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Winter 2013-14 Pattern Discussion III


Marion_NC_WX

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Yeah, the 12z Euro's temperature profiles did go to hell late in the run, but they were good enough for snow with the initial precip and a lot of it for some areas.

 

I'm not sure I buy it being that warm with the ULL passage, either.

 

Verbatim, the Euro changed pretty much everyone over to rain at the end, but a lot of areas saw a significant major winter storm prior to the changeover.

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Post hours 150 or 156.

I hate to be the hype crusher, but the euro starts as winter precip for N of I40, but turns to an all rain event for the southeast according to the euro. lets not forget how all the other models underestimated the warm nose with the last major event. so may not even start as winter precip. But as the 12z, winter precip at onset of event then quick transition to rain once the heavier bands get in. 

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I hate to be the hype crusher, but the euro starts as winter precip for N of I40, but turns to an all rain event for the southeast according to the euro. lets not forget how all the other models underestimated the warm nose with the last major event. so may not even start as winter precip. But as the 12z, winter precip at onset of event then quick transition to rain once the heavier bands get in. 

 

There's snow and a good bit of it for those North and West of 85 probably 8-12 inches or more.  

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I hate to be the hype crusher, but the euro starts as winter precip for N of I40, but turns to an all rain event for the southeast according to the euro. lets not forget how all the other models underestimated the warm nose with the last major event. so may not even start as winter precip. But as the 12z, winter precip at onset of event then quick transition to rain once the heavier bands get in. 

 

I'm not positive the warm nose was necessarily overdone with the last event as much as we lost the snow growth zone (something a lot of us probably weren't looking for).  IIRC, MBY was getting pouring sleet with all layer of the atmospheres below freezing, but the dendritic growth zones weren't cold enough (they were below freezing, but not by enough to form snowflakes).

 

----------------

 

In any case, the Euro has gotten colder for two runs in a row now (let us hope that is a trend we can depend on) and there's no reason to assume today's 12z run will be anywhere close to the final solution.

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I hate to be the hype crusher, but the euro starts as winter precip for N of I40, but turns to an all rain event for the southeast according to the euro. lets not forget how all the other models underestimated the warm nose with the last major event. so may not even start as winter precip. But as the 12z, winter precip at onset of event then quick transition to rain once the heavier bands get in.

The mets have been over this. The warm nose wasn't underestimated, we lost moisture in the growth zone.

Temps during the portion of the storm we mention look safe. 850s are close to -1 and surface temps are at -2.

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I hate to be the hype crusher, but the euro starts as winter precip for N of I40, but turns to an all rain event for the southeast according to the euro. lets not forget how all the other models underestimated the warm nose with the last major event. so may not even start as winter precip. But as the 12z, winter precip at onset of event then quick transition to rain once the heavier bands get in.

Preaching to the choir. But verbatim it was a lot of snow for GSP and the foothills.

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This is off topic but worth pointing out. Quite the pressure gradient over the northern rockies. 996mb over southeast idaho vs 1050mb over northeast montana. nam is slightly weaker but Nam's isobars are packed so tight, you can't even distinguish them.

 

 

 

gfsUS_sfc_temp_015.gif

 

 

nam

 

namUS_sfc_temp_015.gif

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1 think we do have is a dynamic ULL that we didn't last time.  Yes, temps will be a bit more marginal, but dynamics can EASILY overcome that.

yep..would be two totally different scenarios. Can't even compare the two. No need to really go further into the 12z runs more than what has already been talked about at this range anyway.

 

at any rate, I'm still amazed at the temperature drop across nc. Many locations drop 30 degrees in 3 hours with the wedge front.

 

Gfs has temps dropping into the single digits over northeastern nc at hour 84 with below zero readings over a large part of va/mid atlantic. holy hell this is one cold airmass for this time of the year.

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yep..would be two totally different scenarios. Can't even compare the two. No need to really go further into the 12z runs more than what has already been talked about at this range anyway.

 

at any rate, I'm still amazed at the temperature drop across nc. Many locations drop 30 degrees in 3 hours with the wedge front.

Agreed Chris...Did you see my post earlier about the high?

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Verbatim on the warm biased 12Z Euro, it gets to below 32 in main CAD areas and even outside of them (example near Macon) due to a very impressive wedge with heavy precip. even at 1 PM! These areas that are above 0 C at 850 get a solid 1"+ of qpf, which could be anything from major ZR to several inches of IP thanks to a very impressive 1042 mb very cold high dropping down from SE Canada. A 1042 CAD high is a pretty rare thing . That's followed up by a multi inch snow for those under the upper low. So, whereas the storm without either the CAD or the strong upper level cooling would be all rain, it wouldn't be with these two things. As modeled, this would truly a memorable storm for a good number considering heavy qpf. If even just a third of the qpf fell, it would still be big!

If I were in N GA or nearby areas, I wouldn't want anything different from this run as this is about as good as it gets!

Be wary of Euro clowns that isn't 't really all snow!

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Agreed Chris...Did you see my post earlier about the high?

If you are referring to the direction, yeah. I think it is the first time this year it has. But amazingly, That high builds into an airmass that is already incredibly cold.  Normally the cold comes with the damming high..it's not normally already there..so it's an interesting progression.

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This is going to be tough to watch a 35F and rain with a perfect track, slow crawling SLP for us central NC folks, but with the HP sliding out we are so screwed.  Ugghhhh, good thing spring is starting because this would be a bitter way to start a winter, almost like Dec 2009.

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If you are referring to the direction, yeah. I think it is the first time this year it has. But amazingly, That high builds into an airmass that is already incredibly cold.  Normally the cold comes with the damming high..it's not normally already there..so it's an interesting progression.

Yeah, its direction moving in is a first for the year.  Agreed, already cold airmass there.   

 

GFS was a MAJOR step toward the euro tonight.  2m temps, 850 temps were colder....its just a matter of time that we see a euro ish solution....Does CMC show this tonight, does the king hold?

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This is going to be tough to watch a 35F and rain with a perfect track, slow crawling SLP for us central NC folks, but with the HP sliding out we are so screwed.  Ugghhhh, good thing spring is starting because this would be a bitter way to start a winter, almost like Dec 2009.

I think you are jumping the gun just a little bit. This is going to be a powerful wedge..one that we don't normally see that is this strong. Given the setup here, I would expect there to be a really good chance of a meso high forming over the heart of the cad regions.  This is something that has caused many a busted forecast for those taking the models verbatim with the strongest wedges.  So right off the bat the warming the gfs is showing at the surface is virtually impossible from where I sit. So a lot of front end freezing rain and/or sleet here except in nc where 850s actually cool initially because the wedge actually extends up to that level. Although we saw signs of it with our last major storm, it's rare and another sign of the strength involved.

 

Then comes the upper low where the gfs has a near isothermal layer around freezing somewhere to the north of the low. That area is likely to be snow and heavy snow at that. As is the case a lot of times with upper lows though, areas further north might be warmer than areas further south. It all depends on the track of the upper low, where the heavy precip is, etc.

 

 Wedges are hard enough to forecast for as it is. Throw in the fact it's many days away and Throw in a strong upper low and you are talking about a pretty complicated scenario overall that is likely to change big time from run to run.  To pretend like it's going to be all rain, all snow, or anything but everything right now is really silly.

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btw, to drive home the fact the models are going to have a tough time with this. The gfs warms surface temps 5 degrees or so in the very heart of the wedge from hour 132 to 138...despite tons of precip and the high still firmly in damming position. Sun is getting strong this time of year and maybe that's what it's seeing but that is a pretty huge stretch.

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