January 2019 Medium/Long Range Pattern Discussion

[John1122]

25 minutes ago, Bango said:

Fv3 continues to show johns glacier (mid tn to plateau into ky.  Its been pretty consistent over the last few runs it seems. Would be beyond epic for you guys

We will see if/when it blinks. It's a mega ice/sleet/snow event for the western 2/3rds  of the valley region. .5 to 1 inch of zr, 3-8 inches of snow and sleet. My county and sw down the eastern edge of the plateau is the line basically. The far SE of the county gets only zr, but the rest gets 2-8 inches of snow on the FV3. The zr spills off the eastern edge of the plateau into the adjecent counties. 

Models very often underperform the cold air that can slide under in this set up. But the FV3 is either seeing it better than other models or its out to lunch. 

[weathertree4u]

6 minutes ago, John1122 said:

We will see if/when it blinks. It's a mega ice/sleet/snow event for the western 2/3rds  of the valley region. .5 to 1 inch of zr, 3-8 inches of snow and sleet. My county and sw down the eastern edge of the plateau is the line basically. The far SE of the county gets only zr, but the rest gets 2-8 inches of snow on the FV3. The zr spills off the eastern edge of the plateau into the adjecent counties. 

Models very often underperform the cold air that can slide under in this set up. But the FV3 is either seeing it better than other models or its out to lunch. 

Hopefully it is out to lunch but the Canadian has it too. Nearly an inch of ZR in Sumner County would not be pretty. 

[Kentucky]

Snowing in Corbin now, Hoping the back side holds together. jkl seems to think it will 

 

[John1122]

6 minutes ago, Kentucky said:

Snowing in Corbin now, Hoping the back side holds together. jkl seems to think it will 

 

Snowing here as well. Temp is 37. Nothing even showing on the radar right now here. Hopefully the area from Nashville into Kentucky can make it here. 

[weathertree4u]

Just a general statement here. Anyone know why it is that the GFS does not see any of what the replacement GFS does? For example, for this upcoming week, the replacement GFS is still seeing allot of ZR for my area but if you access the regular GFS, nothing. How could the physics used in both be so different? 

[John1122]

FV3 bumps totals up in the eastern valley, maintains in the central/western valley. Huge ice again this run on it.

[John1122]

Just now, weathertree4u said:

Just a general statement here. Anyone know why it is that the GFS does not see any of what the replacement GFS does? For example, for this upcoming week, the replacement GFS is still seeing allot of ZR for my area but if you access the regular GFS, nothing. How could the physics used in both be so different? 

 The FV3 is much much higher resolution and may be seeing the low level cold better than the GFS. It could also have a bias for being too cold. I don't know if it's going to be right, but as I've said a few times already, one of the biggest model struggle I note in winter is how they handle low level cold, both with scouring it out too quickly at times and with moving it in too slowly at times.

[weathertree4u]

1 minute ago, John1122 said:

FV3 bumps totals up in the eastern valley, maintains in the central/western valley. Huge ice again this run on it.

Yea, really not starting to like this model! That much ice is more than enough to do serious damage to things, then to have a dump of arctic air behind it, not good, not good at all. 

[weathertree4u]

Just now, John1122 said:

 The FV3 is much much higher resolution and may be seeing the low level cold better than the GFS. It could also have a bias for being too cold. I don't know if it's going to be right, but as I've said a few times already, one of the biggest model struggle I note in winter is how they handle low level cold, both with scouring it out too quickly at times and with moving it in too slowly at times.

Yea, I would agree, yet the NWS in Nashville is projecting staggering warmth by midweek, near 50, likely heavily weighted on the GFS

[John1122]

1 minute ago, weathertree4u said:

Yea, I would agree, yet the NWS in Nashville is projecting staggering warmth by midweek, near 50, likely heavily weighted on the GFS

The FV3 has Nashville well into the 50s Wednesday morning ahead of the front. It falls to below freezing a by Wednesday evening and the cold is undercutting the precip. The temps are almost exactly the same on the GFS. The GFS is more rain to snow without the zr transition. It also doesn't develop a wave on the front like the FV3 does.  Much bigger precip shield behind on the FV3 due to that wave. 

[Holston_River_Rambler]

6 hours ago, Carvers Gap said:

Another note...I think maybe what is going on in the LR might be related to storms firing in the Indian Ocean.

Maybe I was putting it the wrong way, but that was what I was trying to say all day yesterday. 

That convection there and in Maritime Continent leads to an amped Pac jet (and +MT from the Himalaya), but it definitely looks like it will be muted this time. 

[weathertree4u]

3 minutes ago, John1122 said:

The FV3 has Nashville well into the 50s Wednesday morning ahead of the front. It falls to below freezing a by Wednesday evening and the cold is undercutting the precip. The temps are almost exactly the same on the GFS. The GFS is more rain to snow without the zr transition. It also doesn't develop a wave on the front like the FV3 does.  Much bigger precip shield behind on the FV3 due to that wave. 

Gotcha, I knew there was a difference!

[weathertree4u]

5 minutes ago, John1122 said:

The FV3 has Nashville well into the 50s Wednesday morning ahead of the front. It falls to below freezing a by Wednesday evening and the cold is undercutting the precip. The temps are almost exactly the same on the GFS. The GFS is more rain to snow without the zr transition. It also doesn't develop a wave on the front like the FV3 does.  Much bigger precip shield behind on the FV3 due to that wave. 

I think, if I am not mistaken, we had that same issue in February 1994. Nashville got to a balmy temp I believe, then we had an arctic front come through, a low developed on it and we got slammed by ZR

[Holston_River_Rambler]

Euro still looked pretty good overnight too:

 

Nice to have the Euro showing multiple threats within 10 days. I suspect if the first threat there (been pretty consistent across models) actually happens, it will have more precip given how every.single.other. storm has performed this winter. Who knows though, that'll be the one to buck the trend. 

 

[John1122]

06 FV3 has the same threat as the Euro, but further south. It's another good shot of snow for the central and western valley and points south that eventually gets basically the whole forum. Looks like by the end of this run basically the deep south to the mid south will have gotten a nice bit of model snow. It swings by and drops 5-6 inches in Atlanta even.

[TellicoWx]

00z GEFS mean was about as nice as you could ask for in the south:

 

[weathertree4u]

1 minute ago, John1122 said:

06 FV3 has the same threat as the Euro, but further south. It's another good shot of snow for the central and western valley and points south that eventually gets basically the whole forum. Looks like by the end of this run basically the deep south to the mid south will have gotten a nice bit of model snow. It swings by and drops 5-6 inches in Atlanta even.

One of the things that stand out to me is that it is not the usual snow/ice that the South gets. Whatever falls looks like it will be on the ground, in the trees, etc., for an extended period of time, which is unusual around here. 

[John1122]

It some how manages to snow fairly heavily all around the South except for the Southern Eastern Valley/NE Georgia area. At the 240 mark another southern system is effecting the whole forum with snow and it's pointed at those areas.

[weathertree4u]

3 minutes ago, John1122 said:

It some how manages to snow fairly heavily all around the South except for the Southern Eastern Valley/NE Georgia area. At the 240 mark another southern system is effecting the whole forum with snow and it's pointed at those areas.

Yea, that would be historic, and dont forget, some areas could still be out of power with the icing that will be under that snowpack. 

[Holston_River_Rambler]

I really do think that even though the EPS looks bad, it is just in the process of reseting for more, after the Pac jet hits us briefly one more time in the long range. You can see it starting at the end of its run. Gladly eat this if my reading of it is wrong. 

Also, if you want to see some crazy ice accumulation, the 0z Euro Control's got it days 13-15. 

[TellicoWx]

6 minutes ago, John1122 said:

It some how manages to snow fairly heavily all around the South except for the Southern Eastern Valley/NE Georgia area. At the 240 mark another southern system is effecting the whole forum with snow and it's pointed at those areas.

To me the million dollar question is, Can the front clear the apps? A lot of times the fronts get hungup on the plateau or mtns and that is what the models are trying to sort out.

[Holston_River_Rambler]

Euro Control ice, wow!

 

 

[Holston_River_Rambler]

1 minute ago, TellicoWx said:

Can the front clear the apps?

That's what I've been wondering too, but it seems like so long since we've had a big arctic from come through undercutting precip, it's hard to remember how it plays out. Seems like they do have trouble making it over the plateau, but maybe if you had a wave ride it it could help pull it at least to the crest of the mountains

[TellicoWx]

Another nice run for the south on the 06z Gefs:

[Holston_River_Rambler]

Like you said yesterday Tellico, pretty incredible how far south that 2 inch line is. 

[TellicoWx]

3 minutes ago, Holston_River_Rambler said:

That's what I've been wondering too, but it seems like so long since we've had a big arctic from come through undercutting precip, it's hard to remember how it plays out. Seems like they do have trouble making it over the plateau, but maybe if you had a wave ride it it could help pull it at least to the crest of the mountains

The best I remember is..the deeper the cold, the better the odds for it to clear the plateau. If its shallow as it moves in, the odds for snowfall decrease across the central/southern valley, and ice chances increase over the plateau/middle TN.

[TellicoWx]

5 minutes ago, Holston_River_Rambler said:

Like you said yesterday Tellico, pretty incredible how far south that 2 inch line is. 

Yeah, fairly strong signal for the entire south once the mid week front clears on the Gefs. 

[Holston_River_Rambler]

All the 6z GEFS members:

 

[Holston_River_Rambler]

Found this on another forum. Analogues for 1/31 as the GFS develops it. Since this is developed by the CPC, not sure they can do one for the Euro:

 

Seems like the end of the month storm (27-29th) has been there in almost every run on Euro and American models. What's more, precip. type has yet to be an issue on either model. Hopefully this one has legs for most of the forum! I also like that the tendency so far has been for it to be a little too south and little too progressive. I think we know how those will trend with time. 

 

 

[Carvers Gap]

Regarding the 500 and now surface ensemble(0z EPS, 0z GEPS, 6z GEFS) d10-15 pattern evolution, the evolution of the pattern discussed yesterday AM is very plausible.   Just a quick note on the most recent ensemble runs....I think the Indian Ocean convection will have to be considered as a factor now within LR forecasting.  I give credit to JB for mentioning it yesterday.  It signaled the warm-up in December.  It is there again.  He says that modeling dampens it this time vs it being a long term feature.  IMHO, that could very well signal a thaw in this pattern.  I am not "all-in" on a thaw, but now placing it into consideration.  Again, it is possible that modeling is just breaking down blocking too early.  Happens all of the time.  However, there is a driver behind what is being shown that has already been present this winter.  It may also be just the evolution of the pattern as shown on the Weeklies control.  I do know that Jeff mentioned that a small cluster of analogs(at one point in our discussion of the cold snap) did pull the cold back to the mid-section of the continent.  So here is what we know this morning.  We will very likely have a 7-10 period of winter wx.  Not everyone will get their share as is normal.  But I think it likely someone sees some decent snow.  After that is now a question for me.   I am about 60/40 that the cold pattern continues, but it is far less a certainty than it once appeared.