February/March 2021 - Frigid or Flop? Pattern/Longterm Forecast Thread.

[Mrwolf1972]

Just now, Carvers Gap said:

I think it is two storms.  Boundary gets pressed eastward with each storm.  I "think".....

It is 2 storms one earlier in week with rain in valley our ice in valley is over the weekend.

[Daniel Boone]

Man, sure hope the icing don't come to fruition. Arctic air close by, ph. 7 MJO and blocking lends to that in particular IF blocking is not strong. if it is and not too far west, less icing, more snow. 

[Carvers Gap]

Both the 12z CMC and 12z GFS are back with the original idea of a multi-event overrunning event..  Each event presses the cold eastward towards the Apps.  The SER will push it back...but that is when ice becomes a real risk.  We all know that it is tough to scour cold out of these valleys without a real push of WAA timed just right.

[Daniel Boone]

5 minutes ago, Shocker0 said:

That's an odd looking setup. Are the "clear" areas in the middle part of the state snow or something? Or a warm nose with cold rain?

Good question??

[Carvers Gap]

Just now, Daniel Boone said:

Man, sure hope the icing don't come to fruition. Arctic air close by, ph. 7 MJO and blocking lends to that in particular IF blocking is not strong. if it is and not too far west, less icing, more snow. 

That is a nasty look.  Looks like the CMC and GFS are slightly eastward with the boundary than yesterday.  Who knows if that is right?  Maybe models are "feeling the cold" press now.

[weathertree4u]

5 hours ago, Carvers Gap said:

Seems like wherever this ends up it will not be pretty.

 

[Carvers Gap]

Yeah, these maps are going to look wonky as each storm leaves a stripe of snow, zr, sleet, and rain(maybe some thunder) along their paths.  I did go back and double check my answer after shocker asked that.  

[Daniel Boone]

Yeah, as Carvers noted, nasty outcome and very plausible.

[Carvers Gap]

Just now, weathertree4u said:

 

Yeah, honestly...I don't want to have show-off my madly awesome urban survival skills.  Besides, I have grown to really like electricity.

[Holston_River_Rambler]

4 minutes ago, Vol4Life said:

From a storm evolution standpoint, what needs to happen in order for this to be more of a snow event versus zr?  Clearly, there’s some warming aloft.  Do we need the HP to be stronger or positioned differently?  Or is this more of a storm track issue?

We just would have to hope for a deeper press of cold. All the precip starts as snow, but melts as it hits a warm nose. 3 different soundings from the 12z GFS at this frame:

 

one approx at Knoxville, one approx. at Carthage, one at approx. Union City:

 

 

 

 

 

Each has the characteristic warm nose. (The red line that kind of looks like a person's nose). In the first one (around Knoxville) the nose spends a lot of time above the 0 Celsius line. So the precip begins as snow (the green and the red lines, temp and dewpoint respectively) meet all the way up to around 350 mb (scale on the left side). That means the atmosphere is moist that high up. The little bars on that left side represent forcing and the dashed, bracketed area labelled DGZ is te zone where dendrites (snowflakes) can grow. If there is moisture in that, you have snow. But it falls through the area where the temp is above 0 celsius (32 Farenheit) and so it melts. But notice the temp drops down to 28 at the surface, so you get rain that freezes on contact, no bueno IMO. 

The second has the same problem, but the are of above freezing is much small, so you get maybe a mix. Some snow flakes might survive, but those that melt re freeze as theyt fall through nearly 5000' of sub freezing air, so you get sleet. 

Last one is the easiest. Starts as snow and never gets above freezing. 

 

You may know some of this already, but wasn't sure based on your questions so apologies if it is too much. We want deeper cold so the snow doesn't have a chance to melt. The High being over the Great Lakes might help some as it would shift everything more east. But nothing is really showing anything like that for now, at least for the window I picked above. That high is sliding down the front range of the Canadian Rockies and will likely move in from the NW. Just a question of how far it makes it. 

[Holston_River_Rambler]

Aaaaannnnd I probably spent waayyy too much time on that. Looks like it was answered while I was typing, lol. 

[Carvers Gap]

3 minutes ago, Holston_River_Rambler said:

We just would have to hope for a deeper press of cold. All the precip starts as snow, but melts as it hits a warm nose. 3 different soundings from the 12z GFS at this frame:

 

one approx at Knoxville, one approx. at Carthage, one at approx. Union City:

 

 

 

 

 

Each has the characteristic warm nose. (The red line that kind of looks like a person's nose). In the first one (around Knoxville) the nose spends a lot of time above the 0 Celsius line. So the precip begins as snow (the green and the red lines, temp and dewpoint respectively) meet all the way up to around 350 mb (scale on the left side). That means the atmosphere is moist that high up. The little bars on that left side represent forcing and the dashed, bracketed area labelled DGZ is te zone where dendrites (snowflakes) can grow. If there is moisture in that, you have snow. But it falls through the area where the temp is above 0 celsius (32 Farenheit) and so it melts. But notice the temp drops down to 28 at the surface, so you get rain that freezes on contact, no bueno IMO. 

The second has the same problem, but the are of above freezing is much small, so you get maybe a mix. Some snow flakes might survive, but those that melt re freeze as theyt fall through nearly 5000' of sub freezing air, so you get sleet. 

Last one is the easiest. Starts as snow and never gets above freezing. 

 

You may know some of this already, but wasn't sure based on your questions so apologies if it is too much. We want deeper cold so the snow doesn't have a chance to melt. The High being over the Great Lakes might help some as it would shift everything more east. But nothing is really showing anything like that for now, at least for the window I picked above. That high is sliding down the front range of the Canadian Rockies and will likely move in from the NW. Just a question of how far it makes it. 

A 1049 hp in the Plains is not going to play nicely.  

[Carvers Gap]

2 minutes ago, Holston_River_Rambler said:

Aaaaannnnd I probably spent waayyy too much time on that. Looks like it was answered while I was typing, lol. 

Don't we all!  LOL.  

[weathertree4u]

6 hours ago, Carvers Gap said:

Would suspect that power companies across the region will be putting teams together to discuss scenarios. I know the ice storm we had in 1994, the county finally had to provide protection for the president of the electric company.

 

[Holston_River_Rambler]

Euro is rolling. 

[Nash_LSU]

6 minutes ago, Holston_River_Rambler said:

 

 

Last one is the easiest. Starts as snow and never gets above freezing.

Thank you for taking the time on those. Very informative.

Can you help a newbie out with a question? I'm slowly learning how to read these things. You said the last one is snow all the way down. The dewpoint and temperature meet at about 650 and it's maybe around 2-3 degrees C at that point and then it falls . How do you interpolate that it it snow shown? Is the snow actually being produced further down at like 800 or so?

[CG2]

Looks like someone dumped a pack of Skittles on the map.  Taste the rainbow.

[Olhausen]

26 minutes ago, Blue Moon said:

Check my signature to observe the amount of nuisance snows/trace snowfall amounts measured at Nashville Int'l this winter.

I call this winter the season of the flizzard. I’ve had nickel and dime events bring me to 4 inches this season. A 1 inch snowfall and a 1.25 inch were the biggest snows so far in Whitehouse. Lots of snow events but not a lot to show for it so far. Hopefully that changes over the next week.

[CG2]

6 minutes ago, Holston_River_Rambler said:

Euro is rolling. 

I feel like @Stovepipe has something for this....LOL.

[tnweathernut]

6 minutes ago, Holston_River_Rambler said:

Euro is rolling. 

Could well be the Euro is trolling.......  lol

One thing I will note on the 12z Euro.  I really don't like this interaction early on with the PV in Canada.  It's been on this for several days now and looks much closer to what is happening vs. the American modeling from 3 days ago.  Not sure what that means down the line, guess we will have to see how this plays out down the line.

[Vol4Life]

17 minutes ago, Holston_River_Rambler said:

We just would have to hope for a deeper press of cold. All the precip starts as snow, but melts as it hits a warm nose. 3 different soundings from the 12z GFS at this frame:

 

one approx at Knoxville, one approx. at Carthage, one at approx. Union City:

 

 

 

 

 

Each has the characteristic warm nose. (The red line that kind of looks like a person's nose). In the first one (around Knoxville) the nose spends a lot of time above the 0 Celsius line. So the precip begins as snow (the green and the red lines, temp and dewpoint respectively) meet all the way up to around 350 mb (scale on the left side). That means the atmosphere is moist that high up. The little bars on that left side represent forcing and the dashed, bracketed area labelled DGZ is te zone where dendrites (snowflakes) can grow. If there is moisture in that, you have snow. But it falls through the area where the temp is above 0 celsius (32 Farenheit) and so it melts. But notice the temp drops down to 28 at the surface, so you get rain that freezes on contact, no bueno IMO. 

The second has the same problem, but the are of above freezing is much small, so you get maybe a mix. Some snow flakes might survive, but those that melt re freeze as theyt fall through nearly 5000' of sub freezing air, so you get sleet. 

Last one is the easiest. Starts as snow and never gets above freezing. 

 

You may know some of this already, but wasn't sure based on your questions so apologies if it is too much. We want deeper cold so the snow doesn't have a chance to melt. The High being over the Great Lakes might help some as it would shift everything more east. But nothing is really showing anything like that for now, at least for the window I picked above. That high is sliding down the front range of the Canadian Rockies and will likely move in from the NW. Just a question of how far it makes it. 

Thank you so much Holston!  That was a great explanation!

[John1122]

This year models have struggled big time with the blocking to our north. They are apparently programmed to weigh the MJO heavily along with Nina/La Nina. But nothing affects our weather more than blocking in the regions closest to us.  That's why the SE ridge is gone or pushed back once we get within 3 or 4 days this year. It also shows up in the cutters that end up being Miller As.  We had a few of those this year that trended from Cutter to As. Even a Miller B or two modeled that ended up south of here. The cold was just on the other side of the world when they happened. That's why the higher elevations have done so well this year and it's been nickel and diming every one else.

Now we have extreme cold lurking and a good possibility of a truly widespread winter weather event or even several. The precip hasn't shut down all year. The EURO and GFS about a week ago were giving .2 QPF for two weeks here but that fell apart quickly. 

[Holston_River_Rambler]

14 minutes ago, Nash_LSU said:

Can you help a newbie out with a question? I'm slowly learning how to read these things. You said the last one is snow all the way down. The dewpoint and temperature meet at about 650 and it's maybe around 2-3 degrees C at that point and then it falls . How do you interpolate that it it snow shown? Is the snow actually being produced further down at like 800 or so?

The one thing that takes a bit to get used to in looking at those, is that the dashed black lines go up at and angle, so that the temp in at 650 is maybe -5c:

 

(Sorry I picked a slightly different sounding for this image)

[tnweathernut]

2 minutes ago, John1122 said:

This year models have struggled big time with the blocking to our north. They are apparently programmed to weigh the MJO heavily along with Nina/La Nina. But nothing affects our weather more than blocking in the regions closest to us.  That's why the SE ridge is gone or pushed back once we get within 3 or 4 days this year. It also shows up in the cutters that end up being Miller As.  We had a few of those this year that trended from Cutter to As. Even a Miller B or two modeled that ended up south of here. The cold was just on the other side of the world when they happened. That's why the higher elevations have done so well this year and it's been nickel and diming every one else.

Now we have extreme cold lurking and a good possibility of a truly widespread winter weather event or even several. The precip hasn't shut down all year. The EURO and GFS about a week ago were giving .2 QPF for two weeks here but that fell apart quickly. 

It will be interesting to see if we can continue this trend.  If we do this weekend should be fun.  

[Holston_River_Rambler]

Euro has ticked south again with the cold:

850 temps last 3 runs:

[Nash_LSU]

1 minute ago, Holston_River_Rambler said:

The one thing that takes a bit to get used to in looking at those, is that the dashed black lines go up at and angle, so that the temp in at 650 is maybe -5c:

Ah, makes total sense. Thanks. Now I see what you're talking about in the second one where it barely nudges above freezing. (BTW, they sure do cram a lot of information on those Skew-T''s)

[Holston_River_Rambler]

Hits KY pretty hard with ZR:

[CG2]

The Euro out to 114 is nearly a textbook overrunning set-up...but no precip.  Hmm.

[CG2]

I am with John...not buying the "no precip" scenario just yet.  I think it is either going to be cold and precip or warm and precip IMBY.

[Holston_River_Rambler]

Gonna be fun to watch what happens with the pieces of energy over CA and the Baja: