psuhoffman

Maybe this belongs in the "climo" thread more and if so Mods can move it. But I wanted to point out something regarding what we are struggling with. Since this pattern set in early January we have been cold enough for snow about 90% of the time. Yet 90% of our precipitation has fallen during the 10% we weren't. That isn't just bad luck. That is the most likely outcome at our latitude (south of the mean latitude to support snow) in any pattern without blocking. The current favorable Pac bad Atlantic pattern is better then a no hope shut out the lights pattern we often get if the pac is bad or both are bad. Historically we could overcome a bad pac with a good atlantic sometimes but lately with the PAC on fire and the base state warmer it seems when the pac is bad it just torches the whole continent and the NAO can't save us. So realistically to get a really high probability snowy pattern we need BOTH to cooperate. Still a good pac isnt awful and it will put us in the game and eventually we might get lucky on some waves...but wanted to explain why we need luck. For most this is nothing you don't already know but we have some new posters. I am going to really really really simplify this. And for those that know more yes its possible to get a storm on the back side of a trough in a NW flow with upper level driven energy and vorticity or with localized WAA along a NW to SE oriented front. But those aren't the typical way we score so lets just make this simple here. Most storms are going to lift the thermal boundary north. As they amplify they will pump ridging ahead of them from the southerly flow. The cold boundary will lift with it north. If we don't have anything to resist this...we are too far south to end up on the cold side unless we get extremely lucky and a wave tracks just southeast of us out of pure chance. With blocking that is not the case. I am using Feb 2010 to illustrate this point. Look at the pacific. This would be absolutely awful without blocking. The mean flow into the central US is all from the SW. But we have that huge block with a northerly flow locked into the northeast so we actually want that southwest flow to our west to take the STJ and throw it up into the cold. Now look at the actual storm track. The primary for the 2010 storm was cutting to Ohio. But it ran into the blocked flow and was forced to turn east, develop a secondary, and slide east and out under us. Because of the block we had a HUGE window to win. ANy storm that tried to track anywhere between those green lines was going to end good for us because of the block. Nothing could cut so it would have to turn east under us. Right now we have a great pacific pattern putting a trough in the east. But without a block we have to get that trough to align absolutely perfectly to get a system to track just southeast of us by pure chance. There is nothing to "block" a storm from cutting west. So basically below is our current "win" box. We have to get a storm to accidentally track within that tiny red box. Again, its not impossible. We do get plenty of our snow from these patterns by luck without blocking...and if we get enough chances eventually we should get lucky...but I do think the big winters of 2014 and 2015 which I've said were probably flukes and not indicative of a typical outcome from pac driven no blocking patterns, skewed some wrt what to expect. This pattern is way way better than if the pac was a mess like most of the last 5 years. If we arent going to have a -NAO this at least puts us in the game. But it's a really frustrating pattern in that it is cold and you think it should snow...but we have to get the storm track to be absolutely perfect for it to actually happen.

For this region in general our snowiest period is Dec 1-March 15. About 1/3 of our annual mean snowfall is from Feb 15-March 15. Yet some people want to throw that away every single year. WTF

stop wasting time on the wrong wave and cue up the jaws music

I’ll be honest I’ve been busy the last few days and I think there is potential for waves after this frontal passage…but I’m kinda shocked we’re tracking this in here. I wanted to head up to northern Vermont (Stowe or Sugarbush) next weekend and I was just praying it doesn’t rain (or freezing rain same difference wrt skiing) all the way to northern VT from this and ruin the surface.

Pattern changes that happen in late December and early January often tend to be more indicative of the predominant winter longwave pattern. The current pacific setup has been extremely stable. So long as we continue to see the trough near or just west of the Aleutians and the corresponding epo ridge it will continue to be cold on the average here. If we remain in this pattern long enough I would think eventually we luck into some of these waves. Feb and March offers increasing baroclinic energy for these waves to work with. We were pretty frustrated at this time in 2015 in a pac dominant pattern also. There is still hope this ends well. For lots of places it’s already been going well, have to remind myself I’ve just been unlucky this year.

It was the lack of key wasn’t it?

The PBP yesterday when he wasn't doing it in the other thread was an epic disaster

First Last Final preliminary estimated penultimate primary early late call

One other option I wanted to point out. The end of next week the trough has been trending more strung out. If that continues there could be a threat that what was going to be the cutter becomes multiple weaker waves as the front presses and it’s not an impossible adjustment for that to become a threat if that trend continues.

We want the cutter further west. Recent runs are further east which pushed the boundary too Far East behind it and doesn’t leave enough wave spacing. Both options still alive. Also the option for any waves after.

Been in Baltimore at work. But nice big flakes when I left this morning. Happy Birthday.

I think the super bowl Sunday storm was the best example. Perfect track. Marginal airmass but peak climo. I got 6” and 95 got white rain at 35*. We know it’s warmer so it’s not a stretch to say that might have been a 32* 4-6” snowstorm in years past. Subtract 1-2” from all those other marginal events and suddenly it’s a 8” winter instead of a 15-20” one in the same pattern 50 years ago.

So I think you’re both right. We do have bad stretches of this length. But it’s also true we are in the midst of the worst 6 year run in DC history. I think it might be the worst for Baltimore also, just maybe not BWI which got lucky a couple times compared to the city. Unfortunately I think that’s the new normal. If you look at the patterns and random cycles of good and bad stretches they are pretty random but within that random we will naturally hit random stretches of bad years. But those bad years are getting worse. 12” years became 7”. 7” years became 3”. So each bad stretch is likely to be worse than the last. We don’t eek our way to 10-15” in bad pattern years often anymore. We sometimes even struggle to get much in decent patterns (now) anymore. I think we can still have big years. If we get some legit ninos and don’t get any big snows then it’s 4 alarm time! But we haven’t had that. The big storm drought is simple. No legit ninos since 2016. No storms since 2016. But the bad is definitely worse.

They need to stop with op runs post day 5. Don’t get me wrong the Gfs showing a hit 4 out of 7 runs was indicative of its potent and fun. It’s still not far off now. Ggem too. But the range of permutations ops will bounce around within that lead will still have misses pop up a lot even if it’s a good setup. Once within about 120 hours I’d start to worry if ops are misses. That said I love the gefs look. Don’t get me wrong I still want to see blocking. If we could keep this pac and get one more round of -NAO beside mid March…we can dream. But if we’re not gonna get any HL help this is the best look we can have for snow. The gefs snow mean day 6-16 is pretty good also. I see multiple chances. The day 8-9 threat will depend on the play between the southern wave indicated here and the NS. But while it’s similar look at the trough/ridge axis. Much better. Further west allowing ridging along the coast. We need that in a cold progressive pattern. And it’s following an arctic dump so unless we get a phased bomb it’s likely to contain significant frozen precip if the boundary wave can gain latitude. It repeats out to day 16 and looks stable. Results in these temps with this mean precip following the day 6-7 cutter. That’s as good a look as we could hope for without blocking.

You measure side to side right?

This isn’t a typical setup I do good in. Look at comps. Boxing Day nada. Nemo nada. Jan 2015 1.5”. Jan 2017 nada Bomb 2018 nada March 2018 1” not a great track record with off the coast track storms here.

Got some weird 4” max over me

You need to do PBP.

I think it’s supportive of the idea we want. These temps with this precip profile… but besides the fact they’ve sucked the eps also is all over right now. Gone through some radical shifts day 7-10 lately (not even way out in the 10-15 range we know is fantasy) and there is a huge amount of variability in members now. So I’d lean with gefs for now.

half past the intersect of blue and green

I didn't even make the gray

Dygdfttrt hdssryv kfduttedf gfssrgc jggr sswe igddtt doirdfg hdstfrrcv

Cold as bleep though. Has a nice looking pattern at 240 just dumps the whole trough into the east and squashes everything. A bit too much of a good thing. I'll bank on that being overdone.

Wrong storm. There will be a cutter next week. After that is the threat of a wave along the arctic boundary after it sinks south. Gefs can’t agree on which wave but there are a lot of hits day 9-16 between 3 different waves. Same general setup each time.

It’s time