psuhoffman

One notable improvement on the EPS through day 12, better depth of the trough in the east. That is important because its often what differentiated the "wins" from the "fails" with past similar patterns.

eps looks very "Feb 2015" at day 12.

in this case looks aren't deceiving.

It was 2 different bad patterns though. Dec 20-Jan 1 was a AK vortex -AO pattern. We have been in a pattern flux this week as the NAM flips very positive and the PV centers itself more over the pole/NAO side. During the transition we got some luck as a transient ridge traversed the PNA space...actually the ridge that will get here this weekend and lock in for a week. So we had one bad pattern...and transition week...and now another bad pattern... after that it looks like the next pattern might be more hospitable to sustained cold and snow threats but its too soon to know for sure.

If you don't mind me asking...exactly where are you? I know you are near Newark Delaware but exactly where makes a difference. There is a micro climate there wrt the Chesapeake/Delaware Bay and elevation. If you are where I think you are...it is kinda a snow anus. The low elevation between the Chesapeake and Delaware Bay really hurts you. You are also hurt by a downsloping wind off the hills to your west. I don't know how mobile your work situation is. If you went just 25 miles NNW from your area...some of the hills in that area with some elevation get over 30" per year. Just don't end up in the Susquehanna Valley. That area is a local minimum and would drive you crazy. The hills west of the valley do well for their latitude also. The light blue on that map is about where the 30" avg starts. My area btw.. isn't that much in the middle of nowhere. Hanover PA is only about 7 miles north of me. Westminster 7 miles to my SW and Hampstead MD about 5 miles south. I have 2 walmart supercenters within 5 miles. The westminster Mall is 7 miles away, the Hanover Mall about 9 miles. 2 movie theaters within 10 miles. Gettysburg is only a 30 min drive. My exact location on this ridge is rural but its a very quick drive to 2 towns that have enough to do that I never feel like it's a problem. WRT why the NWS uses avg versus median... I don't know. In a lot of locations that get snow more regularly the average isnt skewed as much away from the median or middle 50% range. In places where they don't get a lot of snow (DC) the fact that they can't get that much below avg because there is a downward limit of 0 allows a few huge snowfalls to skew the avg away from the median. But you are kind of backwards with the concept of how that limit skews things...the fact that it cannot be much BELOW avg because of the limit of 0 means the big years skew it up more than the down years skew it down. Again... you can make of the numbers what you want...you can expect whatever you want...but the numbers show that the most likely outcome for snow in any given year is between 10-11". And that the most significant number of years will fall between 6.7 and 15.8" with a few rare years above or below that. If you want to use 15.4 as "normal" fine but that wont change the fact that it only happens on average 2-3 times out of 10.

I had no problem with your post.

I usually analyze long range patterns through the scope of "how does this impact our chances of snow compared to normal". Doesn't mean HECS or BIG storm. If a pattern is likely to lead to a bunch of 2-3" snowfalls that add up to an above avg snowfall period...or a moderate 3-6" type event...that would still be something I would take notice of. But if the past comps to a particular pattern tended to yield either no snow...or at best a really minor 1-2" event...that would not indicate a good pattern to me. Yea a fluke 1-2" event can pop up in a bad pattern but it's not worth chasing that at long range because there really is no way to pick up on a "threat of a 1" snowfall" at long range. The markers for a particularly snowy period are more rare and therefor a bit easier to identify at range. Doesn't mean we would get a big snow...lots of good looks go to waste, and the pattern could end up completely different than guidance...but sometimes the drivers we need to get a snowy period can show hints at range. We saw the big snow threats (some ended better than others) in December 2018, March 2018, March 2017, January 2016 way in advance. And while the discreet events were hard to pin because of a progressive pattern we saw the potential for a lot of snow way in advance in 2015 and 2014 also. So picking out the threat of a snowy period at range doesn't always end in failure.

No he can question what I say all he wants in the main thread. No one has to use kid gloves with me. But he continually ignores "qualifiers" or misinterprets things people say. It isn't just me. He has gotten into it over that in the NYC sub also. Last week he was taking issue with frd calling a storm to our west a "cutter" because it might not have fit a canonical definition but everyone knew what he meant. With my posts he continually ignores the "if" qualifier and takes a hypothetical scenario as a prediction. When I said ..."If the AO/NAO doesn't improve January is toast" that wasn't a prediction but a possible scenario. It was a scenario I was worried about yes. The guidance right now is improving. They all develop a huge EPO ridge which takes the AO back towards neutral instead of +2/3. That is a significant improvement. But if the AO stays above +2 with that pac look we are toast...there are NO examples of a snowy month in DC with that profile. When I researched analogs to the projected central pac ridge/+AO look in January and it showed that about 80% of the time that pattern in January leads to a below avg snowfall year in DC that wasn't me being pessimistic, its just math. I said the probabilities don't look good. But I made a post that showed the better outcome analogs and what to look for if we wanted those also. But he only commented on the post I made about the "bad" analogs and said I was cancelling winter...when what I said was if that pattern locks in like these bad analogs did then were screwed. He continually takes issue with a specific way someone says something when its not positive, either stating something too strongly (which is ironic because he uses definitive adjectives when he gives positive predictions), or not using the exact perfect term to describe something...imo it doesn't add anything of value but he can continue to question me all he wants. Doesn't affect my day.

All guidance is starting to hit the EPO block hard

There is some divergence in the long range regarding the PNA. The euro is trending towards a PNA ridge...where the GEPS and GFS continue a -PNA. If the NAO remains positive and we get an EPO ridge (all 3 agree on that) I would actually rather a -PNA. 2015 was a great example of a -EPO+PNA+NAO working but there are more examples of that pattern failing. Feb 2015 Feb 1995 AFTER the one snowfall early in the month that took place BEFORE the EPO ridge set up. I could show more examples but frankly 2015 was an anomaly...historically a full latitude PNA/EPO ridge with a +NAO is a dry progressive pattern and when storms do happen they tend to have to amplify so much to come up they end up cutting. On the other hand...there are more examples of a -EPO/-PNA/+NAO pattern working. The key would be the depth of the trough and the alignment. Best example of a win with that look... Feb 2003 An example where our area did OK...but the best results were just North Feb 1994 An example of a fail in that look Feb 1989 You can clearly see the depth of the trough determined the outcome. 1989 the trough was simply not deep enough to keep the boundary south of us. 1994 the boundary ended up right through our region and 2003...well we all remember that. But there are more examples of that pattern leading to a snowy outcome here than the 2015 EPO/PNA ridge look. All of this is predicated on the NAO remaining positive. If the NAO goes negative either look suddenly becomes favorable and none of this matters. The details of all of this remain outside reliable forecast range...this is just to give a profile of what the different options look like. But a SW to NE oriented trough through North America under an EPO ridge with a suppressed SE ridge is a very good look to get progressive waves running at us with cold available, provided the trough ends up suppressed enough by the EPO ridge. The full latitude western ridge look has more mixed results with a couple "wins" March 1993 and Feb 2015 to name some, but a lot of total fails also.

some people KNOW what's going to happen...I am not one of them.

If the monster EPO ridge on all guidance is correct we do not "NEED" the AO/NAO to tank...but we do need it to pull back towards neutral or slightly positive which is what the EPS and GEPS is showing. The GEFS keeps swinging wildly between flipping the NAM negative or not but its been a hot mess lately and should be given much less weight until it starts showing some consistency. The GEPS and EPS especially have been much more consistent with a common progression/theme to the pattern evolution. The EPS idea of a neutral AO combined with that EPO ridge and some PNA ridging is just fine. It's not a HECS look but its a cold look and if we keep getting waves coming across with the active STJ and I would take my chances in that pattern.

By that time...phase 3/4 become more friendly also...and that is important if a wave fires in the IO it gives us more time in cold phases. A death near the dateline followed by a new wave initiation off Africa would give us a nice long extended run without MJO destructive interference. I have been skeptical of favorable MJO help. I am still not dancing in the streets but less pessimistic than a week ago. I know the bias in the guidance is to kill off waves early...but the last wave did die before cold phases, the waters near the MC are boiling, and the guidance was suggesting a stall/loop there which isn't unheard of (last year). But recent developments would favor wave propagation...but I will feel better once those projections get within 10 days. For now things look favorable for a colder period late January into February. Snow...TBD

A little but it wasn’t that far off from the pna ridge/+AO/NAO composite look. We definitely got lucky that a nice vort was passing at exactly the right time given how transient the pna ridge was. Our window was like 12 hours. But there were only 6 of those type storms so it’s not a high probability look but not unheard of. Of course yesterday’s storm wouldn’t show up in my sample because it wasn’t significant in the cities. In our areas we can luck our way to some snow a lot easier in flawed setups.

Moving this here before they come with pitchforks for both of us! Your scenario would be accurate except you forgot the 2 years in 10 that DC gets almost no snow. Those years offset the higher ones somewhat. But again you keep calling average normal. But if DC only gets an average winter 20% of the time is that normal? Those 2 big years skew the average higher than what DC gets the majority of the time. Like I said DC gets between about 7-15” half the time. 25% of the time more and 25% less. To me that makes that 7-15 range normal. You can call whatever you want normal but it won’t change the frequency or probabilities. Wrt your climo, the rain snow line often runs SW to NE in our region due to the fall line and coast. Your north is offset by your east. Your closed to the coast. My elevation is a big benefit. Without it I would only avg a little more than you. Your meso climate is also influenced by the Chesapeake bay to your southwest. That really doesn’t help. Again if you tell me what ball park # and under what conditions you need snow in a season to feel ok with it I could use the local coop data to tell you how often that happens. I could also tell you how far NW you would need to go for that to be a more normal occurrence. I don’t know your personal situation but if you moved only 20 miles to your northwest and to a spot with some decent elevation you could go from about 19” a year to 30, maybe even a little more. Your exact location is pretty bad for snow. And it seems very important to you. So why don’t you move 30 mins NW where a lot of these marginal events would break your way?

Thanks I got lucky today was an early release for students and PD for me. I guess because of that they just said heck with it.

Took a couple shots while my son was sledding on the hill behind Ebb Valley Elementary north of Manchester. This is looking north along 30 towards PA with Dug Hill in the background. My house is on top of the ridge in the background.

This is the snowfall recorded by the coop in Millers a few miles east of us. We have a little elevation advantage but I find their totals to be close to ours most storms. The second to last number is snowfall, the last is depth. They had snowcover from the storm on Jan 4th until sometime after the one on March 18th!

93/94 had such a crazy sharp gradient between places that had a ton of snow and not much. You didn’t have to go far. The closest coop to here in Millers had 44” that winter. That’s only a little above normal but they had snow otg from early January until late March. An incredible run. It seemed like every storm here was like 4” of snow followed by lots of ice. Places not far north of here stayed all snow and had 70”+ that winter. Every storm followed a similar track vs 2015 and 2014 which shifted the boundary around enough to get more regions into the fun. One caution, 2014 was the best but it had a helpful AO much of the time and even some NAO help in periods. If we get the ridge bridge look on the gefs and geps 2014 could be a good match. But if the AO stays positive like the Euro that puts us into a pattern more like Feb 1993, 1994, and 2015. 2015 was the best and it could go down that way again, but the other 2 had a lot of frustration with a string of snowstorms missing just to the northwest. But that look is still light years better than anything lately but given our choice the GEFS look with the epo AND tanking NAM is the better option to get everyone into the action imo.

I had to run to the recycle center in Westminster and it was 40 and significantly less snow otg. High here was only 33. The micro climate on this ridge amazes me every time I leave the immediate area. Turned into a beautiful day though.

Is it that much difference between up here and the high valley there? I’m at 31 now after a high of 33!

It won’t last long with that look up top, especially as we head later in winter.

@Bob Chill gefs would just need another 48 hours. That epo ridge among with the developing -AO would beat down the SE ridge. I don’t care if that takes 17 days v 14 days so long as that’s real I’m happy. It’s still early January. I said a week ago when the disgusting look showed up that if it locked in more than 2 weeks or so that puts us into really ugly analog territory and we wanted to be able to see the “other side” by mid January. It’s only the 8th and the other side might be showing. That’s totally fine by me.

Thanks. Was an inch too high right along the rain snow line maybe.

Small discreet events can pop up in a meh look, but don’t confuse what just happened for that. This was a transient period where we had a legit shot at some snow between patterns as everything was in flux. And this short window of opportunity was forecasted at very long range. At day 15 when it showed up and we couldn’t see past it some were hopeful it was a more permanent pattern shift and not just a transient window between suck fest shutout patterns. What I took some crap for was saying it looked like a transient cold shot as the pattern transitioned from a -NAM AK vortex pac puke pattern to a pac ridge +NAM puke pattern. Ironically the ridge that is progressing to the east and will lock in here for a while created a brief window as it traversed the pna domain, and we timed up a system perfectly for some of the area to get a good snow. But you are 100% that we can luck our way to small fluke snows in flawed patterns. But on the other hand if we want to get to a normal or above winter almost all of those feature a period with a really good pattern look. You won’t find many years where we luck our way above climo without one of those canonical snowy pattern looks I posted. Either a perfect epo or pna or NAM look. So if we just want to get to our “typical” crappy 8-15” winter across the region then yes we can do that with any pattern look with some luck. And when I say it doesn’t look good I don’t mean “no snow at all” just that the odds of getting any appreciable snow in that pattern are below normal. Likewise a great pattern doesn’t guarantee a ton of snow either, just that the odds are higher than normal. Sorry just wanted to explain how I analyze long range patterns wrt climo.