Winter Speculation 17/18 -December Thread

[John1122]

Middle Tennessee and northern Alabama gets crushed right here, the frozen precip line is and west is where the heaviest snow totals shook out. Also where the freezing rain happens, although it looks like it'd also be a lot of sleet. Still the entire forum area sees at least 3 inches of snow that run and most of it sees 6+. Someday we will get a storm like this. It may not be now, but 15-20 inch snow falls have happened in the area before and they will again at some point.

Look at the pink right behind the sleet over the plateau. That's super heavy snow. I'm not sure I've ever seen it go beyond the dark blue on these maps.

 

[John1122]

The EURO is a day slower but otherwise nearly a mirror image of the GFS. At the end of it's run Middle Tennessee has 4-8 inches of snow on the ground, it's pouring snow still and the Eastern areas are getting heavy freezing rain or sleet that is quickly changing to snow. It starts as light rain and changes to heavy freezing precip. The low tracks from South Texas to NE Georgia that run. 

 

[John1122]

I do believe the precip type maps are off. Most of East Tennessee is in the 20s at the surface, the 20s at 925 and well below freezing at 850 and it's still showing ice as the p-type at 240. My area is -4c at 850, -6c at 925 and in the upper 10s at the surface and the p-type map shows ice over me vs snow. 

[John1122]

This is golden for our forum area. I wish it were 48 hours out instead of 228.

[Carvers Gap]

Couple of morning notes about the overnight run of the models.

1.  The arrival of the Arctic front is definitely a timeframe to watch.   Those have tended to be big producers over the Valley, especially if they slow down.  The models had this system yesterday, especially the Euro.  But at d9....I will wait until inside of a week to get too fired up.  The EPS is trending to a slightly different PV setup than modeled during the past few weeks.  That trend will set the tone for the rest of winter potentially...

2.  As for the trend....The cold is definitely, on the models at least, wanting to settle further northwest(maybe the axis is just barely east of the nation's midsection) that the Dec/Jan cold shot.  The February tendency to have a SER is in play as that is very common in a Nina.  For example, last February, winter was gone basically.  The EPS, allows AN heights to eventually build under the trough.  But when one looks at the 2m temps, it depicts cold very slowly bleeding into the SE.  IMO, that is a good set-up.  Precipitation should ride that boundary since it is oriented in a way that is should allow the GOM to be tapped.  W/ the previous cold spell, the trough was too deep and too far to the East.  Everything ran off the coast....remember those big storms on the Outer Banks?  Now, w the cold potentially displaced much further to the NW and also accounting for models usually underestimating how far the cold penetrates, we would likely be in a place where we are fighting temp profiles.  Again, I think the bigger concern once the front passes is how the pattern evolves.  How far does the trough pull back and which side of the boundary are we on?  While unlikely, I can definitely see a scenario where it pulls back, heights build underneath, and we are warm...while the Great Lakes freeze.  I think the more likely scenario is frequent pinwheeling bouts of cold rushing down the Plains into the Upper South.

Overall, good trends...but I do have one eye over my shoulder at the trend on the EPS to pull that trough northward.

[Carvers Gap]

1 hour ago, *Flash* said:

Yeah, as some say...'fear the north/northwest trend'...though unlike past Nina winters this decade...I think most of the forum is lookin' good early Feb. On a side note, does anyone feel this winter is shaping up like 1995-96? I heard that analog put out a few months ago. Can't remember who said it...but the comparison of steadfast winter with transient mild spells is worth noting. 

Good post.  It definitely has some 95-96 in it IMHO.  Need some big snows to drive that home though.  I am going to count on the EPS under-modeling the cold at the 2m level.  If so, this is really a money look.  Just need the trend to stop or slow. The base pattern has been cold...though it is possible that Dec/Jan will end up close to normal or just below when averaged together.  December was above normal for temps here at TRI.   Seems like the warm days are really warm and the cold days really cold.  I do like weak La Nina winters.  I do think, as others have noted, that the coastal looks from the earlier cold shot will now be inland.   I like the pattern that we are heading into...just want to make sure that I am giving accurate info....but if you asked for my opinion, I am a big fan of what I see.  Sure, we may get some raiders...but that look is going to allow the GOM to get involved IMO for the Upper South.  Hey, it is even spitting salt and pepper snow up this way today.  

[Stovepipe]

2 hours ago, *Flash* said:

For real. Where's Stovepipe when you need him?

Holy Moly that's beautiful!  I've been too busy at work lately to check the models.  I very much appreciate reading the breakdown here.  You folks are doing a fantastic job!

Now let's reel in a storm shall we?

[weathertree4u]

12z not as juiced

[John1122]

It's really more north. It still snows some in the area but that's a much less favorable track. 

[jaxjagman]

27 minutes ago, weathertree4u said:

12z not as juiced

Yeah,ridge looks better in the east,front was slower.

[nrgjeff]

12Z suite blanks Chattanooga; so, one has to consider it a legitimate possibility.

[Carvers Gap]

5 minutes ago, nrgjeff said:

12Z suite blanks Chattanooga; so, one has to consider it a legitimate possibility.

If it makes you feel better, TRI isn't exactly the Upper South's version of Buffalo, NY, this winter either.   

[Carvers Gap]

Straight shootin’...

The 12z GEFS and EPS now depict the cold retreating to the nation’s mid-section and not the East.  Now, this happened w some of the original modeling of the Dec 24th cold shot.  Models dumped it West, etc...but that did not happen.  This is a bit different.  The models have hurried the initial cold shot.  The 12z EPS pulls back the cold(after the first cold shot on Feb 2nd) in a trend that would allow the SER to take hold and be a legitimate problem.  Now, the EPS has been too shallow w cold all winter.  So, there is that. But the GEFS is right there with it.  If this trend continues inside of d10, it is time to put the breaks on expectations for February.  February climo supports a SER in correlation w a Nina ENSO state.  In December, suppression was my worry.  Now, it is the SER.  I highly doubt we have a dry month.  That pattern looks soaking wet.  So, I am adjusting my thoughts....it is now possible (50/50) that the base pattern for Feb is warm...the entire month w shots of bitter cold.  I originally thought cold would be the base state based on the Weeklies. I am now adjusting my thinking to equal chances.  It can still snow...and plenty of it depending upon the boundary.   

[Carvers Gap]

Here is the d15 EPS.   I double checked it against the Weeklies....and it is not too far off.  It does allow more AN heights under the trough.  The Weeklies show a bit of a pull back and then slam the trough southward a few weeks later.  I did not catch that on Monday.  Now, here is the big question, "How far does the cold press south?"  We don't live at 500.  Remember in late Dec, that the cold pressed well south of what the 500 maps seemed to show.  On the graphic below, option A is the place where the actual 500 boundary would infer the surface cold would be.  However, if we begin to see big 1040-1050 high pressures coming south out of Canada, the cold will press further than show.  Thus, we have option B.  The cold presses further south than modeled at 500.  The storm track will likely ride that boundary and also tap the GOM as one can see the slight dovetail to northeast due to the SER.  Then, another big question is the strength of the SER.  This is not a slam dunk like it looked a few runs ago.  Work to be done still.  But...it could be a blessing in disguise.  The boundary might be displaced just enough north to put us in business....or it could be cold rain.  Lastly, the EPO ridge is back.  It is usually a positive in that it teleconnects to a trough in the East.

[tnweathernut]

Good post, Carvers.   You have to think with the EPO projected to tank in a similar fashion to December we see the cold press further than current modeling shows.   

How far is anyone's guess and it's likely the end result yields several fronts, each of which move the boundary further south and east with time with brief (even stout warming possible) between them.  We have to remember the ensembles smooth what we visually see in the extended, so it might be best to look at the individuals and see if we find clues there.

At the very least, February won't be an all out torch and at the very best we wind up on the good (snowy) side of the boundary for a couple of systems.  At the very least it looks rather active.  My yard would sure appreciate the moisture, regardless of its form.

[John1122]

If the EPO ridge comes, the cold will too. Models for whatever reason keep showing the bizarre trough under the western ridging that never happens once we move forward in time. They also have tried to pump a SE ridge all winter too, no luck on that one either. The Pacific drives the bus. Especially those EPO ridges. I'm far more worried that there won't be any Atlantic ridging when we need it than I am about having too much.

[John1122]

The 18z and 00z GFS vary a little on track and intensity, but both kept a large portion of the forum area in the snow chance game. The 18 was very heavy again over parts of the Eastern forum but was a miss out West. 00z was very good over SW Kentucky/NWTN but more widespread with 1-3 across more of the forum area.

[Carvers Gap]

0z Euro/EPS.  They both continued building AN heights in the East d10-15.  The term "flipped" can be used to describe the pattern depicted overnight in the lower 48 during that time frame.   Trough west, ridge east....though the -EPO is still there, just further west which allows heights to lower in the West - this is not the over/under error from December.  But the Euro still looks like it is playing games w the trough alignment and holding energy in the West. Among several things that worry me, this fits February climatology where winters abruptly end in the East during Nina winters.  The GEFS shows something similar to a certain extent.  Last winter no matter the 500 alignment, it stayed cold in the West.  That is what last night's run basically was, excluding the d7-10 timeframe.   Again, it could be just be the EPS having difficulty with holding energy back in the southwest...but one more correction like that and the trough will be in the West.  The MJO is going very high amplitude now into phases 6-7 through mid Feb.  I wonder if that is now influencing things.  But overall, a very ugly run of the Euro last night.  The Weeklies should be very warm tonight.  I will now move February solidly into the AN category for the month.  Who knows for snow....  Done posting today unless something changes.  The pattern looks that bad.

 

edit:  It is looking more and more like the models were either too quick or in error in moving the trough eastward.  It will likely happen....but the warmth looks like it will return quickly after the Feb 2-5 cold snap.  The MJO argues that the trough should come back during wks 3-4 of February.  The 6z GEFS holds the cold in the Plains.  The GEPS never changes from the current trough in the West.  Wall-to wall ridge in the East for it.  On a mildly positive not, the d6-10 timeframe looks somewhat interesting.  But I am done discussing the d10-15 for a bit.  If you don't hear from me about the Weeklies tonight...assume they were warm.

[Jed33]

I’m just wondering when we can get some precipitation to verify. I mean more than 0.25. These models keep generating precip for the area this winter, but it has really been a struggle to get it over the plateau into the eastern valley. Or the systems blow up on the Atlantic too far east to benefit us. I am starting to think that it may just be one of those winters that E TN is just left with the scraps. I’m hoping that we can actually get more moisture of any kind in here in these coming months. So far I’m not liking what I’m seeing with these repeating setups to the west and the east.

[nrgjeff]

Yesterday I was posting on-tilt, still pissed off about the Kansas loss. Thanks to the rest of you for a better discussion. Today we look forward to Wichita State... and mid-February!

19 hours ago, nrgjeff said:

12Z suite blanks Chattanooga; so, one has to consider it a legitimate possibility.

I figure the cold pattern will take 7-10 days to become intense. Could be faster if the Midwest snow cover fills in faster. If I had to put my chips on snow it would still be in the 12-20 day range. Model disasters in the 6-15 day do not worry me too much. 

Ensembles and weeklies have hinted at occasional mild blips within the cold pattern, which is in line with history this season - and of no concern. I mean it's snowed twice in Houston and Baton Rouge. Irony vs CHA is pretty rich, but one cannot complain about the overall pattern.

Doubt the weeklies tonight will change my opinion. Perhaps they will drop the best week mid-Feb. I'm going with a building cold pattern. By mid-February Wichita State will be atop the American Conference; Kansas will have a 2-game lead in the Big 12, and hopefully snow will fall in Chattanooga.

If all else fails, maybe we can get some severe weather going, lol.

[Carvers Gap]

2 hours ago, *Flash* said:

Part of me wouldn't mind a Feb 2011 repeat. Great snows the first half...spring preview second half. Obviously the concern is growing as per mentioned. Looking more likely a 24/55 snowchase will be needed next weekend to ensure at least one experiential 6"+ snow for the winter. 

Joe D'Aleo posted this comparison set of maps below on WxBell depicting the similarities of the Dec 10th Euro and the one that ran last night.  I like D'Aleo.  He is a savvy, old school met that has seen a ton of wx.  The -EPO argues that this should correct eastward.  BUT.....notice that the EPO ridge is further to the west this time.  So, it will likely correct less eastward in comparison as there is room for cold in the Plains.  Now, that does fit with what many have been saying in this forum for several days...the storm track will not be located just off the eastern seaboard this time, but inland....maybe even far inland.  What I don't like....is the trend on the EPS to pull that trough westward.  Like I said earlier, one more correction west(of the scale of the overnight run) and trough will stick in the west and hold just like the GEPS depicted at 0z.   Prior to Christmas, the EPS was slowly correcting eastward...right now, the EPS is quickly correcting westward.  While the maps look the same....I am concerned that they are like two ships passing in the night.   They have the same coordinates right now but are moving in opposite directions.  If I knew nothing of the trend, I would simply say that the overnight EPS will correct that trough eastward.  D'Aleo (I think) suspects this corrects eastward, but is unsure.  I am very wary of the trend.  Anyway, wanted to clear up my comments from earlier.  Again, I am intrigued by the d6-10 time frame.  The Weeklies ought to be toasty tonight since they were derived from that warm run....so unless they show anything major, no big updates.  

 

 

Ninja...Jeff has a great post above.  We must have posted at nearly the same time.  

[nrgjeff]

China is in the middle of a brutal cold snap. Siberian air dumped in there. Maybe let the models work through that first. North America has our own cold source region. Remain optimistic. If I'm wrong, we'll take severe instead. 

[tnweathernut]

With a modeled -EPO shown and ridging THAT tall out west I think I'd take my chances with cold and snow somewhere around the TN Valley region at times.  

We don't want the trough axis too far to the east like the last go around.  I'd actually rather take my chances with a couple of warm days (with very cold air nearby) and the potential for a trough that when it's pushed south and east has the chance to develop a storm somewhere in the lower 48.  That situation vs. a storm developing in the Atlantic Ocean (even if that means we mostly rain) would be infinitely more interesting than the weather the last cold snap provided.

Heck, our region might experience both severe AND winter weather next month.

I am on the moisture train, regardless of the form that falls!

[Carvers Gap]

So here is a question...should we be watching the timeframe of Monday into Tuesday? The 12z GFS backed the flow ever so slightly.  Temps look to warm...but if that trends northwest, that could at minimum create precipitation type issues in the mtns.  I had ignored it until the last few runs, but that GFS track at least perks my interest a bit.

[John1122]

I wonder how long the GFS will ride this before it gives it up?

[Carvers Gap]

8 minutes ago, John1122 said:

I wonder how long the GFS will ride this before it gives it up?

I like that look...has a wave rolling along it.  Pops a nice slp in inland North Carolina.  IMHO, that timeframe has "big storm" written all over it for somebody in the East.  Need the flow to slow down just a bit, and back this way.  Might be cold chasing rain unless it slows down.  But I like the synoptic set-up...though it might be a hair too far to the East.  Not even the first coastal system of that run.

[Carvers Gap]

12z GFS is interesting at hours 90, 192, and 240.

[Carvers Gap]

Three systems that tap the GOM during a ten day stretch per the GFS...w/ cold lurking.  

[Carvers Gap]

And I realize that the cold shifts West after d10...but the cold in NA is insane between d10-15!  Incredible.

[Carvers Gap]

It is hour 384...so just for fun...there is a 108 degree temperature gradient from northern Montana to Atlanta, Georgia.  It is conceivable that a person could drive from Atlanta to northern Montana in a day and go from 68 to -40.  One day/one twenty-four hour period, I am going to do that.

edit:  I know guys who live in Yellowstone that travel from there to Belize in a day to fish.  They leave sometimes when it is -30 there and nearly 95 in Belize.  125 degree change in about 6-8 hours.