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Christmas Storm


Cold Rain

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There's been lots of speculation about and hoping for a SE snowstorm around Christmas. Certainly the threat has shown up and vanished on various model iterations. Today's 12Z GFS shows the possibility of such a storm. Since we're inside the 10 day window, we might as well discuss it, just for fun if for no other reason. Look at the 192 500 mb map:

post-987-0-73164200-1292607172.gif

You'll notice a southern stream shortwave that has traversed the country as well as a northern stream wave dropping south. There's a block around Hudson's Bay and a vortex off of SE Canada. There's also moderate ridging over the Rockies:

At 204, the block and vortex are still in place, but due to the progressive flow, the ridging has propogated east. The northern stream and southern streams have phased right over NC:

post-987-0-54712100-1292607178.gif

At 850 at 192, the 850 low is over WV and PA, not a snowy pattern for the SE, which you can see by the 850 0C line west of the mountains:

post-987-0-00720600-1292607196.gif

At 850 at 204, the storm has reformed off the NC coast and the 850 low is now off the VA coast, so presumably, 850s are now favorable for most:

post-987-0-59419100-1292607204.gif

At the surface at 192, you can see what looks to be a Miller B situation (the previous frame had a consolidated low moving in from the west, but this frame shows a redeveloping system). You'll also notice a nice 1036 HP, located in south central Canada:

post-987-0-30739900-1292607210.gif

At the surface at 204, you can see a consolidated storm off the NC coast with precip being thrown back inland. You can also see that the HP has moved farther north into Canada:

post-987-0-52394500-1292607217.gif

So with 850s now cool enough and precip being thrown back inland, portions of NC are receiving snow, right? Well let's take a look at the 700 mb moisture fields at 192 and 204:

post-987-0-52426700-1292607183.gif

post-987-0-72668500-1292607190.gif

As you can see, at 204, the moisture has moved north and east. Remember that precipitation shown on many of these panels is accumulated precip. The temp. and mid-level moisture profiles are specific to that time frame. So in this case the cold moves in and the moisture moves out. At 192, there is precpitation, but it is not snow. At 204, it's cloudy, misty, and cold.

This is just what the GFS is showing many days out. It's certainly not going to have a handle on all these features, especially the phasing of them. The important thing is that the players seem to be on the field, at least on this run. I would really like to see this whole setup press south a bit and have that HP start to show up near the Lakes.

Anyway, beyond that, the pattern shown on the model, which is worth less than my 1978 Le Car, looks pretty decent for something to happen. Hopefully, some of the other models will have the threat and continue to have it as we approach Christmas.

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One crucial thing I've noticed is that the models are trending warmer in the south with subsequent runs overall. Yeah, with the gfs this is expected due to the cold bias but that is not the only reason.

It looks to me that the jet is tightening and the flow from east/west is the culprit as cold air just cannot penetrate southward in that set up. La nina and -pdo really showing up here,i.m.o..

Look how far east the cold air shoots under the LP's while they sit up around the NE coast; all the way up under it!

If, there was a strong ridge positioned in the atlantic connecting with the greenland block then a blocking mechanism would be set up to allow for a deeper trough into the SE even without a ridge out west. I recall Chuck doing a post on how an atlantic block actually provided a colder deeper trough in the east than a greenland one.

Many times you get the connection but, they don't hold as the block disconnects and pinches off over greenland and the other segment around bermuda or just pushes on out eastward. Also, that connection usually starts with an atlantic one that progresses into Greenland and cycles to the aforementioned outcome.

Right now, I would go with the odds of a wet christmas for the SE if the Miller b is strong enough with a trailing front pulling in ample gulf moisture. Not far off from today's 12z gfs depiction; actually makes sense with the pattern,imo.. Depending on timing. sure, may be some residual as well as upslope snow on backside along the western apps in time to partially salvage a white christmas for some folks. Also, the Ohio Valley/ Dc north crew are looking good for a white one this year as the tuesday clipper along with the miller b should lay down a good cover up there,i.m.o.

Of course, all this is speculative and based on model guidance timing. as we all know alot of things change and will, so jmo of a possible outcome or better put, w.a.g.lol..

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Models can't even nail a storm 72 hrs out currently, so what makes you think this one will be different. If this does not pan out, I want a refund on my expectations since they were "guaranteed." Rule #uno in the SE, outside of the mountains, SN is never a guarantee.

I didn't say "where" it was guarenteed...or that it would even be snow. :P

When Cold Rain starts a storm thread, we'll get some snow. You watch, buddy.

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We're in the same cycle. Storms drop in from northwest = no good for the lee areas of southern/southwest NC outside of mountains or any of SC. It could work for I-40 and the mountains and points north and west though, as happened already, and on the west side of the Apps. If it drops futher south in the Plains and taps the Gulf then maybe, but thats asking a lot.

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You're in Southern North Carolina. There aren't too many patterns that are very good for snow down there.

Those "patterns" however, tend to screw the MA and NE, and it looks like we are in one currently, at-least from this end climo speaking. :snowman:

Most storms that effect western NC with heavy snow, will not effect areas north of southeast VA and the lower Delmarva with heavy precip.
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Models can't even nail a storm 72 hrs out currently, so what makes you think this one will be different. If this does not pan out, I want a refund on my expectations since they were "guaranteed." Rule #uno in the SE, outside of the mountains, SN is never a guarantee.

Cold Rain was creator of this thread.

His true intent was to guarantee cold rain. I think he will be proven correct. arrowheadsmiley.png

I'm dreaming of a white Christmas...

I'm dreaming of a cold, rainy Christmas

just like the ones I've always known

Where the treetops drip of rain,

and children shiver inside

to hear raindrops hit the roof

I'm dreaming of a cold, rainy Christmas

With every Christmas card I write

May your days be dreary and wet

And may all your Christmases be 33 and rain

I'm dreaming of a cold, rainy Christmas

With every Christmas card I write

May your days be dreary and wet

And may your Christmases be 33 and rain

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Queencitywx. I've thought about going to the Music City Bowl. That would at least guarantee you a white New Year since I would be away from the Apps...I'm sure that guarantee would cover the Piedmont. In all seriousness, the nw flow appears to be further north on the GFS. Looks warmer. I'm banking on the equal chances January mentioned by the CPC yesterday.

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Queencitywx. I've thought about going to the Music City Bowl. That would at least guarantee you a white New Year since I would be away from the Apps...I'm sure that guarantee would cover the Piedmont. In all seriousness, the nw flow appears to be further north on the GFS. Looks warmer. I'm banking on the equal chances January mentioned by the CPC yesterday.

I'm going to England December 31st-January 9th.

It shall be an epic and snowy period for the SE because of my absence!

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I'm going to England December 31st-January 9th.

It shall be an epic and snowy period for the SE because of my absence!

I have no doubt! If it does, we may take a collection to prolong your trip. However, looking at some models, you may travel from rainy, cloudy conditions and arrive at rainy, cloudy conditions. Enjoy your trip. Sounds good.

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Cold Rain was creator of this thread.

His true intent was to guarantee cold rain. I think he will be proven correct. :arrowhead:

I'm dreaming of a cold, rainy Christmas

just like the ones I've always known

Where the treetops drip of rain,

and children shiver inside

to hear raindrops hit the roof

I'm dreaming of a cold, rainy Christmas

With every Christmas card I write

May your days be dreary and wet

And may all your Christmases be 33 and rain

I'm dreaming of a cold, rainy Christmas

With every Christmas card I write

May your days be dreary and wet

And may your Christmases be 33 and rain

Ha! :lol:

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The Cold Rain Christmas storm is still very much on the table. I know the focus has been on today's event, as it should be, but the 0Z GFS, 0Z Euro, and 0Z Canadian all have either the storm or the potential for it. GFS and Euro look to move the LP just a bit too far north for wintry weather for most, although the GFS does appear to give some backside snows (I can't tell about the Euro). The CMC squashes the shortwave, but it does have a nice 1036 HP in the Plains. I'll post a map or two later when I'm at my other computer, but there is definitely potential here to see *some* wintry weather on or around Christmas. The period after shows a bit of promise as well.

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