Jan 16-17th Boom or Bust

[Holston_River_Rambler]

TBH the 850s look pretty doggone similar to me. 

[TellicoWx]

Would have definitely loved to see the next couple frames 

[Holston_River_Rambler]

Here's Pivotal's precip output:

[PowellVolz]

Here's Pivotal's precip output:

540 up in SE Kentucky


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[Holston_River_Rambler]

I think that 540 line is just more of a guideline, than a hard and fast rule. That being said, climatologically it will be hard to deal with the downsloping for the eastern valley and even me on the plateau off of frozen head with a ENE and NE wind. 

MRX had good points in their PM disco:

"In [my] experience many times Miller B type events, and the resultant snowfall totals are not handled by the long range models especially well due to low topography resolution. One of the biggest things they seem to incorrectly forecast is the strong downsloping that occurs with these systems. The downsloping then results in higher surface/low level temperatures and really eats away at snowfall totals with a slightly warmer atmosphere. Combine this with many of the deterministic models predicting the heaviest snowfall to occur during the daytime hours... and the only slightly below freezing temperatures overnight... and temperatures possibly reaching into the 40`s in the Valley during the day on Saturday/Sunday... It all leads to heavy skepticism in some of the high snowfall totals that some of the deterministic and ensemble amounts being depicted."

In the main thread, Jeff also noted that even NWS offices in West Virginia were worried about a warm nose. 

For my part, I hate anything that even resembles a Miller B. That low is trying to find a thermal gradient to use as a transfer pathway and the lower elevations of East TN create a warm pocket for some part of that low to go.

In my limited experience, Miller Bs have been STJ systems. I know that isn't always part of the KU definition, but for us in the east TN valley, ANYTHING that sends a piece of low pressure up the valley as the energy transfers to the coast, might as well be the same. I can understand people further north using the A/B hybrid distinction, but it really doesn't matter if you live from Chattanooga to Morristown, IMO. This is not a STJ system though. 

The angle of attack for the energy is unusual for us and there have been soooo many shifts, some dramatic, in NWP, over the past few days. That normally suggests ensembles are more useful in unusual situations like this, but we also have to consider that ensembles are compounded iterative differences of initialization conditions, while we're lookin for frinkin' reality. Ensembles suggest, but don't precisely foretell. To me, the OPs have led ensembles for this system, and that also suggests that this is an unusual set up. We've seen a few model cycles where the OP ripped the ensembles out of their happy median and said basically "Nope, we going this way." The smoothed mean can't account for realtime conditions and any small bird fart perturbation chaotically shifts the NWP outcome. I guess all I can say is La Nina. Fast flow in a chaotic medium = chaotic results. 

 

One thing I found of interest on the 18z Euro were the Dewpoints:

 

That's some cold dry air trying to filter over the mts and making some headway at TRI. PSU in the MA forum was commenting on some analogues and says that this antecedent airmass is the coldest among those analogues. Now, they are closer to the HP in the mid Atlantic, so that may not apply here, but it is something to think about. 

I think this storm has one or two more tricks up its sleeve before it's finished, but I am also prepared for my heaping helping of a warm nose, served piping hot, if that happens. 

 

[John1122]

The 18z Euro Mean. 

 

[Daniel Boone]

17 minutes ago, Holston_River_Rambler said:

I think that 540 line is just more of a guideline, than a hard and fast rule. That being said, climatologically it will be hard to deal with the downsloping for the eastern valley and even me on the plateau off of frozen head with a ENE and NE wind. 

MRX had good points in their PM disco:

"In [my] experience many times Miller B type events, and the resultant snowfall totals are not handled by the long range models especially well due to low topography resolution. One of the biggest things they seem to incorrectly forecast is the strong downsloping that occurs with these systems. The downsloping then results in higher surface/low level temperatures and really eats away at snowfall totals with a slightly warmer atmosphere. Combine this with many of the deterministic models predicting the heaviest snowfall to occur during the daytime hours... and the only slightly below freezing temperatures overnight... and temperatures possibly reaching into the 40`s in the Valley during the day on Saturday/Sunday... It all leads to heavy skepticism in some of the high snowfall totals that some of the deterministic and ensemble amounts being depicted."

In the main thread, Jeff also noted that even NWS offices in West Virginia were worried about a warm nose. 

For my part, I hate anything that even resembles a Miller B. That low is trying to find a thermal gradient to use as a transfer pathway and the lower elevations of East TN create a warm pocket for some part of that low to go.

In my limited experience, Miller Bs have been STJ systems. I know that isn't always part of the KU definition, but for us in the east TN valley, ANYTHING that sends a piece of low pressure up the valley as the energy transfers to the coast, might as well be the same. I can understand people further north using the A/B hybrid distinction, but it really doesn't matter if you live from Chattanooga to Morristown, IMO. This is not a STJ system though. 

The angle of attack for the energy is unusual for us and there have been soooo many shifts, some dramatic, in NWP, over the past few days. That normally suggests ensembles are more useful in unusual situations like this, but we also have to consider that ensembles are compounded iterative differences of initialization conditions, while we're lookin for frinkin' reality. Ensembles suggest, but don't precisely foretell. To me, the OPs have led ensembles for this system, and that also suggests that this is an unusual set up. We've seen a few model cycles where the OP ripped the ensembles out of their happy median and said basically "Nope, we going this way." The smoothed mean can't account for realtime conditions and any small bird fart perturbation chaotically shifts the NWP outcome. I guess all I can say is La Nina. Fast flow in a chaotic medium = chaotic results. 

 

One thing I found of interest on the 18z Euro were the Dewpoints:

 

That's some cold dry air trying to filter over the mts and making some headway at TRI. PSU in the MA forum was commenting on some analogues and says that this antecedent airmass is the coldest among those analogues. Now, they are closer to the HP in the mid Atlantic, so that may not apply here, but it is something to think about. 

I think this storm has one or two more tricks up its sleeve before it's finished, but I am also prepared for my heaping helping of a warm nose, served piping hot, if that happens. 

 

My thoughts are that the models are factoring in the dry air. Even with the earlier further north solutions. Those wfo's were all looking at those further north earlier solutions during those discussions. 

      Did any of them remark at all about low dps. ? I dont think so. Really surprises me.

     In light of the south trend and more evident cooler, drier air starting to be shown, I wonder how their next discussion will be.

[John1122]

 

[Holston_River_Rambler]

The NAM, it do be running. Shall we extrapolate? 

 

 

 

 

[Stovepipe]

46 minutes ago, Holston_River_Rambler said:

I think that 540 line is just more of a guideline, than a hard and fast rule. That being said, climatologically it will be hard to deal with the downsloping for the eastern valley and even me on the plateau off of frozen head with a ENE and NE wind. 

MRX had good points in their PM disco:

"In [my] experience many times Miller B type events, and the resultant snowfall totals are not handled by the long range models especially well due to low topography resolution. One of the biggest things they seem to incorrectly forecast is the strong downsloping that occurs with these systems. The downsloping then results in higher surface/low level temperatures and really eats away at snowfall totals with a slightly warmer atmosphere. Combine this with many of the deterministic models predicting the heaviest snowfall to occur during the daytime hours... and the only slightly below freezing temperatures overnight... and temperatures possibly reaching into the 40`s in the Valley during the day on Saturday/Sunday... It all leads to heavy skepticism in some of the high snowfall totals that some of the deterministic and ensemble amounts being depicted."

In the main thread, Jeff also noted that even NWS offices in West Virginia were worried about a warm nose. 

For my part, I hate anything that even resembles a Miller B. That low is trying to find a thermal gradient to use as a transfer pathway and the lower elevations of East TN create a warm pocket for some part of that low to go.

In my limited experience, Miller Bs have been STJ systems. I know that isn't always part of the KU definition, but for us in the east TN valley, ANYTHING that sends a piece of low pressure up the valley as the energy transfers to the coast, might as well be the same. I can understand people further north using the A/B hybrid distinction, but it really doesn't matter if you live from Chattanooga to Morristown, IMO. This is not a STJ system though. 

The angle of attack for the energy is unusual for us and there have been soooo many shifts, some dramatic, in NWP, over the past few days. That normally suggests ensembles are more useful in unusual situations like this, but we also have to consider that ensembles are compounded iterative differences of initialization conditions, while we're lookin for frinkin' reality. Ensembles suggest, but don't precisely foretell. To me, the OPs have led ensembles for this system, and that also suggests that this is an unusual set up. We've seen a few model cycles where the OP ripped the ensembles out of their happy median and said basically "Nope, we going this way." The smoothed mean can't account for realtime conditions and any small bird fart perturbation chaotically shifts the NWP outcome. I guess all I can say is La Nina. Fast flow in a chaotic medium = chaotic results. 

 

One thing I found of interest on the 18z Euro were the Dewpoints:

 

That's some cold dry air trying to filter over the mts and making some headway at TRI. PSU in the MA forum was commenting on some analogues and says that this antecedent airmass is the coldest among those analogues. Now, they are closer to the HP in the mid Atlantic, so that may not apply here, but it is something to think about. 

I think this storm has one or two more tricks up its sleeve before it's finished, but I am also prepared for my heaping helping of a warm nose, served piping hot, if that happens. 

 

This was a great post, thank you for your contributions to this community.  

[Holston_River_Rambler]

Thanks @Stovepipe your posts were one of the reason I joined this community, so you are much appreciated! 

[Carvers Gap]

11 minutes ago, John1122 said:

 

I thought the faster solutions tended to not cut....or is this for the 50/50 which would suppress the second wave?

[Holston_River_Rambler]

IMO NAM will be interesting, it is slower in the primary shortwave as the above post suggests, but has some stronger vorticity at hour 24 

[PowellVolz]

I thought the faster solutions tended to not cut....or is this for the 50/50 which would suppress the second wave?

This is what I thought…. But i start to wonder what else the mods have missed on initiation?


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[Holston_River_Rambler]

I think the Sillin post is regarding the energy in blue, and that piece is important and the one that was sampled earlier today.  But pay attention to the one I've circled in pink as the NAM runs. That is the primary vort in this set up, IMO:

 

 

 

[John1122]

16 minutes ago, Carvers Gap said:

I thought the faster solutions tended to not cut....or is this for the 50/50 which would suppress the second wave?

His reasoning was that the 18z saw this, caused heights to bump up in the region and sent the storm further SE. 

[Vol4Life]

NAM has a gulf Low.  Looks more like a Miller A

[John1122]

18z Euro control may be seeing what he was talking about too. It was a good 150 miles SE of 12z.  

[Bigbald]

17 minutes ago, Vol4Life said:

NAM has a gulf Low.  Looks more like a Miller A

Normally that's a beautiful track for east Tennessee, low just south of mobile, alabama. I wish it would meander over to Appalachacola before turning north but it seems to work for I 40 north. 

[TellicoWx]

Not sure how the other 0z runs will go, but 0z ICON was a little further south...temp profiles seemed off tho on it

[John1122]

5 minutes ago, TellicoWx said:

Not sure how the other 0z runs will go, but 0z ICON was a little further south...temp profiles seemed off tho on it

The ICON, from all I've read, has a warm bias. 

The NAM/ICON are in the almost Miller A camp. Will have to see how it goes the next few days still. I can see plenty of big changes all the way to the event. 

For areas that get snow, you may see huge silver dollar flakes that just plaster everything. For the non elevated or more southern areas you may see monster flakes piling up fast and 10 miles away under lighter returns it may be raining. 

If this comes as it's being modeled today, the power grid will probably take a hit. There were a ton of outages here last January with a 4 or 5 inch paste event. Then more with the endless freezing fog. So hopefully my area has lost enough weak limbs and trees recently that the ones standing are doing okay. 

If these solutions are showing up Friday, I'd recommend anyone reading this get a back up heat source if you use electricity for heat. Just make sure it's a safe to use indoors set up. But this kind of snow threatens the power grid at about 3 inches, more than that and you will see widespread outages most likely. 

[John1122]

RGEM was faster, slightly further south too. It was just smashing West Tennessee. Looks like a front end thump/rain then a back side blitz. 

[Daniel Boone]

15 minutes ago, John1122 said:

The ICON, from all I've read, has a warm bias. 

The NAM/ICON are in the almost Miller A camp. Will have to see how it goes the next few days still. I can see plenty of big changes all the way to the event. 

For areas that get snow, you may see huge silver dollar flakes that just plaster everything. For the non elevated or more southern areas you may see monster flakes piling up fast and 10 miles away under lighter returns it may be raining. 

If this comes as it's being modeled today, the power grid will probably take a hit. There were a ton of outages here last January with a 4 or 5 inch paste event. Then more with the endless freezing fog. So hopefully my area has lost enough weak limbs and trees recently that the ones standing are doing okay. 

If these solutions are showing up Friday, I'd recommend anyone reading this get a back up heat source if you use electricity for heat. Just make sure it's a safe to use indoors set up. But this kind of snow threatens the power grid at about 3 inches, more than that and you will see widespread outages most likely. 

Right with you brother. Been warning folks here of the possibility.

[Wurbus]

GFS went back to the wonky 12z run. Low bouncing all over the place.

[John1122]

GFS buries 40 corridor and North. Gets below 40 in the mid-State as 40 gets furthest north at Nashville. 

[John1122]

The snow shield is better deeper into the south vs 18z. Deeper into Alabama. The random snow hole over Roane and Loudon County, may be some kind of downsloping off the Plateau. Globals struggle with placement of it though. But if you live in an area that gets downsloping in these events, know it's possible. 

[John1122]

GFS is well south and east again vs earlier runs from today when it took the low up into Kentucky on its way to a hand off.  Still on the northern edge of guidance and very amped which was a Para bias as mentioned earlier. I wouldn't be surprised if the Canadian is the furthest north suite here at 00z. But I'd guess it's still south of its 12z run the LP crossing Tennessee. 

[John1122]

Through 54 the Canadian is about 50 miles SE of 12z. 

[TellicoWx]

Big cut in totals on 0z GEFS

[John1122]

Canadian is just pummeling the mid-state at hour 90.