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Pattern Dazzling December

Chazwin said:
That look is honestly not that far off from the January 2004 Super CAD event….that one put the CLT area below freezing for nearly 4 days. It began with several inches of snow and sleet and then the rest of that time saw periods of freezing drizzle/mist with temperatures basically holding in the low 20s for several daysGTG
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I remember that one very well
 
I've always been one to come on here and praise a -NAO. It's right up there with a strong +PNA. Look what it did in Dec 2020. Several close calls with no cold air whatsoever to work with. With a cold available to be tapped a Greenland block can get it done.
 
Myfrotho704_ said:
Euro run no bueno. Let’s see what the EPS shows
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Yeah, can see here at day 10 how the GFS has the blocking more 'up over the top' compared to the Euro / and better on the west coast. Oh well, if there's a model run, let's analyze the heck out of it, lol

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try not to get too caught up in model-to-model swings in how long term storm track and 2m temps are represented- how favorable/unfavorable things look will oscillate. in my experience, i also wouldn't get too discouraged if a "pattern change" gets pushed back a few days or so. seems to always happen. there's a reason "lucy pulling football away" is a pretty evergreen reference on these boards.

frankly i'm not a big pattern/analog sleuth, plenty of amateurs here are probably way more apt at reading a hemispheric 500mb chart and teasing out what telecommunications are good or bad. but i will say that this seems to be the most classic "big -NAO" look we've had since march 2018, which was a month where snow chances seemed to appear out of the ether despite unfavorable climatology. i remember RDU clocked in some snow before I ran the rock n roll half marathon in early april. so take that as you will.
 
The entire hemispheric pattern retrogresses on most NWP during the 2nd week of December, in conjunction w/ the retrograding -NAO. The SE ridge slides westward towards the Rockies as we approach Dec 14-15th ish, suggestive that +PNA may eventually be in order. I think by around then we should have some decent snow coverage to our north from preceding storms to work with. Pretty typical evolution here for an evolving Scandinavian >> -NAO blocking ridge.

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12z Euro Ensemble member cluster analysis for days 11 to 15. Not a ton of difference though the weakest cluster on the far right has more ridging along the east coast and the top cluster on the far left is tucking low pressure underneath the block and rolling it through the Great Lakes at Day 11 and into the Northeast at Day 15 with a stronger low pressure. This would be an ideal progression as getting low pressure to strengthen and slow down as it moves into the Northeast and off the Northeast coast would set the stage for the next waves in the flow arriving from the west to slow down, head south, and deepen the eastern trough, a key component to driving colder air and the storm track farther south

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Broken024 said:
Weird ---- going on with the 18z gfs. Lows going the wrong direction lol.
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Snowfan said:
That ain’t weird. That’s the 18z GFS being the 18z GFS.
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Ha, that's what happens when the flow gets blocked....things start backing up and causing trouble, lol. GFS started out slow, but ended with a bang

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