Winter 2013-14 Pattern Discussion

[dsaur]

He is thinking a Texas, Georgia, NC, Maine type track.

i can sure see it from last nights 0z, it's nebulas, but there for the taking, though climo probably just sniffs.

[CAD_Wedge_NC]

But this would NOT be a CAD storm... this is something better!

 

All I see is a "west of the Apps" cutter on the GFS. Is this the storm you are referring to?

[tnweathernut]

All I see is a "west of the Apps" cutter on the GFS. Is this the storm you are referring to?

Without a block it's hard seeing anything going from Texas to Georgia and not gaining more latitude than that. I could easily see a cutter, hope we can get some confluence or weak blocking to help.

[CAD_Wedge_NC]

In a nutshell - the southern oscillation index will usually indicate upcoming el-nino like conditions when there is a drop into negative territory.    Positive = la nina conditions.  It's a LOT more involved than that I am sure, but that's the gist.

 

Yep, that is the high level summary in a nutshell.

[rduwx]

There is a big storm showing up on the models in 13-16 timeframe but looks like a big rain storm for the SE.

[pcbjr]

In a nutshell - the southern oscillation index will usually indicate upcoming el-nino like conditions when there is a drop into negative territory.    Positive = la nina conditions.  It's a LOT more involved than that I am sure, but that's the gist.

 Doesn't that equate with a wetter, cooler south east, but a more zonal flow with less arctic cold?

[rduwx]

Without a block it's hard seeing anything going from Texas to Georgia and not gaining more latitude than that. I could easily see a cutter, hope we can get some confluence or weak blocking to help.

 

12z euro coming in with a cutter on 12/15.

[POWERSTROKE]

There is a big storm showing up on the models in 13-16 timeframe but looks like a big rain storm for the SE.

yep looks warmer until January after this storm but who knows as models been all over the place

[tnweathernut]

Not a terrible look at 500 on the Euro at 144. A lot of confluence and a weak -NAO look with ridging toward the west coast and a shortwave in the southwest. I like the Aleutian low shown too.

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[tnweathernut]

though the next frames easily push out the developing -NAO, lift the confluence, and lose the ridging out west, sending  a cutter straight to the Great Lakes

[Cold Rain]

though the next frames easily push out the developing -NAO, lift the confluence, and lose the ridging out west, sending a cutter straight to the Great Lakes

But wasn't that 144 image a huge SE ridge and deep -PNA trough a couple of days ago?

[tnweathernut]

But wasn't that 144 image a huge SE ridge and deep -PNA trough a couple of days ago?

I am not sure, but the long range look keeps changing. I don't see a "torch" in the foreseeable future.  It's been a pretty normal December here in east TN with plenty of variability.  Much more so than the last few years.  I am encouraged by all the cold in Canada, the large high pressures, and a different Atlantic.  I think our patience will pay off as we head deeper into what is truly the "heart" of winter for the SE. (Jan & Feb)

[SnowGoose69]

But wasn't that 144 image a huge SE ridge and deep -PNA trough a couple of days ago?

Yes, the EURO has become a very cutter happy model from roughly day 6 onward ever since it's upgrade 4 or so years ago. Its obviously right at times but generally I have noticed the Euro likes medium or long range cutters in a pattern where they CAN happen ever since that upgrade and often times it ends up wrong.

[Cold Rain]

I am not sure, but the long range look keeps changing. I don't see a "torch" in the foreseeable future. It's been a pretty normal December here in east TN with plenty of variability. Much more so than the last few years. I am encouraged by all the cold in Canada, the large high pressures, and a different Atlantic. I think our patience will pay off as we head deeper into what is truly the "heart" of winter for the SE. (Jan & Feb)

I'm with you there. Totally agree!

[tnweathernut]

I'm with you there. Totally agree!

I meant to say different Pacific.

[Cold Rain]

Yes, the EURO has become a very cutter happy model from roughly day 6 onward ever since it's upgrade 4 or so years ago. Its obviously right at times but generally I have noticed the Euro likes medium or long range cutters in a pattern where they CAN happen ever since that upgrade and often times it ends up wrong.

Hopefully in this case, we can get a break down here and keep a suppressed flow. It sounds like the GFS is sniffing a cutter around this period as well, so maybe that idea does have more credibility this time? I'm on the road today and don't have map access, so I may be talking about a different system altogether. Anyway, the models have been inconsistent in the LR , so it's hard to put a lot of stock in any sustained major warm-ups or cool-downs.

[GaWx]

 The 12Z Euro *fwiw* does suggest a ZR threat for the main CAD areas of NC/SC/GA for 12/8-9.Looking at just 850's, I wouldn't think it would involve more than W NC. However, this is a king of CAD's being modeled (which makes me take it with a huge grain, of course, especially since the GFS has nothing like it). So, for example, at hour 192, it has Athens' 850 at ~54 F but the 2 M is only at ~36 F with light rain!! That would be an 18 F differential, which is almost unheard of in these parts. Then again, how often is the CAD high modeled as strong as 1044 mb? Not too often I suspect.

 

 Also, keep in mind that the Euro has a strong warm bias at two meters during wintertime steady precip. events for which there is evap. cooling. I've seen it be off close to 10 F in the too warm direction. So, if we just were to take 5 F from Athens's temp., they'd be at 31 F with zr.

 

 However, as mentioned, I'm taking this 12Z Euro run with a huge grain. Besides, it is a whopping eight days out...still in semi-fantasyland. I'm looking at it as just one possibility of many and near the worst (best depending on what one wants) case scenario. The odds of it verifying closely are pretty low that far out. The Euro sometimes has too strong a high at the surface in the NE US, especially at 8 days out. I wouldn't bet on a 1044 mb high actually verifying at least as of now. So, if it is weaker, it would likely be less cold in the CAD areas. The CAD in GA looks too strong vs. history when considering 850's.

 

 In summary, this is still largely just for entertainment from my perspective (especially considering even the king Euro has been way off with wintry threats at times), but it shows what could happen if everything lines up just right (or wrong). The period around 12/8-9 has been showing a good number of threats on a number of model runs of the GFS, too. So, it is a legit. threat period as of now..

 

 Followup: Noting what I bolded above from my post six days ago, sure enough the high now being modeled by the Euro (and the GFS) is only at 1036 mb while over S Quebec vs. 1044 mb six days ago. So, it has weakened by 8 mb/0.24" in just these last six days. As a consequence, it isn't as cold in the SE US CAD regions as what that Euro had. This case only solidifies my feeling that the Euro has a bias of making surface highs too strong in the NE US, especially when looking out a good number of days. In this case it was eight days out.

 

 Lesson to me: continue to be wary of the modeled strength of NE US highs when the Euro has them stronger than model consensus.

[Cold Rain]

I meant to say different Pacific.

Yeah, I figured. Thanks for posting the maps and analysis!

[Snowless in Carrollton]

I am not sure, but the long range look keeps changing. I don't see a "torch" in the foreseeable future. It's been a pretty normal December here in east TN with plenty of variability. Much more so than the last few years. I am encouraged by all the cold in Canada, the large high pressures, and a different Atlantic. I think our patience will pay off as we head deeper into what is truly the "heart" of winter for the SE. (Jan & Feb)

why is feb considered the heart of winter but dec isn't ? Dec is slightly colder than Feb on average in the interior southeast. Also in Feb, you have to deal with an increasingly high sun angle, particularly in late Feb.

[Cold Rain]

why is feb considered the heart of winter but dec isn't ? Dec is slightly colder than Feb on average in the interior southeast. Also in Feb, you have to deal with an increasingly high sun angle, particularly in late Feb.

Please...not the sun angle yet. Please! Feb does average more snow than Dec, though.

[Brick Tamland]

Please...not the sun angle yet. Please! Feb does average more snow than Dec, though.

 

I think since 2000 we have had just as much if not more snow in December and January in central NC.

[superjames1992]

why is feb considered the heart of winter but dec isn't ? Dec is slightly colder than Feb on average in the interior southeast. Also in Feb, you have to deal with an increasingly high sun angle, particularly in late Feb.

 

Because, on average, most of us average 2x+ as much snow in February as December.  We can get a lot of big storms in February.  There's a lot of built-up cold ready to come firing south.  Then you get the clashing of air masses with the increased possibility of "heat" waves.

 

Unfortunately, February has lacked here in recent years.

 

There was February 2010 for the deeper south, though.

[tnweathernut]

why is feb considered the heart of winter but dec isn't ? Dec is slightly colder than Feb on average in the interior southeast. Also in Feb, you have to deal with an increasingly high sun angle, particularly in late Feb

Simply put, it's just the better time vs. December for getting snow.  There is a phrase which originated in Scandinavia (I believe) that says as the days grow longer, the cold grows stronger. 

 

It's just easier to get snow later in the winter.  The way the wavelengths are in December often puts the mean trough in an unfavorable position for snow in the southeast.

[griteater]

why is feb considered the heart of winter but dec isn't ? Dec is slightly colder than Feb on average in the interior southeast. Also in Feb, you have to deal with an increasingly high sun angle, particularly in late Feb.

 

If you look at climo for 500mb heights, the lowest heights are in Jan, followed by Feb, then Dec.  So climo speaking, it's slightly easier to get a more southerly storm track in Feb as compared to Dec.

[griteater]

The way the wavelengths are in December often puts the mean trough in an unfavorable position for snow in the southeast.

 

Was just looking at this, and in fact, the climo for 500mb heights in mid-Dec has the mean trough centered across the center part of the country, where as in January the mean trough is located in the eastern U.S.  For Feb, it's somewhere in between those two

[Southern Track]

Correct me if I'm wrong, but I believe cut off lows are more prevalent in late winter as well, a setup that has resulted in some big snows for the SE in pretty recent years. You don't see those in December.

[tnweathernut]

Was just looking at this, and in fact, the climo for 500mb heights in mid-Dec has the mean trough centered across the center part of the country, where as in January the mean trough is located in the eastern U.S.  For Feb, it's somewhere in between those two

This is why I haven't had any concern for this winter at this point.  A LOT of things are different this year and although we haven't had any blocking on the Atlantic side so far, things seem to be pretty much where they ought to be for this time of year.

[tnweathernut]

Correct me if I'm wrong, but I believe cut off lows are more prevalent in late winter as well, a setup that has resulted in some big snows for the SE in pretty recent years. You don't see those in December.

cutoff lows are a lot more prevalent in late winter, with many coming in March and even April.

[griteater]

Correct me if I'm wrong, but I believe cut off lows are more prevalent in late winter as well, a setup that has resulted in some big snows for the SE in pretty recent years. You don't see those in December.

 

Definitely agree

[deltadog03]

The big SOI drop will help keep the southern branch very active.