Stormchaserchuck1

Thanks all. I didn't make a point whether the storm would happen or not, just that the SE ridge was being underestimated, given the Pacific pattern and the extreme nature of it vs what was happening downstream. Sometimes when a ridge corrects, the northern stream energy will get sheared out and there is no storm, or it's delayed a few days. If the storm date ends up being 40s and sunny, I think that's a win.

Long range 12z EPS today brings cold back the last week of Feb

The -AO trough is lifting out, as the Polar Vortex places over Alaska at Days 3-5, flushing out the cold and warming up the US pattern. Then the N. Pacific High starts building and establishing. At that point we are already in the Upper 30s, with no cold air reinforcement: The -NAO/-AO is weakening and lifting out. The N. Pacific ridge then gets very strong, a >5820dm block. That does overwhelm weak things in February where the wavelengths are longer. Of course, the further along we go, the warmer it gets.

Yeah, the further out in time we go the lower the chance we have with that pattern establishing and flexing.

I think so.

I would do another LES chase sometime. Would you?

The original thought was that we were coming out of deep -AO, rising back to neutral, so this could be the big storm. But the Pacific pattern is entering an extreme, and a now projected +450dm -PNA north Pacific High pressure is going to in trend, squash that EC trough, to at least make it warm enough to rain imo. The NAO ridge is right over top, so when the Pacific pattern changes it sometimes take 3 days to impact us downstream, this one is part of the now-time pattern, with a trough perhaps sticking beneath upper latitude ridging. The GEFS has basically brought the NAO to neutral, as you pointed out and the EPS is weakly negative. At this range the ensemble guidance and big picture pattern is the way to go.

Well I do enjoy some of our discussions. Just realize that models have really trended away from -NAO for the medium range threat.

Don't pay attention to them.. they are cyber bullies. Adults who get on you if you don't make posts about how it's going to snow. I am "super annoying" for responding to 2 PSU posts linking me yesterday, just saying that the pattern is bad and it's probably going to rain. They are talking about this magical -NAO, but it's like not even negative for the storm.. neutral. Easy call, imo. The pattern is changing quickly in the next few days.

Yeah, I don't want that big negative anomaly on south Alaska/NW Canada. It takes some time to bring back a good pattern after that. I think the last few days of Feb may shift back, but the decadal signal 2018-2025 -PNA is so strong.. I wonder if it will just keep going.

I just don't think it's that negative of a NAO. It's pretty negative the next few days when the EPO goes raging positive, but then it lets up... I mean it is your coming out of -NAO storm, but you don't want that big trough in the SW.

I was saying before that we maybe were moving toward something workable around Feb 20.. but tonight's runs don't look like that. If there is a pattern change back to cold, it's probably going to occur in the last few days of Feb, unless models are just way wrong about the Aleutian ridge. I think the MJO is moving into supported phases for the pattern.

This last cold pattern was impressive though? There is a middle ground in there.. we are just changing states in the Pacific pretty extremely, from what I see on models today and the last few days. +400dm Aleutian ridge with sub-5000dm heights in Alaska is one extreme. It's not like we are borderline favorable and it's always going warm.. we are just in pattern flux for the last several years. That +100dm anomaly in the map I posted above for a 2-month timeframe over 8 consecutive years is a ridiculous anomaly! I get that the SE ridge ridge didn't used to always be impenetrable in -PNA in the 60s. I think one difference is the WPO has been positive every Winter except 21-22 and this Winter since 2016-17.

How much snow are we averaging in Feb-March during this stretch? This is even with ridging extending into Alaska - replace that AK anomaly with a trough and it turns into a nightmare. March 2018 is probably the only big snow, and had a much stronger -NAO than what is being projected.

Maybe but the pattern has been batting a near perfect average for the last 7-8 years

After we were just in the 10s and 20s for 2 weeks? The Pacific pattern is unfavorable dude, not just the PNA but the orientation of it with a strong trough over the top and to the NE.. floods with the US with warm air.

That trough over Alaska is low level warm air. I've just seen the pattern so many times over the years, and the downstream bias this range.. it will verify warmer here if the Pacific H5 verifies.

^In the very long range it looks like it's moving toward something workable. I'm more talking about the medium range and all these storm chances coming with above average precip probably through like Feb 20. I think they are rain. After Feb 20, the strong seasonal pattern of -AO may continue, and I did an analog research of WC ridge vs EC trough in Dec-Jan and found that after a short break in Feb, the pattern usually resumes in March, most of the time. Actually somewhat of the same pattern usually continues through the following Apr-Aug, more times than not.

I'm really seeing how extreme it looks on models. The last few days I was thinking the seasonal pattern of -AO may be enough to overcome it, or help the ridge go poleward hooking up, eventually, but today's models really went south. The classic measurements aren't going to have super low readings, but the 12z EPS has +400dm on the mean, with a trough over top of it in Alaska. What happens in Alaska and NW Canada has a lot to do with what happens with the PNA downstream too. Since 1998, we have been in this pattern of more troughing over AK/NW Canada vs the 1960s. NAO ridging isn't strong enough to cancel out that strong Pacific pattern, once the pattern change happens quickly in 4-5 days.

SSW November's? I don't know. Maybe 10? On my old computer I plotted all 10mb events since 1948, but I don't have that data anymore, just memory of what the end result showed. 10mb warmings are lagged to AO, and 10mb coolings happen with AO in now-time (0-day)

@GaWx Did a research earlier this season and found that a Nov SSW had a significantly high correlation with cold December and January. I found in my research that a Nov SSW had ~+35-40 day lag with the -AO/NAO, and that worked out this year, but the correlation numbers weren't so high on the Pacific pattern. Gawx also found that -ENSO/-PNA Decembers led +PNA January's 10/10 times! donsoutherland did an independent research and found the same thing. It worked out this year time 11/11. Why? I don't really know. The opposite side +ENSO/+PNA Decembers leading -PNA January's doesn't work out the same.

By the way, check out the ENSO subsurface. Torching

I'll always take a chance with this +PNA low pressure correlation (both sides are considered, -pna is opposite)

I just want a favorable Pacific pattern - I don't care so much about the NAO. In mid to late February, our average high creeps up to the low to mid 40s, so we do need a below average pattern. +EPO/-PNA won't do that >90% of the time. It is pretty bad that we had a lot of favorable patterns the last 2 Winters with not much precip, but that's a Nina STJ.

I don't like that look, the EPO is positive. The trough in eastern Alaska and western Canada is a mechanism to cause a fast Pacific jet and surface level warmth here in the east that you don't really see on 500mb. Sometimes in +EPO, the H5 will be neutral or slightly negative, but low level warmth dominates. We need that -PNA ridge to go poleward further east or NE. Otherwise we'll be in the upper 30s/low 40s for storms.