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December Forecast Discussion


Wow

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Wow... west coast trough and an aleutian high isn't good...... is it going to take a met for you to understand that isn't a good pattern for the SE?

You should learn how to read some of the maps.

In fact you should go back a few pages and read some of Brandon's post about a -pna and -nao pattern producing cold and snow. I never said it was a great pattern or that it's the perfect pattern. With this type of pattern it will be below normal temp wise in the southeast with a suppressed flow.

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Euro 500 mb map at Day 7 actually pretty darned close to GFS. Questions is -- in Day 8-10 range will it dump the cold like GFS does.

It's weaker in its profile but still goes sub 1000mb just E of ILM. Precip is rather light on the Euro. If the previous storm located near Newfoundland can trend stronger and pull in HP over the NE ala GFS, I'd feel better.

Regardless, still 8+ days out. But the general agreement of the GFS and Euro of a generally strong southern low during this time frame is good.

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12z Euro bears little resemblance to (cold-biased) GFS in Day 9-10 range. Euro shows west coast trough forming at Day 10.

Euro is slower with the progression compared to the GFS. If you compare Euro 240 to 12z GFS at 204, they look more similar.

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12z Euro bears little resemblance to (cold-biased) GFS in Day 9-10 range. Euro shows west coast trough forming at Day 10.

12z Euro also bears little resemblance to the 0z Euro, which took a strong closed low from northern Louisianna to WV.

When the Euro gets inside 7 days, yes, its superior. When its beyond 168 - it has its own set of issues. Sometimes it explodes low pressure over the eastern US, sometimes it holds energy back and creates a completely different solution.

The GFS ensembles were all over this at 12z on Friday. Like half the members had a gulf type low pressure and snow for the TN Valley.

I wouldn't get my hopes up anywhere south and east of a tupelo to Huntsville to Atlanda to Charlotte line. This will likely be an ohio valley or tn valley storm. True SE folks chances will come if the PNA ridge returns, ala 0z GFS extended.

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and 0 line nowhere in the SE except for NW NC. Gotta build in more HP.

This is a rare Split flow, eastern Canada style. We're used to Pacific split flow, but this has happened before. Even once this Fall recently a Baffin Ridge formed and forced a storm much futher south than expected, but I dont' recall which one it was. The reason this split shows up is because of the north Atlantic Vortex that began showing up a few days ago, which carves out the Greenland Ridge/East Canada ridge.

As for temps profile, you can see a little bit of damming on both models at first, with an inverted trough through the eastern Tenn. Valley but there's not much damming because of a lack of good surface high in the Lakes. The thing to watch in future runs is the first storm that carves out a 50/50 low in the Northeast Coast, which causes a good deal of confluence. Some runs showed this, even old runs on ECMWF , even when it was taking the second main storm through the Spine of the Apps., so it's a possibility future runs will show more damming , more inverted troughing and more high pressure and a slightly colder 850 field.

Now on thicknesses. Not much point on making that big a deal yet on temp profiles, since we have to first establish a more certain track, but on the ECMWF frames the

1) height lines crashe continuously, which usually happens with incoming upper lows

2) Thicknesses have big spread between threshold thikness like 540 to 546 thkns at 5H across the northern halves of Ms,Al, Ga and through NC to TN, so there is ample room for dynamic cooling.

3) Dynamic cooling and deformation bands on nw shield of strong upper lows almost always win out on temps, but this one of course is so close, its too far out to make a call, but I think there's plenty of room for the areas I mentioned to cool down enough on part of the storm.

I'm not sold on this track, and I wouldn't be surprised to see it lift more north. I highly doubt we'll see it shift any more south. Interesting that this could be one of those storms that doesn't go up the East Coast. Usually most would, but since things are pretty progressive out west, and theres the blocking all over Canada and esp. Eastern Canada to Greenland, and this one time we have the giant northern Atlantic vortex that may just keep it mostly eastward moving. Be prepared for some run to run swings, but with all that blocking now looking likely, mostly it should be a southern to MidSouth possibly even MidAtlantic system. Atleast it's something to follow, whereas last year the models never gave us anything to follow, even out to 384 hour fantasyland.

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12z Euro also bears little resemblance to the 0z Euro, which took a strong closed low from northern Louisianna to WV.

When the Euro gets inside 7 days, yes, its superior. When its beyond 168 - it has its own set of issues. Sometimes it explodes low pressure over the eastern US, sometimes it holds energy back and creates a completely different solution.

The GFS ensembles were all over this at 12z on Friday. Like half the members had a gulf type low pressure and snow for the TN Valley.

I wouldn't get my hopes up anywhere south and east of a tupelo to Huntsville to Atlanda to Charlotte line. This will likely be an ohio valley or tn valley storm. True SE folks chances will come if the PNA ridge returns, ala 0z GFS extended.

lol weenie post much?

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Like I alluded to earlier this morning, the Euro solution at 0z played into one of its known biases with dumping too much energy into Southwest. We have seen it go away from that scenario with the 12z run, and the result it a much farther south track of the system....overall, fairly similar to the GFS, albeit slower.

I think most know this, but I can't urge enough caution. Just take a look at this snapshot at 500mb. There is so much energy aloft racing around in the pattern.

I could see this particular storm even vanishing altogether in future runs. There has to be a certain spacing and relationship between disturbances to allow this type of amplification, and if one aspect of that changes, the whole scenario changes.

post-390-0-48378900-1355256016_thumb.png

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Nice post Robert..stress the part about not getting caught up on the 850 line and detailed temps at this point. As you said many swings to come cliff divers and nay sayers. Its something for us winter lovers to WATCH...not live or die by. Cant imagine the hype and the pessimism we'll see over the next week but that's what we've been waiting on...SOMETHING CREDIBLE TO FOLLOW and it's still early! Looking beyond that seems pretty likeable as well for those of us that like cold and frozen precip possibilities.

It may not turn ice age when December is said and done but the pattern change looks real!

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Like I alluded to earlier this morning, the Euro solution at 0z played into one of its known biases with dumping too much energy into Southwest. We have seen it go away from that scenario with the 12z run, and the result it a much farther south track of the system....overall, fairly similar to the GFS, albeit slower.

I think most know this, but I can't urge enough caution. Just take a look at this snapshot at 500mb. There is so much energy aloft racing around in the pattern.

I could see this particular storm even vanishing altogether in future runs. There has to be a certain spacing and relationship between disturbances to allow this type of amplification, and if one aspect of that changes, the whole scenario changes.

post-390-0-48378900-1355256016_thumb.png

Nice video this AM, Matthew. I see a few running with the idea that if this storm plays out as modeled, as in, if it tracks in the SE and not more west and cuts up toward the lakes, that the resulting pattern that we're hoping for will be destroyed. Not sure if they're just basing this off of NH maps after the storm on these runs or believe it to be almost a 100% possibility. Do you have any ideas about that? Can we get this storm and STILL do well as far as a snow supporting pattern, or should snow lovers hope this storm doesn't come to fruition in the SE?

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Like I alluded to earlier this morning, the Euro solution at 0z played into one of its known biases with dumping too much energy into Southwest. We have seen it go away from that scenario with the 12z run, and the result it a much farther south track of the system....overall, fairly similar to the GFS, albeit slower.

I think most know this, but I can't urge enough caution. Just take a look at this snapshot at 500mb. There is so much energy aloft racing around in the pattern.

I could see this particular storm even vanishing altogether in future runs. There has to be a certain spacing and relationship between disturbances to allow this type of amplification, and if one aspect of that changes, the whole scenario changes.

post-390-0-48378900-1355256016_thumb.png

Great blog this morning Matt and thanks for yours and Robert's input. You were spot on with Dr No! I for one hope this thing holds together enough so that I can watch Andy get bombarded on his blog this weekend! Lol

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You should learn how to read some of the maps.

In fact you should go back a few pages and read some of Brandon's post about a -pna and -nao pattern producing cold and snow. I never said it was a great pattern or that it's the perfect pattern. With this type of pattern it will be below normal temp wise in the southeast with a suppressed flow.

great job buddy! I appreciate your maps.

Sounds just like "hyperbell" has been saying for weeks.

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This might belong in the banter thread, but I just wanted to say thanks to Robert and Matthew for sharing their insight about the upcoming pattern. There are several other excellent pro mets on the SE board and I always find myself reading extra carefully when one of the "red tags" makes a post! Thanks also to several of the "amateurs" whose weather knowledge far exceeds mine. It's always exciting to track a potential winter weather event and watch the pros dissect the model runs. What a great wealth of knowledge contained on this Board!

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Like I alluded to earlier this morning, the Euro solution at 0z played into one of its known biases with dumping too much energy into Southwest. We have seen it go away from that scenario with the 12z run, and the result it a much farther south track of the system....overall, fairly similar to the GFS, albeit slower.

I think most know this, but I can't urge enough caution. Just take a look at this snapshot at 500mb. There is so much energy aloft racing around in the pattern.

I could see this particular storm even vanishing altogether in future runs. There has to be a certain spacing and relationship between disturbances to allow this type of amplification, and if one aspect of that changes, the whole scenario changes.

Agreed, I think this has just as much chance of getting squashed by all the other waves moving through the northern stream as it does of amplifying too much too soon and cutting to the lakes. The Canadian and Ukmet models do this.

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