Stormchaserchuck1

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.