bluewave

The blocking just south of Greenland since June has been unprecedented. It’s well ahead of 2012. Just hoping that means we can see a SSW this January like in 2013. I know it’s a small sample size but I can still hope. Would love to see a repeat of Nemo.

It was a great year for the extended snow cover fans. But 95-96 still wasn’t able to get challenged. Time Series Summary for ISLIP-LI MACARTHUR AP, NY - Oct through Sep Click column heading to sort ascending, click again to sort descending. Rank Season Number of Days Snow Depth >= 1 Missing Count 1 1995-1996 62 0 2 2004-2005 55 0 3 1977-1978 53 1 4 2014-2015 48 0 5 1993-1994 46 3 6 2010-2011 45 0 7 2013-2014 39 0 - 2000-2001 39 23 8 1964-1965 37 1 9 1976-1977 36 0 10 1963-1964 35 7

The most recent MEI update is weak and moderate looks like the current ceiling if we keep seeing these small increases.

From the recent ENSO blog post. https://www.climate.gov/news-features/blogs/october-2023-el-nino-update-big-cats So how about peaking at or above 2.0 °C? Forecasters give that around a 3-in-10 chance for November­–January. The climate models have a fairly wide range of potential outcomes—if they were concentrated above 2.0 °C, we’d probably be able to give more confident chances. Also, while there is still a good amount of heat under the surface of the Pacific—this warmer water provides a source to the surface—it’s not quite at the level we’ve seen during previous historically strong El Niños like 1982–83, 1997–98, or 2015–16. Each dot on this scatterplot shows the subsurface temperature anomaly (difference from the long-term average) in the central tropical Pacific each September (horizontal axis) since 1979 versus the oceanic ENSO conditions the following November–January (vertical axis). The vertical red line show the September 2023 subsurface temperature anomaly. The amount of warmer-than-average water under the surface in September has a strong relationship with the oceanic ENSO conditions later in the year. Previous very strong El Niño events, 1982–83,1997–98, and 2015–16, had more subsurface warm water than 2023. Data from CPC, image by Climate.gov. This is a small sample of very strong events, though, and the current moderate subsurface temperature certainly doesn’t preclude this event peaking above 2.0 °C. It just contributes to a tempering of the odds.

I would take that JMA composite and run since you know the snowfall would be an improvement over the last few winters. This is one year that I really hope the JMA has a clue. I just have to be cautious since it did struggle with its last El Niño forecast in 18-19 even though this event is somewhat better coupled. But we still have that -PDO which I would like to see flip positive or at least become uncoupled.

The much lower upper ocean heat is really holding this event back. That weak cold pool from 100-200 meters under 3.4 looks really out of place vs the strongest events. Same goes for the highly anomalous warm pool near and west of the Dateline where a cold pool is supposed to be.

Big temperature swing next week from lows the 30s and 40s to highs in the 70s.

Yeah, we all have our own criteria for what makes a great winter. I weigh more heavily being near the jackpot of a high ranking KU event than extended snow cover or cold. I enjoyed the January 2016 event more than any of the multiple smaller events in 13-14 and 14-15. I don’t mind if a big snowfall begins melting right after the event. One thing left I haven’t seen is 10” of snow in one hour. Any winter that produces that event will be an A in my ratings regardless of what the rest of the winter does. Same goes for any winter that produces one single 40-50” event which I haven’t experienced yet.

I guess it’s all a matter of personal opinion. While the 15-16 winter was one of the warmest of all-time, it did have the greatest NYC snowstorm of all-time. This was followed by another double digit snowfall in early February on Long Island. Plus NYC had its first subzero reading since 1994. So I actually enjoyed that winter more than 14-15. I am not that big a fan of extended snow cover if it’s from a bunch of smaller to moderate events. The one event that stands out from the 14-15 winter is the late January storm missing east vs model forecasts. But I did enjoy the extended snow cover in 10-11 which was the result of three great KU events.

We have seen very low skill forecasts issued in late November for December. The EPS weeklies completely missed how warm things got in December 2015 from the November 22nd forecast. So these weekly to monthly and seasonal outlooks can have significant errors.

Better El Niño forcing yes, but we need to lose the coupled -PDO so we don’t end up with a trough near the West caped by a +PNA ridge in Canada. That would drive the downstream ridge over the Northeast which we don’t want. It was what the Euro seasonal was showing. Plus my comment was more to how well the model did with the last non-La Niña winter. Not that this was a copy so far of that year. Outside the Pacific, we have had very impressive blocking on the Atlantic side since June.

Yeah, we would want to see the PDO remain uncoupled if it does stay negative. While the JMA has done OK with recent La Niña winters, it didn’t do very well with the El Niño in 18-19 that couldn’t couple. So it put all its eggs in the Modoki basket which didn’t verify. The well coupled -PDO wound up running the table instead.

It’s a significantly warmer winter temperature version of the 02-03, 09-10, and 14-15, Modoki El Niño forcing west of the Dateline. Even though the PDO is neutral to negative with warmth north of Hawaii, it doesn’t look like the PDO is coupled enough to drive the bus. That strong -EPO +PNA is more +PDO-like. It’s also giving a solid -AO signature. The winter temperatures aren’t nearly as cold as the composite but I am sure that 500 mb look would be better than the last few winters for snowfall. The only colder areas are south of 40N along the East Coast.

One of these winters we may just have to rely on the new warmer 91-20 climate normals. The warmer winter averages could help with a winter that gets close but would have been warm under 81-10 normals. This is how we got a cooler summer in the Northeast this year. The new warmer 91-20 climate normals allowed the Northeast to finish the summer at -0.2. But under the cooler 81-10 climate normals it would have been +0.4.

It goes beyond the ENSO to the multi-winter warm pattern since 15-16. We will eventually see another cold winter in the Northeast. But I am not even sure what type of indication we would get before the season to make that call in October or November. The warmth has become so persistent that it’s uncertain what would be required to shift that pattern colder.

I only use the PDO in reference to what is happening north and northwest of Hawaii. The absolute PDO values are only relevant when it’s well coupled with the 500 mb pattern. I like Simon Lee’s 500 mb classification pattern since it emphasizes the more important 500 mb patterns. The Pacific ridge pattern is classic -PDO. And the Alaskan Ridge is closer to +PDO. It really simplifies things. The Alaskan ridge pattern drove the record +PDO in 14-15. But most winters since then have been the Pacific ridge. My guess is that the PDO is being driven more by what is happening in the WPAC tropics and subtropics. So the actual SSTs may only be secondary to the 500 mb patterns. But extended coupled phases probably reinforce each other.

These PDO fluctuations between -0.5 and -2.5 have been the norm this year. Notice the big up and down pattern since January. So we want to see some actual positives sustain to get a sense that the PDO is shifting. A cold pool would need to develop north and northwest of Hawaii for a true +PDO. This would be indicative of a more Nino-like Aleutian Low. But continued ridging near the Aleutians even if the PDO becomes more neutral is still problematic since it promotes a Western Trough and SE Ridge.

Same old model bias from recent years with the day 11-15 forecasts missing the ridge axis near the Aleutians and trough in the West. New run Old run

May be the first time the subsurface cooled so much under 1+2 and increased under 4 this time of year. No real oceanic kelvin waves to speak of just sloshing back and forth. So this year continues to do its own thing.

This has been the warmest more Niña-like -PDO pattern for Northern New England on record for the first half of October. Plenty of La Niña Octobers on the list.

The warm mins at Caribou are more impressive than the maxes. They are running +7.6 on the maxes and +10.0 on the mins. Still haven’t had their first freeze which is very late for them.

Finally getting a WWB pattern after the relaxation in September. So all regions except 1+2 have been rising. But Nino 4 continues to be the only region in record territory for this time of year. The strongest WWBs still lean west so Nino 4 may continue to be the stand out. Nino 3.4 needs to push back up above +1.7 to make some new highs for this event. But it’s uncertain how high it can go with the much cooler subsurface than the past strongest events like 15-16, 97-98, and 82-83. The one thing this year confirms is the importance of WWBs to move the El Niño forward as seen with the acceleration in August and slowdown from September into early October.

The Northeast is on track for another warmer October. Some parts of Maine are close to +10. Next few weeks look like more of the same.

While it’s true that the first group didn’t have a -PNA, it did have a trough near California which pumped the ridge over the NE for a warmer winter in the composite mean. That’s why I like using the 500 mb composites more often than than the raw indices. The raw PNA index for the composite below is +0.46. The Euro seasonal is showing a similar effect with a +PNA in Canada but a trough in the Western US. So the best outcome would probably be a strong PDO reversal or uncoupled -PDO. Then well coupled forcing near the Dateline and decent blocking on the Atlantic side. We just don’t want any competition from -PDO which can unfavorably interact with an El Niño pattern. A compromise we would like would be getting a dominant El Niño pattern with Atlantic blocking from late January into February. The Euro is trying to show something like this in the monthlies. Hopefully, it’s correct and not just defaulting to El Niño climatology.

I still think the subsurface looks more like a strong than super for Nino 3.4 in terms of ONI .Thinking the MEI peaks somewhere weak to moderate. Main concern is how strong the -PDO influence will be during winter? Plus we have the polar domain with AO and NAO which is always a wild card.