bluewave

Multi-year winter patterns are important. We have had 8 warmer than average winters in a row. So just hoping that we can do better in the snowfall department than last year. Even if it we make it 9 warmer than average winters in a row. Regardless of El Niño or La Niña, the warm anomalies end up in the East and the cold departures somewhere out West. This has been the winning winter temperature forecast since the super El Niño.

Some of that is related to measuring snow differently now than we did back then. But the 09-10 to 17-18 snowfall was probably a 100 year event for rarity. We seem to be settling into a lower baseline since 18-19 than that epic period for snowfall. But we can still sneak in decent seasons with great snowstorms like 20-21 or January 22. https://news.ucar.edu/14009/snowfall-measurement-flaky-history

February 2015 was our biggest outlier month since 2010.

HRRR has us getting warm sectored to around 70° today.

The EPS is starting to show the winter pattern in a few weeks that we get when we have an El Niño +PNA ridge in Canada that gets undercut by the La Niña background or -PDO SW trough.

It will be a good WWB, but it’s coming a little late to move the needle much. I guess it’s possible we can get a daily or weekly OISST closer to super, but every spike had a pullback so the monthly will average below super.

Looks like Nino 3.4 is getting closer to peaking below super levels. Its one of the few years when the September and October were nearly the same. This event really ran out of momentum after August. Makes sense since we have never had a super El Niño after a 3 year La Niña before. Too much of a lag with the well established La Niña background state. https://www.cpc.ncep.noaa.gov/data/indices/ersst5.nino.mth.91-20.ascii ERSST JUL….1.02 AUG…1.35 SEP…..1.60 OCT….1.66

That’s why I am a big fan of using the 500 composites since where the anomalies are located can often add more value than just looking at the raw indices.

I meant the PNA. https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.pna.monthly.b5001.current.ascii.table

You are correct with the PNA coming in at +0.21 last January with a strong 500 mb ridge in Canada and a trough tucked underneath near the SW.

But we can still get a trough in the West with + PNA during an El Niño when the PDO is negative. That trough would pump the ridge over the East resulting in the 9th warmer than normal winter in a row for us. So this is why we don’t want a La Niña background state to combine with the El Niño this winter. If the PDO remains negative like all the models show with the big warm pool NW of Hawaii, it needs to be uncoupled to allow a clean El Niño response from late January into February.

But those years like 2009, 1972, and 2002 had very different 500 mb and forcing with the the MJO orbiting various phases.

This doesn’t look like a MJO phase 1 pattern with the dominant forcing in the WPAC. Plus those MJO 500 mb composites based on ENSO from the French site can be inaccurate due to the very small sample size of cases. Better to stick with JMA or CPC for composites which have a very large number of past cases.

We would expect to see a strong La Niña background state with the WPAC warm pool at the 3rd warmest on record for the month of October. So that strong -AAM makes sense. https://psl.noaa.gov/cgi-bin/data/timeseries/timeseries.pl?ntype=1&var=SST&level=2000&lat1=40&lat2=0&lon1=100&lon2=180&iseas=1&mon1=9&mon2=9&iarea=0&typeout=1&Submit=Create+Timeseries

And yet the mid-November pattern being advertised is classic La Niña.

Same old Aleutians ridge with trough out West pumping the Southeast ridge. This is why it’s so difficult to sustain any colder temperatures here.

It does look like the Euro is trying to blend the El Niño and La Niña influences for December. The strong Canadian ridging is classic El Niño for December. But the Southeast or Western Atlantic ridge is more a La Niña influence. The hope is that we get some semblance of a cleaner El Niño look from late January into February since that is usually prime time for El Niños. Don’t want to see a La Niña influence in February since that is typically when La Ninas influence is warmest. https://ds.data.jma.go.jp/tcc/tcc/products/clisys/enso_statistics/index.html

Just open the base time drop down menus at the top and all Euro monthly and seasonal forecasts are archived back to January 2017. Select dimensions…base time… https://charts.ecmwf.int/products/seasonal_system5_standard_z500?area=GLOB&base_time=202311010000&stats=ensm&valid_time=202312020000

Unfortunately, the Euro seasonal doesn’t have much skill beyond the first month which in this case would be November. But even that can vary quite a bit from reality once the month verifies. We can remember how the Euro was going for a repeat of 13-14 or 14-15 with the 18-19 El Niño. Granted this is a much stronger event than that one, but I won’t buy a cold look like that until it shows up in a 6-10 or 11-15 day EPS mean. For some reason the Euro seasonal couldn’t see the La Niña background state influence in the 18-19 winter. And this fall so far has been a blend of El Niño and La Niña influences. Not a pure El Niño composite.

While OISST hasn’t updated in a while, CRW follows the trend of not being able to sustain a SST increase due to the lower upper ocean content then normal for this El Niño. This makes getting an official ONI to average at +2.0 or greater even more unlikely than it was before. This is due to El Niños historically beginning to peak in November and December. So this is the period when steady and sustained increases are required to reach higher El Niño levels. Most years during an El Niño the November 3.4 reading is the same as December. So if the OISST pulls back to +1.7 like CRW, then the peak for this event may be very close.

Yeah, I hear what you are saying. The MEI being much lower last summer into winter than the ONI did a great job explaining the La Niña on steroids pattern. I try to stick to the sensible weather since that is what most people can relate to.

The atmospheric response at 500 mb has been a mix of El Niño and La Niña influences. So we could make the argument that the weaker MEI still reflects an element of the La Niña background state. That’s more valuable for forecasting the sensible weather outside the tropics than just looking at what the OLR and SOI are doing. The ridge NW of Hawaii and over Hudson Bay is more a La Niña feature. While the ridging around Alaska is more El Niño-like in October. The Aleutian low is in an intermediate position between the El Niño and La Niña composites.

I like to use the area NW of a Hawaii since it’s usually the deciding factor when the PDO is technically negative but we still get a +PDO 500 mb pattern like 09-10. When the waters off of California are warmer like in 14-15, I agree with you that the East is going to be colder. The snowfall outcome in 09-10 and 14-15 were both historic. Around Boston in 14-15 and DC to Philly in 09-10. So the more +PDO 500mb patterns were outstanding for snow even if the temperatures differed a bit. Modoki forcing near the Dateline with a +PDO El Niño and cold pool NW of Hawaii have been traditionally cold and snowy in the East.

Just remember that Modoki or forcing near the Dateline is warm during an El Niño when it combines with a -PDO. So I don’t think it matters as much this year whether this gets defined as east based, basin-wide, or Modoki. It’s the state of the PDO or presence of a La Niña background state that will probably decide the winter more than how warm any of the Nino regions get. Any warm pooling and ridging NW of Hawaii will result in a warm outcome when combined with El Niño whether they stays strong or gets closer to borderline super. But snowfall is more variable and can be influenced by the AO if it can combine with some favorable +PNA intervals.

Plenty of competing influences with the AAM still in La Niña mode.