December 2017 Mid-Long Range Disco 2

[NorthArlington101]

  On 12/15/2017 at 1:00 AM, BristowWx said:

You can definitely see the CAD on the temp map for 24-35 Dec.  I can’t remember if the models tend to overdo or underestimate CAD.  I know it is often slow to erode but that could just mean long period of lows 40s and drizzle.  

They tend to underestimate it. It's one of the ways we often score an over performer.

[AfewUniversesBelowNormal]

  On 12/15/2017 at 1:01 AM, BristowWx said:

Of AN temps?  Or precip?  Or both

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The pattern is arranging itself now. It's going to be +PNA. Medium-long range model error is probably greatest with EPO. 

[BTRWx's Thanks Giving]

  On 12/15/2017 at 1:05 AM, StormchaserChuck said:

The pattern is arranging itself now. It's going to be +PNA Pacific. Medium-long range model error is probably greatest with EPO. 

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[AfewUniversesBelowNormal]

A high anomaly is peaking at 10mb, and there will be cold waves rotating around it in the medium and long range, because this is what happens. The most consistent area where it will fit like a jigsaw piece is between Alaska and Hawaii. 

[Bob Chill]

  On 12/15/2017 at 1:01 AM, NorthArlington101 said:

 

They tend to underestimate it. It's one of the ways we often score an over performer.

 

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No doubt. But we need to be in the short range before figuring that stuff out. Once we know the depth of the CAD we can look at surface wind plots and figure out how much staying power it will have. Globals almost always scour it out to fast. This error gets compounded when the actual temp is off a few degrees on the high side as well. Rgem is the only model I've seen get it wrong by being too cold. Nam 3k seems like it does pretty well. 

There have been many events where the surface progs go above freezing but actual temps never do. CAD is cool like that. Lol. 

[gymengineer]

  On 12/15/2017 at 1:12 AM, Bob Chill said:

No doubt. But we need to be in the short range before figuring that stuff out. Once we know the depth of the CAD we can look at surface wind plots and figure out how much staying power it will have. Globals almost always scour it out to fast. This error gets compounded when the actual temp is off a few degrees on the high side as well. Rgem is the only model I've seen get it wrong by being too cold. Nam 3k seems like it does pretty well. 

There have been many events where the surface progs go above freezing but actual temps never do. CAD is cool like that. Lol. 

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There is so much empirical evidence of that. I don’t pay the GFS any attention for surface temps until within like 12-hrs for a ZR event. And there have been ZR events the past four seasons where even the RGEM predicted pushing above freezing too early. (Of course, 2015 was just bonkers with a legit sidewalk glaze event in March.)

Last season was terrible overall obviously, but even it had a true-to-form ice event in December where going with the slowest changeover model worked out. 

[BristowWx]

Lots to consider with ice from what I remember.  32 with heavy precip doesn't do that well.  You need like below 30 and better at night. Sun angle should be good on Dec 25th.  Nice to have a pre ice snow fall.  Aside from the hazards it is fun to track.

[Vice-Regent]

  On 12/15/2017 at 1:00 AM, StormchaserChuck said:

no chance

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Above average December with all the cold incursions and model hype - unprecedented. 

[Bob Chill]

  On 12/15/2017 at 2:02 AM, Vice-Regent said:

Above average December with all the cold incursions and model hype - unprecedented. 

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 You making a good weather post without a climate change spin would be unprecendented. BiGLY

[Vice-Regent]

  On 12/15/2017 at 2:30 AM, Bob Chill said:

 You making a good weather post without a climate change spin would be unprecendented. BiGLY

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It is merely what the empirical evidence states at this time. We wait for verification. It's not like I will wake up in the morning and regret having cold smoke on Christmas.

[AfewUniversesBelowNormal]

At this moment is a 956mb Low in the middle of nowhere Canada, and a 1023mb High 1000 miles away. Could be big changes day to day. I think the 3-7day will be cooler. 7-14 day lots of snow. 

[poolz1]

Looks like 00z may be more progressive with the trof in the west....not digging nearly as much.  

[BristowWx]

  On 12/15/2017 at 4:19 AM, poolz1 said:

Looks like 00z may be more progressive with the trof in the west....not digging nearly as much.  

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Just thought that but didn't want to jinx it.  Thanks for being the jinx.  Just kidding.

[poolz1]

  On 12/15/2017 at 4:24 AM, BristowWx said:

Just thought that but didn't want to jinx it.  Thanks for being the jinx.  Just kidding.

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lol..it's very possible I did jinx it..

So far at 500 it looks very different than 18z...

[BristowWx]

  On 12/15/2017 at 4:26 AM, poolz1 said:

lol..it's very possible I did jinx it..

So far at 500 it looks very different than 18z...

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Yeah I would say that's true.  Looks much different than the last 4-5 runs of GFS.  Might not like it as much.  I was getting excited about the ice storm theory.  

[Cobalt]

  On 12/15/2017 at 4:32 AM, BristowWx said:

Yeah I would say that's true.  Looks much different than the last 4-5 runs of GFS.  Might not like it as much.  I was getting excited about the ice storm theory.  

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No ice storm, but colder. Of course colder and dry, but the SE ridge is far more suppressed on Dec 24th.

[pasnownut]

  On 12/15/2017 at 4:32 AM, BristowWx said:

Yeah I would say that's true.  Looks much different than the last 4-5 runs of GFS.  Might not like it as much.  I was getting excited about the ice storm theory.  

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500 looks much quicker with the trough getting back into the east 12/23.  surface shows a 200 mile southward shift of 540.  If yall dont like it....i sure do.

Nut

[BristowWx]

  On 12/15/2017 at 4:40 AM, pasnownut said:

500 looks much quicker with the trough getting back into the east 12/23.  surface shows a 200 mile southward shift of 540.  If yall dont like it....i sure do.

Nut

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I like it but it's boring dry coast to coast.  That was one wild swing however.  Far from clear picture.

[Interstate]

Well Christmas would be cold that is for sure

[AfewUniversesBelowNormal]

Crazy stuff coming up... look at how everything on these maps is elongated

[mitchnick]

Long range looks much better.  Eps are a thing of beauty how they squeeze the Se ridge out of the picture. GEFS & GEPS do likewise,  and are wet.

[mitchnick]

I could live with this 6z Gfs end of run.

 

[showmethesnow]

Trying to nail down what to expect 7 days out and through the extended is probably a lost cause at this point. He!!, I think inside of 7 days is still not set in stone yet and would not be surprised to see some major changes there. All I can say is there is a lot of potential setting up but there is also the possibility of a lot of heart ache as well. Should be fun to watch this unfold over the coming days.

[BristowWx]

  On 12/15/2017 at 11:04 AM, showmethesnow said:

Trying to nail down what to expect 7 days out and through the extended is probably a lost cause at this point. He!!, I think inside of 7 days is still not set in stone yet and would not be surprised to see some major changes there. All I can say is there is a lot of potential setting up but there is also the possibility of a lot of heart ache as well. Should be fun to watch this unfold over the coming days.

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That was evident with the 0z/6z GFS op runs.  Huge differences with thiose.  

[showmethesnow]

  On 12/15/2017 at 11:02 AM, mitchnick said:

I could live with this 6z Gfs end of run.

 

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Looks suppressive. Nudge that look north a couple hundred miles and then I think we would be talking.

[mitchnick]

  On 12/15/2017 at 11:07 AM, showmethesnow said:

Looks suppressive. Nudge that look north a couple hundred miles and then I think we would be talking.

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Welp, I doubt it would look like that for long!

[showmethesnow]

  On 12/15/2017 at 11:07 AM, BristowWx said:

That was evident with the 0z/6z GFS op runs.  Huge differences with thiose.  

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Until we see how the models want to resolve the SW trough I think all options being thrown out are still on the table. And those options will fluctuate from one extreme to the other. So at this point you might as well flip a coin on what to expect through the Holidays and beyond. 

[CAPE]

  On 12/15/2017 at 9:33 AM, mitchnick said:

Long range looks much better.  Eps are a thing of beauty how they squeeze the Se ridge out of the picture. GEFS & GEPS do likewise,  and are wet.

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Sure does. After a couple really crappy runs with the SER sticking around for a while, the last couple of EPS runs crush it pretty quickly. And looky here..we have a ridge building into GL at the end of the 0z run.

 

[BristowWx]

  On 12/15/2017 at 11:14 AM, showmethesnow said:

Until we see how the models want to resolve the SW trough I think all options being thrown out are still on the table. And those options will fluctuate from one extreme to the other. So at this point you might as well flip a coin on what to expect through the Holidays and beyond. 

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I feel like the leading contender is some sort of stalled front with SER flexing.  Maybe not at 0z but 6z likes that one again.

[Neblizzard]

  On 12/15/2017 at 11:29 AM, C.A.P.E. said:

Sure does. After a couple really crappy runs with the SER sticking around for a while, the last couple of EPS runs crush it pretty quickly. And looky here..we have a ridge building into GL at the end of the 0z run.

 

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If those models are right , the pattern has great overrunning potential and with the SE ridge more suppressed on this run...we would likely be on the favorable side of the gradient. So after a brief relaxation , the pattern looks to be promising right around Christmas into the new year.