Jan 16-17th Boom or Bust

[Carvers Gap]

I am still not bought-in on this storm yet.  Too many good forecasters say to be wary, but the 0z NAM was used by MRX to mention a non wintry solution.  6z changed.  I am glad I am not in their shoes.  This comparison is in no way a criticism of them as it came out AFTER their morning disco.  Normally, I wouldn't use the NAM at range, but since it was mentioned in a disco, thought it was worth a look.  The single frame is the end of the 12k 6z NAM.  The double frame is a comparison of the last two runs.  The 6z NAM is pretty much the same as the 6z Euro.

 

[Silas Lang]

Can't say I am really that excited about this for the valley. Complex systems don't seem to work too well for us as too much can ( and usually does) goes wrong. 

Looks like some warm air will find a way along with downsloping and marginal temps.  I am personally not seeing it.  I expect a sloppy inch here at most. 

 

[Dsty2001]

I know this is totally newbie questions, but from my understanding is we want the LP to be further south but not TOO far south?  

[Carvers Gap]

1 minute ago, Silas Lang said:

Can't say I am really that excited about this for the valley. Complex systems don't seem to work too well for us as too much can ( and usually does) goes wrong. 

Looks like some warm air will find a way along with downsloping and marginal temps.  I am personally not seeing it.  I expect a sloppy inch here at most. 

 

Downsloping could/will be an issue.  Thing is, if the slp placement is wrong on the GFS....it should be less.  My concern is that this starts as rain north of I-40, and the surface cools due to evaporation cooling (overnight onset).  That could creat an ice situation on the west side of the eastern valley as cold air gets banked against the Cumberlands.

[Carvers Gap]

2 minutes ago, Dsty2001 said:

I know this is totally newbie questions, but from my understanding is we want the LP to be further south but not TOO far south?  

Problem is that we don't have a ton of fresh, cold air in place.  Really depending more on the track.  This system has been on modeling since almost day 16(?).  This is the beginning of a cold cycle within this pattern which is why.  Normally(and this depends on where one live...but will use the eastern valley as an example), a track from New Orleans/Mobile into South Georgia to inside Hatteras...that is the money track.  That is called an inland runner.  The closer that gets to the coast, the more difficult it is to get precip to come over the mountains.  The close that track gets to us(unless cold air is in place already), the more mixing becomes a problem - see the last two storms for that reference.  Also depends on the strength of the system. Stronger - need it on the outside of the best track envelop.  Weaker - need it closer like running along inside edge of the coastal plain.  Middle TN actually benefits from a track through E TN or along the spine of the Apps or W NC.  The exciting thing about the pattern after this, plenty of cold in reserve.

[Dsty2001]

Very good explanation, so essentially we are threading a needle here.

[PowellVolz]

I know this is totally newbie questions, but from my understanding is we want the LP to be further south but not TOO far south?  

We have a surface low that tracking along the coast of the GOM. We also have an 850mb low pressure tracking on or just south or the southern Tennessee state line. The 850 low pressure is basically our weather maker. If we can get it about 50 miles further south it would really open up Tennessee.


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[Holston_River_Rambler]

As I was trying to find a picture to help Dsty's question (I was looking for an ideal situation for the eastern valley), I found this reanalysis image from Feb 2014:

 

This energy is much stouter, but we have a similar HP to deal with:

Here is the radar of what that produced

 

Again the energy that is creating this storm is stronger, so there is more worry of WAA and downsloping, but notice in 2014 we also had a kicker dropping in. Sure I would like to see a 2014 repeat, but I don't think that is exactly where we are headed. I will say though that that storm was one of the top analogues the MA folks kept throwing around a day or two ago. 

[Carvers Gap]

9 minutes ago, Dsty2001 said:

Very good explanation, so essentially we are threading a needle here.

Unless Arctic air is in place....pretty much the case at this latitude.  GOM and mountains just add an extra degree of difficulty. 

[Holston_River_Rambler]

9 minutes ago, Dsty2001 said:

Very good explanation, so essentially we are threading a needle here.

If the TN Valley had a motto for winter storms, that would be it, lol. 

Ligans aculas

[PowellVolz]

Very good explanation, so essentially we are threading a needle here.

So me and a few other guys are on a Tennessee sports message board. I joined that site in 2004 and we have been chasing these storms since then. In the 18 years I’ve been chasing snow on VQ, I can only remember 1 or 2 storms where we didn’t have a temp profile issue somewhere in the column. The valley is always threading the needle but as we go you will see that for whatever reason, interstate 40 turns out to be the R/S line 90% of the time. A good example is the last storm. I’m 20 min north of Knoxville in Halls and the last storm I stayed all snow. One of my good friends lives 2 miles south of 40 in west Knoxville and he was 50/50 rain snow. Knoxville is wild


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[Dsty2001]

I have noticed in Greene Co as well a huge discrepancy in how much snow can fall over short distances.  I live on the western side closer to Morristown and have gotten several inches more/less than areas 10 miles away.  

[Carvers Gap]

1 minute ago, Dsty2001 said:

I have noticed in Greene Co as well a huge discrepancy in how much snow can fall over short distances.  I live on the western side closer to Morristown and have gotten several inches more/less than areas 10 miles away.  

Greene is crazy.  Used to have a poster over that way who posted a bunch @waltrip.  Think @Math/Metis over there as well...or at least follows the wind situation at Camp Creek.  Micro-climates galore in Greene Co.  

[PowellVolz]

I have noticed in Greene Co as well a huge discrepancy in how much snow can fall over short distances.  I live on the western side closer to Morristown and have gotten several inches more/less than areas 10 miles away.  

One of the things I love about ETn weather are the microclimates. All of us have one but some have bigger influences than others. For my location I know I need a NNW wind to cash in on some NW flow snow. If my wind is straight out of the NW, I’ll get downsloped from Anderson Co.


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[Holston_River_Rambler]

I think part of the problem we are seeing with the lp locations, has to do with the fact that this big ball of energy is just dropping in from the NNW. Normally with a bowling ball system like this it rolls in from the 4 corners and so pops an initial low in TX or the Gulf, but this system already has a surface low dropping in and so as the energy makes the turn, that low gets confused ( I know its not alive, but hear me out) wrt which boundary to jump to. Does it jump up into the eastern TN valley? Does it jump down to the toasty Gulf coastal waters? Does it stay near its energy? And while all this is going on, the system is moving, so pretty soon the Gulf stream becomes an option too. 

 

I think we want this energy to drop in so far south that there is never a doubt about where the low pops: the Gulf. I wish I knew more about the physics and meteorology of surface low formation so I could convince myself that the warm Gulf waters would override these other options. 

[Icy Hot]

7 hours ago, Dsty2001 said:

What I find funny is everybody around my area is convinced we are getting a 93 repeat, and all I can do is shake my head and ask where the heck they are getting that information from.  Interesting enough a local news station was saying up to a foot is possible which threw me aback, the models don't seem to be in any agreement right now and honestly I don't think we will know for sure to right before the event starts

AccuWeather says 8-12 inches for Kingsport on Sunday night. Lol

[Holston_River_Rambler]

now here's a real

 

 weenie post, looks like the SREF members like em some gulf lows, lol:

 

I count 16 gulf lows or gulf coastal lows and 8 inland ones.

[Jed33]

3 minutes ago, Holston_River_Rambler said:

I think part of the problem we are seeing with the lp locations, has to do with the fact that this big ball of energy is just dropping in from the NNW. Normally with a bowling ball system like this it rolls in from the 4 corners and so pops an initial low in TX or the Gulf, but this system already has a surface low dropping in and so as the energy makes the turn, that low gets confused ( I know its not alive, but hear me out) wrt which boundary to jump to. Does it jump up into the eastern TN valley? Does it jump down to the toasty Gulf coastal waters? Does it stay near its energy? And while all this is going on, the system is moving, so pretty soon the Gulf stream becomes an option too. 

 

I think we want this energy to drop in so far south that there is never a doubt about where the low pops: the Gulf. I wish I knew more about the physics and meteorology of surface low formation so I could convince myself that the warm Gulf waters would override these other options. 

Excellent posts this morning. I agree Holston, we have had several other storms in the past couple years where the models couldn’t figure out where to run the low pressure centers. Some bounced east of the mtns, some west, and some right up the spine. Until the energy gets sorted out, going to be some bouncing around, but this is nothing we haven’t seen before. Just gotta be patient and see how it plays out. I know it’s hard to do though lol.

[Greyhound]

24 minutes ago, PowellVolz said:

So me and a few other guys are on a Tennessee sports message board. I joined that site in 2004 and we have been chasing these storms since then. In the 18 years I’ve been chasing snow on VQ, I can only remember 1 or 2 storms where we didn’t have a temp profile issue somewhere in the column. The valley is always threading the needle but as we go you will see that for whatever reason, interstate 40 turns out to be the R/S line 90% of the time. A good example is the last storm. I’m 20 min north of Knoxville in Halls and the last storm I stayed all snow. One of my good friends lives 2 miles south of 40 in west Knoxville and he was 50/50 rain snow. Knoxville is wild


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To add to your post......I live about 10ish miles south of you in Fountain City, and we flip-flopped between a mix and snow.  Think we had about an inch or so of accumulation.  My general approach the last few years is to take the model with the worst output for my area, then shave 75% off that total.  That way my frustration at the lack of winter precip is not preceded by doubt/worry and doesn't come as a complete shock.  Surprisingly (and sadly), that approach has worked quite well in regards to totals the past few years.  

[The Waterboy]

15 minutes ago, Holston_River_Rambler said:

now here's a real

 

 weenie post, looks like the SREF members like em some gulf lows, lol:

 

I count 16 gulf lows or gulf coastal lows and 8 inland ones.

Holston, 

What is the link to this site?  I’d like to see this earlier in the run for my area in AR.  Thanks!  

[Holston_River_Rambler]

11 minutes ago, The Waterboy said:

Holston, 

What is the link to this site?  I’d like to see this earlier in the run for my area in AR.  Thanks!  

https://www.spc.noaa.gov/exper/sref/

There are lots of parameters to toggle at the top. 

[Holston_River_Rambler]

I think there is a hair more confluence on the NAM at hr 39. Like 4 pixels worth, lol. 

[TellicoWx]

1 hour ago, PowellVolz said:

We have a surface low that tracking along the coast of the GOM. We also have an 850mb low pressure tracking on or just south or the southern Tennessee state line. The 850 low pressure is basically our weather maker. If we can get it about 50 miles further south it would really open up Tennessee.


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That's the million dollar question...how does the 850 track. While the setup is different, the 850 is close to the same track as the last system. Globals were off with it (kept the 850 close to the TN border), when it actually came up to almost I40. 850 has to slide south of your area, or this storm will be a No Go. If this was a stacked system, then the actual surface reflection would have more weight.

[Holston_River_Rambler]

Noticeably more confluence over NE I would say at hour 45. It isn't much, but enough to make a difference. 

[Holston_River_Rambler]

Some of the subtle differences are starting to pay dividends at hour 57. Base of the vort is probably 150 miles south of 6z. 

[Carvers Gap]

1 minute ago, Holston_River_Rambler said:

Some of the subtle differences are starting to pay dividends at hour 57. Base of the vort is probably 150 miles south of 6z. 

Looks colder across the forum area.

[Holston_River_Rambler]

Looks like it is trying to pop a 1008 mb low around Mobile at hour 60. 

[Carvers Gap]

This is a fairly sizable change by the 12 NAM through 60.  It is the NAM at range so that could be the case....

[Carvers Gap]

That is so far south at 65, it doesn't even look like the same storm.  LOL.  

[Holston_River_Rambler]

yeah, what a south jump: