December 2017 Observations and Discussions

[Tom]

Shades of '13 cold showing up right around the same time we saw the first push of true Arctic air that year.  Sub zero overnight lows near the MW/GL's between the 11th-15th???  You'll need a snow cover in order to do that but the chances of snow are increasing in this region.  I could see several clippers, some could be strong, rotating around the base of a massive trough across SE C.A.  Hudson Bay vortex will park itself much farther south than normal as the blocking does its work.  

 

00z GEFS showing a wetter look across the southern Plains Day 6-12 up the OV....

 

[jaster220]

What's crazy is that there's a second system up the pipe somewhere 4-5(ish) days after the first one and there's really no telling what is going to happen with that one.

 

Yes, I mentioned the BSB's (Bering Sea Bombs) as a tandem pair not unlike the two hits on 10-11 and 10-14 (the Flood Warning qpf bomb up my way). Should be some serious tracking for our sub from about Dec 7th onward for those two. Can't wait. Christmas come early if that Euro Control run has half a clue for SWMI 

[jaster220]

snow hole in cedar rapids /iowa city lol

 

You IA guys are the new Nebraska. I saw a post on AmWx that some areas of Iowa just set a new record of 700 days (and counting) since the last 3"+ snow fall??? OMG! that's kraziness! 

[jaster220]

00z EPS showing more members hinting at a CO Low that tracks up towards the GL's and strengthens.  It's showing the 2 pieces of energy with one tracking through the Dakotas and the secondary piece over CO/KS that eventually phase into a strong GL's storm.  Need to keep an eye on that southern energy because this season we have seen this being the main player.  

 

Which time-frame are you speaking of, this system you showed via the GGEM next week, or the potential later systems via the BSR? 

[Tom]

Which time-frame are you speaking of, this system you showed via the GGEM next week, or the potential later systems via the BSR? 

Sorry for the confusion.  This was meant for the Dec 4th-6th system.  It was still a bit early when I made this comment and I haven't had my cup of coffee yet!

[jaster220]

Sorry for the confusion.  This was meant for the Dec 4th-6th system.  It was still a bit early when I made this comment and I haven't had my cup of coffee yet!

 

    Yeah, anything prior to my morning Java is subject to the same problem..no worries mate. It would be nice if we could get a system to take shape as the cold regime takes over. Not just another mostly dry CF passage. I'd still likely have a shot at LES here, but I much prefer the other scenario, even if it means rain here. 

[Tom]

The cold that is coming Week 2 is as locked and loaded as you will see across all the models.  After a couple days in the 60's and 40's in the forecast for the next 6 days, the system will be shocked to the bones when it hits and holds.  Probably will be one of the most dramatic flips from Autumn to full blow winter mode.

 

If the LRC is right, the 11th-15th time frame should have a southern system tracking E/NE up into the S MW/OV/GL's during this period.  Several long range forecasting tools are mimicking this storm potential.  If we can get a nice phasing storm system, it will likely drop the Polar Vortex into our sub forum sometime around the end of this period and likely post-storm.

 

When I see the 00z EPS look like this...you can already see the signal of the southern energy down near TX.

 

http://wx.graphics/models/ecmwf/2017112900/noram/eps_z500s_noram_360.png

 

http://wx.graphics/models/ecmwf/2017112900/noram/eps_mslp_anom_noram_360.png

 

 

 

Day 15...Barney will be re-appearing...

 

http://wx.graphics/models/ecmwf/2017112900/noram/eps_t2m_anom_noram_360.png

[Niko]

Coldest weather of the season is looking likely to arrive for next week. Lots of peeps on here will shiver.

[Minny_Weather]

I'm gonna saw off the SW part of the country so the ridge follows them.

[jaster220]

    Yeah, anything prior to my morning Java is subject to the same problem..no worries mate. It would be nice if we could get a system to take shape as the cold regime takes over. Not just another mostly dry CF passage. I'd still likely have a shot at LES here, but I much prefer the other scenario, even if it means rain here. 

 

If the LRC is right, the 11th-15th time frame should have a southern system tracking E/NE up into the S MW/OV/GL's during this period.  Several long range forecasting tools are mimicking this storm potential.  If we can get a nice phasing storm system, it will likely drop the Polar Vortex into our sub forum sometime around the end of this period and likely post-storm.

 

Per a nice post on AmWx from a LOT Met, we shouldn't automatically presume cold-n-suppressed. Tho that scenario happens all too often, two strong analogs to this season both featured cold-n-moist. Nice read here:

 

"Bringing up December 2000 is an excellent example to disprove the frequent assumption that an amplified +PNA/-EPO ridge automatically means cold and dry away from the lake effect belts. Another example of this is January 2014. Comparing the 500 mb composites for December 2000 and January 2014 with day 15 of the 12z 12/28 European ensemble, they're strikingly similar.

 

This isn't to say that we're headed for a historic stretch of snow outside the lake belts, but that northwest flow implied on the ensemble mean is not a guaranteed mainly dry pattern. The position of the ridge axis is important, with farther west as in December 2000 and January 2014 and by extension what's shown on the EPS prog one that can be quite favorable for an active pattern with clippers/hybrids from polar jet. Also, if the progged -NAO block trends weaker as shown on today's EPS, that gives a better chance of favorable storm tracks from phased waves due to influence of southeast Ridge/WAR.

 

So, moving forward, we need to watch for the position of the +PNA/-EPO ridge axis in terms of attaining a more active pattern vs being drier with moisture starved clippers. Overall, I'm fairly optimistic for at least some opportunities for light-moderate events outside of the lake belts, because temperatures correlate pretty well with snow and it's less common to get largely shut out in very cold patterns than it is to cash in with at least somewhat near normal snow. With all this being said, obviously possible that we do end up in a very cold but mainly dry pattern."

[Niko]

Models will continue to have a hard time figuring out where any storms will be forming, especially, w the flip of the pattern coming next week. I believe that by end of next week, computer models will start handling storm systems much better.

[Minny_Weather]

 

[gosaints]

That cold snap will be a relatively poor pattern for storm prospects it seems

[St Paul Storm]

Models will continue to have a hard time figuring out where any storms will be forming, especially, w the flip of the pattern coming next week. I believe that by end of next week, computer models will start handling storm systems much better.

Can we hold you to that last statement? Haha!

[Niko]

Can we hold you to that last statement? Haha!

 

I think it makes sense to think that models cannot forecast correctly during a pattern flip, until that change has occurred.

[Craig-OmahaWX]

Latest GEM loses again snd last nights run was just a pipe dream lol

[jaster220]

That cold snap will be a relatively poor pattern for storm prospects it seems

 

But seemingly good to great for LES regions. Only a couple of us in here that could gain excitement from this, and I personally like synoptic snow much more than LES. Nonetheless, it seems that with this potential historic cold wave, the lakes could really light up. A lot TBD at this range ofc, but this looks enticing to say the least.

 

 

 

Related post from LES thd elsewhere:

 

 

 

That GFS run was just incredible. One of the best for long duration LES that I've seen. The blocking across the Atlantic and the positive PNA allows the PV to pay a visit to midwest and northeast in a series of waves riding along the elongated trough axis. I count a total of 3-4 over the course of 10 days. It reminds me of Dec 2001 or Jan 1985 setups. I do not see any sustained NW flow with this regime and that H5 setup. I do see long duration lake effect snows from NW to SW flow over the course of the next 3 weeks starting on Dec 5-7th.  The CIPS analogs are all on board, and once we get closer can pinpoint certain events. 72 hour totals of over 2 feet in favored locations. As cold air is most likely a certainty at this point, I am worried about dry air. Some of the long range models do not have as good moisture profiles as the GFS has.

[Niko]

But seemingly good to great for LES regions. Only a couple of us in here that could gain excitement from this, and I personally like synoptic snow much more than LES. Nonetheless, it seems that with this potential historic cold wave, the lakes could really light up. A lot TBD at this range ofc, but this looks enticing to say the least.

 

20171127 12-14d Snowfall from CIPS analogs.jpg

 

Related post from LES thd elsewhere:

4-8 for me...Umm, I'll take it.

[OKwx2k4]

But seemingly good to great for LES regions. Only a couple of us in here that could gain excitement from this, and I personally like synoptic snow much more than LES. Nonetheless, it seems that with this potential historic cold wave, the lakes could really light up. A lot TBD at this range ofc, but this looks enticing to say the least.

 

20171127 12-14d Snowfall from CIPS analogs.jpg

 

Related post from LES thd elsewhere:

Nice map.

[OKwx2k4]

Per Jaster's shared AmWx post and analogs, glad to hear 2013-14 and 2000 mentioned. I've heard a lot of 1988-89 talk as well. What is setting up should be amazing.

If they can get down to 2010-11 levels and more of 1917-18 or 1978-79 levels then this winter literally won't stop much more until it's over.

[hlcater]

That cold snap will be a relatively poor pattern for storm prospects it seems

I partially disagree. Based on RC's post on amwx, and a TLE of the past 8 or so GFS fantasy range runs, I feel decently confident that we will at least be seeing several clippers in this pattern, each producing light-moderate accumulations. As Tom briefly mentioned, the LRC would have a potentially significant system out of the southwest some time during this time period, but I wouldn't count on that. I see plenty of snow chances, but big storm chances being below average.

[jaster220]

Latest GEM loses again snd last nights run was just a pipe dream lol

 

Care to post GFS 12z? Heard it was wintery looking?

[jaster220]

I partially disagree. Based on RC's post on amwx, and a TLE of the past 8 or so GFS fantasy range runs, I feel decently confident that we will at least be seeing several clippers in this pattern, each producing light-moderate accumulations. As Tom briefly mentioned, the LRC would have a potentially significant system out of the southwest some time during this time period, but I wouldn't count on that. I see plenty of snow chances, but big storm chances being below average.

 

Ofc, just when you go there, the GFS says "Ah ha! I see a storm" 

[Minny_Weather]

Latest GEM loses again snd last nights run was just a pipe dream lol

It didn't lose it, it just shifted it way SE and made it weaker. I honestly think its new track is unrealistic. I don't think there will be a storm. If there were to be, it would not take the track it just showed.

[jaster220]

Care to post GFS 12z? Heard it was wintery looking?

 

Nm, I got it

 

It didn't lose it, it just shifted it way SE and made it weaker. I honestly think its new track is unrealistic. I don't think there will be a storm. If there were to be, it would not take the track it just showed.

 

Kinda early to make such a call in this dynamic of a situation that's unfolding..

 

 

[jaster220]

GRR's long term afd:

 

.LONG TERM...(Friday night through Tuesday)

Issued at 321 AM EST Wed Nov 29 2017

Quiet weather to end the week, will turn more unsettled early next
week. Colder air should arrive into Tuesday and beyond with some
potential for snow.

Zonal flow will persist into the weekend. Little sensible weather
is expected with temps fairly uniform from day to day, with highs in
the mid and upper 40s for the weekend.

The next chance of pcpn should hold off until Sunday night or
Monday. By then a Western U.S. upper trough begins to deepen, with
the northern and southern stream flows merging, developing surface
lows over Western KS and the Dakotas. The Gulf opens up and solid
warm advection should begin to produce rain showers over the Great
Lakes in this time frame.

The models continue to intensify the surface low as it heads
northeast toward the Superior Region by Monday night. The ECMWF
shows a much more mature synoptic low, while the GFS is weaker. Tend
to like the ECMWF over the GFS at this point. This should bring in
a surge of warm air Sunday night and Monday, helping to maintain all
rain. The weaker GFS is more progressive with the system and
therefore brings the colder air and snow in here by Monday night.
But feel a slower solution will verify given the dynamic nature. So
will continue with rain Monday night. Given the current timing we
should see falling temps on Tuesday as a cold front is dragged
through. The pcpn should diminish as the front passes, but there
could be a few snow flakes mixing in.

As an outlook: This will set the stage for much colder temps into
mid week. An upper trough is progged to move in on Wednesday. Lake
enhanced measurable snow seems probable Wednesday into Wednesday
night.

 

Only a week out..hmm

[Minny_Weather]

Kinda early to make such a call in this dynamic of a situation that's unfolding..

I'm talking about mid-next week.

[Craig-OmahaWX]

I dont trust anything beyond 84 hours gor a storm syste. Judt will dissapear

[jaster220]

I'm talking about mid-next week.

 

Oh, my bad..so many systems in the pipes, eh?    Looked closely at the 12z GFS and its typical progressive bias (cold and SE with everything) is plain to see. Has that 2nd potential major system dumping on LA - yeah, right  , (sorry OKwx I know that's gotta be so nice to see). Climo, the LRC, analogs, etc.. aren't all wrong and won't be trumped by a 380 hr model run. On the system I posted above, a slight bump north (very likely imho) and SENE is right in the game    

[Tom]

12z Euro trending towards the LRC and a northerly track which I had anticipated.  Dynamic storm is in the works for the GL's region.  Some shifts should be expected at this range but looking more likely for a cutter into W GL's.

[hlcater]

12z Euro trending towards the LRC and a northerly track which I had anticipated.  Dynamic storm is in the works for the GL's region.  Some shifts should be expected at this range but looking more likely for a cutter into W GL's.

How does it interact with the incoming cold? To late? Also, what do you consider west lakes, Chicago or more up into Green Bay?

[Tom]

How does it interact with the incoming cold? To late? Also, what do you consider west lakes, Chicago or more up into Green Bay?

W GL’s = GRB region

 

Not enough blocking in S CA and warmth downstream do not suggest to me a wintry potential around Chicago. This storm has eyes for MM posters, but if it could develop sooner, then maybe even include IA peeps or even WI folks for wrap around snows.

[james1976]

W GL’s = GRB region

 

Not enough blocking in S CA and warmth downstream do not suggest to me a wintry potential around Chicago. This storm has eyes for MM posters, but if it could develop sooner, then maybe even include IA peeps or even WI folks for wrap around snows.

You talkin mid next week?

[Craig-OmahaWX]

Worst possible pattern ever for snow in the plains. Extreme cold air to supress anything.

[james1976]

[NEJeremy]

Cold, windy, and flurries for Nebraska on the 12Z run! NW flow dominates again. Zzzzzzz.....

[Minny_Weather]

Good to see this D**n warm weather is finally going away. Now let's get a storm.

[bud2380]

I'd love to see a good clipper parade, like the one we had in December 2000.  As long as they are producing 1-3/2-4"+ each run.  Not these clippers that are nothing more than flurries.  Every once in awhile we get some good storms in the NW flow as well, like the Nov 20th 2015 storm that dropped several inches across much of our areas.  

[james1976]

I'd love to see a good clipper parade, like the one we had in December 2000. As long as they are producing 1-3/2-4"+ each run. Not these clippers that are nothing more than flurries. Every once in awhile we get some good storms in the NW flow as well, like the Nov 20th 2015 storm that dropped several inches across much of our areas.

Yup ive had great luck up my way with clippers!

[Minny_Weather]

Yup ive had great luck up my way with clippers!

We haven't had a productive clipper here since February 2015.