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Bob Chill

December 2017 Long Range Disco

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3 minutes ago, StormchaserChuck said:

A few comments:

1. The medium range should be cooler than models, to the point where light rain threats could be mixed with snow. 

2. A cross-flow, anti-wavetrain pattern rarely holds for more than a few days at a time. Models have this for more than a week straight. I think the cold air will either move in sooner, or have trouble moving in at all (SE ridge). 

3. Lots of moisture on models Dec 7-10. Probably 1 or 2 events, the colder it is, more digging and pressure, and the more precip will likely associate. 

4. I've seen this Northern Hemisphere progression maybe 20 times on models in many years. It always underperforms cold wise, and ends up being a big +EPO like +20-35 days from now. (On ensemble mean next few day warmth in United States is greater than cross-polar arctic cutoff cold anomaly, weird. 

5. Maybe a big snowstorm Dec 7-10, but that's about it in this pattern I think., mid-late December should warm up nicely. 

If you list all the possibilities you will always be right. Good job

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1 minute ago, stormtracker said:

Co sign

Models may be unpredictable but our long range thread is as predictable as an atomic clock. There is one thing more predictble than an atomic clock....avanti vice reject hiatus' steaming turd posts. If you can manage to cringe your way through it it's actually effin hilarious. Except for the turd posts. That dude seriously needs help or his keyboard taken away. One or the other. 

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1 minute ago, Bob Chill said:

Models may be unpredictable but our long range thread is as predictable as an atomic clock. There is one thing more predictble than an atomic clock....avanti vice reject hiatus' steaming turd posts. If you can manage to cringe your way through it it's actually effin hilarious. Except for the turd posts. That dude seriously needs help or his keyboard taken away. One or the other. 

Sniff sniff..it smells like turd, looks like turd, it is a turd.

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2 minutes ago, StormchaserChuck said:

Models have a tendency to automatically run Pacific wave train forward a few days. When this sometimes is cutoff, it's colder. 

But at this point in time,  your previous post is really not shown on the ensembles with the nice warmup mid-late December and storm chances ending after 7-10 December.  -EPO and -AO still quite evident with the only hint of SE ridging post 348 on the GEFS at 18z and even that is more of a flat flow east of the Rockies with a stout ridge in the PAC.  Hardly a cause for alarm I would think.  

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Be wary of the GEFS following the op.  Remember @Bob Chill pointing this out during tropical season and it was certainly the case then...I remember thinking that this flaw could send us spinning during the winter season if it continued.  Something to monitor....is it coincidence that the op went to a west trough and then the gefs seemed to follow? 

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13 minutes ago, BristowWx said:

But at this point in time,  your previous post is really not shown on the ensembles with the nice warmup mid-late December and storm chances ending after 7-10 December.  -EPO and -AO still quite evident with the only hint of SE ridging post 348 on the GEFS at 18z and even that is more of a flat flow east of the Rockies with a stout ridge in the PAC.  Hardly a cause for alarm I would think.  

The blocking doesn't really anchor and without feedback, and nowtime warm verfication, the long range usually verifies a faster jet warm pattern. 

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14 minutes ago, poolz1 said:

Be wary of the GEFS following the op.  Remember @Bob Chill pointing this out during tropical season and it was certainly the case then...I remember thinking that this flaw could send us spinning during the winter season if it continued.  Something to monitor....is it coincidence that the op went to a west trough and then the gefs seemed to follow? 

Seems to be the case again. Especially through d10. The only thing we know with confidence right now is the flip to a colder pattern is coming about this time next week. Beyond that is anyone's guess. All possibilities are on the table. Going by climo rules it feels like a clean snowstorm like the 12z euro is probably the least likely. But still possible nonetheless. 

I disagree with Chuck saying the blocking isn't anchoring. While I certainly don't know for sure, there are many previous cases saying it probably will. The -ao regime already started last week. It will wax and wane. It always does. But I would put a good wager on Dec averaging neg in the AO domain. 

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this seems no different than grasping at a model run showing a change to cold with little to no support. Just flip the plot. No need to get nervous of a model run showing some warmth later in the run. It’s just as likely to verify as those phantom changes to cold we chased all of the last 2 years. 

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1 hour ago, WxUSAF said:

Looking forward to getting a real threat so I can start hiding trash posts. 

It doesn’t have to wait until then. Crap posts feed others to making crap posts

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40 minutes ago, Bob Chill said:

Seems to be the case again. Especially through d10. The only thing we know with confidence right now is the flip to a colder pattern is coming about this time next week. Beyond that is anyone's guess. All possibilities are on the table. Going by climo rules it feels like a clean snowstorm like the 12z euro is probably the least likely. But still possible nonetheless. 

I disagree with Chuck saying the blocking isn't anchoring. While I certainly don't know for sure, there are many previous cases saying it probably will. The -ao regime already started last week. It will wax and wane. It always does. But I would put a good wager on Dec averaging neg in the AO domain. 

It def had a glaring issue with the track of a specific trop low pressure in the med range during that time period but I didnt eval the whole NA h5 pattern at the time.  Is this just a micro issue?

I do agree that dec will avg a -AO...things would have to start shifting dramatically in the LR for it not to.  Possibilities...all you can say right now.

 

 

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Given the signs that a lot of the upcoming cold is -EPO driven and motivated by some posts on twitters regarding past -EPO winter regimes, I went back and took a look for myself to see what sort of tea leaves maybe can be read through analogs.  Three months (at least in my quick view, and focused more on December and January than February/March) show some similarities with the advertised pattern.  

December 2000

Weather/Climate Plot

 

January 2014

Weather/Climate Plot

 

And December 1989, the grandaddy of cold Decembers in the Mid-Atlantic.  

Weather/Climate Plot

 

All three have a very -EPO, -NAO, -AO, and +PNA pattern that we are being advertised.  The differences are mostly in the depth of the eastern CONUS trough itself, where it's axis lies, and what is happening upstream in the Atlantic.  Jan '14 had a big WAR, which helped bring some storm activity into our area, while Dec '00 did not really have that, and Dec '89 has that mega trough at 50°N latitude all across the Atlantic.  

In terms of sensible weather, all 3 were cold months, well below normal temps:  Jan '14 was -5.5F, Dec '00 was -6.7F, and Dec '89 was -11.4F (all at BWI).  All three also had below normal precip, with Jan '14 being closest to average at BWI.  Snow-wise is different, with both Jan '14 and Dec '89 above normal snowfall at BWI (Dec '89 much above normal), and Dec '00 only getting 1.3" at BWI.  

 

So, let's compare to the pattern that we're being advertised.  Here's the D10 12z EPS at 500mb:

If blank, model image not available

Just by eye you can see it's most similar to Jan '14 with a fairly large WAR that's getting pushed eastward by our #epicapattern trough.  Does not have the Atlantic 50°N troughiness that Dec '89 had in spades and Dec '00 had to a lesser extent.  

 

Jumping forward 5 days:

If blank, model image not available

Now perhaps it looks a bit more like Dec '00, at least more than it did at D10, with the WAR knocked down a bit.  

 

So, what does it all mean?  I'm not sure that the position of the WAR is truly the be-all/end-all for -EPO dominated patterns, but it certainly is important for determining where the storm track is going to fall.  I'll note that Jan '14 had a solid snowstorm (Jan 21 2014, 5.1" at BWI) near the beginning of the big -EPO reload during that 2nd half of that month.  Here's the previous 5 days leading into that storm:

Weather/Climate Plot

Not a horrible match to that D10 EPS...

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18 minutes ago, WxUSAF said:

Given the signs that a lot of the upcoming cold is -EPO driven and motivated by some posts on twitters regarding past -EPO winter regimes, I went back and took a look for myself to see what sort of tea leaves maybe can be read through analogs.  Three months (at least in my quick view, and focused more on December and January than February/March) show some similarities with the advertised pattern.  

December 2000

January 2014

And December 1989, the grandaddy of cold Decembers in the Mid-Atlantic.  

All three have a very -EPO, -NAO, -AO, and +PNA pattern that we are being advertised.  The differences are mostly in the depth of the eastern CONUS trough itself, where it's axis lies, and what is happening upstream in the Atlantic.  Jan '14 had a big WAR, which helped bring some storm activity into our area, while Dec '00 did not really have that, and Dec '89 has that mega trough at 50°N latitude all across the Atlantic.  

In terms of sensible weather, all 3 were cold months, well below normal temps:  Jan '14 was -5.5F, Dec '00 was -6.7F, and Dec '89 was -11.4F (all at BWI).  All three also had below normal precip, with Jan '14 being closest to average at BWI.  Snow-wise is different, with both Jan '14 and Dec '89 above normal snowfall at BWI (Dec '89 much above normal), and Dec '00 only getting 1.3" at BWI.  

 

So, let's compare to the pattern that we're being advertised.  Here's the D10 12z EPS at 500mb:

 

Just by eye you can see it's most similar to Jan '14 with a fairly large WAR that's getting pushed eastward by our #epicapattern trough.  Does not have the Atlantic 50°N troughiness that Dec '89 had in spades and Dec '00 had to a lesser extent.  

 

Jumping forward 5 days:

 

Now perhaps it looks a bit more like Dec '00, at least more than it did at D10, with the WAR knocked down a bit.  

 

So, what does it all mean?  I'm not sure that the position of the WAR is truly the be-all/end-all for -EPO dominated patterns, but it certainly is important for determining where the storm track is going to fall.  I'll note that Jan '14 had a solid snowstorm (Jan 21 2014, 5.1" at BWI) near the beginning of the big -EPO reload during that 2nd half of that month.  Here's the previous 5 days leading into that storm:

 

Not a horrible match to that D10 EPS...

My analysis on your analysis:  https://www.youtube.com/watch?v=-CFF4CbngWo

 

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28 minutes ago, Bob Chill said:

Excellent post WxUSAF. I have the epo daily data going back to 1950 and was thinking about digging some analogs. Don't need to now. Lol

There's probably more.  I looked at half a dozen others and didn't see any that matched as well.  But I probably missed some.  Certainly I knew Jan 14 and Dec 89 without checking, but I saw some other folks on twitter mention Dec 00.  After looking at the snowfall, I'm not surprised I have no memory of that even though I was up at PSU then.  

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24 minutes ago, WxUSAF said:

There's probably more.  I looked at half a dozen others and didn't see any that matched as well.  But I probably missed some.  Certainly I knew Jan 14 and Dec 89 without checking, but I saw some other folks on twitter mention Dec 00.  After looking at the snowfall, I'm not surprised I have no memory of that even though I was up at PSU then.  

I'm going to take a look and pull ones with a big -epo event in the ballpark of at least 10 days and maybe separate by enso. Might be some clues...or might confirm chaos not telling me anything. Lol

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3 hours ago, StormchaserChuck said:

A few comments:

1. The medium range should be cooler than models, maybe where light rain threats could be mixed with snow. 

2. A cross-flow, anti-wavetrain pattern rarely holds for more than a few days at a time. Models have this for more than a week straight. I think the cold air will either move in sooner, or have trouble moving in at all (SE ridge). 

3. Lots of moisture on models Dec 7-10. Probably 1 or 2 events, the colder it is, more digging and pressure, more precip will likely associate. 

4. I've seen this Northern Hemisphere progression maybe 20 times on models in many years. It always underperforms cold wise, and ends up being a big +EPO like +20-35 days from now. (On ensemble mean next few day warmth in United States is greater than cross-polar arctic cutoff cold anomaly, weird.)

5. Maybe a big snowstorm Dec 7-10, but that's about it in this pattern I think., mid-late December should warm up nicely. 

I'll focus on #4&5

"seen this pattern on models 20+ times?"  I call bs. I'm not sure exactly how old you are but I am pretty sure your not one of the old timers and so you haven't been following things much longer then me. This pattern rarely presents itself. It's been several years since we have seen anything like this.  Unless your talking about one or two fluke runs of an operational at range. But guidance all consistently licking in on this pattern, no. Getting a -epo, AO, and nao all at the same time and to this magnitude is extremely rare.  Now I'm not saying it has to happen even with the guidance all showing it but your dismissive attitude is rediculous. 

"It always underperforms cold wise". BS again. the current analogs would take issue with that statement. This pattern is rare but when it does happen leads to some pretty extreme cold and has also lead to some pretty significant snow. Again not saying that's our fate for sure but your casual dismissal is unfounded. 

"That's about it mid December should warm up nicely". Maybe but you imply this pattern is usually a quick blip when data actually suggests when the AO tanks this time of year like this it's a fairly stable thing and even is likely to persist and be recurring. You have even implied as much before. But now your contradicting. 

i hate to assume another persons motives but I feel like you have to be just trolling at this point.  (No idea why)

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