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2024-2025 La Nina


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23 hours ago, GaWx said:

Today’s AO: +3.4

A new record obliterating high AO peak for Oct is still on track over the next two days with high +4s to near +5 still progged by GEFS. Current record +3.754 set 10/24/2008 (Oct records have been late in the month more often than early, which is intuitive to me). This new record will also be higher than the Nov record of +4.544 (11/2/1978).

Followup: Today’s AO is as has been well forecasted by GEFS easily a new record high for Oct back to 1950 at +4.578. The old record was 3.754 set 10/24/2008. The GEFS is still suggesting it could peak a little higher tomorrow before starting a plunge. There’s little correlation to the subsequent mean DJF AO. Winters following Octobers with very high AO spikes have varied from strong + to neutral to solid - with avg AO of only +0.1 for all of the subsequent winters combined.

https://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.ao.gefs.z1000.120days.csv

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On 10/22/2024 at 10:18 AM, GaWx said:

Followup: Today’s AO is as has been well forecasted by GEFS easily a new record high for Oct back to 1950 at +4.578. The old record was 3.754 set 10/24/2008. The GEFS is still suggesting it could peak a little higher tomorrow before starting a plunge. There’s little correlation to the subsequent mean DJF AO. Winters following Octobers with very high AO spikes have varied from strong + to neutral to solid - with avg AO of only +0.1 for all of the subsequent winters combined.

https://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.ao.gefs.z1000.120days.csv

 Today as expected was the 2nd day in a row setting a new record high Oct. AO. It was 4.873. The old Oct record high was set yesterday at 4.578. Before 2024, the Oct. record was only 3.754.
 The 4.873 also sets a new record high for met. autumn. The old record was 4.578 set yesterday.

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Broke the record for +AO today and yesterday, as Gawx has been pointing out. Broke it by 120%

Here is how +AO in October rolls forward to the Winter

December

1A-28.gif

January

1A-29.gif

Been getting a lot of stuff for a +AO/+NAO January

February

1CC-3.gif

Once again we have a major +NAO/AO event happening a short time after a flux in solar activity. This wasn't really modeled to be so strong in the medium-range/long range.  

1aaa.png

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The latest CFSv2 forecast for November indicates that most of the CONUS will be warmer than normal.

image.png.b2ee345b60810b77a70152f37cb7c4dc.png

Thus, the question becomes what kind of winter would be likely to follow such a November. With the December 2024-February 2025 Relative ENSO Region 3.4 Index (RONI) likely to average -0.500 or below, it makes some sense to examine how CONUS  winters have fared in the past with winter values of -0.500 or below following widespread November warmth in the CONUS (1951-2010 baseline) since 1949-50.

image.png.aa3490a7a0a758c25f4b3f39eb78e18b.png

The Composite Temperature Anomalies for North America (1991-2020 baseline, as the larger period was not available) were as follows:

November:

image.png.8a2dfb05f67c23d2052b8325b0ff0471.png

December-February:

image.png.a329b4de1c7a2bd957efdedfbbfe999b.png

The most recent C3S Multi-Ensemble Forecast for December 2024-2025:

image.png.2f445a1715393740685625469d4567b6.png

It should be noted that even warm winters have often seen periods of cold. In cases, there have been some periods of severe cold.

Overall, the forecast winter anomalies are reasonably in line with those that have followed the kind of November that is forecast when the winter RONI averaged -0.500 or below.

 

 

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27 minutes ago, donsutherland1 said:

The latest CFSv2 forecast for November indicates that most of the CONUS will be warmer than normal.

image.png.b2ee345b60810b77a70152f37cb7c4dc.png

Thus, the question becomes what kind of winter would be likely to follow such a November. With the December 2024-February 2025 Relative ENSO Region 3.4 Index (RONI) likely to average -0.500 or below, it makes some sense to examine how CONUS  winters have fared in the past with winter values of -0.500 or below following widespread November warmth in the CONUS (1951-2010 baseline) since 1949-50.

image.png.aa3490a7a0a758c25f4b3f39eb78e18b.png

The Composite Temperature Anomalies for North America (1991-2020 baseline, as the larger period was not available) were as follows:

November:

image.png.8a2dfb05f67c23d2052b8325b0ff0471.png

December-February:

image.png.a329b4de1c7a2bd957efdedfbbfe999b.png

The most recent C3S Multi-Ensemble Forecast for December 2024-2025:

image.png.2f445a1715393740685625469d4567b6.png

It should be noted that even warm winters have often seen periods of cold. In cases, there have been some periods of severe cold.

Overall, the forecast winter anomalies are reasonably in line with those that have followed the kind of November that is forecast when the winter RONI averaged -0.500 or below.

 

 

Went over this before, but it's worth repeating. The Cfs2, as all other seasonal modeling, has December as a dumpster fire, which all have acknowledged.  The question is what about January and February, as the Dec-Feb average is and has been skewed by December's warmth. This can be seen on the monthly temps link below. I am going verbatim just as your post, and clearly January and February are not as bad is December, and never have been for that matter for the last month. Whether the Cfs2 and other modeling is accurate is whole different discussion. 

https://www.cpc.ncep.noaa.gov/products/CFSv2/htmls/usT2me3Mon.html

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12 hours ago, mitchnick said:

Went over this before, but it's worth repeating. The Cfs2, as all other seasonal modeling, has December as a dumpster fire, which all have acknowledged.  The question is what about January and February, as the Dec-Feb average is and has been skewed by December's warmth. This can be seen on the monthly temps link below. I am going verbatim just as your post, and clearly January and February are not as bad is December, and never have been for that matter for the last month. Whether the Cfs2 and other modeling is accurate is whole different discussion. 

https://www.cpc.ncep.noaa.gov/products/CFSv2/htmls/usT2me3Mon.html

On a month-to-month basis, it remains to be seen how things will ultimately fare. The CFSv2 now shows January as having the potential to have more widespread cold than February. Much can still change between now and the final forecasts. Overall, confidence that the winter as a whole will be mild (though I don't see it being as warm as the past two in the East) has increased. There will be some opportunities for cold and snow--more than the past two winters unless there are some big hostile changes.

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27 minutes ago, snowman19 said:

Typical Nina/-IOD forcing developing @Bluewave
 

The extreme +EPO pattern this month looks like a blend of influences. La Niña background forcing, marine heatwave east of Japan/-PDO, and some MJO. Notice how the MJO 6 composite is much weaker than the pattern we got. So the other influences are at work. Also notice how well defined the warm pool near Japan and the Cold SST pool near Alaska has become with the +EPO.


IMG_1666.gif.15455510e691af0a0b663f5ef7ce6769.gif

IMG_1662.png.dfff626eae51dd158cc266801adeacb5.pngIMG_1665.png.662b3000eddab061b758c61c85082d69.png

 

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2 minutes ago, 40/70 Benchmark said:

The month is going to be warm in the mean....no question. Just saying there could be a colder stretch in there if the MJO cooperates before it warms up again. 

It would be nice if the next mjo wave starts mid November in phase 4 and makes it to 8 and 1 by early-mid  December. 

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4 minutes ago, binbisso said:

It would be nice if the next mjo wave starts mid November in phase 4 and makes it to 8 and 1 by early-mid  December. 

Looks like it could try to sneak into the better phases at a low amplitude in November, but it would probaly need to be stronger to not get washed out by the baseline warm pool.

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23 minutes ago, binbisso said:

Will be interesting to see if this wave can go 8 thru 3. Hasn't really happened in late fall and winter the last few years. 

Euro says no 2nd image.

Gfs 1st image 

 

image.png

image.png

 

Fwiw, Cfs2 and and bias corrected Bomm get it thru 3.

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27 minutes ago, 40/70 Benchmark said:

I think November will have a really nice stretch.

I defintely should have been more measured with this statement. I can see how it could have a colder stetch, but we would need some breaks. Anway, its not like I was referring to an early east coast snowstorm or anything...don't want to be misleading.

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1 hour ago, binbisso said:

Will be interesting to see if this wave can go 8 thru 3. Hasn't really happened in late fall and winter the last few years. 

Euro says no 2nd image.

Gfs 1st image 

 

image.png

image.png

 

Either way, we should do another pass through 4-6 in December, before we take aim at the colder phases late Dec through mid-Jan, give or take a week or so. That will be the window of opportunity I’m watching for the MA.

The initial pass through 8-1-2 (weak or not) might yield some results for great lakes through interior NE, but just seasonal cool weather for the MA. 

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16 hours ago, mitchnick said:

Went over this before, but it's worth repeating. The Cfs2, as all other seasonal modeling, has December as a dumpster fire, which all have acknowledged.  The question is what about January and February, as the Dec-Feb average is and has been skewed by December's warmth. This can be seen on the monthly temps link below. I am going verbatim just as your post, and clearly January and February are not as bad is December, and never have been for that matter for the last month. Whether the Cfs2 and other modeling is accurate is whole different discussion. 

https://www.cpc.ncep.noaa.gov/products/CFSv2/htmls/usT2me3Mon.html

Actually I wouldnt call December a dumpster fire. Your area looks 0.5-1C warmer than avg on the CFS for December.

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15 minutes ago, 40/70 Benchmark said:

Which is probably enough to constitute  a dumpser fire in the lower terrain of the mid atlantic during December as it relates to snowfall.

Yeah the lower terrain of the mid Atlantic needs a lot of help in December. Even my area December climo kinda sucks the first half of the month

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26 minutes ago, michsnowfreak said:

Actually I wouldnt call December a dumpster fire. Your area looks 0.5-1C warmer than avg on the CFS for December.

Cfs2 has been cooling the last  week, but I  assume it's too cool. If the trend continues, an updated forecast....err, guess may be needed. Lol

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