Winter 2021/2022 February Thread

[nrgjeff]

Yeah look for WAA at 700 mb and 850 mb. GFS and Canadian have it. Ukie too. NAM does not at 00Z Sunday and neither did the Euro. We eagerly await the 12Z Euro!

Getting to root causes of forecast differences is indeed the OV PVA. We need Southern to dominate. Carvers explains very well the pitfalls. Event has a high ceiling AND high bust potential, more than usual even here.

Maybe if I jawbone in the severe thread it'll help, haha!

[Holston_River_Rambler]

6 minutes ago, Silas Lang said:

Ah okay, that makes it easier to visualize as I feel like we have seen that set-up dozens of times the past few years here in the east. lol 

Do you know of any historical events that gave us snow here in the east similar to this storm? 

Here are the top CIPS analogues out to hour 60 based on the 12z NAM (I wish that CIPS site gave analogues based off the RGEM, lol):

 

site:

http://www.eas.slu.edu/CIPS/ANALOG/DFHR.php?reg=SE&fhr=F060&rundt=2022020912&map=COOP2perc

[Carvers Gap]

34 minutes ago, Silas Lang said:

Ah okay, that makes it easier to visualize as I feel like we have seen that set-up dozens of times the past few years here in the east. lol 

Do you know of any historical events that gave us snow here in the east similar to this storm? 

It is an odd, double barrel low set-up.  Honestly, it has been a while since we have seen that set-up east of the mountains.  The lee side low is a good set-up in and of itself.  The energy transfer to the coast could cause the snow to go poof over E TN or it could accentuate it depending on where it fires.  I will tag @John1122who will know the answer to the question most likely.  I would have to dig back through the threads.  I usually just make a mental note that double barrel lows are infamous and notorious regarding modeling being able to accurate depict them.  Seems like I remember one where the lee side low was weak and we didn't get anything, and maybe one where the lee side low trended into an inland runner.  

[Holston_River_Rambler]

Here's the radar from the top CIPS analogue:

 

and the H5/ MSLP pattern:

 

Honestly the radar doesn't look too different from what some of the models have been spitting out. 

 

12z RGEM at 60 hours:

[Holston_River_Rambler]

I don't know that we had a storm thread for it (maybe I missed it) but the obs for this start on page 12:

 

[Silas Lang]

4 minutes ago, Holston_River_Rambler said:

I don't know that we had a storm thread for it (maybe I missed it) but the obs for this start on page 12:

 

I will take that analogue in a heartbeat. Looks like a wide spread 2 to 4 inch event in East TN according to the thread. 

[Carvers Gap]

And the 12z Euro is rolling...

[Carvers Gap]

The northern stream is quicker and southern stream slower at 63

[Carvers Gap]

Looks like the Euro may swing and miss.  Trough is too positively tilted.  Let's see if something still pops.

[Carvers Gap]

12z Euro 500 configuration is way different.  LOL.  On to the next suite...consensus denied.

[Holston_River_Rambler]

I think it had a better interaction with the secondary N. stream piece (blue circle), than it has had in previous runs, but yeah, still too positively tilted with the main vort to the south. 

[Vol4Life]

2 minutes ago, Carvers Gap said:

12z Euro 500 configuration is way different.  LOL.  On to the next suite...consensus denied.

In the past, this would have really concerned me, but the Euro just isn’t what it used to be.  GFS has been doing a much better job sniffing out storms in the long range, trends in the short range, etc

[Shocker0]

45 minutes ago, Holston_River_Rambler said:

I don't know that we had a storm thread for it (maybe I missed it) but the obs for this start on page 12:

 

I believe most or all of East TN dipped below 0 on January 28 of that year. Or between the 24th and 29th at least.

[nrgjeff]

This is a big test for the EC. As @Vol4Life points out the Euro is having an off season.

Still I'd like to see even a little tiny hint of WAA at 700/850 mb but the EC upper trough interaction remains a no-go.

My personal conceptual model remains Upper Plateau to Mountains and a decent chance MRX to TRI. Lazy general pattern recognition is right 90% of the time.

Those are the regions that can squeeze from the northern stream if the southern craps out. Hedge your bets!

[Stovepipe]

1 hour ago, Holston_River_Rambler said:

I don't know that we had a storm thread for it (maybe I missed it) but the obs for this start on page 12:

 

That was a really fun event.  Robert nailed it.

[dwagner88]

2 hours ago, Stovepipe said:

That was a really fun event.  Robert nailed it.

Only time in my life I had to abandon my car and walk home. And it only snowed a little over an inch. This was the infamous Atlanta snowpocalypse. 

[nrgjeff]

Oh my the 18Z NAM has the correct WAA look 700/850 mb. 500 mb vort max digs better. Going to issue a Snow Lovers Heart Ripped Out by NAM watch.

[Holston_River_Rambler]

15 minutes ago, nrgjeff said:

Oh my the 18Z NAM has the correct WAA look 700/850 mb. 500 mb vort max digs better. Going to issue a Snow Lovers Heart Ripped Out by NAM watch.

But the 18z GFS hates everyone but TRI and wants us to die  

[John1122]

This reminds me of a storm from Feb 2014 that just was all over the place on models. The GFS and Euro could never agree. It kept showing a late bloomer in the Gulf that ended up going up the Eastern Seaboard but too far East for most of us.  As late as 24 hours out models were showing between 1 inch and 1 foot across the area.

[Wintersnow888]

This is from Morristown

Discussion:

At least one more day of very warm temperatures is expected on
Friday as warm air is advected into the area ahead of an approaching
front over the weekend. Friday still looks to be the warmest day of
the next week with temperatures in the Valley reaching around 60
across much of the area. Front is expected to make it`s way into the
eastern Tennessee Valley during the day on Saturday and slowly move
eastward through the day and into Sunday morning. Models are still
trying to figure out 2 main aspects of this system. The synoptic
forcing that will help propel the system, and the moisture in the
atmosphere as it moves through the southeast U.S.

Better forcing will be likely develop to our south and east as this
system swings through and most models want to develop/strengthen the
surface low when it`s closer to the Atlantic coast. Past few runs of
ensemble models are hinting at an increase in moisture availability,
and in response QPF amounts have increased in the forecast. This is
still however the lowest confidence aspect of the forecast with
several models keeping PWAT values fairly low, around 0.25 inches
while others are a bit more optimistic on moisture return with PWATs
closer to 0.50 inches. In response have increased PoP chances in
southwest VA closer to some of the better synoptic forcing along the
front, and have slightly bumped up QPF amounts over the weekend.
This all really comes into play as temperatures overnight drop below
freezing and we possibly transition to a wintry mix of precipitation
early Sunday. Ensemble models are mostly still fairly light on
snowfall totals with the highest amounts in the mountains and
southwest VA... Still a bit early to get into specifics of the
amounts as models will undoubtedly change once again overnight...
But with very warm temperatures and sunny skies the rest of this
week and just ahead of the front, expect a lot of melting of snow
once it hits the ground, so hopefully impacts from any snow will be
minimal.

Chance for a quick second round of light wintry weather on Monday,
but models have bounced around a lot with how to handle a quick
shortwave on Monday... So confidence is pretty low in this actually
occurring, but will include mentionable PoPs in southwest VA on
Monday.

Next week surface and mid level ridging builds in fairly quickly and
we`ll see above normal temperatures by Tuesday.

ABM

&&

[Carvers Gap]

Man, the ground here is barely unfrozen.  I still see ice on small creeks where I run.  The ground is not warm at TRI..maybe extreme south facing slopes, but otherwise, the ground is super cold.

[Wintersnow888]

20 minutes ago, Carvers Gap said:

Man, the ground here is barely unfrozen.  I still see ice on small creeks where I run.  The ground is not warm at TRI..maybe extreme south facing slopes, but otherwise, the ground is super cold.

Same here in Cumberland county..... seems to be frozen a couple inches down here

[John1122]

46 minutes ago, Carvers Gap said:

Man, the ground here is barely unfrozen.  I still see ice on small creeks where I run.  The ground is not warm at TRI..maybe extreme south facing slopes, but otherwise, the ground is super cold.

The cliff sides here still have heavy ice on them. It was in the 10s just three nights ago and lows have been in the low 20s the last two.

[Dsty2001]

3 hours ago, Carvers Gap said:

Man, the ground here is barely unfrozen.  I still see ice on small creeks where I run.  The ground is not warm at TRI..maybe extreme south facing slopes, but otherwise, the ground is super cold.

Typical MRX statement, a few days of warmth automatically correlates to = warm ground temperatures.  

[John1122]

The GFS is back on board. The JiC (John in Chattanooga) correlation is still strong. I think models are flopping because I have to go to an event Friday night, which is normally the day I'd head to Nooga, so I have to wait til Saturday to go.

[Dsty2001]

Looks like a broad 3-4 across NE TN with higher amounts but I have no idea how to zoom in on tropical lol

[Dsty2001]

Still there on 6z, would be a nice little event if verified

[nrgjeff]

Yeah they might want to ask Memphis truck drivers about that, lol!

12 hours ago, Dsty2001 said:

Typical MRX statement, a few days of warmth automatically correlates to = warm ground temperatures.  

Models could have been better overnight. Southeast Tenn gonna need more @John1122 Feb 2014 vibes. That one got us.

[Carvers Gap]

Keep an eye on what comes after the big cutter in the Plains.  Thunder here...and you know what might come next.  TIMS models activation may be in order.  Modeling is showing a system to our SE(low road) right after that cutter.  The northwest trend is the real deal during late Feb.

[Dsty2001]

Keep seeing reference to TIMS, what is that about if somebody doesn't mind explaining