Winter 2021/2022 January Thread

[Carvers Gap]

The trend at 0z was to phase a bit later which is not great for this area.  The 6z GFS run was pretty much the same synoptics as 12z yesterday, but phased between where the 12 run and the 18z run phased.  We need the slp to form in the eastern GOM in order to have the best shot on this one.  Could be something.  Could be nothing.  At this point, we just want to be inside the cone.  Right now we are on the western side of model runs.   

update: 6z runs are trending with an earlier phase than 0z runs, but not as early as 12z yesterday.  

[Carvers Gap]

Looking at the 0z Euro, that would have been a pretty decent set-up for an upslope snow event for favored areas.  If this simply devolves into a powerful clipper(hoping it doesn't jog northward which most eventually do), that would work.  Canadian is a similar look but weaker. Right now, all three models have the synoptics for snow next weekend for some portion of the forum area:  a strong clipper(s) and/or a coastal.  I am not so sure the 6z Euro wouldn't have been better.  I have to use the EPS control, because I don't have access to anything past 90 for the 6z deterministic Euro runs.  If someone has the vort maps for that deterministic run, please share.  Anyway, here are the 0z (putrid but still light snow due to a clipper) and the 6z EPS control runs.  The control run I am assuming is probably similar to the deterministic.  The robust 12z run yesterday dug a bit more west in OK/TX than 6z.  Still, 6z is an improvement to 0z.   Slower system along with an earlier and more powerful phase.  This is when the 6z run stops.  

 

[Carvers Gap]

9 hours ago, EastTNWeatherAdmirer said:

I have a question…perhaps some of you smart weather needs and geeks on here could provide some insight. During the winter, are there any key atmospheric features(things like teleconnections, MJO, storm timing, ULL’s, SLL’s, trough tilt) that have a strong effect and influence on whether southern stream storm systems “phase” with the northern cold upper jet to create significant snow storms? In other words, are there any deeper answers to why the pattern doesn’t work out for some(even those in the south) because of suppression other than blaming a “strong -AO”?

It is all about confluence.  It is why many of us in E TN like -NAOs.  As we learned this year, the -NAO has its greatest influence in mid and late winter, not December.  We also tend to see snow right as the NAO exits which did exactly that this year (in spades for man).  The -NAO forces confluence(the merging of the two jets) to occur in areas which are favorable for the eastern seaboard.  A 50/50 low or a low over SE Canada will also do the trick but it is often very temporary(48-72 hours max).   Generally you want a phasing trough to go neutral(axis is vertical) right as it slides over our forum area.  That will often cause a slp to run up the coast from the central or eastern Gulf Coast.  Right now we are in a Pacific dominated pattern, and confluence tends to scoot off the coast without some blocking or a 50/50 low.  However, cold is more dependable in this current Pacific set-up I think.  So we aren't fighting marginal thermal profiles.  Kind of a trade off:  cold/poor confluence vs less cold/better confluence regarding the current NAO cycle.  

I should note there are several cases where the northern stream actually can be its own winter storm.  The 6z GFS and 0z Euro are very close to that for next weekend.  Miller Bs are not terrible as long as the energy jumps from the northern stream and not southern stream.  Southern stream Miller Bs are warm nose city.  The position of the NA trough next weekend is almost exactly where EC posters want it in terms of its ability to allow cyclogenesis along the EC or just inland.  One poster asked if this could trend northwest.  The way this is set-up, it is almost locked right on the coast if it forms.   The storms which originates in the southern stream is dependent on the northern stream energy to phase with it.  For now, we need those systems phased over the Prairies and not TN which the 0z runs did.  We need both pieces of energy to be reasonably potent.  

And what is crazy, we can get confluence even during terrible patterns.  And it sometimes will not snow even when there is great confluence.  The energy has to be there or the confluence of the two jets doesn't matter in terms of snow.  There is a bit of a "game of chance" involved in much of this.  I am not big into luck, but there is an element of good fortune.  I am sure there are about 100 ways for confluence to occur.  One of the great things about this region...even though latitude is a huge issue, we will often track some big storms during our lifetimes simply due to our proximity to both cold and three salt water bodies(Pac, Atlantic, GOM).  

For me, this is what I talk about when I look for windows.  When does precip and cold show up over our area at the same time? Next weekend has potential, but is certainly not set in stone or even close to it. 

[Carvers Gap]

12z NAM rolling in with a very amped solution for the Tuesday timeframe.  If there is any doubt that model (at long range) is amped with systems to our SE, that should answer the question.  While other models have trended to nothing for that day, the NAM is going strong.   But who knows, maybe it is right?  LOL.  It is oing to have to get some support though from other modeling.  It did catch the NW jog of at least one of the last two system, but that may just be a model bias which made it look right....Kind of like the CMC is always cold.  That doesn't mean it is right when it finally turns cold.  Kind of a broken clock is right twice per day.

[Silas Lang]

Yeah, the NAM is showing snow for Georgia and Alabama but rain for Tennessee? What's up with that? Looks cold enough, expect for marginal surface temps. 

[Carvers Gap]

8 minutes ago, Silas Lang said:

Yeah, the NAM is showing snow for Georgia and Alabama but rain for Tennessee? What's up with that? Looks cold enough, expect for marginal surface temps. 

Wild look for sure.  It is probably super amped, but I am guessing that rates and a marginal air mass probably produce that look.  Also, it looks like elevation may play a part there.  But hey, it happened with the last system for folks at TRI.  Rained here when it was snowing in Alabama and Georgia. LOL.  The ICON is slightly more robust than its earlier run.  Wouldn't surprise me to see that system trend north some.  Just a super marginal air mass.  It is a conundrum of sorts...get good interaction with the northern stream and we get marginal temps for precip or we get no interaction with the northern branch and we have no precip.  

[Carvers Gap]

Regarding next weekend...the 12z ICON has a nice "light snow falling into cold air" front.  Guessing ratios would be nice if real.  I can live with that scenario given the outcomes IMBY up to this point.   

[Carvers Gap]

12z GFS is rolling.  Out to 90, the energy for the EC storm is slower.  Those solutions have generally produced a storm closer to the coast.  Faster systems have gone to the fishes.  Let's see what happens.

[Carvers Gap]

Looks very similar to 12z yesterday, with the exception of a front running vortex which is on modeling at 96.  We probably want that to be a bit weaker.

[Chattownsnow]

Man it’s so unfortunate because the timing of that Tuesday storm is just terrible in this excellent pattern. Smack in the middle of a small relaxation period. Oh well what can ya do? Sandwiched between two northern stream waves in the flow. Everything is taking the low road for now. 

[Carvers Gap]

Through 108, next weekend's system is digging quite a bit more than the previous two runs.  Could create a storm which cuts more inland or could get squashed.  Either is on the table.  Looks robust though.

[Carvers Gap]

At 114, phasing between the two jets has begun over the western Plains.  At 126, looks like this could be potent.  We will see.

[Carvers Gap]

By 138, it has dug so much, it risks getting sheered out.  Let's see if the pendulum(SLP) kicks out.

[Carvers Gap]

By 150(low in the Lakes I don't like), the slp is shown in the GOM.  Let's see if it cranks.

[Carvers Gap]

By 156, looks a little strung out.  This is another variation of this system.  That said, light snow is present over the forum area with this look.

[Carvers Gap]

By 165, the phase will be a bit too late for us.  As is, a nice front with snow along it for most in the forum area.  Honestly, this is not a bad look for those in Chattanooga.  

[Carvers Gap]

But the 12z GFS for those who live in E TN is a look which we take 10/10 times at this range.  Nice low, albeit a bit strung out, slides underneath and then gains latitude and strength along the EC.  Details are not the key for me right now.  Just wanting to see if a storm is going to be there.  If it is, good deal.  

[jaxjagman]

Hand me a dart please,think i have a better chance to figure this out

[Carvers Gap]

Yeah, agree with Jax.  They are just all over the place right now.  I think there is a plausible/even likely chance, that we see an EC storm sometime next weekend.  The CMC jumps on a piece of energy that wasn't there or was very week on the 0z run, and that does not allow for enough space between it and the actually system we are watching.  The GFS pops a slp and then has another right after that.  To me, we are looking at lots of energy in the northern stream and southern stream right now.  Chances of a phase are high due to that and also the confluence along the EC being likely.  Bout all we can say right now.  Models are generally showing some type of storm on each run, but are having trouble dialing in.  I suspect this circles back to a coastal storm.  The GEFS slp placement for 12z shows a cluster of lows near Hatteras, a couple of inland runners, and even a cutter west of the Apps.  Without a big high over the top, this storm is free to come northward and free to trend westward IMHO....if it doesn't get strung out.

[EastTNWeatherAdmirer]

3 hours ago, Carvers Gap said:

It is all about confluence.  It is why many of us in E TN like -NAOs.  As we learned this year, the -NAO has its greatest influence in mid and late winter, not December.  We also tend to see snow right as the NAO exits which did exactly that this year (in spades for man).  The -NAO forces confluence(the merging of the two jets) to occur in areas which are favorable for the eastern seaboard.  A 50/50 low or a low over SE Canada will also do the trick but it is often very temporary(48-72 hours max).   Generally you want a phasing trough to go neutral(axis is vertical) right as it slides over our forum area.  That will often cause a slp to run up the coast from the central or eastern Gulf Coast.  Right now we are in a Pacific dominated pattern, and confluence tends to scoot off the coast without some blocking or a 50/50 low.  However, cold is more dependable in this current Pacific set-up I think.  So we aren't fighting marginal thermal profiles.  Kind of a trade off:  cold/poor confluence vs less cold/better confluence regarding the current NAO cycle.  

I should note there are several cases where the northern stream actually can be its own winter storm.  The 6z GFS and 0z Euro are very close to that for next weekend.  Miller Bs are not terrible as long as the energy jumps from the northern stream and not southern stream.  Southern stream Miller Bs are warm nose city.  The position of the NA trough next weekend is almost exactly where EC posters want it in terms of its ability to allow cyclogenesis along the EC or just inland.  One poster asked if this could trend northwest.  The way this is set-up, it is almost locked right on the coast if it forms.   The storms which originates in the southern stream is dependent on the northern stream energy to phase with it.  For now, we need those systems phased over the Prairies and not TN which the 0z runs did.  We need both pieces of energy to be reasonably potent.  

And what is crazy, we can get confluence even during terrible patterns.  And it sometimes will not snow even when there is great confluence.  The energy has to be there or the confluence of the two jets doesn't matter in terms of snow.  There is a bit of a "game of chance" involved in much of this.  I am not big into luck, but there is an element of good fortune.  I am sure there are about 100 ways for confluence to occur.  One of the great things about this region...even though latitude is a huge issue, we will often track some big storms during our lifetimes simply due to our proximity to both cold and three salt water bodies(Pac, Atlantic, GOM).  

For me, this is what I talk about when I look for windows.  When does precip and cold show up over our area at the same time? Next weekend has potential, but is certainly not set in stone or even close to it. 

To Carvers Gap: Thank you very much for your well-informed thoughts and analysis. Your explanation helped to illustrate the circumstances that support necessary confluence and the importance of the NAO. I am 17 years old and enjoy studying the weather but don't have close to the experience and knowledge you all have. Thank you very much for your insight!

[jaxjagman]

On 1/18/2022 at 10:09 AM, jaxjagman said:

GEFS shows  the height rise in East Asia which could warm us up briefly  but watch the back end,that patten don't last very long

 

 

 

Edit:Ackkk,that was the GFS.GEFS still breaks it down,we shall see,just need to Euro to start showing this in a few days

 

We should be looking at another possible change in the pattern  around wk.2 of Feb.,just need the teleconnections to work out.Heights dropping in Eadt China,Korea and Japan usually mean a east trough

[jaxjagman]

[Carvers Gap]

33 minutes ago, EastTNWeatherAdmirer said:

To Carvers Gap: Thank you very much for your well-informed thoughts and analysis. Your explanation helped to illustrate the circumstances that support necessary confluence and the importance of the NAO. I am 17 years old and enjoy studying the weather but don't have close to the experience and knowledge you all have. Thank you very much for your insight!

Awesome.  One of the cool things about the SE forum several years ago...some of their younger posters went on to become meteorologists I think.   I took one meteorology class at UT many years ago and really enjoyed it.  I don't think I realized how much I enjoyed the science of it until I was out of school.   

[Carvers Gap]

To me the Euro is on an island at 12z.  It is completely missing the southern stream energy which is on both the GFS and CMC.  It looked like the various pieces of energy were nailed down yesterday.  Nope.

 

To sum up the 12z suite and a nod to Jax for the quote....Like a person blindfolded and throwing darts!  

[Carvers Gap]

This may well become a northern stream dominant winter storm.  The Euro and GFS/CMC are about ~750 apart in their phasing solutions right now.

[Carvers Gap]

Interestingly, both the 12z GFS, CMC, and Euro have a trailing system which could be a second storm or the main storm.  This may be modeling finding a "caboose" system.  Now, that is fun and games for hobby folks - not.  If that is the case, modeling will have trouble sorting through which to accentuate.  In reality, could be one big storm or the spacing could wash-out both storms due to spacing.  The 12z Euro verbatim is two events within about 48-60 hours(or less).  Storm signal is still there for next weekend.

[nrgjeff]

Yes @jaxjagman a -ABNA could keep the Southeast US colder than just one week in Feb. I'm still for a mild back half of Feb. However one more week of chances (after the rest of January) mathematically increases snow odds for everyone here. 

I'll withhold comment about next week until something is within 3 days. Well maybe 36 hours is safer. 

[Carvers Gap]

18z GFS is rolling.  At hour 90, more spacing between the front-running vortex and the main system.  That front running vortex normally sheers out.  Extra spacing may allow that main system to climb in latitude.  Not going to fill up the thread with an off-run PBP, but interesting.  

[Carvers Gap]

18z GFS is a nice run out to 156.  

[Carvers Gap]

The 18z GFS is very similar to the wild 12z run from yesterday.  Big storm.