psuhoffman

I got a slushy dusting this morning. Elevation helped. Going north to Hanover to get breakfast there was nothing otg once off the ridges.

Yea without blocking to slow down the flow a -epo/-pna is actually a better chance for a decent snow. It also increases the chances of a cutter but you have to roll the dice to win. With an epo/pna ridge we really actually want some southeast ridge or else it’s a dry look.

York area got 1-2” from that convective band that went just to our north earlier.

Truth is with a late developing coastal the further northeast the better. These often develop slower than guidance and screw over whoever thought they were in the southern area of snowfall. I also get annoyed with the “it jumped over us” thing. It didn’t jump over us. If the primary tracks to our south we do fine with a miller b. When that happens it’s usually a miller a/b hybrid since a pure northern stream miller b has a hard time digging far enough south and not get squashed doing it to work. But when a system comes at us from the west at our latitude it doesn’t jump. The best lift from the WAA associated with the low simply goes north of us and the mirage of good precip from the upslope to our west dries up when it downslopes. Same as with a clipper. We will always get less precip from a southwesterly flow due to downslope in any system. Then the coastal is going to develop a ccb way too late if it’s developing at our latitude. The only reason it looks like a jump is the mountains to our west create the illusion the system created snow all around us. Really the snow just went to our northwest as the primary tracked to our northwest or too close to us to keep us in the best WAA precip to the north of the track and downsloping killed the rest. The coastal is irrelevant since it develops after the system passes us. If the primary tracks to our south we do fine as we keep enough of an easterly wind component. That just doesn’t happen often because we are too far south. ETA: Once every long while there is a true system that transfers over a long distance and “jumps” completely over an area but it’s way more rare than we use that term for any system reaching west to east that develops into a coastal late.

No doubt it’s off. If you add up the members snowfall at DCA it’s mean is about 1.8” yet it shows almost nothing.

@C.A.P.E. @showmethesnow @Bob Chill One other thing to consider...the mjo/Indian Ocean/tropical pac forcing doesn’t always drive the bus. But within the last 18 months it largely has correlated well with our patterns. With the effects of most recent wave through cold phases wearing off its likely we fight that for a time. But just because last year it went into warm phase hell and mostly stayed there all winter doesn’t mean it does again. The warm/cold pools around Australia and in the Indian Ocean have shifted since then. Let’s see how the mjo behaves. It’s been spending a lot of time in phases that would be good come winter. If it cycles through the maritime continent regions quickly this time I’m confident we don’t waste much time. If it starts to stall and go ape in phases 4-6 then I will concede our prospects of a good year are probably shot. Even then though I will adjust my expectations and chase whatever scraps we may get.

There is a lot of divergence within the members past day 10.

Nope you’re right. I’m a dum dum and hit the cm instead if in link. It’s just off. Someone should shoot them a message to figure out what the glitch is. If it actually is using median that’s actually probably a more useful tool than the mean which is always skewed by a couple weenie members.

It’s not a good sign. But I’m also not getting too worked up yet for several reasons. The TPV is going through a major migration and its unknown if it actually sets up shop there or continues and gets displaced into Quebec. We will know soon but as of now it’s not definitive. The PV continues to take a beating and we will have to see what happens with that but some of the analogs had a +AO period early then a more favorable one later. But the biggest reason is I’ve pretty much written off the AO/NAO and am looking for how to win without because for the last 8 years we have been in the worst stretch regarding those 2 features ever and yet DC has had 4 above avg and 4 below avg snowfall years in that span. And region wide our average during that period is about where it should be. So to think a bad AO is doom isn’t true. I have some ideas as to why. For whatever reason the North Pacific has had a tendency for extreme ridging that floods North America with cold at times. That has offset the neee for blocking some. On top of that the tightening of the thermal boundaries (perhaps related to you know what) seems to increase the chances of these progressive waves in epo patterns having some juice to them. And (perhaps due to the same thing) when we do get the rare transient blocking help we seem to score at a higher rate than historically. All that said it’s not good to have a positive AO. We have had 3 totally god awful seasons in those 8 and no AO help would open the door to that. So I hope no one thinks I’m saying forget the AO. I guess I’ve just come to accept we are in a prolonged cycle where we will have to find ways to snow without much help there.

The color key is different. When you look at the ensemble mean the gray starts at 1” and the blue starts at 5”. It gives the impression the mean is different from the individual members. Still stupid to change the key that way. Adds confusion unnecessarily.

So you’ve met DT...

Yea the flip sucked but that’s looking way too far out to use analogs that way. Also our area did manage a couple more snowfalls even during the crappy warm Jan/Feb.

Several notable Decembers show up in the top 10 analogs from the GEFS superensembles today. December 1963 is the top analog. Dec 2002, 2009 also show up. 1989 is in there, I know that was a somewhat frustrating month snowfall wise but it certainly was cold! Of course the problem with the long range analogs is they are only valid assuming the advertised pattern on the GEFS is correct.

The CFS has been shifting to a colder look lately. The weeklies already shifted the god awfull look to only a couple weeks before its building a decent look up top again towards January. The whole run after week 3 is ambiguous and useless garbage actually but the idea of a wall to wall suckfest seems to be evaporating on the long range guidance.

Since we are getting to the time when we can start legit tracking, and specific patterns matter for our snow chances thought I would post this. This first image is the composite of our 5 biggest snowfalls region wide in the last 50 years. All of these featured a nearly identical setup and this is the money h5 look if we want an HECS What sticks out here is the NAO blocking as well as a perfectly aligned PNA ridge in the mountain west and the presence of the lower heights to our northeast indicating the 50/50 feature. That trifecta is the best look for a snowstorm here. But most of our snowstorms aren't an HECS and we often have to work with a "flawed" pattern. I see lots of posts worrying about one feature or another and what phase it needs to be and often its not that simple. Take, for example, the EPO in that image above. Without the NAO that pacific look would be atrocious and would flood the CONUS with pac puke air. But with the combo of the NAO/PNA it works. There are a lot of moving parts that play off each other. Changing one impacts what we need from another. It's like a big balancing act to get the general longwave pattern to line up in a way favorable for us. So if the guidance is correct and we head towards a -EPO, -PNA, +NAO pattern what would that look like? First of all we need the EPO to be centered far enough east that the ridge builds over the top of the PNA trough into northwest Canada. This look from last February did not work because the EPO was centered too far west to suppress the height patterns over the east and prevent the SE ridge from going ape. Look where the pacific ridge is centered, south of Alaska and north of Hawaii. Way too far west to do us any good. There was some ridging over the top but not enough to offset that problem. We needed either a further east EPO ridge or more blocking. It was frustratingly close to good, and we did get some snow during that period, but in the end it was mostly a let down. But we have had snow in a -EPO, -PNA, +NAO period before. This is a composite of several decent winter events across our area from such a pattern. I also only used years that had some similarities to this one and were in my analog set for one reason or another. The composites are centered around the snowfall events of Dec 5 2002, Feb 6 2003, Feb 26 2003, Dec 8 2013, Dec 10 2013, and Mar 5 2015. You can see the difference in where that EPO ridge is centered compared to last year. All of these systems had some commonality. They were all progressive waves. That doesn't mean a decent snowfall isn't possible. Some of those dropped as much as 8" in parts of the area, but it is not an HECS or even MECS pattern. Anything that is too amplified is very likely to cut. It is a big storm pattern for the Lakes and New England as a wave that amplifies would be perfect for them in this setup. For us we want a progressive pattern and ideally get something slightly amplified with some 50/50 help to get a moderate event out of it. But it is far from ideal and there are many examples of a -EPO pattern that is just cold and dry and it warms up before any organized system comes along. But it is not a shutout pattern and we have had snow from this look, and these were examples of somewhat similar years where that happened to some part of our region. We can all look at the guidance and decide which pattern this coming one seems more similar too but of course proceed with caution as the guidance is likely to adjust some with the look at day 10-15...but for the record this is the current advertised look on the GEFS for early December. I do like where the EPO ridge is centered there and where the trough axis is across the CONUS. But...that doesn't guaruntee anything. It just means that IF the guidance is correct that would be a pattern that could produce something if we get lucky. But there are a lot of if's in that statement. But if these looks are close, perhaps our first legit threat window for frozen is close at hand. Happy tracking!!!

We can survive a -pdo if the epo ridge builds over the top into NW Canada which suppresses the flow across the conus some. Problem last year was even when we had an epo ridge it was centered too far west which allowed the se ridge to pump.

One other thing wrt an epo pattern, there isn’t much correlation between the epo and snow. But that’s because a west based or shallow epo ridge doesn’t help at all. But when the epo ridge is east based or builds over the top into Canada it does seem to correlate with snow here better.

If this becomes an epo dominant pattern something to keep in mind was how ( Ithink it was 2013/14) the guidance kept muting the epo ridge in the long range and absent NAO help torching us. That of course never happened.

I've never tried them but I've heard they are really meaty!

The Sunday system would be a nice snowstorm if this were a month later.

Actually you couldnt get a better H5 match to the long range GEFS look than early December 2013. DC south didn't do so well (frankly their climo early December is a BIG problem) but everywhere NW of there had a pretty good run with several snow/ice events during that period. Of course everyone won when that look repeated again and again during prime climo.

GEFS goes ape with the epo ridge in early December and floods the whole conus with cold. Enough SE ridge though to suggest the boundary would be close enough for some threats. That kind of a pattern is when some SE ridge isn’t a bad thing. Otherwise it would just be cold and dry.

CMC has a similar idea. Forces the system under the block just slightly too far north for us. Frozen Mason Dixon north. But same idea for that range.

This place is always good for pure entertainment regardless of the weather. I love you guys! Winter is almost here. Snow or not let’s try to enjoy the ride.