psuhoffman

Interesting developments wrt the high latitudes on tonight’s ops and not forever out in time either. Definitely need to watch this for a possible phase change in the AO NAO which would seriously change the calculation for snow in the current pattern in our favor.

People question these frontal wave setups all the time but they can work. Problem is because they are discreet waves in a progressive pattern they are incredibly finicky and hard for guidance to pin down with any accuracy at range. So when they are on guidance at day 7 or 10 there is very little chance they will be right. Either there is no wave or the boundary isn’t located exactly right at that lead so it’s somewhere else. We’re getting close enough to start taking it seriously but there will be adjustments and shifts even within 48 hours with these. Anyone who says they know what is going to happen is full of it. Slight adjustments in the timing, press of cold, and amplification are the difference between rain, snow, and a squashed wave. I feel like we’re in the game but I won’t feel confident about a setup like this until very short range. That’s why people “think” they never work. When they do we usually didn’t see them coming. When we see them from range they often don’t.

I ventured into the nyc sub before the last storm and it was a bunch of “hey look at this model that shows what I want and that’s what we should expect and ignore everything else” each run and he was leading the weenie charge.

Most of us want snow but let’s not turn this sub thread into the same wishcast weenie fest the NYC forum was with the last storm. Please and thank you.

Check out the gfs and euro.

Keep me posted

Everything is white rain when you’re under water.

That’s my take also. If we can start the whole pattern cycle of the last 30 days again but going into mid winter next time I think we will like the results.

It’s common enough. Is it a guarantee to evolve from there to a -NAO no. But it’s been how we’ve had some of our best blocking recently. Imo when we get ridging to come over the pole and displace the PV it’s much more effective as setting up a long lasting stable blocking pattern. Ridging over the top of the pole had a hand in both severe blocks in 2009/10, and in what was our most recent sustained cold season blocking in March 2018. Early stages of the Dec 2009 block Jan 2010 block developing Feb 2008 before the March blocking. It’s not the only way. 2011 the block progressed out of wave breaking from the mid latitudes on our side. But it’s been a common way we get good lasting blocking.

Eps is on board with scand ridging building day 10-15 also. It’s now universal across guidance. That’s important imo because it’s often a precursor to getting out of the crappy NAO look we’re stuck in now. Wave breaking on our side can temporarily help but if we want a permanent flip displacing the entire PV from ridging over the top is a good way to do it. ETA. If it is a sign of a flip we are ahead of past years that flipped and with a much more favorable temperature profile and pac pattern then recently. Something to watch with long range trends.

GEPS has the idea of the scand ridge pressuring the TPV over the top but with a better Pacific too.

all 3 globals look to be tanking the AO around day 10.

That's not bad...but what made 13-14 so rare was that the fronts kept stalling and elongating west to east through our area allowing waves to ride along them. Part of that was how the TPV kept setting up across to our north. The more w-e oriented we can get the front the better chance of something.

I like how you roll. I know some cringe at the "storm after the storm" thing but that is a typical progression for us.

I was about to say your prognostic skills are amazing. You can clearly see height building over the top from the scand ridge at the end of the run. It’s a common progression, similar to 2016, when the AO NAO do flip. Still too far out but hopefully that trend continues.

@mappy incoming... its just 24 hours too fast with the timing...plenty of time to correct

obvious disclaimer that this is all for "fun" but come on its holiday season we can dream. I could envision that energy crashing out west in this look arriving just in time for a merry Christmas!

A lot of time to change but yea it's going the wrong way. I am starting to get interested in the look after that. And this is certainly an interesting development. Yea its just an op run but its only 8-9 days out not day 15 and we know things can flip pretty suddenly without much warning up top sometimes. But this look is certainly "interesting".

The immediate lead up was classic but I was referring to the pattern progression weeks before. There bears some similarities to this coming situation. We were coming off of this torchmass crap pattern. Couldnt get any worse. But the eventual flip started with scand ridging that built over the top. Because all of north america was void of any cold at all we then wasted about 10 days of a pretty good pattern and a couple perfect track storms. Even up here I remember getting heavy rain with some slush bombs mixed in from a perfect track coastal in January and was like come on man! We finally built up just enough mid latitude cold under the blocking to get that one big hit. But the high latitudes stayed favorable the rest of winter and we had another 3-4 storms that without the super nino wrecking the mid latitude temperature profile across the CONUS would have been snow. But we can hope for a similar type of progression up top and with a less hostile temperature profile this time.

The blocking that helped with 2016 did mostly originate from across the pole. The Kara block was a major player. I am not sure it was every really rain, but the models did show a very marginal temp setup and some runs had a mix from 10-12 days out. From about day 9 in they started to lock in though.

The guidance, especially the euro, has continually tried to progress the pacific pattern and crash a trough into the west. In reality the Aleutian low keeps reforming and pumping the epo ridge. Any breakdown is brief.

More about AAM. I had that data from earlier filed away from a few years back when there was another debate wrt AAM and snowfall. But I wanted to look this up on a hunch. Low AAM is usually associated with a Nina and high AAM with a nino. So yes they do skew somewhat the way you would expect. But there may be some wag the dog going on there. If we take out Nina’s and cold neutral following Nina’s and only look at years similar to this one, neutral or weak warm enso following neutral or warm enso years...what would the results be for -AAM? Well there have been 8 such years with a -AAM. 1960-61, 1961-62, 1962-63, 1966-67, 1967-68, 1981-82, 1993-94, 2013-14. 6/8 had above avg snowfall. And get this, the 2 that didn’t were 1962 and 1994. Both were barely below normal at DCA but above for most west of 95 and both were memorable winters for various reasons. None of the 8 were “bad”. Finally im not even sure how - the AAM is going to be. It was running historically low in the fall but has been on the rise and is near neutral now. It’s also hard to predict. So using it as a predictor past 10-15 days is risky. Putting all that data together, I’m just not sure that one factor is worth much concern. I see nothing to indicate a -AAM enso neutral NOT following a Nina year would be a bad thing wrt snowfall. On the contrary the historical data says it’s good for snowfall. Furthermore, I’m not even 100% sold the AAM stays low all winter.

Apparently helping create a weenie catastrophe in the NYC sub earlier this week wasn't good enough for snow88, he decided to spread the love.

You seem to be in a dark place so I will throw out some numbers that might soothe the soul. ESRL kept records on the GLAAM from 1958 to 2014. They no longer update that. There are places to get it but I just used those years of record. In the last 50 years DCA has had 38 months with 6" or more of snowfall The GLAMM was - 12 times, Neutral 14 times, and +12 times DCA had 10" or more of snow 19 times The GLAMM was - 6 times, Neutral 7 times, + 6 times. There have been 17 seasons where 2/3 reporting stations had above normal snowfall during that period. The GLAMM was - 6 times, Neutral 5 times, + 6 times. Since 1950 the January/February months following a +AO December were 12 negative AO, 16 Neutral AO, 20 positive AO.