bluewave

Those were the old days when North America used to get really cold during the winter. The 93-94 winter was the last time Canada had a top 10 coldest winter. Most recent years have been top 10 warmth.

It looks like today will probably be the last 80° potential of the season for the usual warm spots. While the models are still warmer than average going forward, the departures are forecast to be smaller than the last week. Even with all the record warmth in recent years, we haven’t been able to go over 80° after the first week of November. The last time we had mid-November 80° warmth was way back in 1993. It was also the last time we reached 100° after August. So those two records have been very tough to beat. Less warm is the new cool First/Last Summary for NEWARK LIBERTY INTL AP, NJ Each section contains date and year of occurrence, value on that date. Click column heading to sort ascending, click again to sort descending. 1993 04-20 (1993) 80 11-15 (1993) 80 208 2022 04-14 (2022) 88 11-07 (2022) 81 206 1948 05-10 (1948) 87 11-06 (1948) 80 179 2003 04-15 (2003) 81 11-03 (2003) 81 201 1982 04-25 (1982) 81 11-02 (1982) 80 190 1950 04-04 (1950) 82 11-02 (1950) 84 211 1974 04-22 (1974) 81 11-01 (1974) 81 192

The interesting thing about the recent +EPO pattern this fall is that the vortex near Alaska has been weaker than in past +EPO events. So there may very well be more neutral to negative episodes in the seasonal mix. But the +EPO ridge over North America has been as strong or stronger than when the Alaskan Vortex was deeper. I have noticed this pattern in recent years where the -PNA trough has been weaker than in the old days but the Southeast Ridge was stronger. This may be a function of 500mb heights increasing as the atmosphere warms. So the old one to one relationship with the magnitude of the troughs over the Pacific and corresponding ridges has been changing. So we don’t need as deep a trough anymore to get such strong to record breaking ridges and warmth over North America.

The state of the pattern at the start of December and the medium range forecasts at the time have spoken volumes about the winter patterns especially during La Ninas over the last decade. But sometimes we had to wait for periods which went against the La Niña and -PDO like Jan 22. Even last winter during an El Niño the winter pattern locked in early December which was rare for an El Niño. Before the last decade or so the weather patterns didn’t exhibit the pattern persistence that they have in recent times. It could be a feedback between the numerous marine heatwaves and 500mb patterns leading to these standing waves which have become the new normal.

The LES snowstorm details for the Great Lakes will probably come down to the state of the winter EPO. We haven had a +EPO dominant La Niña winter since 11-12. That resulted in a sharp LES gradient pattern. Buffalo finished in the top 5 lowest winters for snowfall while Marquette was only the 20th lowest. So improvement relative to the averages and absolutes the further north you went. Hopefully for your area this current +EPO isn’t a preview of the upcoming winter. We will probably have a better idea of more micro details like that once we get into the first week of December and see what the pattern and modeling indicates at that time.

Anything above a T would be a win at this point.

The Euro did much better with the winter temperature forecast in 21-22 than the last two winters. It had close to a +1C departure for parts of the Northeast which was fairly close. But it required the big MJO 8 in January to go against the La Niña and -PDO at least for one month. So I think the only way the Euro seasonal will end up being closer this winter is for at least one month to go against the -PDO and La Niña background enough.

It’s been a while since the models had measurable rain within about 120 hrs. Hopefully, the development of the Plains trough pays off for us. We’ll take what ever we can get and need to at least start putting some rainfall points on the board.

Seems to be closing the gap a bit between the DMI volume. But the DMI is still lower. The October temperatures above 80N were warmest on record by a wide margin.

For the 22-23 La Niña the Euro was too warm in the West and too cool in the East. So the Euro was too cool under where the La Niña SE Ridge set up. The +1C forecast in those areas verified closer to +3.5C.

Very little cold relative to the means anywhere in the world going back to last year.

I think that is just due to this being a La Niña instead of an El Niño.

The Euro forecast was much too cold for last winter as it only had +1C anomaly over the Upper Midwest where a +5C anomaly verified. It would have looked more dramatic if the forecast was in F instead. So the takeaway is that the Euro during recent years has been significantly underestimating the warm departures under the strongest 500mb height anomalies. So we’ll probably have to wait and see where the main ridge axis sets up and then adjust warmer. The only time the Euro wasn’t biased too cold in recent years was during mismatch patterns when the 500mb pattern went against the La Niña and -PDO.

The record subsurface warmth east of Japan goes down a remarkable 300 meters making it very difficult to shift.

I am glad you were able to use it. The Euro seasonal that just updated continues this expanded subtropical ridge and marine heatwave pattern for the entire run. While not looking at exact temperature departures and 500 mb height anomalies, it’s noteworthy how little cold air is available in the Northern Hemisphere for the winter forecast in the means.

The next few weeks will be a good test to see if the September and October record dry pattern was just a blip or the start of an extended dry pattern. Notice the record 500 mb ridge over the CONUS to our west blocking all the rainfall from reaching us. Almost like a rain shadow east of a mountain ridge. The forecast next few weeks is for a trough to return to the Plains. If some of this moisture can find its way into the East then we can hope the worst of the dry pattern is behind us. But if the Southeast Ridge becomes strong enough and continues the dry pattern then we may have to deal with an extended drought.

I don’t think it’s a coincidence that the rapid warming of the subtropical Pacific and Atlantic occurred with the super El Niño temperature jump in 15-16. This warming has been associated with the rapid expansion of the subtropical ridge near the East Coast of the U.S. and East of Japan to south of the Aleutians. This pattern has only become reinforced by the further record global temperature jump over the past 15 to 18 months. So this could be the result of a threshold effect related to the much warmer base state. It’s why the North Pacific pattern is so different from past -PDO instances. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022GL101078 The Pacific Decadal Oscillation (PDO) is a widely used measure of the temperature variability in the North Pacific Ocean. The PDO is the result of a well-known technique called empirical orthogonal function (EOF) analysis that isolates the most energetic modes of variability of the analyzed variable. The first time EOF analysis was applied to oceanographic data was in the 1970's when it was used to identify the most energetic modes of North Pacific sea surface temperature (SST). The first EOF of North Pacific SST has proved so useful as a measure that it received the moniker PDO. Our analysis suggests that a period of persistent marine heatwaves in the North Pacific since 2014 has been so powerful that this first mode of variability of SST has fundamentally changed and the PDO may not be as useful an indicator as it once was.

One of the sources for uncertainty is that several recent studies have found that the cool blob in the North Atlantic is associated with lower pressures and stronger winds rather than changes in the AMOC. In addition, it has recently been shown that the observed reduction in sea surface temperatures in the subpolar North Atlantic (also known as the warming hole), often assumed to be an indication of the AMOC slowdown, could largely be driven by the atmosphere alone without any changes in ocean circulation2

Nearly all of the winter Aleutian Ridge 500mb anomaly since 1999 is a result of 16-17 to 23-24.

The one early snowfall indicator which has worked for every La Niña winter in NYC going back to the 95-96 has been the December La Niña snowfall. Years with 3 or more inches December have gone on to above normal seasonal snowfall. Every December with under 3” has had a below average snowfall season. This is why December is so important with La Ninas around NYC. 22-23….Dec snow…..T……season….2.3 21-22…..Dec snow….0.2…season…..17.9 20-21…..Dec snow….10.5…season…38.6 17-18……Dec snow….7.7…..season…40.9 16-17…….Dec snow…3.2…..season…30.2 11-12…….Dec snow….0…….season….7.4 10-11…….Dec snow….20.1….season….61.9 08-09…..Dec snow….6.0……season….27.6 07-08…..Dec snow…..2.9…..season….11.9 05-06…..Dec snow…..9.7…….season…40.0 00-01……Dec snow….13.4……season….35.0 99-00…..Dec snow…..T……….season….16.3 98-99…..Dec snow…..2.0……..season….12.7 95-96…..Dec snow…..11.5……..season….75.6

That was before the Pacific became so hostile.

That’s the strongest the Aleutian Ridge out near the Dateline has been from January into October. 2020 5631.444 2021 5647.413 2022 5622.112 2023 5646.048 2024 5655.698

SMQ already set the record by a good margin at 121 days reaching 80° since they didn’t have the sea breeze to deal with this summer. Time Series Summary for SOMERSET AIRPORT, NJ - Jan through Dec Click column heading to sort ascending, click again to sort descending. 1 2024 121 58 2 2016 117 0 3 2007 111 0 4 2005 109 1 5 2020 105 0

EWR needs two more 80° days to tie the record of 118 days set back in 2015. Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Jan through Dec Click column heading to sort ascending, click again to sort descending. 1 2015 118 0 2 2024 116 58 - 2021 116 0 3 1994 114 0 4 2016 113 0 - 1993 113 0 - 1991 113 0 5 2011 111 0 - 2010 111 0