December/January 2019/20 Winter Speculation Thread

[AMZ8990]

35 minutes ago, Carvers Gap said:

12z GEFS remains very, very cold with the onset of the pattern at 156

GEFS seems Locked in at this point.  Will make for a cold week if it verifies.  

[Holston_River_Rambler]

A lot of ash being thrown into the atmosphere just N of MJO 4/5 regions from Taal in the Phillippines. Hope all the people are able to evacuate, but also wonder what impact if any this may have downstream. That's the most ash I've seen on a satellite:

Looks like it is calming down a bit in the most recent images. 

[Holston_River_Rambler]

12z EPS, looks like it has 2 distinct colder periods now, one around the 20 -23 and then a longer one after a brief moderation:

 

[Carvers Gap]

Very true about the GEFS if it verifies...will be cold.  And then I am reminded that it has been too cold for pretty much every event.  That model fools me often.

I do think it is safe to say that the weather pattern is being pushed back now in that the trough cannot hold until very late in several model runs.  I am not into sugar coating things, and will try not to now.  Originally, it looked like the trough on the 17th would do it on the Euro suite.  Then, it would be the trough after that swing by and retrograde into the pattern.  Looks to me like a back-and-forth type pattern with some chances embedded which is still better than the one we have this week in terms of wintry weather.  The northern Rockies are now being pounded with snowstorm after snowstorm which is similar to last winter, but earlier.  The 12z EPS is a significant step back not in the overall outcome but the timing of the event.  We may well see sustained winter, but beware when the EPS begins to push things back.   IF(big IF) this pattern verifies as a flip to winter, it now appears the way to do this is via a retrograding pattern.  I still do think we see that trough hold in the East, but it is a far less likely outcome than it was a few days ago.

[PowellVolz]

Very true about the GEFS if it verifies...will be cold.  And then I am reminded that it has been too cold for pretty much every event.  That model fools me often.
I do think it is safe to say that the weather pattern is being pushed back now in that the trough cannot hold until very late in several model runs.  I am not into sugar coating things, and will try not to now.  Originally, it looked like the trough on the 17th would do it on the Euro suite.  Then, it would be the trough after that swing by and retrograde into the pattern.  Looks to me like a back-and-forth type pattern with some chances embedded which is still better than the one we have this week in terms of wintry weather.  The northern Rockies are now being pounded with snowstorm after snowstorm which is similar to last winter, but earlier.  The 12z EPS is a significant step back not in the overall outcome but the timing of the event.  We may well see sustained winter, but beware when the EPS begins to push things back.   IF(big IF) this pattern verifies as a flip to winter, it now appears the way to do this is via a retrograding pattern.  I still do think we see that trough hold in the East, but it is a far less likely outcome than it was a few days ago.

I was very hopeful at the start of the season when mods handled CF’s and cold shots very well, they even under bid the cold air with the light snow we got in December. I think we’ve all figured out that when mods show a flip but never make inside d10 and this goes on for a while it ain’t happening. We tracked this a few years ago starting in January looking at 15-20 degrees BN. When it finally happened in March, 15-20 degrees BN wasn’t even cold enough for snow.


.

[weathertree4u]

37 minutes ago, PowellVolz said:

 

I was very hopeful at the start of the season when mods handled CF’s and cold shots very well, they even under bid the cold air with the light snow we got in December. I think we’ve all figured out that when mods show a flip but never make inside d10 and this goes on for a while it ain’t happening. We tracked this a few years ago starting in January looking at 15-20 degrees BN. When it finally happened in March, 15-20 degrees BN wasn’t even cold enough for snow.


.

 

Seems like someone mentioned all this yesterday but was poo pooed, looks very very much like another head fake of a winter. 

[Carvers Gap]

I don't think the pattern change is a head fake.  The pattern is likely about to be much different with those changes to the NA pattern beginning next weekend.  I think the extreme to which modeling was going to take the pattern might be a head fake.  That said, one of the d11+ analogs for today is from 1978.   I think it is growing less likely that this pattern has sustained cold just based on 36 hour trends.  I also don't give the GFS/GEFS much weight as it has just been egregious this winter on multiple levels.  I still look at the model and enjoy its runs, but it is similar to watching pro wrestling.  I could be wrong, but I think the cold on the GEFS is a mirage.  It busted on the MJO a few weeks ago by trying to take us into the cold phases when in reality we hustled into high amplitude warm phases.  The GEFS MJO is going to try to take us into 7/8 while the Euro is going to crash through 7 and loops back into the COD with a trajectory into the warm phases.  The EPS smoked the GEFS last go around...I think it will again.  So the real question now is does the MJO go into the COD and just flame out OR does it loop back into 4, 5, 6?  Nobody knows that answer right now.  We could go gangbusters into winter if the GEFS is right OR we could cycle in and out of the COD like the EPS.  Both can still bring us winter chances...but they both produce really different weather maps in the LR.

The EPS still has the shake-up beginning with the first cold push around the 18/19. Heck, it along with the other ensembles, is very cold.  I am not seeing support for the ensemble from operational which should have it by now.  I just like what it is doing at 500.   The surface temp pattern has actually not changed as much during the last 24 hours.  I just am not sure that the actual resulting pattern is going to be an eastern trough.  I don't think it will be a western trough either like we have now.  I think the West is about to warm quite a bit over the next few months.  An early spring their would not shock me which is the opposite of last winter.  I think we are going to seem some strong cold shots, but also some warm shots as well.  Variability will be the word.  We haven't had much variability during the last 6-7 weeks.  It has been warm and rainy.

But probably wouldn't hurt to pump the breaks a bit on a sustained cold pattern.  End of the western ridge?  Very likely. Sustained eastern trough?  Less likely than it was two days ago.  Last year, the trough never left the West.  I think it highly likely that pattern is done minus cold building in the Rockies and heading East.  If I was going to rank the probability(edit) our options I would begin with:

1.  Variable Pattern w/ maybe an eastern trough 60% of the time through February.  Nino climatology with a trough building underneath without extreme cold.

2.  Eastern trough with very cold air through February.  The one other thing in the back of my mind is how bad modeling is when very cold pattern enters the pattern.  I also remember how badly the Euro missed in November.  We are now about to enter another shoulder season and it could repeat that.  As someone noted...what if the Euro is holding back energy and that is skewing the model?

2.  Zonal.  Bet that one surprised some folks. It is possible that the trough simply lifts out and we are flooded with Pacific air in the Lower 48 w short intrusions of cold air

4.  Western trough(edit) dominates.

So right now it is not that modeling is flipping back...It is just that the new pattern might not be all sunshine and rainbows.  I do think our chances for snow are going to go up...I mean is there anywhere to go but up?  LOL.  I have been banging the warm drum for weeks on end.  I think that time is done.  I am just not prepared to bang the cold drum.  There are still PLENTY of things in our favor...I just don't like seeing promising patterns being delayed.  As Powell noted, we have been there, done that, and have the T-shirt to show for it.

 

[Carvers Gap]

And the CPC forecast looks like this. That is a BIG change from our current pattern.  So, I think we have the pattern change part correct.  I just think there is a lot of back-and-forth coming up that was not on modeling a few days ago.

 

[Carvers Gap]

Another big question is where does the winter storm track set up?  Would be nice for once to get the right amount of cold and have the battleground over the forum area.

[weathertree4u]

11 minutes ago, Carvers Gap said:

I don't think the pattern change is a head fake.  The pattern is likely about to be much different with those changes to the NA pattern beginning next weekend.  I think the extreme to which modeling was going to take the pattern might be a head fake.  That said, one of the d11+ analogs for today is from 1978.   I think it is growing less likely that this pattern has sustained cold just based on 36 hour trends.  I also don't give the GFS/GEFS much weight as it has just been egregious this winter on multiple levels.  I still look at the model and enjoy its runs, but it is similar to watching pro wrestling.  I could be wrong, but I think the cold on the GEFS is a mirage.  It busted on the MJO a few weeks ago by trying to take us into the cold phases when in reality we hustled into high amplitude warm phases.  The GEFS MJO is going to try to take us into 7/8 while the Euro is going to crash through 7 and loops back into the COD with a trajectory into the warm phases.  The EPS smoked the GEFS last go around...I think it will again.  So the real question now is does the MJO go into the COD and just flame out OR does it loop back into 4, 5, 6?  Nobody knows that answer right now.  We could go gangbusters into winter if the GEFS is right OR we could cycle in and out of the COD like the EPS.  Both can still bring us winter chances...but they both produce really different weather maps in the LR.

The EPS still has the shake-up beginning with the first cold push around the 18/19. Heck, it along with the other ensembles, is very cold.  I am not seeing support for the ensemble from operational which should have it by now.  I just like what it is doing at 500.   The surface temp pattern has actually not changed as much during the last 24 hours.  I just am not sure that the actual resulting pattern is going to be an eastern trough.  I don't think it will be a western trough either like we have now.  I think the West is about to warm quite a bit over the next few months.  An early spring their would not shock me which is the opposite of last winter.  I think we are going to seem some strong cold shots, but also some warm shots as well.  Variability will be the word.  We haven't had much variability during the last 6-7 weeks.  It has been warm and rainy.

But probably wouldn't hurt to pump the breaks a bit on a sustained cold pattern.  End of the western ridge?  Very likely. Sustained eastern trough?  Less likely than it was two days ago.  Last year, the trough never left the West.  I think it highly likely that pattern is done minus cold building in the Rockies and heading East.  If I was going to rank our options I would begin with:

1.  Variable Pattern w/ maybe an eastern trough 60% of the time through February.  Nino climatology with a trough building underneath without extreme cold.

2.  Eastern trough with very cold air through February.  The one other thing in the back of my mind is how bad modeling is when very cold pattern enters the pattern.  I also remember how badly the Euro missed in November.  We are now about to enter another shoulder season and it could repeat that.  As someone noted...what if the Euro is holding back energy and that is skewing the model?

2.  Zonal.  Bet that one surprised some folks. It is possible that the trough simply lifts out and we are flooded with Pacific air in the Lower 48 w short intrusions of cold air

4.  Western trough(edit) dominates.

So right now it is not that modeling is flipping back...It is just that the new pattern might not be all sunshine and rainbows.  I do think our chances for snow are going to go up...I mean is there anywhere to go but up?  LOL.  I have been banging the warm drum for weeks on end.  I think that time is done.  I am just not prepared to bang the cold drum.  There are still PLENTY of things in our favor...I just don't like seeing promising patterns being delayed.  As Powell noted, we have been there, done that, and have the T-shirt to show for it.

 

Hopefully you are right!

[Carvers Gap]

2 minutes ago, weathertree4u said:

Hopefully you are right!

And may we all remember that there is a reason most of us don't do this for a living.  LOL.  I actually hope I am wrong and it gets really cold for a sustained amount of time.  I will take variability but after this warm stretch...would still feel like a loss.  Maybe this is a step down pattern cold and the EPS verifies.  But man, I don't like seeing ensemble modeling like the EPS push things back like it has done today.  Again, the pattern from the past few months I think is history next week.  I just think there is a lot of uncertainty in what takes it place...The 12z Euro/EPS suite was really unremarkable.  Let's hope that was a hiccup.

[Carvers Gap]

2 hours ago, Holston_River_Rambler said:

A lot of ash being thrown into the atmosphere just N of MJO 4/5 regions from Taal in the Phillippines. Hope all the people are able to evacuate, but also wonder what impact if any this may have downstream. That's the most ash I've seen on a satellite:

Looks like it is calming down a bit in the most recent images. 

That is a great point.  I have no idea.  Nice share.

[John1122]

The pattern shift is within 6 days on the models now. It may simply shift to seasonal weather, but season is good enough to get snow here in the Jan 15-February 15th timeframe. Ending the death march in the Pacific is priority 1. Unfortunately we are in model madness now. No OPs agree very well with their ENS and none of them agree with each other either, other than that the really bad ditch we've been in, we are about to jump out of.

[John1122]

GFS fires up a +PNA driven miller A that brings snow or ice to a good bit of the Valley region.

[John1122]

South and east areas win that run. NE Georgia gets bullseyed with 10+ fantasy inches.  South of 40 wins pretty big too, as does east of I-81.

[Carvers Gap]

8 minutes ago, John1122 said:

GFS fires up a +PNA driven miller A that brings snow or ice to a good bit of the Valley region.

I wonder if the change in modeling has more to do with split flow developing.  That seems to be something that is becoming really apparent.  

[Holston_River_Rambler]

I don't think it's a head fake either. We have burned ever winter since I joined the forum though, so it's hard to like anything that starts delaying or pushing back a change. 

I think there may be two things going on regarding models.

1) The storm the MA people are talking about either this coming weekend or early next week was picked up on by ensembles at range as a smoothed out pattern that looked like it might be the long awaited change. 

Example, let's go back 5 days and look at the 12z EPS from Jan 7

If we were looking at that in the middle of the pattern models had been showing, we probably said something like: "Wow, that's different from what it's been showing, is it a blip or will it hold?" 

 

The EPS didn't do too bad spotting a possible storm window for somewhere in the east at that range.

But now also notice where the EPS missed the mark bigly: a) cut off ridge in the EPO area rolling into NW Territories and Yukon and its corresponding trough in the Gulf of Alaska b)how big that Greenland/ N Atlantic ridging is showing up. It sorta kinda saw both, but the reality of a OP run is never smoothed and will always have bigger anomalies, for better or worse.

2) Maybe this 20th or so window was never a real pattern change, but just a storm window. There were some people in the MA talking about an Archambault event with this system. Maybe there is a big dog for the NE or Canadian maritimes that flips that Greenland ridging and then helps with the western ridging. I'd like to have the full gamut of blocking too, but I will take an EPO dominated pattern at this point. The really good looks that the models have been showing have always been after the 23rd or so anyway

While I was writing this I went to look at a comparison of the 0z and 12z EPS today and TBH, they weren't that different. I think the Euro Op is spooking a lot of people this PM, me included, lol. Maybe it should? 

I also think this big cut off ridge in the arctic and associated troughs up there are messing with the models. What resources do the models have up there? 

This?

Now don't get me wrong, the models obviously do a good job regardless, given what they are, but how many times have we said a cut off low is hard to predict and how many times has that panned out? Lots, I would say, and that is with the better resolution of GOES 16 and 17 at our latitudes. How much more difficult is it for them to correctly anticipate a cut off anticyclone with the above satellite data. 

I guess my point is, let's wait and see what happens with this big wobbly ridge as it dances across Canada and what it ultimately does.

I also think Carver's makes a good point. 

Watch as the storms "break" in the Pac, the first one hits the Pac NW, the next couple hit British Columbia, and the the last one breaks in the Gulf of Alaska. The location where the waves stop and head more poleward regresses over time. I think that's the evolution we are going to se as an EPO dominant pattern tried to develop as the ensembles have been showing. 

 

[John1122]

It's looking like the roller coaster for a while instead of all down hill after the massive uphill we climbed. The GFS finally is popping a mega -EPO and pushing cold our way at 360 after a couple of days of warming after the potential stormy period. The EPO ridge is just slightly off in it's orientation to do great for us. If we can get there, Siberia is blisteringly cold and the air would crash over the pole and down our way. Huge IF as always and late in the run too. Regardless of what happens day 13+, should get cold by day 6 and potentially stormy as the cold air retreats.

[Carvers Gap]

I think one of the things to watch for is where does confluence set up if we have split flow.  In other words, if there is a phase where does that happen.  The GFS has it over our area which is not terrible.  Do I think it is right?  Probably not.  Another reason I don't trust the GEFS is that it was very stubborn to recognize that the western ridge had broken down.  Now it is very stubborn with eastern cold as evidenced by another very cold run at 18z.  Seems like the Euro/EPS continues the Plains storm track despite their colder looks.  That would imply a "warm-up and rain" pattern.  Thing is...if we maintain this active pattern with cold air, we should have some chances.  I agree with John, roller coaster coming up.  

[Holston_River_Rambler]

Here's another thought too.

I think we can all agree that the Pac jet as it comes off of Asia is pretty stout now, right?

 

Well it should stay that way until the MJO interferes with it. Now, with those big ridges in the North Pac trying to develop, even as soon as now:

You have to think they will mess with that energy as the jet drives it east and maybe even get trapped in unexpected ways by those ridges.  You can see it with the Euro above as it buckles and shifts in the Arctic. 

The energy gets slung around even more as it is sheared away from the jet by the positive vorticity (500mb ridging):

[Carvers Gap]

That energy wave buried Wyoming and Montana last winter.  Probably will do so again this week.  What we probably want is that energy undercutting the EPO and getting split flow.  

[John1122]

The GEFS mean was very beefy, but skewed some by two monster storms, one that would make the bizzard of 1993 a distant memory. Something like 25-30 inches over Northern Alabama and East/MiddleTennessee with 16-20 over west Tennessee. I doubt such a storm is even possible under the best conditions. 

[John1122]

Really cold Euro OP and it looks like it could've evolved into a reload if it went beyond 240. Aleutian low looked like it might pump an EPO ridge if the progression had continued. 

[weathertree4u]

3 hours ago, John1122 said:

The GEFS mean was very beefy, but skewed some by two monster storms, one that would make the bizzard of 1993 a distant memory. Something like 25-30 inches over Northern Alabama and East/MiddleTennessee with 16-20 over west Tennessee. I doubt such a storm is even possible under the best conditions. 

Where does one look at the maps you are referencing?

[John1122]

41 minutes ago, weathertree4u said:

Where does one look at the maps you are referencing?

It's the college of DuPage weather lab page. #19 is the nearly impossible snowpocalypse on there. 

 

[John1122]

The GFS goes bananas with western ridging and looks like it's trying to get a -NAO going. Just need that massive western Ridge about five hundred miles west and those heights near Greenland about 500 miles east and north. 

 

[Holston_River_Rambler]

Interested to see if we can get some nice storms over the next couple of days. Seems like they have over-performed in the SE:

I'm guessing nothing severe and really don't want that anyway after Saturday, but some plain old thunderstorms might be fun.

 

 

[weathertree4u]

3 hours ago, John1122 said:

It's the college of DuPage weather lab page. #19 is the nearly impossible snowpocalypse on there. 

 

Did the 6am run have issues? 

[jaxjagman]

11 minutes ago, weathertree4u said:

Did the 6am run have issues? 

Some of NOAA'a sites seem to be down

[Carvers Gap]

In regards to cold...the 12z CMC just said, "Hold my beer."  @ 216 there are -30F anomalies as departures over NE TN and it is cold pretty much over the entire forum area on that run. Wow.  Surface temps are in the low single digits or below zero here.