February/March 2020 Winter's Last Chance Thread

[Carvers Gap]

The correction(not idea of temporary or permanent) on the Euro at 132 is significant.  It actually leaves the cutoff in the Southwest.  It opens the door for the next potential winter event if true.  This cutoff has been a thorn on modeling for almost a couple of weeks.  It has yet to be sorted out.  I doubt the 12z GFS is likely not valid as it is too progressive, but I also have my doubts about the Euro as it has a really tendency to dig too much into the West.   The problem is there is very little middle ground.  Either the cut-off moves along and doesn't dig into the West OR the northern stream uses that cut-off to dig the trough into the West OR the northern stream leaves the cutoff and digs into the East.  I am not so sure that the Euro didn't just bend pretty heavily to the other operational models.  At 222, the Euro has a 1045 surface high in the Midwest.

 

[Carvers Gap]

2 minutes ago, Holston_River_Rambler said:

Euro looks like it is trying to get it done. Nice AO vibes, but Euro does the old dump the energy in the W. At least there seems to be more often than not lower heights in the Aleutians and the ridging occasionally makes it to western Canada. 

Look at the surface late in the run...that is not warm.  Right?

[Holston_River_Rambler]

2 minutes ago, Carvers Gap said:

Look at the surface late in the run...that is not warm.  Right?

Indeed it does. HP in the lakes, looks nippy and no more 13" rain totals, lol:

[Holston_River_Rambler]

Lest there be any confusion, what I was trying to say was that despite the 500mb look, still chilly at the surface and 850s. If that cutoff gets kicked out quicker, maybe a ridge would pop in the west on the Euro. 

[John1122]

The massive 10-12 inch rains have backed off. Granted 4 of those inches have already fallen, but it's looking more like 2-5 more over the next 10 days vs the 6-8 after this event that had been shown. Granted it will probably waffle back towards us if the colder solutions don't happen. 

[Carvers Gap]

2 minutes ago, Holston_River_Rambler said:

Indeed it does. HP in the lakes, looks nippy and no more 13" rain totals, lol:

That run of the 12z Euro is no less wonky than the 12z CMC or 12z GFS.  The 500 maps after 200 hours don't even look like the surface.  LOL.  IMHO, this is yet another bounce back and forth with what to do with the Southwest cutoff.  That is a western ridge at the surface and an eastern trough after 200.   Something is afoot.  Not sure what...but something has changed at 12z.  Might be temporary.  But something has been inputed that has changed the surface pattern.  We have seen that before, but worth watching.

[Holston_River_Rambler]

The Euro MJO forecast did take a step toward the GFS suite. Not a big one, but it does gain some amplitude in 5 and 6 before crashing, instead of hanging out in the COD forever. 

maybe that's it? Not sure though. 

[Holston_River_Rambler]

Satellite looks about like it has been, maybe even worse in the 5/6 regions, but there was also a big flare up over S. Africa this afternoon, but not sure if that is a normal diurnal thing there:

No big changes to how Euro or GFS see the SPV from 0z, so no help there. 

[Carvers Gap]

5 minutes ago, Holston_River_Rambler said:

Lest there be any confusion, what I was trying to say was that despite the 500mb look, still chilly at the surface and 850s. If that cutoff gets kicked out quicker, maybe a ridge would pop in the west on the Euro. 

The cutoff is the problem along with how the northern stream does or does not interact with it.  That was part of that long post from the other day.  (I took that post down as it just sounded too much like another post I had read....)Combine that with the MJO moving at higher amplitude into warm phases but moving more quickly towards colder phases...not sure what is up, but I welcome the change.  Poor MJOs can be overcome by cold.  Plenty of precedent for that, but it doesn't happen often.  Anyway, very interesting to see the operationals budge and the GEFS.  Now don't get me wrong, I don't trust the GEFS as far as I can throw it....but model changes on ensembles do sometimes indicate flux.  Anyway, will interesting to watch.  I will not be surprised to see modeling flip back to warm or double down on cold.  But both are worthy of consideration at this point.  We will get some clarity in future runs.  12z was such a tease.  

[snowmaker]

What do you think about the system coming into Tennessee tonight Carver? Do you think parts of middle and west tn may get a 1/2 inch or so. I would just be happy to wake up early in the morning around 5 and see a flizzard and the ground have a good dusting anyway. I think the plateau and mountains may actually get 2-3 inches out of this, at least portions of the plateau and mountains. Here's hoping us snow lovers at least get to see some snow flying late tonight and tomorrow.

 

[Carvers Gap]

32 minutes ago, snowmaker said:

What do you think about the system coming into Tennessee tonight Carver? Do you think parts of middle and west tn may get a 1/2 inch or so. I would just be happy to wake up early in the morning around 5 and see a flizzard and the ground have a good dusting anyway. I think the plateau and mountains may actually get 2-3 inches out of this, at least portions of the plateau and mountains. Here's hoping us snow lovers at least get to see some snow flying late tonight and tomorrow.

 

There are winter weather advisories up for portions of middle TN now.  Holston has even started a thread for that event.  I don't think anything is a given this winter, but I think some accumulation is likely in northern middle and the Plateau.  However, people in Nashville know the routine.  Not been an easy score there for a while.

[Carvers Gap]

So the 12z ICON, GFS, CMC, and Euro(much colder) show fairly significant changes at the surface after Feb 10th.  The GEFS looks much different after 300.  Not sure a soul trusts the GEFS at LR anymore nor should they.  GEPS and EPS at 12z not biting, though the EPS control looks very GFS like around 300.  I am going to need to see another model suite before giving more than passing consideration that the global operationals are onto something, especially without EPS support.  Worth watching for sure and interesting to discuss...but going to need modeling to back-up those earlier runs.  Ensembles will be slower to change, and that is worth noting, but the EPS did not budge.  Time will tell.

[Carvers Gap]

The 18z GEFS again has the cold front and the storm on the ~14th.  After that it wises up and has more zonal and some western trough after 300.  So, looks like we may fight off the SER until after the 14th? Still don't think modeling after the 10th is nailed down.  Pretty crazy given that is only about four days away.  Still have my doubts on how much and how long any western trough can hang in there.  The ridge pattern might be getting pushed back for once?

[Carvers Gap]

Definitely an element of a +PNA on the GFS after the 10th.

[Carvers Gap]

And now the 18z GEFS has matched the operational.  Not getting too hyped about that, but interesting for sure to see large scale changes to the 500 pattern at relatively close range on an ensemble.  Gotta see the EPS bend before serious consideration, but that is another model flipping a good chunk of its run.

[Holston_River_Rambler]

For future reference, the variety of NWS products issued as of 0z 2/7/20:

 

[mempho]

As an agent of death, I probably shouldn't say this but it is snowing outside.

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[PowellVolz]

As an agent of death, I probably shouldn't say this but it is snowing outside.

Sent from my SM-G950U using Tapatalk

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[Stovepipe]

5 hours ago, PowellVolz said:

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[Carvers Gap]

Looks to me like another cold front on Feb 14th.  My guess is the Euro is under-modeling that system if real.  Remember how the Euro backed off temps for last night's and today's system(and into the weekend) to the point it barely had any negative anomalies at all?  Here is what it has now for hour 12.  Below are the 6z initialized temps for hour 12.  Departures range from 5 to 20 degrees.  Negative departures(not as cold as below) are forecast to remain in place until Sunday evening.

Major differences in modeling begin as early as mid-week next week.  The GFS and CMC still handle the cutoff in the Southwest much differently.  The Euro(and this is an opinion) is having issues with that cutoff in the Southwest(edit...a well known bias, but also sometimes verifies).  Is that causing it to struggle in the mid-range?  Plenty of arguments in either direction.  The MJO heading into phase 5 this morning supports it.  But if I was going to take any model against all others(which it is currently), it would be the Euro/EPS combo.  That said, IMHO it is again under-doing a potential trough centered around the 14th.  I think it might not hurt to blend the Euro op and the GFS/CMC operationals.  The first is likely too warm and the other two are likely too cold.  Next few runs will tell me if that hunch is correct.  

 

[Carvers Gap]

This is why I don't go anywhere without the EPS.  When we started talking about the trough this weekend, it was ~15 days ago.  IMHO, pretty good work by this forum working through the pros and cons to the look.   This is Holston's EPS loop from 12z on January 23rd...

On 1/23/2020 at 3:11 PM, Holston_River_Rambler said:

Yum:

But as we all know, it is still in that mythical 10+ day time.

Nailing a trough placement from 15 days out is impressive.  It may have a cold bias due to the anomalous warmth from the past several weeks, but it did very well with this trough at 500.  Also, it should be noted that the GFS/CMC combo did fairly well with this.   Even more impressive is the trough is lifting out at the end of this run, and the components for next week's western cutoff are descending southward along the spine of the Rockies.  While modeling has been less than stellar this year, this was a good look.  Interestingly, I will dig back through some more posts later, but I believe the Euro operational erroneously dug this trough into the Southwest and kept it there.  (edit...The main error with the EPS is that its timing from fifteen days ago was maybe 24-30 hours off...which is not bad at all from that range.). But the idea of three waves running a front (w the last being our shot) has been on models for more many, many runs.  

[Carvers Gap]

To tag onto Holston's post above and to illustrate the strength of this trough that is passing through...here is the advisory/warning product map for the United States this morning.  Winter weather advisories stretch from NE MS through middle/ west TN at lower elevations w higher elevation products issued for the Plateau an eastern mountains.  Flooding was experienced in many areas which was then followed by light snow accumulations.  This morning snow was was falling in Kingsport while simultaneously we were experiencing some of the worst urban flooding in recent memory.  The flooding and winter threats were discussed extensively for several days on this forum in specificity by many.  Again, a great job by everyone.  

[snowmaker]

Received right at a inch here in Montgomery County on elevated surfaces, probably about 3/4 inch on the ground. If the ground had been colder at the onset we would have picked up 2-3 here. We had 2 separate rounds where it snowed pretty steady for a few hours at a time. As bad as the winter has been, I am a little more confident this morning that we still may have a chance or 2 to score a bigger snow before winters end. But if we don't at least we was able to salvage something in a overall bad winter pattern for most of the year.

[Carvers Gap]

All GFS runs for the rest of the winter have an assumed TIFWIW caveat and a yes we know caveat.  But the 12z GFS has a snowstorm at 156.

[Carvers Gap]

1035-1039 hp riding over the top of a low running through the GC states.   Hard not to like that look.  Definitely a chance that jogs north and the cold verifies in KY or the Ohio River Valley, but verbatim....good look on that run.

[Holston_River_Rambler]

Yeah, GFS looked even better at 0z. It's just so different from the Euro. Maybe they upgraded the GFS again, but something feels wonky these past 24 hours with it. More than usual. Or maybe instead of a rug pull, everything flips randomly to good for once this year. 

[Carvers Gap]

1 minute ago, Holston_River_Rambler said:

Yeah, GFS looked even better at 0z. It's just so different from the Euro. Maybe they upgraded the GFS again, but something feels wonky these past 24 hours with it. More than usual. Or maybe instead of a rug pull, everything flips randomly to good for once this year. 

Definitely something afoot...  Thing is the GFS and CMC may have potentially sniffed out a cold front around the 14th that the Euro missed and a cool front around the 12th. .    After that, who knows...I think there is a really tendency for models to bury these cutoff and it is screwing up the run at that point.  My guess is those cut offs either move east or get completely cut-off under a ridge.    I am wondering if the changing wavelengths(as we approach spring) are causing havoc as well?  But what looked like a really warm period between the 10th and 20th may at least have some things of passing interest.  But again, sometimes those cutoffs are legit.  But to me, looks like way too many cut-offs and that is likely feedback.  OTH, keep sticking cut-offs in the Southwest and they are going to eventually head eastward.  

[Holston_River_Rambler]

1 minute ago, Carvers Gap said:

My guess is those cut offs either move east or get completely cut-off under a ridge.

Along those lines, and maybe I'm misremembering, I feel like this storm got booted out of the SW quicker than the Euro originally wanted it to. Looking at the overnight Euro, if you get that shortwave to roll east a little faster, and the northern stream verifies a little faster then you get something more akin to the GFS solution. 

[Carvers Gap]

CMC has a similar set-up at 12z around 156 with a similarly strong high.  I think what is happening is that as we get closer to verification those cutoff lows are not just sitting there and digging...they are kicking out.  Might be that we are going to have to watch for that.  Now, the trough should dig into the West given the MJO...but right now I am suspicious of any low just spinning in the Southwest.   

[Holston_River_Rambler]

By "this storm" I mean how the current one was forecast at range