psuhoffman

Lol at flipping from suppression to warm layer worries...but the fact is both have to be a legit concern and the real culprit is the terrifyingly pathetic lack of true cold despite a freaking textbook perfect setup for a mid Atlantic snowstorm in absolute prime climo. We can’t blame pac puke this time. As I pointed out yesterday everything went right and this airmass was seeded from the Arctic. But it’s just not that cold. But the result is a double bind. The flow is perfect but that means it’s somewhat suppressive. So we can’t work with a really weak wave that doesn’t pump any ridging because that threatens being squashed. But without a deep cold airmass any wave that does amplify threatens to press a warm layer too far north. The area that gets good snow isn’t nearly as expansive as it should be in this setup. We could definitely still score here because this is a textbook perfect setup for a DC snowstorm. But it’s frustratingly more difficult then it should be given how good this setup is. Im out of ideas wrt temps. Everything went exactly the way we needed. Got the epo ridge to go up and cut off the puke. Got Canada seeded with air from the Arctic not the pac. And it’s still just not cold enough.

@losetoa6 this is the furthest south the cold press at mid levels gets during precip. And we can assume 850 doesn’t catch the exact warmest layer. So imo go 10 miles NW of the 0 line here and anyone south of that gets no snow on this run. This is where the 850 isotherm is as the best precip with the WAA band moves through. Anyone near or south of the line here isn’t going to get a significant snow, maybe a minor event (1-3”) before flipping but certainly nothing that would leave us feeling like we ended the curse lol remember the snow Map counts ice as snow. Even up here it looks like only about 2” of snow then changing over and we’re the northern edge of this forum. Yuck.

It’s no snow in DC. There is a warm layer at 850 that never gets south of about Baltimore to Leesburg. Anywhere south of that line is pretty much all Ice or rain. Those 2 are the same to me (I have no interest in ice) so I don’t bother to dig into that but it’s definitely no snow that run in DC. Yes some freezing rain.

I love your optimism but let’s be real since most can’t see the run. The 6z euro control would be a complete and utter disaster and lead to a forum meltdown. It’s all rain for anyone south of a Baltimore to leesburgh line and even up here it’s only a few inches changing to ice/rain. The entire DC area gets no snow...again.

1”% 3”% 6”%

EPS still likes the 28th/29th ETA: so it’s debatable whether this is capturing 2 different events over these 4 days or if it’s one event with timing differences. There aren’t any members with two hits. But members that eject a wave around the 28 that’s it. Other members wash that out and develop the next wave instead a day later. But bottom line is eps really like something between the 28-31

This captures the whole event

Straight filth

The setup has some similarities. That was a nino so a healthier STJ. This will hit a brick wall similar to how that one did. Similar blocking.

But is snowed a couple hours longer.

That block is legit. If the NS doesn’t phase with the TPV like the gfs...this won’t gain much latitude imo. But there is always room for a 30 mile tweak that gets the death band to Carroll county lol.

Perfect run for DC. Flush hit.

Euro still handling the tpv interaction different from gfs, hopefully same result as cmc & previous run Gfs euro

@Ji the 28th threat definitely not dead on the geps. Quite a few members with a storm there. I count 12/20.

Simply guidance tonight trended towards a much weaker wave ejecting out west. The ridge out west was actually better on the gfs. No real change in the longwave pattern. The setup is still there. But what had been a very healthy wave being ejected from the western trough suddenly went poof tonight. ETA: there are a handful of members in the gefs that still have it. Let’s see what the eps does before declaring it dead.

The cmc/euro and gfs are night and day how they handle the interaction between the western trough and the tpv between 100-120 hours. I wanted to show it clearer but the h5 plots for Canada weren’t updated yet for the cmc but you can see it here...by 120 it’s a done deal cmc/euro v gfs/Icon progression. cmc at 120 the tpv elongated on top of the western trough and did not phase. It’s instead suppressing the northern stream wave (NSW) lol. gfs same time the tpv had phased with the NS wave and look at that ridging east of it. It’s game over already at that point the divergence after is the result of that singular difference which actually happens around 100 hours up in Canada but those maps weren’t out yet. by 144 you can see the end result cmc the tpv elongated and broke a piece off that came across on top and crushed the NS wave. The SSW was left to amplify and you see the ridging in front to combat the shred factory on top from the blocking. gfs at 144 the phased NS system came across on top end wrecked our temps but also the flow under that is squashing the SSW. No chance in that progression. cmc and euro are both handling that the same way. Just trying to point out the why behind it. Hope someone finds this interesting.

Welcome to 2021

Lol I haven’t even started to analyze it. While Ji moves from precip plot to precip plot looking for blue I’m OCD analyzing all the different levels and details to see why exactly the run did what it did. Haven’t even got to the cmc yet.

It’s 150 out. That’s fine. You know details will shift slightly even inside 48 hours let alone 150. But again shame in this setup look at that rather pathetic scope of snowfall. It makes it harder to get a hit when the margin of error is so small.

Big if here...but if the euro cmc have the right idea with not phasing the tpv out west and crushing the NS front runner...then suppression is by far the bigger threat for places north of DC from the southern wave. That block is legit. The NS wave only cuts because it phases with a piece of that tpv. If it misses that boat it’s getting crushed and that southern wave will struggle to gain much latitude in this flow.

You aren’t going to like this but I’m not sure the gfs is going to cave. I still won’t bet against the euro when it’s rock steady over several days like this...and has the cmc on its side. But something keeps nagging me in the back of my mind. The way the gfs handles that western TPV is simpler. Less convoluted. Simply merges it with the strong NS wave diving into it. The euro on the other hand does this weird elongation and split to avoid that and instead through that odd progression ends up suppressing and squashing the NS SW. But 2 things bug me. 1 we are in a northern stream dominant regime. 2 the gfs progression is simpler and simple usually wins v convoluted. So yea the better guidance is on our side. But Nina climo, recent trends, and history of simple v convoluted setups are on the other side.

See that feature in Quebec on the euro. That was the piece of the tpv that came across in front and squashed the northern wave. On the gfs that instead phases with the northern wave. After that it’s a done deal both ways.

That’s because of the NS. Gfs still dropping too much energy from the TPV in western Canada into the western trough. That pumps ridging ahead of it and so the result is the NS wave on top can amplify. That becomes the show. The southern wave has no chance with an amplifying NS wave right on top and in front of it. The euro handles that tpv different. Elongates it down on top and squashed the NS wave. With that wave eliminated the southern stream wave has room to amplify.

Funny thing is it did at 6/12z and everyone kinda figured the fight was over but then it reverted at 18z and now has a buddy in the Icon.