December/January 2019/20 Winter Speculation Thread

[Carvers Gap]

And it may very well be that a surface trough over the SE persists for a couple of weeks beginning next week, but the trough at 500 on the 18z GEFS is not there for more than a a few hours. Not great news in terms of potential longevity, but we know the drill.   I doubt this story has taken its final twist either.

[weathertree4u]

11 minutes ago, Carvers Gap said:

At any rate, the sustained big eastern trough/western ridge(EPO) at 500 that was seen universally on modeling for days...has now mostly disappeared on the 18z GEFS and 12z EPS.  And when I mean disappeared...like it is barely on those runs at all.

Paint me surprised lol

[Carvers Gap]

11 minutes ago, weathertree4u said:

Paint me surprised lol

At least we know the drill this time.  Ensembles haven't  reverted(yet) to the old pattern.  The pattern change is legit.  Looks to me like variability is the key.  The RMM1 MJO this morning was the red flag.  I listed "zonal" as a probability the other day.  So here are my new rankings for the new change:

1.  Variable pattern which leans cold

2.  Zonal after the first cold shot(close second)

3.  Sustained eastern cold defined east 15-20 days(distant third)

4.  Western Ridge

[Carvers Gap]

The other red flag was when the Euro operational simply did not agree with the EPS and never developed a deep trough.  The Euro operational has been very solid.  

[Mr. Kevin]

Guys i think winter is over other than transient cold shots. They happen in the warmest winters. We are getting everything going against us for some reason this winter. Let's save this information and reconvene at the end of winter to see if i was correct or incorrect. Not being a debbie downer but being realistic and giving my opinion. 

[Stovepipe]

4 minutes ago, Mr. Kevin said:

Guys i think winter is over other than transient cold shots. They happen in the warmest winters. We are getting everything going against us for some reason this winter. Let's save this information and reconvene at the end of winter to see if i was correct or incorrect. Not being a debbie downer but being realistic and giving my opinion. 

Might as well plant some veggies early amirite?  March seedlings in January for the win!    

(light cycle may be a factor, please do not do this)

[John1122]

Very cold run of the GFS there. Of course it warms up enough to rain in the middle of the cold. Rather than fleeting cold, the pattern is base cold with a fleeting warm shot. It was close to glory for us late run. Buries Central Kentucky and north and we still squeeze out 1-3 inches with some 4 inch dollops. Very long way to go on specific storm threats though. 

[John1122]

GEFS is cold but basically lacks the warm extreme we see on the GFS Op. First half of the run is absolutely frigid once we pass the new few warm days.

[weathertree4u]

5 hours ago, Mr. Kevin said:

Guys i think winter is over other than transient cold shots. They happen in the warmest winters. We are getting everything going against us for some reason this winter. Let's save this information and reconvene at the end of winter to see if i was correct or incorrect. Not being a debbie downer but being realistic and giving my opinion. 

In reality, I think all of us are aware of the brief window compared to other areas of the county that we have for Winter in the Upper South, at least we are not pulling our hair out like members in some other forums, will not specifically mention them by name. My point is, I know for myself, I get my fix with about one winter storm, after that, I am good. I keep hoping for a winter that is a repeat of childhood winters of the 1970's - perhaps the erupting volcano in the tropics can make that happen for next year - but soon we will be turning the page anyway, so I will take what I can get and at least we have something to track, whether the pattern lasts or not, allot more fun than this time last year!

[John1122]

Long ways out still, but the storm 10 days out on the 06z GFS was a much better look for East Tennessee. Verbatim that run was best for the Plateau and Mtns. But with that track up the South Carolina coast and inside the cape with temps in the 30s, its workable for more of us than it showed. It also shows that in January the nighttime low can be 6 or 8 degrees AN and it can still snow as the normal low is low to mid 20s in parts of the area this time of year. 

Before that storm some northern stream energy will come through some part of the area. That run gave some flakes to the western areas from it. 

[Holston_River_Rambler]

Yeah John, I was just going through soundings for that system and it was doing that thing again where it shows rain, but the "best guess precip. type" was snow, at least for our locations. 

[Holston_River_Rambler]

I know they've tweaked it since they first released the Fv3, so I have to wonder if they tweaked the precip. output, since it was often showing 40 degree rains as snowfall last winter. 

[Holston_River_Rambler]

Isotherm's forecast has been pretty good so far, might be a good time for a re read (bolding is my own):

 

 

"January

Alterations should begin to initiate across the Arctic domain as the month progresses onward, due in part to downward propagating easterly shear stress via the transitioning QBO. Poleward Pacific ridging tendencies are possible, and, a priori, these ridges may connect with developing Arctic geopotential heights to facilitate a stronger transport of polar/arctic air into the Rockies and Northern Plains. However, the momentum backdrop should be neutral to negative, and its distribution continuing to promote sub-tropical ridging.

The resultant sensible weather should near to colder than normal temperatures in the N Rockies/N Plains/Upper Mid-west, and generally warmer than normal in the East/South. Snowfall departures, accordingly, should be below normal for most of the East outside of Northern New England. Central New England may see closer to normal snowfall in January due to increased jet suppression via spasmodic Pacific poleward ridging. Precipitation will be above normal in the OH Valley, interior Northeast, and Lakes, via an active SW-NE storm track.

February

Of the three meteorological winter months, February will differ most from the mean pattern. It is in this month that easterly shear stress will have a more significant effect on the AO and NAO domain, though mediated in significant part by anticipated, enhanced tropospheric receptivity to the genesis of blocking action centers. Higher than normal geopotential heights should dominate the Arctic domain, in concert with some North Pacific ridging. However, there will still be some persistence of SE US ridging via the angular momentum tendencies and backdrop. This should otherwise obviate would could have been very cold and snowy month on the East Coast. Nonetheless, the month should be the coldest and snowiest of the winter, compared to December and January. Still, the expectation is that these conditions will not be sufficient for many of the East Coast cities to reach their average snowfall for the season. Temperatures will be colder than normal across the northern tier and warmer than normal across the South, and near normal elsewhere. Snowfall will be near or above normal across most of the Lakes, OH Valley, Northeast and Northern Mid-Atlantic. There may still be a gradient across the Mid-Atlantic due to SE US ridging, thereby preventing much snowfall south of Washington DC."

 

 

 

Sounds like it is on track so far. Started to see some hints of arctic ridging, but just not a ton yet. I'm not saying Isotherm is right in everything, (no meaningful mention of what we are seeing in the MJO/ tropics right now), but in terms of the general state of the atmosphere in the N Hemisphere, he's looking pretty good now. 

[Daniel Boone]

2 hours ago, Holston_River_Rambler said:

I know they've tweaked it since they first released the Fv3, so I have to wonder if they tweaked the precip. output, since it was often showing 40 degree rains as snowfall last winter. 

Yeah, they tweaked too much as now they have rain at 34 @ 2m with -5 @ 850.  Also, over emphasize Downsloping in this area and under emphasize upslope in SEKY. 

[Carvers Gap]

Key takeaways from the 12z GFS:

1.  It is all over the place.  Unlikely its timing is remotely correct with so much energy running around.

2.  There is a lot of energy in what is a loosely defined split flow pattern.

3.  There might be "just enough" cold air.  Classic, classic El Nino SE trough stuck under a ridge.

4.  I think we can safely say that a suppressed pattern is about as unlikely as snow in July.  Looks to me like getting cold to hold is going to be the biggest struggle.  What is being modeled (at least for today...we now that will change) is a "warm-up and rain" pattern with some chances for WAA to overrun cold air.  

5.  It is highly unlikely that modeling has any of this worked out yet.  However, looks to me like our first legit chances to track winter storms might be later next week during tnweathernut's storm window.  

6.  The bleeding has slowed down (meaning pattern going to crap) on the GFS.  Trends are still not great, but the spiral has slowed.

 

[Carvers Gap]

And I should add, there is suppression on the GFS later in its run...However, as we have been getting closer to verification it very much seem like our nemesis is going to be cutters, WAA, or even zonal flow.  We may need stuff tracking to Cuba at LR with no blocking in the Atlantic...which oddly the GFS did try to build and then squared.

[Carvers Gap]

Bottom line so far at 12z:  One will rarely find a pattern as hostile to winter as the one this week.  The pattern shake-up next week is still a go.   To me, it is not a great pattern nor nearly as good as a few runs ago.  However, it is better than this week's which is not saying much but it simply couldn't get any worse.  We can steal a storm in the upcoming pattern.  It is both active and has cold shots.   A sustained pattern with multiple winter events is not on modeling at this time.  That could change, but if the cold doesn't hold...tough to get the timing right for a storm at this latitude.   

[Carvers Gap]

12z GEFS is rolling.  Slightly colder with next week's shot of cold air.  Moderation is slightly warmer after that.  Another shot of colder air at the end of the run which is colder than 6z.  Good signs in that we don't want to see any more steps backward.  That was basically a hold or even slight improvement.

[tnweathernut]

2 minutes ago, Carvers Gap said:

Bottom line so far at 12z:  One will rarely find a pattern as hostile to winter as the one this week.  The pattern shake-up next week is still a go.   To me, it is not a great pattern nor nearly as good as a few runs ago.  However, it is better than this week's which is not saying much but it simply couldn't get any worse.  We can steal a storm in the upcoming pattern.  It is both active and has cold shots.   A sustained pattern with multiple winter events is not on modeling at this time.  That could change, but if the cold doesn't hold...tough to get the timing right for a storm at this latitude.   

Regarding the bolded..........  Life in the mid-south. lol

I feel optimistic the change next week throws us a bone.  Might be a splintered chicken bone and not a meaty T-bone.... or it could simply be even worse, a bone we all choke on?  If you look at the OP modeling across the board there are so many lobes of energy flying around.  There is no way these models will be accurate beyond day 5.  It's probably best to passively look for the next best opportunity and just hope like heck we can get something inside of 5 days.....

[Carvers Gap]

Really nice post by PSU in the MA forum.  Now, it should be noted that the pattern in DC does not affect most of us.  For those living in TRI, I have found that some of their setups do deliver here.  Anyway, pay careful attention to the patterns that provided big snows on the coast and their similarities to what is being shown on ensembles.  It wouldn't take many adjustments for that to impact us here.   Anyway, with not blocking in the Atlantic we need a 50/50 low and that is what is missing on modeling that seems like it should have more storms.  I will tag @psuhoffman so he knows I have quoted his post.  PSU, hope you don't mind the share. 

10 minutes ago, psuhoffman said:

Here is how the look for around day 10-12 has shifted on the GEFS (EPS is similar).   Now this time we are comparing a day 15 look to day 10..(last time it was day 10 to 7) so the shifts are going to be a bit more drastic...but still the large scale longwave pattern wasn't awful.

GEFS from a few days ago

This was a very cold look, big EPO ridge with cross polar flow directed right into the eastern US.  But it's also a dry one, and I mentioned that a few days ago when this look was being tossed out.  This was likely to be very cold but very dry.  The other 2 major features were the PV situated across the NAO domain across the pole into the Kara region, eastern trough, trough in the Pac NE of Hawaii.  

This is how it has shifted 

So again it was too far west with the pac trough...this shift pressed the epo ridge into more of a Hudson Bay ridge.  It was correct with its NAM depiction and the trough in the east.   Now this has a positive and a negative.  It cuts off the cross polar flow, so this is a much less cold look.   But this is also much more likely to get something to amplify into the southeastern US.  That blocking ridge across Canada will cut off arctic cold but there is a shot of cold into the east ahead of this...and so long as that is trapped under the block and not scoured out that usually is good enough in January.  Ideally I would like a 50/50...that could end up being the big issue here if too much ridging in the northeast allows the system to cut... but this still has potential imo.  

This is a composite of 16 warning level snowfalls at BWI with a Hudson Bay centered ridge. 

The obvious thing missing is the 50/50 low.  But that is a composite, not ALL 16 of those had a 50/50, but most hence the mean.  But at this range a feature like that could be missed, perhaps an unseen vort next week, Ralphs clipper, can bomb out into the 50/50 space, or perhaps the day 11 storm does cut but becomes the 50/50 for the day 14 threat.  Either way, this look is way closer to a big snow look than the one a few days ago.  It's not nearly as cold...and it could end up a rain look also...but you have to play with fire to have a nice BBQ!  

If you did want a week or frigid cold dry weather...I apologize, things are not moving in the right direction for that.  

 

 

 

[tnweathernut]

1 minute ago, Carvers Gap said:

Really nice post by PSU in the MA forum.  Now, it should be noted that the pattern in DC does not affect most of us.  For those living in TRI, I have found that some of their setups do deliver here.  Anyway, pay careful attention to the patterns that provided big snows on the coast and their similarities to what is being shown on ensembles.  It wouldn't take many adjustments for that to impact us here.   Anyway, with not blocking in the Atlantic we need a 50/50 low and that is what is missing on modeling that seems like it should have more storms.  I will tag @psuhoffman so he knows I have quoted his post.  PSU, hope you don't mind the share. 

 

Definitely noted the HB centered ridge.  Give me that and I will take my chances for scoring something down the line.  It's certainly not a slam dunk for winter in the mid-south, but it increases the odds drastically. 

The way I look at the pattern, two weeks ago we were wondering if we'd EVER break the record warm pattern.  One week ago we were salivating at the LR.  Currently, we can see a different pattern coming, one light years better than the one two weeks ago, but still not a slam dunk for what we all want to see - snow.  Sounds pretty typical of winter life in the mid-south which mostly includes a "hurry up and wait" philosophy.

[Carvers Gap]

On both the GEFS and GEPS at 12z, there is a signal of another cold shot later in both of those model runs.  Again, when an ensemble moves a bit...probably should take note.  The MJO is also very much in doubt after phase 7.  We have definitely had the exact same situation occur once already.  Does it loop back into 5/6 or just die in the COD.  I lean towards the COD after seeing the EMON yesterday and after seeing a slight balk on the Euro MJO this morning.  It runs right up to 6 and stops for three days.  On the EMON, it takes that trajectory and reverses back into the COD.  The loop back towards 6 is likely why models are showing a warmup in the mid range and then move back to colder solutions.  Let's HOPE that the MJO does not go back into 6....if so, would be mid-Feb before we likely see anything decent in terms of cold again.  

[Holston_River_Rambler]

Euro Op finally showing a stable Aleutian low. There's that at least. 

Sorry, should be more specific, it is showing it from hr 168 through the end. 

[Carvers Gap]

As John would say, the 12z Euro operational is pretty much a turd in the punch bowl.

[Carvers Gap]

Sorry, Holston.  Must have posted at the same time.  No reference to you post.  Basically NA loses its BN temp anomalies until very late in the run when the Yukon reloads.  The Yukon reload of cold might be the only positive thing I see on that map along with Holston's Aleutian low.  When I am in January having to look at d10 for any hope...we are in a rough stretch.   We better hope the EPS has something...because that operational run means the EPS from a few days ago will absolutely not verify or even be close.  That is what we call a bust.

[Carvers Gap]

The pattern did change which modeling did get correct.  It has been woefully incorrect about the new patten for Jan 17-24.  Lots of zonal components to the new pattern and what once looked like strong cold fronts are nothing more than seasonal(or above) frontal passages.  Can't really be called a head fake since the pattern did change.  The trough in the West is pretty much gone.  But it looks like it is going to be nearly total bust(all three ensembles) with the exclusion of the 2-3 day cold snap next week.  Hopefully, we see a continued step down later in the month.  At this point that is a variable pattern which is base warm.

[Holston_River_Rambler]

No worries. I heard the beep on a post right as I was about to hit enter, lol.

Yeah, the GFS storm (23 -26th ish) not so hot on the Euro, but I suspect the EPS tries to roll the ridging over Hudson's Bay, back to the west, but it will get less and less certain as it progs out in time (i.e. the anomalies will look less anomalous) 

[Holston_River_Rambler]

Here's the full shebang.

Looks Ninoish with chances to me. Of course it is still in that magical 10 day + window, but at least the OP was popping that Aleutian low now and what the EPS is showing looks to match up going forward from the end of the OP:

 

 

 

[John1122]

Who know if the Euro is right, but I'll take that all day in late January. We can be AN and get snow over a good bit of the valley during late January. My normal low bottoms out at around 21 degrees around January 25th-30th. It can be 10 AN and still snow here.

[Holston_River_Rambler]

psuhoffman mentioned the EPS looked good to his southwest between days 10 -15,so I thought I'd have a look.

Almost every single member shows a storm here between day 10 and 15. member 47 showed 2 , lol

There were so many I had to make 3 gifs for them all. Every one of these is a different member, except one (member 47).