Barents Sea and Baffin Bay had the lowest December extent on record, and northeast of Svalbard the average pack ice edge was north of 81°N November 2025 and December into January 2026 500mb composites

Great to see our first 12”+ event since January 2022 at multiple locations including the official observations at Bridgeport and Islip. Bridgeport Airport 15.3 in 0700 AM 01/26 Official NWS Obs Islip Airport 13.0 in 0700 AM 01/26 Official NWS Obs

I don’t have a dedicated snowboard spot where I live for consistent measurements like the official airport OBS and COOP sites. I took 50 measurements in a nearby open baseball dirt field and hour ago away from any obstructions which averaged at 9”. The field had completely lost any snowpack from the last event. Closer to the fence line the average was 10-12” with a maximum peak of 15” right behind the long fence. In closer to the houses here my average is also 10-12”. So I can understand the variability in the official NWS OBS from urban to rural locations and between the public, CO-OP, and other readings. Prior to this weekend I measured 13” from the collection of smaller events with marginal temperatures at times.

I don’t have a dedicated snowboard spot where I live for consistent measurements like the official airport OBS and COOP sites. I took 50 measurements in a nearby open baseball dirt field and hour ago away from any obstructions which averaged at 9”. The field had completely lost any snowpack from the last event. Closer to the fence line the average was 10-12” with a maximum peak of 15” right behind the long fence. In closer to the houses here my average is also 10-12”. So I can understand the variability in the official NWS OBS from urban to rural locations and between the public, CO-OP, and other readings. Prior to this weekend I measured 13” from the collection of smaller events with marginal temperatures at times.

The record for NYC at or below 32° is 16 days and below 32° the same at 16 days in 1961. Number of Consecutive Days Max Temperature <= 32 for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. 1 16 1961-01-19 through 1961-02-03 2 15 1881-01-23 through 1881-02-06 3 14 2017-12-26 through 2018-01-08 4 13 2000-12-22 through 2001-01-03 - 13 1893-01-10 through 1893-01-22 5 12 2003-01-14 through 2003-01-25 - 12 1978-01-27 through 1978-02-07 - 12 1958-02-08 through 1958-02-19 - 12 1936-01-23 through 1936-02-03 6 11 1981-01-08 through 1981-01-18 - 11 1979-02-09 through 1979-02-19 - 11 1935-12-21 through 1935-12-31 - 11 1892-12-21 through 1892-12-31 7 10 1958-12-07 through 1958-12-16 - 10 1948-01-23 through 1948-02-01 - 10 1918-01-27 through 1918-02-05 - 10 1895-02-02 through 1895-02-11 - 10 1886-01-07 through 1886-01-16 - 10 1873-01-24 through 1873-02-02 8 9 2005-01-16 through 2005-01-24 - 9 2004-01-23 through 2004-01-31 - 9 1996-01-03 through 1996-01-11 - 9 1989-12-17 through 1989-12-25 - 9 1977-01-11 through 1977-01-19 - 9 1968-01-05 through 1968-01-13 - 9 1945-12-16 through 1945-12-24 - 9 1934-02-02 through 1934-02-10 - 9 1899-02-06 through 1899-02-14 - 9 1876-12-17 through 1876-12-25 9 8 1984-01-15 through 1984-01-22 - 8 1982-01-08 through 1982-01-15 - 8 1930-01-19 through 1930-01-26 - 8 1917-12-29 through 1918-01-05 - 8 1912-01-25 through 1912-02-01 - 8 1905-01-29 through 1905-02-05 - 8 1899-12-28 through 1900-01-04 - 8 1897-01-24 through 1897-01-31 - 8 1885-02-17 through 1885-02-24 - 8 1880-11-21 through 1880-11-28 - 8 1875-01-14 through 1875-01-21 10 7 2014-02-06 through 2014-02-12 - 7 2000-01-17 through 2000-01-23 - 7 1988-01-05 through 1988-01-11 - 7 1963-12-15 through 1963-12-21 - 7 1962-12-10 through 1962-12-16 - 7 1920-01-14 through 1920-01-20 - 7 1919-12-15 through 1919-12-21 - 7 1914-02-15 through 1914-02-21 - 7 1912-02-29 through 1912-03-06 - 7 1912-02-08 through 1912-02-14 - 7 1898-01-28 through 1898-02-03 - 7 1896-01-04 through 1896-01-10 - 7 1888-01-18 through 1888-01-24 - 7 1886-02-01 through 1886-02-07 - 7 1885-03-17 through 1885-03-23 - 7 1870-12-22 through 1870-12-28 Number of Consecutive Days Max Temperature < 32 for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. 1 16 1961-01-19 through 1961-02-03 2 15 1881-01-23 through 1881-02-06 3 14 2017-12-26 through 2018-01-08 4 13 1893-01-10 through 1893-01-22 5 12 1978-01-27 through 1978-02-07 - 12 1936-01-23 through 1936-02-03 6 11 1979-02-09 through 1979-02-19 - 11 1958-02-09 through 1958-02-19 - 11 1935-12-21 through 1935-12-31 7 10 1958-12-07 through 1958-12-16 - 10 1895-02-02 through 1895-02-11 - 10 1892-12-21 through 1892-12-30 - 10 1886-01-07 through 1886-01-16 8 9 2005-01-16 through 2005-01-24 - 9 2004-01-23 through 2004-01-31 - 9 1996-01-03 through 1996-01-11 - 9 1977-01-11 through 1977-01-19 - 9 1968-01-05 through 1968-01-13 - 9 1945-12-16 through 1945-12-24 - 9 1899-02-06 through 1899-02-14 9 8 1982-01-08 through 1982-01-15 - 8 1917-12-29 through 1918-01-05 - 8 1905-01-29 through 1905-02-05 - 8 1897-01-24 through 1897-01-31 - 8 1885-02-17 through 1885-02-24 - 8 1875-01-14 through 1875-01-21 10 7 2000-01-17 through 2000-01-23 - 7 1963-12-15 through 1963-12-21 - 7 1920-01-14 through 1920-01-20 - 7 1919-12-15 through 1919-12-21 - 7 1918-01-30 through 1918-02-05 - 7 1912-02-08 through 1912-02-14 - 7 1899-12-28 through 1900-01-03 - 7 1888-01-18 through 1888-01-24 - 7 1886-02-01 through 1886-02-07 - 7 1885-03-17 through 1885-03-23 - 7 1876-12-19 through 1876-12-25 - 7 1873-01-24 through 1873-01-30

The initial event back in late November was possibly caused by an interaction between the record low Arctic Sea ice and the -QBO. https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2025JD044403 one model, HadGEM3-GC31-MM, has a statistically significant equatorward shift in vortex latitude, deceleration of vortex winds, and increase in sudden stratospheric warmings. Its response is found to be highly state-dependent, significant only in the easterly phase of the quasi-biennial oscillation (QBO). Though we cannot comprehensively conclude why models simulate this range of responses, our analysis does highlight areas for consideration in future work to better constrain the stratospheric response to Arctic sea-ice loss. We explore the role of ensemble size, resolution and basic state, including zonal-mean winds in the polar and midlatitude stratosphere and upper troposphere, as well as the QBO.

The one of the earliest stratospheric polar vortex disruptions back in late November has been a big player this winter.

This has been one of the rare instances of significant aspects of the winter 500 mb pattern becoming established in November and carrying over into the winter.

Following the snowstorm this weekend I would like to see the ridge axis out West back off a little to allow coastal development closer in instead of further offshore like the EPS and EPS-AIFS into next weekend. Many times we get a snow event at the start of a pattern and at the end. So it looks like the snow potential will continue into at least early or perhaps mid-February with the exact storm dates to be determined later. I am happy that the long advertised more active STJ pattern came to pass as there is only so much snow we can get exclusively from Northern Stream disturbances here.

The 540 line is only a rough approximation when the AI doesn’t show the P-Types chart. Right now I would probably use the NAM as the floor for NYC and Long Island with at least 6-8” before any mixing later Sunday. The RGEM and other guidance at 10-12” would probably be the ceiling. I used the kuchera to account for the higher ratios at the start gradually falling back closer to 10:1 later Sunday.

Good signal from the 6z Euro for at least a 6-8” floor around NYC and LI before any sleet potential later Sunday using conservative 10-1 ratios which could be on the low side.

They don’t have the precipitation type and rate for the ECMWF-AIFS like they do for the other models on Pivitol.

Yeah, they don’t have p-types for that model. So we just have to estimate the p-types from the thickness values and compare to the Euro which has p-types. My guess is that we are going to get a very heavy front end thump on Sunday with at least 6-8” potential before any mixing. This has been the case with past SWFEs. We just have to watch the Southeast ridge next few days in the forecasts to refine the amounts.

It’s interesting how our coldest low temperatures during the 2010s and 2020s were during our warmest winters. The early February 2023 cold was in a sea of warm. Same story with the only below 0° in NYC since 1994 during the 2015-2016 winter. It’s funny that the back to back cold winters of 2013-2014 and 2014-2015 couldn’t produce a below 0° reading in NYC. Time Series Summary for NY CITY CENTRAL PARK, NY - Dec through Feb lowest temperatures Click column heading to sort ascending, click again to sort descending. 2025-2026 16 38 2024-2025 10 0 2023-2024 17 0 2022-2023 3 0 2021-2022 10 0 2020-2021 14 0 2019-2020 14 0 2018-2019 2 0 2017-2018 5 0 2016-2017 14 0 2015-2016 -1 0 2014-2015 2 0 2013-2014 4 0 Monthly Data for February 2023 for Upton NY NWS CWA Click column heading to sort ascending, click again to sort descending. NY CARMEL 4N COOP -10 CT OXFORD WATERBURY WBAN -9 CT DANBURY COOP -7 CT GROTON COOP -6 CT MERIDEN MARKHAM MUNICIPAL AP WBAN -6 CT DANBURY MUNICIPAL AP WBAN -5 CT NORWICH PUBLIC UTILITY PLANT COOP -5 CT GUILFORD COOP -5 NY SHRUB OAK COOP -4 CT IGOR I SIKORSKY MEMORIAL AIRPORT WBAN -4 NY MATTITUCK COOP -4 CT GROTON NEW LONDON AP WBAN -4 NY PORT JERVIS COOP -4 NJ CHARLOTTEBURG RESERVOIR COOP -3 NY MONTGOMERY ORANGE COUNTY AP WBAN -3 CT NEW HAVEN TWEED AP WBAN -3 NY WEST POINT COOP -2 NY ORIENT POINT STATE PARK COOP -2 NY RIVERHEAD RESEARCH FARM COOP -1 NY WESTHAMPTON GABRESKI AP WBAN 0 NY BAITING HOLLOW COOP 0 NY UPTON COOP - NWSFO NEW YORK COOP 0 NY MONTAUK AIRPORT WBAN 0 NY WESTCHESTER CO AP WBAN 1 NY SHIRLEY BROOKHAVEN AIRPORT WBAN 1 NY SYOSSET COOP 2 NJ TETERBORO AIRPORT WBAN 2 NY CENTERPORT COOP 3 NY ISLIP-LI MACARTHUR AP WBAN 3 NY NY CITY CENTRAL PARK WBAN 3 Monthly Data for February 2016 for Upton NY NWS CWA Click column heading to sort ascending, click again to sort descending. NY CARMEL 4N COOP -13 CT MIDDLETOWN 4 W COOP -12 CT SAUGATUCK RESERVOIR COOP -10 CT DANBURY MUNICIPAL AP WBAN -10 CT DANBURY COOP -10 CT ANSONIA 1 NW COOP -9 CT MOUNT CARMEL COOP -9 NY WESTHAMPTON GABRESKI AP WBAN -9 NY PORT JERVIS COOP -9 NJ CHARLOTTEBURG RESERVOIR COOP -8 NY SHRUB OAK COOP -8 CT MERIDEN MARKHAM MUNICIPAL AP WBAN -8 CT GROTON NEW LONDON AP WBAN -8 CT GROTON COOP -8 NY YORKTOWN HEIGHTS 1W COOP -8 NY WEST POINT COOP -7 CT NORWICH PUBLIC UTILITY PLANT COOP -7 CT TRUMBULL COOP -7 CT NEW HAVEN TWEED AP WBAN -6 CT IGOR I SIKORSKY MEMORIAL AIRPORT WBAN -6 NY MONTGOMERY ORANGE COUNTY AP WBAN -5 NY MATTITUCK COOP -5 NY UPTON COOP - NWSFO NEW YORK COOP -5 CT STAMFORD 5 N COOP -5 NY BAITING HOLLOW COOP -4 NY SETAUKET STRONG COOP -3 NY RIVERHEAD RESEARCH FARM COOP -3 NY MOUNT SINAI COOP -3 CT PUTNAM LAKE COOP -3 NY WESTCHESTER CO AP WBAN -3 NY SHIRLEY BROOKHAVEN AIRPORT WBAN -2 NJ CALDWELL ESSEX COUNTY AP WBAN -2 NY MONTAUK AIRPORT WBAN -2 NY CENTERPORT COOP -2 NJ TETERBORO AIRPORT COOP -1 NY WEST NYACK COOP -1 NY NY CITY CENTRAL PARK WBAN -1 NJ TETERBORO AIRPORT WBAN -1 NY ISLIP-LI MACARTHUR AP WBAN 0 NJ CRANFORD COOP 0 NJ NEWARK LIBERTY INTL AP WBAN 0 NJ CANOE BROOK COOP 0 NJ HARRISON COOP 0