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December Medium/Long Range Discussion


WxUSAF
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Holy $&@&$ 

Yep the h5 left just enough room to let this pull up the coast after a weaker start. Perfect track. I wouldn't worry about this weird warm pocket in the mid levels. Frankly looks wrong. Even if it's right it's sleet after heavy snow. But i don't buy that kind of thing from this range. Not with that track. 

IMG_7865.thumb.PNG.a87ef51388fe889998f5cecd950118cc.PNG

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2 minutes ago, Bob Chill said:

Dc barely mixes. Like a foot along 95. Close to 2 feet in central va. 15 in my yard 

The euro has a weird mid level warm layer for a time. I doubt it's right. Could I see mixing for a time as low passes with that track year. Hell 96 went to sleet all the way to Dulles for a time. But in heavy banding I doubt it. Any minor warm layer would mix out so it's not like we would waste much accumulation. Obviously just speaking about "if" this track were accurate. 

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1 minute ago, psuhoffman said:

The euro has a weird mid level warm layer for a time. I doubt it's right. Could I see mixing for a time as low passes with that track year. Hell 96 went to sleet all the way to Dulles for a time. But in heavy banding I doubt it. Any minor warm layer would mix out so it's not like we would waste much accumulation. Obviously just speaking about "if" this track were accurate. 

If we were inside of 4 days I would over analyze it. Gfs and euro are very similar now. Ens on board big time. Many of the necessary ingredients for a sig MA storm are in place. 

Northern stream stuff can be really hard to model beyond 4 days. If something is coming that will screw this up I would look there first.  So far so good but a lot of days to get through. 

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12 minutes ago, Maestrobjwa said:

*flag* False start--PSU 2 post penalty, repeat better analysis

Announcer: Wow Jim, PSU is gettin' a little jumpy--must mean he's starting to buy into this one!

Yea my analysis was a mess. I do buy this as a legit threat. I have for several days now. It fits the pattern. It's looked good since it came into range on the very end of the ensembles. That doesn't mean it's going to happen for sure but I do think there is a high risk of a significant snow in the mid Atlantic. 

In fairness the run did start out suppressed. Through 144 compare it to the past 2 runs and it's south and weaker with a stronger high on top and more confluence. 

Then even at 168 it's a weaker system down in Georgia but the trough axis is further west which allows enough ridging to pop along the coast and the northern stream gets out of the way just in time for the system to gain latitude and go to town. It was a late save. But that's almost perfect for what we want.

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Eps snowfall mean has backed off some from its 12Z run. Shaving roughly 2" off across the board.

917851512_00zepssnowfallmean..thumb.gif.6e2d5858a8a5e1df9235c5930c189f98.gif

 

Looking through the individual members, at this point the EPS has pretty much taken a full blown cutter off the table. We do see a few members start to cut but are forced to transfer eastward early in the evolution as they run into the blocking. One thing that we do see is that we have quite a few members now showing very strong blocking running in front and/or over top of the storm which is suppressing the system and in some cases killing it.

This stronger blocking could possibly be a concern for the DC/Balt crew and we have seen the eps trending in this direction.

Below we have a run from 2 days ago. Notice the high pressures located over the developing storm.

eps12zpressures.gif.ecba798b04290615457c03745f0a5f8c.gif

 

Now compare to the latest run. As you can see we have stronger pressures over-top as the storm tries to gain latitude. This would tend to suppress the system more so then the previous example.

epsoozpressures.gif.24ec4b0bcbb0e03136f5ac43c90b3e78.gif

 

Now the EPS isn't the only model seeing this tendency for stronger pressures. The GEFS is as well.

Here is yesterdays run.

gfsdec1pressures.gif.83b6af16e58f5d11adcd3f0a2450e8a2.gif

 

Now compare to the latest run. Again we are seeing higher pressures. 

gfsdec2pressures.gif.23c7c03a4c62216cb84b619496b9a1d9.gif

 

Now this isn't to say we don't need the blocking because we do. It helps to keep the storm from cutting to our west as it amplifies as well as helps to lock in the cold through our region. But too much of a good thing in this case means congrats Va or even NC as DC and north looks on.

Now we are still talking a week away so much can change but it may be worth keeping an eye on how the models are handling that blocking in future runs.

 

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Overnight runs were good I see. Now get your coffee and buckle up. Time to rinse and repeat. Only what, 6 more days of this? lol.

Meanwhile looking further down the road, the 'warm period' continues to look brief/muted. The AK trough is still a dominant feature, but in the LR it appears to retro enough to allow a PNA ridge to build. Baby steps, but this isn't bad. Rolling it forward (optimistically), one can envision how the pattern could get good again pretty quickly.  850 temps for Canada are what you would expect for this h5 panel- pretty torchy relative to average, so not a lot of cold air in our source region.

eps_z500a_noram_61.thumb.png.d3181a25d0200fd07454ca232353ac40.png

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@showmethesnow

Good write up. I have noticed that too on both the EPS and GEFS. Looks like the guidance is suggesting the strong confluence may inhibit the storm some as it moves further N and E. We have seen a few op runs where the low gains latitude then seems to move back to the south and east. Something to keep an eye on, and of course lots can change 6+ days out.

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8 minutes ago, C.A.P.E. said:

Overnight runs were good I see. Now get your coffee and buckle up. Time to rinse and repeat. Only what, 6 more days of this? lol.

Meanwhile looking further down the road, the 'warm period' continues to look brief/muted. The AK trough is still a dominant feature, but in the LR it appears to retro enough to allow a PNA ridge to build. Baby steps, but this isn't bad. Rolling it forward (optimistically), one can envision how the pattern could get good again pretty quickly.  850 temps for Canada are what you would expect for this h5 panel- pretty torchy relative to average, so not a lot of cold air in our source region.

eps_z500a_noram_61.thumb.png.d3181a25d0200fd07454ca232353ac40.png

LR is definitely improving. One thing I have liked seeing that the warm anomalies in Canada have muted quite a bit from just a week or so ago. Though warmer then average they now mostly are falling at freezing or below. Should not be too much damage (snow cover) to our source region for cold compared to what it was looking like before. Much easier to recover the cold through the CONUS vs. what we were looking at before.

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2 minutes ago, showmethesnow said:

LR is definitely improving. One thing I have liked seeing that the warm anomalies in Canada have muted quite a bit from just a week or so ago. Though warmer then average they now mostly are falling at freezing or below. Should not be too much damage (snow cover) to our source region for cold compared to what it was looking like before. Much easier to recover the cold through the CONUS vs. what we were looking at before.

Yeah it would be a pretty quick recovery if the AK trough retros back over the Aleutians and an EPO ridge can build. The latest edition of the weeklies did exactly that, but not until early Jan. Hopefully that process occurs a little sooner.

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4 minutes ago, C.A.P.E. said:

@showmethesnow

Good write up. I have noticed that too on both the EPS and GEFS. Looks like the guidance is suggesting the strong confluence may inhibit the storm some as it moves further N and E. We have seen a few op runs where the low gains latitude then seems to move back to the south and east. Something to keep an eye on, and of course lots can change 6+ days out.

I am not too concerned yet. Slightly different timing with the blocking over top and/or better cooperation at 500 mb with the shortwave and this is all a big nothing burger. Despite what I posted I have a very good feeling leading into this as I have had for almost a week now. 

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