Stormchaserchuck1

In other news, we continue to get warm US conditions in warm Stratosphere, and cold conditions in cold Stratosphere. You would say that makes sense, but it's main effect at the surface is AO/NAO. The NAO has a 0.5 temperature correlation in the eastern 2/3 of the US.. negative (warm Stratosphere +time) being cold, and positive (cold Stratosphere 0-time) being warm. Last Winter we had the warmest Winter on record for CONUS and it was during 4 Stratosphere warmings. The mean for the Winter was +500dm at 10mb. This Winter the opposite occurred, -500dm 10mb, but now after this March Stratosphere warming, in the allotted time where it's suppose to have NAO correlation, we have a major SE ridge signal on models, and possibly 80s. Another point is this -NAO correlation with SE ridge after the coldest day of the year (Jan 27th). For the last few years, the NAO has anomalously low correlation to it's usual tendencies in the late Winter/early Spring. I've found that even "potential -NAO events" (like a "downwelled" Stratosphere warming, or MJO wave cycle) have occurred with a flexed SE ridge in that time.

The AMO is still near the high peak of its positive cycle. For now, it's not in a descending state, it's sustaining or slightly continuing to increase. There is an overlap between the AMO and NAO. When the NAO is positive there is a -0.3 correlation to Atlantic SSTs. This is what happened last Summer - it wasn't that we were cooling because of an oncoming -AMO state, it was cooling because we had a near record +NAO occurring. If you think we will see more +NAO in the future, associated with Solar Max, that could be a cooler AMO.. It's around the timeframe now where decadal states have shifted, but I just don't see the "first Wave down" happening yet. Here is a chart going through 2023 of the current +phase

Nice SE ridge showing up on models April 5-7. We could break the 80s sometime around those days.

+PNA has really correlated with cold this year! It's underrated. That's what we need going forward (next Winter).

I can definitely see the strongest ridge being over the west coast this Summer.

Close to some flurries here! Hopefully this cooler trend associated with +PNA carries into next Winter.

Surprised no one mentioned the 18z GFS snows on us like 6 different times. It probably won't happen but the Stratosphere warming occurring now is going to create some more neutral conditions toward the end of the month to possibly keep us cooler.

^We were a -NAO away from having a good Winter pattern, it would have pushed the mean trough SW. Instead we had +NAO (SLP difference in the N. Atlantic between the Azores and south of Iceland), and it kept everything progressive. It's a shame we had -60dm 50/50 low, favorable Pacific, and really so little snow.. although places down south had average.

^I was pointing out in the Fall that 1955 was the only PDO analog that was close to our Fall PDO. That was interesting, because 55-56 was a cold Dec-Jan in the eastern 2/3 despite record neg PDO, then a warmer Feb. March isn't a match though. But for DJF, the 55-56 analog did come close to this year.

18z GEFS has a lot of "downwelled warmth" from the Stratsphere warming Days 10+ north of 60N in the northern hemisphere. That kind of a signal should correlate with at least a weak -NAO.

Nino 3.4 has been on one heck of a warming trend.. made it up to +0.3, then finally down for the first day in a while today.

This is the start of a legit warming btw

6 months of bare trees for 10" of snow? 3 months of cold for 10" of snow? I'm going with a "D". The positive was having snowcover through most of January though, and it did flurry or more 19 times (mostly in Dec and Jan).

-NAO may continue into the 2nd week of April..

That's not close either, it's likely going to be a top 10 warmest March for the CONUS. Chicago hit 79* yesterday, its highest March temp since 2012. Check out this March trend even before this year:

The Stratosphere lag that I was talking about looks to be hitting, as models are trending toward more -NAO for the last week of March. https://www.meteo.psu.edu/ewall/ENSHGTAVGNH_12z/ensloopmref.html They didn't have that before. It would be interesting to see what LR model biases are when a Stratosphere warming happens weeks before.

October was a completely different pattern in the Pacific.. like opposite. I think some of November was too. I understand that this was the coldest nationwide since 13-14/14-15, but some of our cold this Winter was also -NAO driven, 13-14 had mostly +NAO for the Winter.. and now March is pretty much opposite again. The similarity was in the EPO Dec-Feb, as this was the first solidly neg EPO Winter since 13-14/14-15.

Climate change is also an easy way of coming up with a non-scientific explanation. There is usually a pattern or feature that is responsible for why X happens, but saying the whole earth is 2 degrees warmer or whatever, is something that is used a lot. It's also a little exhausting always having to conversate CC to the weather being discussed. Rarely are we getting down the science of meteorology.. Climate change is not making the PNA be negative, or making there be more La Nina's, or the NAO running positive. All 3 are responsible for the significant dip in annual snowfall in the East, US lately. We haven't spent much energy coming up with what is actually causing these indices to be so.

I've just noticed -PNA/+EPO has a higher tendency to break it consistently, and it's usually by a lot. We've actually been doing this "busting through model forecasts" a lot over the last several years after the low yearly min temp happens on Jan 27, after that in February and March we have been going higher quite often.

When the Pacific is in -PNA/+EPO, we blow past forecasts. When +PNA/-EPO, not so much (although this pattern has been more rare in the last 8 years). NAO is in a 3-sigma block right now and it's 70 degrees... that has gone in an opposite correlation since about 2007 or 2013.. Pacific is just as unfavorable for cold, if not moreso, when the NAO is negative a lot lately.. Pacific trumps.

It wasn't the same pattern as the last few Winters because the Southeast got several snowstorms. They were shut out the last few years. You act like because New York City had the same amount of snowfall as the last few Winter's that the pattern wasn't different, but it wasn't the same, at least through December and January. It was just drier. That drier pattern started last Summer when the cap wasn't breaking for anything, despite hot temperatures and high humidity in the Northeast. This "drought" pattern really only started in 2024.

Scandinavia loading pattern at the very end of 12z GEFS, March 24th. That is aligned with Stratosphere warming for possibly -NAO last few days of the month into early April.

The time it should connect with -NAO is last week of March, into early April. I'm not sure that's in the range of modeling yet.

+EPO/+WPO/-PNA really hit hard there. I think the Pacific has more effect.. we have started to cool down -NAO's/-AO's in the last 2 Winters though.. although we have this 70s day coming up with a 3 sigma -NAO block around March 10-11. I think the majority of the time, the NAO state is correct as a cold/warm signal.. those correlation maps I posted input all data, so it has 1,000 data points going back to 1948, everything included.

Yeah, but the NAO is a North Atlantic pressure difference index. Between the Azores and ~Iceland. So a lot of these "west-based -NAO blocks" over the Davis Strait and Baffin Island really have nothing to do with the North Atlantic ocean. But I said earlier, sometimes when these blocks are too far north, because we are south of 45N, there can be unfavorable troughs that form underneath of them at even a higher latitude than ours.. that is what happened when the -5 AO storm cut inland.. The -300dm at 45-50N in the N. Atlantic Ocean favored that inland track, and that was the closer and more anomalous (volatility/latitude) pattern to us. I agree that I have no idea what the CPC is seeing in their index states some of the time... this Winter was not #1 +PNA non-El Nino in 75 years lol. We would have been colder in the east.