bluewave

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.

Models backing off a bit in the cold that was forecast for this week. This often happens when we are getting closer to a moderation of a colder pattern. So the La Niña seasonal progression is right on track. New run Old run

It could be. The strong winds this month through the Great Lakes have kept the minimum at JFK a little warmer than December was. It will be interesting to see if this is the first winter since 2000 that the coldest low of winter happened in December. Monthly Lowest Min Temperature for JFK INTERNATIONAL AIRPORT, NY Click column heading to sort ascending, click again to sort descending. 2024-2025 12 13 M 12 2023-2024 25 18 21 18 2022-2023 7 29 4 4 2021-2022 24 9 15 9 2020-2021 18 15 17 15 2019-2020 17 19 14 14 2018-2019 24 3 11 3 2017-2018 9 4 16 4 2016-2017 19 13 19 13 2015-2016 34 12 1 1 2014-2015 26 8 3 3 2013-2014 20 3 11 3 2012-2013 28 12 17 12 2011-2012 21 13 21 13 2010-2011 19 6 16 6 2009-2010 16 14 16 14 2008-2009 14 7 12 7 2007-2008 20 14 11 11 2006-2007 19 9 9 9 2005-2006 15 14 15 14 2004-2005 12 6 16 6 2003-2004 21 1 14 1 2002-2003 18 7 9 7 2001-2002 21 22 19 19 2000-2001 14 15 16 14

New study finds that cloud feedbacks amplify the warming more than previously thought. https://cpo.noaa.gov/scientists-find-cloud-feedbacks-amplify-warming-more-than-previously-thought/ Scientists find cloud feedbacks amplify warming more than previously thought Clouds play an important role in how much the Earth warms when greenhouse gases like carbon dioxide increase. However, scientists have struggled to determine whether low-level clouds in the tropics slow down or speed up global warming, creating uncertainty in climate predictions. A new study published in Nature and funded by the Climate Program Office’s Modeling, Analysis, Predictions, and Projections (MAPP) program adds to the growing evidence that cloud feedback is very likely to amplify warming in the climate system, rather than reduce it. The study found that the impact of clouds in the tropical Pacific and Atlantic Oceans, two areas where low clouds are especially important, is much stronger than scientists previously thought — 71% higher. It also ruled out the possibility that tropical low clouds could have a cooling effect to offset warming. These findings narrow the uncertainty around one of the biggest unknowns in climate science and enable more accurate predictions of how much warming we might expect. This work was possible thanks to new techniques that balanced conflicting data from different regions, giving clearer answers. The results show that Earth’s climate is likely more sensitive to rising carbon dioxide levels than many models have suggested. A stronger positive cloud feedback means faster and higher levels of warming. It also highlights the need to improve how climate models represent clouds, especially in tropical areas, to prepare better for the challenges of a changing climate. The investigators will extend the value of this study by developing and delivering a piece of software to NOAA that will diagnose issues with low cloud feedback in new versions of NOAA’s modeling systems. This will lead to improvements in NOAA models’ ability to capture appropriate levels of cloud feedback, and improvements in processes that lead to weather and climate prediction skill. In the early 2000s, climate scientists could not say with confidence whether clouds would mitigate or amplify climate change. Some hypothesized that clouds might work to oppose a significant portion of human-caused warming by reflecting more incoming solar energy back out to space, while others hypothesized that particular changes in clouds might magnify warming by trapping more energy in the atmosphere. In 2001, NOAA’s Geophysical Fluid Dynamics climate model was one of only three that simulated the type of significant positive cloud feedback we now know is likely happening. The MAPP and Climate Variability & Predictability (CVP) programs are advancing cloud representation in climate models through ongoing funded projects. By studying tropical cloud processes and precipitation and improving how they are represented across scales, these efforts are strengthening predictions and providing a clearer picture of our climate future. Read the study »

Yeah, 1978-1979 was the coldest winter since 1895 across the CONUS. Contiguous U.S. Average Temperature December-February December 1978-February 1979 26.62°F 1 -5.61°F December 1935-February 1936 27.78°F 2 -4.45°F December 1898-February 1899 27.95°F 3 -4.28°F December 1909-February 1910 28.17°F 4 -4.06°F December 1904-February 1905 28.69°F 5 -3.54°F December 1928-February 1929 28.73°F 6 -3.50°F December 1977-February 1978 29.04°F 7 -3.19°F December 1916-February 1917 29.10°F 8 -3.13°F December 1917-February 1918 29.11°F 9 -3.12°F December 1911-February 1912 29.35°F 10 -2.88°F

Winter so far across the area from December 1st through January 23rd is averaging -1.4°. New Brunswick…..-1.9….32.8° EWR….-1.1….34.7° NYC….-2.1°…34.7° LGA…..-2.1°…35.6° JFK…..+0.1°…36.2° HPN….-1.2°….31.7° BDR….-1.7°…..33.0° ISP……-1.3°….33.7°

February 5th through 20th in 1979 was the greatest 16 day stretch of cold and snow on record at ISP. Data for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. 1979-02-05 32 15 0.0 0 1979-02-06 25 13 0.0 0 1979-02-07 22 13 6.5 0 1979-02-08 30 17 0.3 7 1979-02-09 19 8 0.0 6 1979-02-10 15 -1 0.0 5 1979-02-11 11 -2 0.0 4 1979-02-12 15 -6 0.9 2 1979-02-13 12 5 T 3 1979-02-14 13 -1 0.0 3 1979-02-15 20 9 T 2 1979-02-16 18 8 0.2 1 1979-02-17 10 -0 0.0 1 1979-02-18 14 -2 0.0 1 1979-02-19 24 10 8.8 2 1979-02-20 32 8 0.0 10

Yeah, these jet stream and 500mb patterns have been getting pretty wild lately.

While that has been the case, this is a very extreme example of it. Climatological Data for VAN BUREN 2, ME - January 2025 Click column heading to sort ascending, click again to sort descending. Sum 545 193 - - 1184 0 1.22 8.3 - Average 22.7 8.0 15.4 7.5 - - - - 5.0 Normal 19.3 -3.5 7.9 - 1371 0 2.27 19.1 2025-01-01 42 27 34.5 23.6 30 0 0.00 0.0 0 2025-01-02 39 30 34.5 23.9 30 0 0.31 0.5 0 2025-01-03 34 20 27.0 16.8 38 0 0.12 0.5 1 2025-01-04 20 11 15.5 5.6 49 0 0.09 0.8 2 2025-01-05 13 1 7.0 -2.6 58 0 T T 2 2025-01-06 9 1 5.0 -4.3 60 0 0.00 0.0 2 2025-01-07 16 9 12.5 3.5 52 0 T T 2 2025-01-08 25 15 20.0 11.2 45 0 0.05 1.7 4 2025-01-09 26 18 22.0 13.5 43 0 0.32 4.0 8 2025-01-10 33 25 29.0 20.8 36 0 0.00 0.0 8 2025-01-11 31 16 23.5 15.5 41 0 0.00 0.0 8 2025-01-12 25 18 21.5 13.8 43 0 0.00 0.0 8 2025-01-13 22 17 19.5 12.0 45 0 0.07 0.3 7 2025-01-14 21 10 15.5 8.2 49 0 0.07 0.5 7 2025-01-15 23 11 17.0 9.9 48 0 T T 8 2025-01-16 18 13 15.5 8.6 49 0 T T 7 2025-01-17 19 -2 8.5 1.8 56 0 0.00 0.0 7 2025-01-18 22 2 12.0 5.5 53 0 0.00 0.0 7 2025-01-19 37 16 26.5 20.1 38 0 0.19 0.0 6 2025-01-20 32 8 20.0 13.8 45 0 T T 5 2025-01-21 9 -20 -5.5 -11.6 70 0 0.00 0.0 5 2025-01-22 8 -21 -6.5 -12.5 71 0 0.00 0.0 5 2025-01-23 9 -21 -6.0 -11.9 71 0 0.00 0.0 5 2025-01-24 12 -11 0.5 -5.3 64 0 T T 6 2025-01-25 M M M M M M M M M 2025-01-26 M M M M M M M M M 2025-01-27 M M M M M M M M M 2025-01-28 M M M M M M M M M 2025-01-29 M M M M M M M M M 2025-01-30 M M M M M M M M M 2025-01-31 M M M M M M M M M Climatological Data for Charleston Area, WV (ThreadEx) - January 2025 Click column heading to sort ascending, click again to sort descending. Sum 760 393 - - 976 0 2.18 17.9 - Average 31.7 16.4 24.0 -10.9 - - - - 3.5 Normal 43.7 26.1 34.9 - 722 0 2.53 8.0 2025-01-01 40 32 36.0 0.2 29 0 0.06 T 0 2025-01-02 40 27 33.5 -2.1 31 0 T T 0 2025-01-03 35 26 30.5 -5.0 34 0 0.05 0.2 0 2025-01-04 31 20 25.5 -9.9 39 0 T 0.3 T 2025-01-05 28 17 22.5 -12.8 42 0 0.74 5.5 0 2025-01-06 31 24 27.5 -7.7 37 0 0.75 1.2 4 2025-01-07 25 20 22.5 -12.6 42 0 T 0.8 5 2025-01-08 25 20 22.5 -12.5 42 0 0.01 1.2 6 2025-01-09 20 12 16.0 -18.9 49 0 T T 5 2025-01-10 24 7 15.5 -19.3 49 0 0.11 2.6 4 2025-01-11 30 24 27.0 -7.8 38 0 0.12 1.9 8 2025-01-12 37 12 24.5 -10.2 40 0 0.00 0.0 8 2025-01-13 40 24 32.0 -2.7 33 0 0.00 0.0 5 2025-01-14 32 12 22.0 -12.7 43 0 T M 4 2025-01-15 26 7 16.5 -18.1 48 0 0.00 0.0 4 2025-01-16 41 12 26.5 -8.1 38 0 T T 4 2025-01-17 46 27 36.5 1.9 28 0 0.00 0.0 3 2025-01-18 43 29 36.0 1.4 29 0 0.09 0.0 2 2025-01-19 36 20 28.0 -6.6 37 0 0.23 4.1 1 2025-01-20 20 1 10.5 -24.2 54 0 0.02 T 5 2025-01-21 20 1 10.5 -24.2 54 0 T T 4 2025-01-22 24 -2 11.0 -23.7 54 0 T 0.1 4 2025-01-23 33 3 18.0 -16.8 47 0 0.00 0.0 4 2025-01-24 33 18 25.5 -9.4 39 0 T M M 2025-01-25 M M M M M M M M M 2025-01-26 M M M M M M M M M 2025-01-27 M M M M M M M M M 2025-01-28 M M M M M M M M M 2025-01-29 M M M M M M M M M 2025-01-30 M M M M M M M M M 2025-01-31 M M M M M M M M M

This is our first January with a -10 in West Virginia and a +7 in Northern Maine.

Yeah, everything lined up perfectly for a below 0°reading in NYC on 2-14-16. Record blocking north of Alaska driving the core of the cold and Arctic high pressure down at a perfect angle. Didn’t matter that it was one of the warmest winters on record or how much UHI there was. We couldn’t even get to or below 0° in NYC during the much colder winters in 13-14 or 14-15. Here at HVN some of our coldest readings have occurred in recent years on strong northerly flow events. Even though 22-23 was another top warmest winter, we still were able to go below 0° here like in 2016. So shorter Arctic outbreaks are still very possible even if we haven’t had a top 10 coldest winter month since February 2015 and top 10 coldest winter since the 1970s. Coldest temperatures at HVN since 47-48 Series Summary for NEW HAVEN TWEED AP, CT - Dec through Feb Click column heading to sort ascending, click again to sort descending. 1 1947-1948 -8 31 2 1960-1961 -7 0 3 2015-2016 -6 0 - 1956-1957 -6 0 4 1967-1968 -5 0 5 2008-2009 -4 0 - 1962-1963 -4 0 6 2022-2023 -3 0 - 2014-2015 -3 0 - 2003-2004 -3 0 - 1966-1967 -3 0 - 1948-1949 -3 0 Climatological Data for NEW HAVEN TWEED AP, CT - February 2023 Click column heading to sort ascending, click again to sort descending. Sum 1314 762 - - 774 0 0.67 Average 46.9 27.2 37.1 5.1 - - - Normal 40.2 23.9 32.0 - 923 0 2023-02-01 37 27 32.0 1.8 33 0 T 2023-02-02 40 20 30.0 -0.3 35 0 0.00 2023-02-03 39 3 21.0 -9.4 44 0 T 2023-02-04 30 -3 13.5 -17.0 51 0 0.00 2023-02-05 43 29 36.0 5.4 29 0 0.00 2023-02-06 56 27 41.5 10.8 23 0 0.00 2023-02-07 41 26 33.5 2.7 31 0 0.07 2023-02-08 53 29 41.0 10.1 24 0 0.00 2023-02-09 52 25 38.5 7.4 26 0 0.00 2023-02-10 62 35 48.5 17.3 16 0 0.00 2023-02-11 47 27 37.0 5.7 28 0 0.00 2023-02-12 47 25 36.0 4.5 29 0 0.00 2023-02-13 54 38 46.0 14.4 19 0 0.01 2023-02-14 55 32 43.5 11.7 21 0 0.00 2023-02-15 58 33 45.5 13.5 19 0 0.00 2023-02-16 68 47 57.5 25.4 7 0 0.03 2023-02-17 56 31 43.5 11.2 21 0 0.21 2023-02-18 42 27 34.5 2.0 30 0 0.00 2023-02-19 48 31 39.5 6.8 25 0 0.00 2023-02-20 58 41 49.5 16.6 15 0 0.00 2023-02-21 48 36 42.0 8.9 23 0 T 2023-02-22 44 27 35.5 2.3 29 0 0.05 2023-02-23 41 36 38.5 5.1 26 0 0.05 2023-02-24 44 24 34.0 0.4 31 0 0.02 2023-02-25 30 19 24.5 -9.3 40 0 0.03 2023-02-26 42 17 29.5 -4.6 35 0 0.00 2023-02-27 42 22 32.0 -2.3 33 0 0.06 2023-02-28 37 31 34.0 -0.5 31 0 0.14

Brooklyn got down to -4° on 1-21-85 when Newark was -8°. So really not sure why Central Park couldn’t go below -2° as even LGA was -3°. I was out on the Long Beach Boardwalk that morning viewing the greatest display of Arctic seasmoke and steamnadoes that I saw there. It was my only time there experiencing temps on the Long Beach Boardwalk in the 0° to -1° range combined with 40-50mph gusts. Data for January 21, 1985 through January 21, 1985 Click column heading to sort ascending, click again to sort descending. NJ ESSEX FELLS SERVICE BLDG COOP -14 NJ CHARLOTTEBURG RESERVOIR COOP -12 NJ WANAQUE RAYMOND DAM COOP -12 NY MIDDLETOWN 2 NW COOP -10 NJ CRANFORD COOP -10 NY PORT JERVIS COOP -9 NJ NEWARK LIBERTY INTL AP WBAN -8 NJ LITTLE FALLS COOP -8 NY YORKTOWN HEIGHTS 1W COOP -8 NY WEST POINT COOP -7 NJ CANOE BROOK COOP -7 CT DANBURY COOP -7 NY GARNERVILLE COOP -6 NJ PLAINFIELD COOP -6 NJ TETERBORO AIRPORT WBAN -6 NY WALDEN 1 ESE COOP -6 NY DOBBS FERRY-ARDSLEY COOP -5 NY NY WESTERLEIGH STAT IS COOP -5 NY SCARSDALE COOP -5 CT NORWICH PUBLIC UTILITY PLANT COOP -5 NY NEW YORK AVE V BROOKLYN COOP -4 CT STAMFORD 5 N COOP -4 NY WESTCHESTER CO AP WBAN -4 NY WESTBURY COOP -4 NY LAGUARDIA AIRPORT WBAN -3 CT MOUNT CARMEL COOP -3 NY PATCHOGUE 2 N COOP -3 NY WANTAGH CEDAR CREEK COOP -3 NY NY CITY CENTRAL PARK WBAN -2 CT NORWALK GAS PLANT COOP -2 CT IGOR I SIKORSKY MEMORIAL AIRPORT WBAN -2 NY JFK INTERNATIONAL AIRPORT WBAN -2

Yeah, the only reason NYC didn’t drop below -10° with all the amazing Arctic outbreaks between December 1976 and January 1994 was the wind direction during those events. That era was known for W to NW flow Arctic outbreaks with the Arctic highs dropping to our SW. February 1934 had a record 1050 MB high north of Cleveland with a N to NNW flow. Many of those winters in the CONUS were as cold or even colder than any of the 1930s Arctic outbreaks. The other time NYC dipped below -10° was December 1917 and that was on a northerly flow down the Hudson Valley also. The only other known time since 1850 that NYC dipped below -10° was 1-10-1859 and that was probably a northerly flow Arctic outbreak also. https://www.ncei.noaa.gov/pub/orders/IPS/IPS-83B7C91F-D13A-41BD-8DA6-B04751ABCF72.pdf https://www.ncei.noaa.gov/pub/orders/IPS/IPS-B52AC2FB-E0E2-4D85-B828-754842FD43C9.pdf k City Temperatures Monday, January 10, 1859 Max. –1.5° Min. –12.0° Mean: -6.75° 12 a.m.: -1.5 (i) 4 a.m.: -2.5 (ii) 7 a.m.: -3.7 (ii) 11 a.m.: -7.5 (ii) 12 noon: -9.0 (iii) 2 p.m.: -3.8 (ii) 9 p.m.: -8.0 (ii) 12 a.m.: -12.0 (iv) (i) Estimate; (ii) Erasmus Hall, Brooklyn, N.Y. readings; (iii) Coldest Weather In Seventy Years. The New York Times, 11 Jan. 1859; (iv) Jamaica, Queens

Yeah, the Euro and GFS were too suppressed to the south with the snowfall forecast being 10-20” too low while the NAM did a great job. https://ams.confex.com/ams/44Broadcast/webprogram/Paper294758.html The snowstorm of 22-23 January 2016 in the northeastern United States produced one of the largest snowfalls ever recorded in the metropolitan corridor that extends from Washington, DC to New York, NY. The indication for major cyclogenesis with a potential significant east coast snowfall was predicted 12 days and 6 days in advance by the GFS and the ECMWF models, respectively. Early and consistent model forecasts led to high confidence in predicting very heavy snowfall for Virginia, Maryland and southeastern Pennsylvania including the cities of Washington, Baltimore, and Philadelphia. Further, the models consistently indicated that there would be a very strong gradient in snowfall accumulation near the northern extent of the precipitation shield, which was predicted to fall within 100km north or south of the New York City metropolitan region. Variations in the northern extent of snowfall across the operational and ensemble model suites led to significant uncertainty in snowfall predictions for New York City. Just 12 hours before the onset of precipitation in New York City, deterministic model forecasts varied greatly with snowfall forecasts from the GFS, ECMWF, NAM, and WSI's RPM being 12, 11, 26, and 29 inches respectively. Further, NCEP's short-range ensemble forecasts (SREF) had even larger spread with ranges from 1" to over 32" of snow. Retrospective analysis of global model forecasts and of NCEP's short-range ensemble forecasts system (SREF) revealed that forecasts based on the WRF-ARW dynamical core (including WSI RPM) were much more consistent and accurate at predicting the northern extent of heavy precipitation than forecasts based on other dynamical cores (NAM, GFS, and ECMWF). This presentation will provide both an analysis of the available real-time numerical weather prediction models, as well as an analysis of retrospective runs of the RPM system (using its WRF-ARW core) to reveal what components of the WRF-ARW contributed to the accurate snowfall forecasts, especially in the northern part of this snowstorm.

UHI can’t stop CAA when the airmass is cold enough. This is why Chicago had colder temperatures in the 1980s with much more UHI than the late 1880s. Cities like NYC always needed strong CAA since around 1900 when UHI become firmly established in NYC. The same goes for areas near the Long Island Sound and the South Shore. Coastal areas need the winds to stay up in order to deliver the coldest readings. Manhattan Island probably was never a great radiational cooling spot even before the Dutch arrived. The February 1934 Arctic outbreak was much colder than anything we have seen since then. If we could recreate that Arctic airmass again urbanized areas would have no problem dropping from-10 to -20 as Chicago recently proved with -20s back in January 2019. You need the cold right down to the the coast like in February 1934 in order to get so much ice on the local waterways which we have not seen since. Click on top title below to get video to load

February 1934 was the last time we had widespread -10° to -20° readings near the coast. Monthly Data for February 1934 for Upton NY NWS CWA Click column heading to sort ascending, click again to sort descending. NJ CANOE BROOK COOP -26 NY WALDEN 2 NE COOP -24 NY CARMEL COOP -24 NJ CHARLOTTEBURG RESERVOIR COOP -21 CT COLCHESTER 2 W COOP -21 CT NORWALK COOP -20 CT BRIDGEPORT COOP -20 NY PORT JERVIS COOP -19 NY BEDFORD HILLS COOP -19 NJ LITTLE FALLS COOP -18 NY SCARSDALE COOP -18 NJ PLAINFIELD COOP -17 NJ RIDGEFIELD COOP -17 NY WEST POINT COOP -17 CT NEW LONDON COOP -17 NJ PATERSON COOP -16 CT WATERBURY ANACONDA COOP -16 CT WATERBURY CITY HALL COOP -16 NJ ELIZABETH COOP -15 NY NY CITY CENTRAL PARK WBAN -15 NJ JERSEY CITY COOP -14 NJ NEWARK LIBERTY INTL AP WBAN -14 NY WORLD TRADE CENTER WBAN -14 NY FLUSHING COOP -14 NY MOUNT VERNON COOP -14 NY FARMINGDALE 2 NE COOP -12 NY BRIDGEHAMPTON COOP -12 NY SETAUKET STRONG COOP -11 NY CUTCHOGUE COOP -10

New all-time highest wind gust for Ireland.