bluewave

This winter so far is more evidence that there seem to have been two pattern shifts to our winters starting with the 15-16 super El Niño. The first shift is that all our winters since then have been warmer to record warmer. So this winter will mark a record breaking 9 consecutive warmer winters. The beginning of the warmer period from 15-16 to 17-18 still was producing record snowfall within the 09-10 to 17-18 window. Then around 18-19 we started to see a decline in snowfall to a lower baseline than before 2010-2018. The common denominator seems to be a more amplified MJO 4-7 pattern and a stronger ridge near the Northeast. It will be interesting to see if we can at least change up the snowfall equation and sneak in another year like 20-21 over the next few winters.

The recent analysis from Cowtan is that the rate of warming since 2010 has increased but the magnitude of the increase is still uncertain. https://tamino.wordpress.com/2024/01/05/global-warming-picks-up-speed/ What about the trend in the adjusted data, i.e. apart from the factors that make those incessant fluctuations? I can apply the same analysis and get this: Much is essentially the same as with the original, raw data: there is undoubtedly a change in rate around 1970, and there is evidence of another change around 2010. But this time the uncertainty range is narrower, the uncertainties are a lot smaller, and the evidence for recent change is now conclusive. Conclusion: since 1950 the adjusted data show at least three different warming rates: near zero from 1950 until about 1970, then about +0.02 °C/yr until around 2010, and about +0.027 °C/yr since. Not just the above analysis, but other statistical tests confirm that although the uncertainty in the current rate is considerable, we conclude with confidence that it’s faster than it was during the preceding decades. Global warming picks up speed. That’s using the data from HadCRU, and the story is the same when using data from NASA (the GISTemp data from the Goddard Institute for Space Studies), from NOAA (the National Oceanic and Atmospheric Administration), from the Berkeley Earth surface temperature project, or the ERA5 data from Europe’s Copernicus Climate

The 24° high in NYC on Wednesday was the coldest in two years. Time Series Summary for NY CITY CENTRAL PARK, NY - Jan through Dec Click column heading to sort ascending, click again to sort descending. Year Lowest Max Temperature Missing Count 2024 24 349 2023 27 0 2022 15 0 2021 25 0 2020 31 0 2019 14 0 2018 13 0 2017 18 0 2016 15 0 2015 19 0 2014 17 0 2013 20 0 2012 27 0 2011 24 0 2010 20 0

I am thinking the varying model solutions are due to the MJO forecast to go into phase 7 near the start of February. Phase 7 is much better for us in January than February during an El Niño. The models with a stronger -EPO +PNA have more of a phase 7 look for January. The phase 7 composite in February has more of a ridge across the CONUS. Both the extended EPS and GEFS slow the MJO down in 7 in early February. My guess due to the record SSTs near the Dateline.

The favorable 500 mb pattern for the 1-23-16 blizzard actually began around the 7th several weeks before the blizzard. Notice the great extended blocking pattern with the -AO peaking near -5. So the 50/50 low was well established. The final pieces came together just after the 20th when the Pacific relaxed enough for the record blizzard.

I think we were mainly discussing a 1 week window for a while now this month with the lagged phase 3 response. But it’s challenging to put together more than a 1-3 or 2-4 event for NYC with such a short window. Especially with so many adjacent warm MJO phases. What I loved about 16-17 is that we were able to put together blizzards in a sea of 60° days with only briefly favorable patterns.

Another case of the coldest departures and temperatures dropping to our west.

Just wish we didn’t get the warm layer just above the surface.

Officially my worst freezing rain conditions of the 2020s so far. 1.5” of snow followed by around .10 of ice. Still some very light freezing rain and 30° just east of HVN.

My favorite was 12 /22/15 +4.503 to 1/16/16 -4.898 due to the record breaking snowstorm shortly after.

Switched over to a mix of sleet and freezing and 27° here just east of KHVN. The 3km NAM more accurate here than the HRRR.

I think its more related to the Euro regularly underestimating the strength of the ridge over the Western Atlantic.

The -5.285 AO rise to +5.536 in under 30 days back in 2021 may be the most extreme short term AO reversal we have seen. https://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.ao.index.b500101.current.ascii 2021 2 10 -5.285 2021 3 11 5.536

These rapid and highly amplified NAO and AO swings from one phase to another have become more common for us since the study was published in 2009. https://www.eurekalert.org/news-releases/922025 The research team found the variability of the NAO decade-to-decade (multi-decadal scale) has been larger, swinging more wildly, during the late twentieth century than in the early 1800s, suggesting that variability is linked to the mean temperature of the Northern Hemisphere. This confirms variability previously reported in past terrestrial reconstructions. "When the Industrial Revolution begins and atmospheric temperature becomes warmer, the NAO takes on a much stronger pattern in longer-term behavior," said Goodkin. "That was suspected before in the instrumental records, but this is the first time it has been documented in records from both the ocean and the atmosphere." The North Atlantic Oscillation is described by the NAO index, calculated as a weighted difference between the polar low and the subtropical high during the winter season. In a positive phase, both the low-pressure zone over Iceland and high pressure over the Azores are intensified, resulting in changes in the strength, incidence, and pathway of winter storms crossing the Atlantic. In a negative phase, a weak subtropical high and a weak Icelandic low results in fewer and weaker winter storms crossing on a more west-east pathway. The NAO index varies from year to year, but also exhibits a tendency to remain in one phase for intervals lasting more than a decade. An unusually long period of positive phase between 1970-2000 led to the suggestion that global warming was affecting the behavior of the NAO. "Anthropogenic (human-related) warming does not appear to be altering whether the NAO is in a positive or negative phase at multi-decadal time scales," said WHOI paleoclimatologist Konrad Hughen. "It does seem to be increasing variability. Clearly, this has implications for the future." "As temperatures get warmer, there's potential for more violent swings of the NAO — the phases becoming even more positive and even more negative," Hughen added. "If the NAO locks more into these patterns, intense storms will become more intense and droughts will become more severe."

The record SSTs near 60E drove the very amplified MJO 2 response and deep trough out West.

One of the biggest snow extent reversals for North America that we have seen. https://www.star.nesdis.noaa.gov/smcd/emb/snow/HTML/snow_extent_monitor.html

It could be. 12-24-15 was +33 and 2-14-16 was -27.

The greatest Arctic outbreak in NYC since 1994 occurred during our 2nd warmest winter in 15-16. It was colder than any of the readings in the 13-14 and 14-15 winters. The low of 3 last winter was similar to both those winters which were much colder. Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Rank Season Mean Avg Temperature Minimum Temperature 1 2001-2002 41.5 19 2 2022-2023 41.0 3 - 2015-2016 41.0 -1 3 2011-2012 40.5 13 4 1931-1932 40.1 18 5 1997-1998 39.6 14 Lowest temperature 2014-2015 2 0 2013-2014 4 0 Winter average temperature 2014-2015 31.4 0 2013-2014 32.9 0

NYC finished in 3rd place for warmest 1st half of winter. Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Mean Avg Temperature Dec 1 to Jan 14 Missing Count 1 2016-01-14 45.8 0 2 2007-01-14 44.4 0 3 2024-01-14 43.2 0 4 2012-01-14 41.7 0 5 2002-01-14 41.6 0 - 1932-01-14 41.6 0

I can’t remember the last time we ever had 3 distinctly different 500 mb teleconnection patterns during a two week interval this time of year.

We may set a new record for late January pattern changes with how amped up this MJO action is.

Some of the locals said this was the best snow squall in the last few years for Albany.

Best chance of the season so far for NYC to drop below 15° or maybe even 10° next weekend. Impressive Arctic high pressure moves east and turns the winds more NW to NNW. So this should be more of a cold air drain down the Hudson Valley instead of crossing the warm Great Lakes. Fresh snow cover from the system right before would be greatly appreciated to give NYC a better shot at maximizing its cold potential.

The Euro continues its suppression issues with East Coast storm tracks. Big NW correction from around 5 days out to the most recent model runs. Had the same issue with the previous storm where the heaviest snowfall totals shifted from around NYC NW back to Orange County NY. So either the actual low or the rain-snow line comes NW. Sometimes it’s just one and other times both.