psuhoffman

Pattern the last 7 days pattern the next 7 One of those gives us a much better chance of snow. And rolls forward only an even better chance. Snowfall on your yard is an awful way to determine whether there’s been a pattern change since even a better pattern can fall to produce snow. An awful pattern might yield a 5% chance of snow and a good one a 50% chance. Both might end up with the same ground truth, no snow, but that doesn’t make them the same. A couple weeks ago we got snow when a SW flow and 60 degree temps ahead of it! The SW flow isn’t the problem other than at the start. The problem on that run was there was no cold even behind the SW flow!

Most yes. There seem to be 3 groups. One that sees it and openly talks about it. One that sees it but would rather not bring it up. And one group that seems in denial (for whatever reason) and argues it’s all bad luck or cyclical and likes to find that one factor that’s not perfect to assign blame every time a marginal threat goes wrong. It’s that last group that my comments are directed at not the majority. But your right it’s beating a dead horse at this point and there are likely to be better threats ahead with more cold to overcome the thermal disadvantages we face.

Is that one of those IA models?

Everything is a see saw equation. It used to be that kind of H5 progression would overcome a marginal air mass in front. And it’s not day 1 of the pattern. We’ve had 5-7 days of a better flow into our source regions. How long do we need to wait. 10 days. 14. Do we need a good pattern to lock in for 20 days before we can snow? What if the whole pattern only lasts 10 days? By the time we get cold it’s too late! That’s what keeps happening the last few years. Im truly done. Some of y’all just don’t want to see it. Don’t want to admit it. It’s clear as day to me. Setups that used to tilt toward snow now tilt rain. It’s getting harder to snow. We’re losing storms on the margins. Deny it if you want. I’ve shown the evidence. The data backs it up. Doesn’t mean we won’t snow. Just we need more variables to be perfect now. Mainly we need a true cold airmass. Marginal air masses where in the past we relied on other factors to overcome the boundary temps are all tilting the wrong way lately EVEN WHEN WE GET EVERYTHING ELSE to go right! Our snowfall is declining. If some don’t want to accept that so be it.

You are looking macro. Pull back and look at the hemisphere long wave pattern. Look where that NS energy originates a few days before. It comes down from near the Yukon and dives through Manitoba. This isn’t some cut off southern treat subtropical system. It’s a NS wave diving down from northwest Canada. And look at the flow. As it dives into the upper Midwest the flow into our source regions is still directly from the north. Now as the wave digs to our west and turns east yes we have a southwest flow. But one that’s true of any wave approaching from the west. Anytime any wave is west of us we will have a southerly flow ahead of it. So what are you saying we can only snow from some negative tilt capture scenario where a wave bongs south of us and pulls due north? Good luck with that. Second look at the larger flow. Look where the air to our southwest originates. The larger flow to our area is still straight from the arctic! after this the upper low is amplifying and tracks to our south. Even if we concede the initial surface track is such that it would start as rain in DC there is absolutely no excuse why it’s not snow once the surface low is 988 off the coast with an amplified NS upper low whose SW originated in northern Canada and a deform band puking heavy precip on us. Finally, yes there are minor imperfections here you can point to and try to say “but if this or that variable had been more perfect” but I did a case study it every 4” snowstorm at BWI going back to 1950 years ago. And almost all of them were flawed in some way. The ones that weren’t were the HECS storms. Yes if we want 20” we need it to be textbook. 50/50, cold high, block, perfect track in every way. But that’s not true of almost all the 4-8” type storms we’ve had over the last 75 years! The reason they weren’t a HECS was whatever flaw it had. But one or two minor flaws wasn’t a reason we can’t get snow at all! There are a ton of variances. Micro. Macro. We could go over like 10+ important variables that influence a snowstorm to some degree. If we need every single one to line up perfect we’re screwed! I’m not saying we can’t snow if we get like every possible thing right. Of course we will still get a hecs if we get a 3 std dv block with a 50/50 and a 1045 arctic high over Montreal and a bonbinh 980 STJ system tracking up the east coast. I know that will still work. But that setup will happen once a decade. Are we F’d the rest of the time?

True but the fact we’ve had so little snow recently seems related to what we’re complaining about lol

There is a middle ground. After calculating the avg of the analogs I came to with I did reduce the snowfall to factor in warming. The number was still so high because the best matches to this winter were some of our snowiest winters ever. I acknowledged the risk and my fears regarding warning. We will see when it’s over if I miscalculated. Maybe the gfs is too warm. Maybe this storm doesn’t even happen. Maybe this is the one storm that falls into my “reduced” calculation and we still get 2 big snows in Feb and we end up with 35” instead of 45” and I was correct. We don’t know yet. But I love snow so the thought of losing and storms bothers me. Sorry. I totally get that some would rather try to ignore something that’s depressing and they can’t control. That’s probably healthier.

You make a good point. But it HAS been happening. People have just been sticking their head in the sand when it does. Super Bowl 2021 was the best example. There was a perfect track rainstorm last winter also.

This…Terp everything you said is why I said it “should be snow”. But the surface is torched. What’s terrifying imo is we all know our biggest years come in ninos typically without arctic air. This isn’t applicable to those times we get a wave in a true arctic regime. But we know 75% of our snow doesn’t come that way. If things keep warming eventually we will lose what makes up the large majority of our snow. I agree that one run is likely in error. But maybe we might be closer to that day then I thought.

I’m going to say this then I’m done commenting on that gfs run. If we actually get a few scenarios like that this winter (or like that Super Bowl storm in 2021) then my seasonal forecast will fail for one reason. I failed to correctly account for warning and it’s worse than I thought.

No because it’s irrelevant. The fact a sophisticated simulation (which frankly is biased cold) says that’s the most likely outcome based on its current data and physics is alarming. It shouldn’t be possible to have a vertically stacked bombing low there with a deform band right over us in January in a pattern where we’ve had a NW flow into the east for a week and get rain. How that doesn’t bother anyone is beyond me.

I don’t agree with the analysis based solely on the surface track. Details matter. The storm on the 6z gfs is tucked in tight but it’s coming at us from a southerly trajectory and it’s bombing and vertically stacked to 500mb by the time it tucks in close to DC. Notice the precip is wrapped up tight to the surface low. There are examples of that track producing nice snows for us. Yea it probably should mix at the height but with a vertically stacked system wound up like that as soon as the low is east of our longitude it should flip in the deform band. The track argument is really silly if you pull back and don’t focus on our own yard. How this frame isn’t conclusive and alarming is beyond me. What’s track have to do with it? Even if you cling to the “it tracks to close for DC” its rain the way to the NW fringe of precip in the deform except for high elevations which mitigates the boundary layer. Frankly that frame is absolutely terrifying to me. Were no longer a day into the pattern by then. We’ve had an NW flow into the eastern US for a week by then to establish a colder regime. Everything went 100% perfect for places a bit NW of DC (even DC should get a decent snow there) and it’s just rain.

True but I thought you were going at it with Stormy.

This was day 12-19 on guidance 10 days ago This is what it looks like now! Amazing job by guidance! You picked a weird time to start in with this anti long range crusade of yours when the long range guidance has been absolutely killing it lately.

If you don’t like to be corrected don’t post incorrect information. If you want to defend your position you are free to do so. Making personal attacks on me does not, however, validate anything you said or refute anything I said. Merry Christmas.

You’re entitled to your take. I’ve stayed out of it in that thread. But in a -pdo cycle both Nina’s and neutral winters are usually putrid for our area. El Niños are by FAR our best chance as a snowy winter. 5 of the past 6 above avg snow season in DC we’re a Nino. And the only exception was a neutral during an extremely +PDO. Something we likely won’t see anytime soon! So excuse us if we’re a bit hesitant to just toss what history and data says us by far our best chance at actually getting a snowy season following our least snowy 7 years ever! So tell me…with a Nina coming during a continued -pdo cycle…when is this “someday it will snow again” coming?

In late November we were excited by a projected blocking regime and what that portends for a Nino winter. And the block did happen. No one was discussing a snow threat for us from that. Guidance showed a warm pattern. The guidance I was referencing was NCEP analogs. It wasn’t a forecast, it wasn’t the predicting 1996 and 2002, what that product was showing is that in the past similar patterns to this have produced varying results. Some good some not. Subtle differences could be the difference. We all are familiar with your feelings regarding NWP. That’s fine. You’re entitled to your opinion. But these weren't good examples to plant your flag. It’s not the 1990s. Guidance has become incredibly good at identifying the long wave pattern day 5-10. I can’t remember the last snowy period that guidance didn’t indicate was coming way before day 5. Frankly usually we see the signs before day 10. A discreet event might not show until inside day 5. But lately the vast majority of even discreet threats show before day 5. Even that marginal funky anafront wave showed up on guidance from 5 days out! A pattern change doesn’t mean we instantly snow. You seem overly focused on snow otg but in the long range we’re often discussing a process. There was no cold anywhere in North America. We can’t go from that snow by snapping a finger. It’s taking some time after the long wave pattern flips to establish enough cold in our area to get snow. Even then we will need luck. It is a pretty good pattern to get a snowstorm in the eastern US. But it could go just north of us. Just south. Cut island a bit. Out to sea. A good pattern doesn’t guarantee snow. We also need luck.

All I want for Christmas is fringed

Pattern analogs are useless right now. They’re spitting out some incredibly snowy periods (1996,2010) and some years that had almost no snow (2002, 1981). Subtle differences can tilt this either way.

Guess I missed all the fun. Merry Christmas everyone.

Because there isn’t an eminent threat before that to discuss. If we had a storm 3 days away no one would be looking at day 15

But the pna

But the pna

I know it can still snow if everything goes right. The issue is most of our snow comes from marginal flawed setups. And lately most marginal situations seem to be tipping the same way and it’s not the way we want.

We were discussing that model run though. My point was on that simulation we got everything to go right wrt the track of that clipper and it just didn’t matter because the boundary temps were too warm anyways.