bluewave

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.

Front-loaded winter cold last December was a top 10 coldest December low temperature. Monthly Data for December 2022 for Rowan County, NC Click column heading to sort ascending, click again to sort descending. Name Station Type Lowest Min Temperature SALISBURY COOP 8 SALISBURY 9 WNW COOP 8 Time Series Summary for SALISBURY 9 WNW, NC - Month of Dec Click column heading to sort ascending, click again to sort descending. Rank Year Lowest Min Temperature Missing Count 1 1962 0 0 2 1983 2 0 - 1958 2 0 3 1957 3 0 4 1989 5 0 5 1960 6 0 6 2010 7 0 - 1980 7 0 7 2022 8 0 - 1963 8 0 8 2004 9 0 - 1985 9 0 - 1981 9 0 - 1975 9 0 9 1976 10 0 - 1964 10 0 - 1955 10 0

I saw that also. What the Euro is forecasting would be rare. Only 5 out of 44 SSWs on record occurred before January 1st. https://csl.noaa.gov/groups/csl8/sswcompendium/majorevents.html

One of the issues with some of these monthly seasonal forecasts is that they just repeat the initial conditions at the start of the month for the whole month. The CANSIPS and the CFS do this often. But sometimes the Euro monthly issued on the 5th does well with the whole first month. But it has been rare for any of these seasonal models to get the 2nd month or beyond correct in recent years.

Looks like 35° was the official low in NYC. https://www.weather.gov/wrh/timeseries?site=knyc NYC…35° LGA….38° JFK….34° FRG…32° ISP…..28° EWR..35° HPN…28° HVN…29°

A record breaking 56° drop from the 80s to 20s here in Southern CT for a 5 day fall period. https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=169&network=CT_ASOS&zstation=MMK&v=tmpf&hours=114&month=fall&dir=cool&how=exact&_r=t&dpi=100&_fmt=png

It makes it feel much colder compared to how warm it was.

3rd greatest 5 day temperature drop at SMQ during the fall of 53°. https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=169&network=NJ_ASOS&zstation=SMQ&v=tmpf&hours=114&month=fall&dir=cool&how=exact&_r=t&dpi=100&_fmt=png

Temp still dropping here down to 30°.

My first freeze as it’s 31° near KHVN. I am closer to the shoreline with areas just to my north around 25°.

Yeah, sustained cold has been non-existent since the super El Niño in 15-16. The best cold periods were late Dec 17 into early Jan 18 and Jan 22. NYC Feb 23…+5.2 Jan 23…+9.8 Dec 22…-0.6 …………..+4.8 Feb 22….+1.4 Jan 22….-3.2 Dec 21….+4.7 ……………..+1.0 Feb 21….-1.7 Jan 21….+1.1 Dec 20…+1.7 …………..+0.4 Feb 20…+4.8 Jan 20….+6.5 Dec 19….+0.8 …………….+4.0 Feb 19….+0.9 Jan 19….-0.1 Dec 18…+2.6 …………….+1.1 Feb 18…+6.7 Jan 18….-0.9 Dec 17…..-2.5 …………….+1.1 Feb 17…..+6.3 Jan 17….+5.4 Dec 16….+0.8 …………….+4.2 Feb 16….+2.4 Jan 16….+1.9 Dec 15….+13.3 …………….+5.9

The Aleutian ridge NW of Hawaii keeps popping up driving a trough into the Western US and a ridge near our area.