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Chill Storm Discussion and Obs


WinterWxLuvr

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Doesn't really matter because we all lost again...another snowless holiday period/December in the MA...ho ho ho

Seems the prudent thing to do in the future is to follow the models out to 120 hours or so and then stop there because they're just unreliable past that point in time. I'd be interested if someone could explain the reason the blocking was so different on the 12z run.

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You can see the change in height patterns start showing up early on the GFS. By 72 hours they're obvious. Seems our storm is very sensitive to any small change. With 4 days yet to go, this probably isn't a done deal yet.

That's something that has been bugging me for days now. It's very sensitive and subtle what is going on in se canada and the maritimes. At this stage in the game it's getting much easier to resolve than 6+ days out. So, the trends today are unnerving. Not a done deal yes. Getting back to where we were yesterday and then going better? That's a tall order. Sure I want to hope for it but I think we only have a few chapters left before we have to suck it up.

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Seems the prudent thing to do in the future is to follow the models out to 120 hours or so and then stop there because they're just unreliable past that point in time. I'd be interested if someone could explain the reason the blocking was so different on the 12z run.

Runs the 500 vort loops with the last 3 gfs runs. Last night it kept the blocking ull low intact as the system approaches. 6z it stays in tact long enough but opens up at the end. 12z it opens up and ejects before it can help.

The type of blocking feature isn't classic. It's transient and always has been. But multiple runs showed it hanging out for long enough and strong enough so it's not like it wasn't possible. But the last gfs (and I assume the euro) just ejects it out and lets some ridging build in in it's place. Which in turn lets the ull and 850 low take a further west track. The risk of this happening has been there the whole time. It just gave the appearance that the risk was going away...until today...

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Picture worth a thousand words. Same point in time with the last 3 gfs runs below.

0z looks great. Closed elongated ull just acting like a perfect block. No storm is going to go straight into it.

6z starts showing the problem. Closed low still there but further east and ridging starting to push into se canada. But the 50-50 is good enough to keep the track from going west.

12z shows the blocking low wide open and moving east. No chance it can keep the track from going west...and here we are...

Is todays solution correct? Heck if I know but the trend is super easy to see in the 3 panels below.

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Seems the prudent thing to do in the future is to follow the models out to 120 hours or so and then stop there because they're just unreliable past that point in time. I'd be interested if someone could explain the reason the blocking was so different on the 12z run.

If you're looking for a snowstorm but if you just want to know whether it might be sunny versus having precip it has been pretty doggone good pretty far out in time. It's all about expectations.

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Runs the 500 vort loops with the last 3 gfs runs. Last night it kept the blocking ull low intact as the system approaches. 6z it stays in tact long enough but opens up at the end. 12z it opens up and ejects before it can help.

The type of blocking feature isn't classic. It's transient and always has been. But multiple runs showed it hanging out for long enough and strong enough so it's not like it wasn't possible. But the last gfs (and I assume the euro) just ejects it out and lets some ridging build in in it's place. Which in turn lets the ull and 850 low take a further west track. The risk of this happening has been there the whole time. It just gave the appearance that the risk was going away...until today...

Thanks, Bob. Fwiw, JMA still hanging tough for us lol.

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Doesn't really matter because we all lost again...another snowless holiday period/December in the MA...ho ho ho

Well at least its not a torch. We don't typically get anything good in the MA in late December anyway, and with the really crappy Pacific the odds were always stacked against anything good happening. Who knows maybe the models are still under forecasting the strength(or existence) of the block, but the recent trends aren't encouraging.

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If you're looking for a snowstorm but if you just want to know whether it might be sunny versus having precip it has been pretty doggone good pretty far out in time. It's all about expectations.

I give the GFS credit. It had the storm in this "general" location at roughly the same date and time for nearly 2 weeks. Obviously it was all over the place on the thermal profiles and the track it takes from the gulf states, but otherwise it has been onto this storm from the long range.

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Picture worth a thousand words. Same point in time with the last 3 gfs runs below.

0z looks great. Closed elongated ull just acting like a perfect block. No storm is going to go straight into it.

6z starts showing the problem. Closed low still there but further east and ridging starting to push into se canada. But the 50-50 is good enough to keep the track from going west.

12z shows the blocking low wide open and moving east. No chance it can keep the track from going west...and here we are...

Is todays solution correct? Heck if I know but the trend is super easy to see in the 3 panels below.

Is the storm also appearing to becoming more negatively tilted in the 6 and 12z runs also?

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And if we want to restore hope the focus should be on the maritimes area with future model runs. If the track inches back east later today and tonight but the condition of the block isn't greatly improving at the same time then the shift in track shouldn't be considered a move back to where we were yesterday.

Everything hinges on the evolution of the big storm that moved through yesterday and if the christmas vort helps or hurts. When I run the 6z it give the impression that the xmas vort helps pull the block further east but I'm not sure it maters much because it's already opening up and ejecting before the xmas vort gets to the same latitude.

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Is the storm also appearing to becoming more negatively tilted in the 6 and 12z runs also?

I suppose it does when you look at the panels and compare but the reason it looks like that is because the block is becoming less effective so ridging can start to build. So, I guess what I'm trying to say is the more neg tilt is more of an effect of the deteriorating block placement than anything else.

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I give the GFS credit. It had the storm in this "general" location at roughly the same date and time for nearly 2 weeks. Obviously it was all over the place on the thermal profiles and the track it takes from the gulf states, but otherwise it has been onto this storm from the long range.

The GFS is really good on the whole. I like its record at least anecdotally when it comes to sniffing out long range threats. Any model bouncing a lot from run to run without much support should be downgraded at least while doing so though.

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How can we give up on this 5 days out? A simple change in the block (back to where we were), and we're back in the game easily.

Heh, nobody here gives up until the fat lady. Loosely translated the day or 2 before the storm. Or on the day of. We may act like it but everybody will be watching every run for the entire winter.

Things can improve for sure but the trend is unnerving considering where we are in time. I will gladly eat these words at 18 and 0z.

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Anytime there's a noticeable jump in one model run it makes you wonder if there was a big change in initial data. Way out in time those differences don't necessarily show up because you expect there will be big shifts. But under 5 days makes you wonder if the latest data had that much of an influence. But, the differences really aren't all that great in the upper levels but they make a big difference at the surface. Of course it was always marginal on track and temps so any change back west was going to have a big impact.

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Anytime there's a noticeable jump in one model run it makes you wonder if there was a big change in initial data. Way out in time those differences don't necessarily show up because you expect there will be big shifts. But under 5 days makes you wonder if the latest data had that much of an influence. But, the differences really aren't all that great in the upper levels but they make a big difference at the surface. Of course it was always marginal on track and temps so any change back west was going to have a big impact.

I can't recall if it was Wes or some other met, though I think it was Wes, that said the models always over do the 50/50 or block to our N & NE the further out you are, thus why we get soooo many proged snow events 4 days+

as we get closer to the event 3 day or less, reality sets in and the storms go north or west (the NINA effect I'll call it)

still time, but I think the writing is clearly on the wall that things won't play out as some of the snowier/wintry runs have been showing for the last 2-4 days

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Anytime there's a noticeable jump in one model run it makes you wonder if there was a big change in initial data. Way out in time those differences don't necessarily show up because you expect there will be big shifts. But under 5 days makes you wonder if the latest data had that much of an influence. But, the differences really aren't all that great in the upper levels but they make a big difference at the surface. Of course it was always marginal on track and temps so any change back west was going to have a big impact.

I wouldn't be surprised to see the gfs jump back towards the east this run as the models are really having trouble with the pattern over Canada though that might still not save most of us but could help you. IF so then of course the next run might jump back west again.

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I wouldn't be surprised to see the gfs jump back towards the east this run as the models are really having trouble with the pattern over Canada though that might still not save most of us but could help you. IF so then of course the next run might jump back west again.

18z GFS is the only run Ji should look at. If it's bad, we're really in trouble..

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no one believe all snow but western burbs getting a few inches and then ice before rain seemed on the table

Wes makes a good point. With models struggling in Canada, I don't think you can say that solution is of the table. If anybody is 500mb savvy, you can see how the Vort lobe in Canada is all over the place on guidance, as well as that block.

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