January Medium-Long Range Discussion

[Carvers Gap]

And remember the Euro had a Miller A before going to the anafront.  I remember John talking about that, and I hadn't noticed the slp running the coast a few days ago.  This almost looks like a classic case of the system being lost days 5-7 (almost disappeared on some modeling overnight), and then reappears.   I agree with John as well.  In reality, that is a good look.  We don't need a ton of precip w/ cold air in the northwest quadrant and likely high rations.  However, that would likely fill-in nicely.

[fountainguy97]

3 minutes ago, Carvers Gap said:

JB called it this morning.  He said that operationals(euro specifically) were too amped.  I have noticed multiple ensemble members which were sliders or even went into the Gulf States as a slider.  Not many have turned the corner like the Euro just did, but the solution has been there buried in ensembles.  It might be the primary solution.  I thought it might just be smoothing.  JB noted that high pressure over the top should flatten it out.  It looks to me like models are abandoning the anafront, holding energy back after first flattening the front.  It almost creates an overrunning event over TN.

But that's the question. Does this just flatten into a non-event? Verbatim euro is basically a swing and a miss for the SE with a late blooming surface low. I guess the ceiling is much higher with this look but it'll be easy for this to be too late for most of the E US besides New England.

[Carvers Gap]

The GFS and the CMC had nearly the same set-up...just different iterations.  But I will say this, we want the Euro on board when things are complex.

[Carvers Gap]

7 minutes ago, fountainguy97 said:

But that's the question. Does this just flatten into a non-event? Verbatim euro is basically a swing and a miss for the SE with a late blooming surface low. I guess the ceiling is much higher with this look but it'll be easy for this to be too late for most of the E US besides New England.

If this is correct and it makes sense....

I think the front running cold front(which dies out) will send precip out ahead, the rest of the energy holds back along the GOM as the cold front hits the GOM, and then dynamite.  I have been wondering how a strong cold front like that didn't create a storm.  The Memphis system a few years back slowed and there was overrunning.  Cold air like that is notorious for just oozing southward.  Many great storms of the past have their genesis along a strong Arctic boundary that stalls.  It is possible/plausible that this could all get squashed, but the energy is gonna have to go somewhere.  I don't think it will just burn out over Louisiana.  It certainly could go out to sea.  But....a strong storm would likely trend Northwest.   I feel a bit better about having seen the GFS and CMC try the same thing.  Plus, several ensemble members have been well south of the operational.  I think we have noted over the past couple of days that the ensemble means were well south of the operational.  Now, what we need to see is the ensembles and operationals converge on a track like the Euro just had.  Let's hope the operationals are not moving completely to the suppressed ensemble means from the past few days.

[PowellVolz]

I still believe the Euro has QPF under modeling issues.

Doesn’t it also have NW precip shield issues?


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[PowellVolz]

JB called it this morning.  He said that operationals(euro specifically) were too amped.  I have noticed multiple ensemble members which were sliders or even went into the Gulf States as a slider.  Not many have turned the corner like the Euro just did, but the solution has been there buried in ensembles.  It might be the primary solution.  I thought it might just be smoothing.  JB noted that high pressure over the top should flatten it out.  It looks to me like models are abandoning the anafront, holding energy back after first flattening the front.  It almost creates an overrunning event over TN.

2015?


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[Carvers Gap]

What a run!  The Euro wasn't just satisfied w/ one winter storm and one cold front.  The end of that run...wow

[Carvers Gap]

5 minutes ago, PowellVolz said:

2015?


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I think he has been saying something like Feb 7, 1967....and then maybe some aspects of '96, but he is not calling for a 96 redux by any means.  

[PowellVolz]

I think he has been saying something like Feb 7, 1967....and then maybe some aspects of '96, but he is not calling for a 96 redux by any means.  

I’m terrible with years but I remember (maybe 2015) we had two weeks of brutal cold and a couple of overrunning events right after a polar front? Like I said I’m terrible with dates, even years for that matter.


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[Carvers Gap]

3 minutes ago, PowellVolz said:

I’m terrible with years but I remember (maybe 2015) we had two weeks of brutal cold and a couple of overrunning events right after a polar front? Like I said I’m terrible with dates, even years for that matter.


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I had to go look it up.  I read the article on WxBell about it earlier today, but there is the snow map I found....Interestingly, I think it came right on the heels of a cutter that hit Chicago w/ a big snowstorm.

 

[fountainguy97]

21 minutes ago, Carvers Gap said:

If this is correct and it makes sense....

I think the front running cold front(which dies out) will send precip out ahead, the rest of the energy holds back along the GOM as the cold front hits the GOM, and then dynamite.  I have been wondering how a strong cold front like that didn't create a storm.  The Memphis system a few years back slowed and there was overrunning.  Cold air like that is notorious for just oozing southward.  Many great storms of the past have their genesis along a strong Arctic boundary that stalls.  It is possible/plausible that this could all get squashed, but the energy is gonna have to go somewhere.  I don't think it will just burn out over Louisiana.  It certainly could go out to sea.  But....a strong storm would likely trend Northwest.   I feel a bit better about having seen the GFS and CMC try the same thing.  Plus, several ensemble members have been well south of the operational.  I think we have noted over the past couple of days that the ensemble means were well south of the operational.  Now, what we need to see is the ensembles and operationals converge on a track like the Euro just had.  Let's hope the operationals are not moving completely to the suppressed ensemble means from the past few days.

Thats a good summary. Models seem to be trending more toward the holding back solution but I hope we don't end up in an awkward inbetween solution where the front is dead and the back energy is too late 

[Carvers Gap]

2 minutes ago, fountainguy97 said:

Thats a good summary. Models seem to be trending more toward the holding back solution but I hope we don't end up in an awkward inbetween solution where the front is dead and the back energy is too late 

That could definitely happen.  Front dies and then the SLP is too far to the East.  

That said, that solution made sense and has some support by other modeling.  I am going to cash in some chips on a NW jog.  LOL.

[Carvers Gap]

The 12z Euro is worth your time, especially after the storm.  There is another system around the 19th and 20th.  Then this baby comes East.  Just looking at temps, a very large area of cold gets trapped under that banana high.  

 

[WishingForWarmWeather]

Hey y’all - where do I go to follow along with the models? Usually I only use tropical tidbits during hurricane season. But I’ve found myself now living about 45 min north of Nashville. I don’t typically follow winter weather. Which models to ignore for being weenied out always, which are best - and where do I find the best maps for following along the windshield wiping trends? 

[Carvers Gap]

Here is the 12z EPS (26-50 snow members...first half looks similar as well).  You can see the model spread now w/ two tracks.

 

[Vol4Life]

Alex, I’ll take 30 or 31 please!

[Daniel Boone]

30 minutes ago, Carvers Gap said:

I had to go look it up.  I read the article on WxBell about it earlier today, but there is the snow map I found....Interestingly, I think it came right on the heels of a cutter that hit Chicago w/ a big snowstorm.

 

Yeah, Chicago's big Blizzard back then . Over 20" there. 

[Greyhound]

I’m terrible with years but I remember (maybe 2015) we had two weeks of brutal cold and a couple of overrunning events right after a polar front? Like I said I’m terrible with dates, even years for that matter.


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It was right around Valentine’s Day in 2015


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[John1122]

1 hour ago, tnweathernut said:

Only caution would be this isn't a full gulf tap with a strong low.  It's an overrunning look.  I have no clue if it makes a difference how the Euro handles QPF, but it's a different setup for sure

.

Overrunning = no warm nose so good for our south siders as a rule. 

[PowellVolz]

I know it’s still early but MRX has taken rain out of my forecast for Sunday/Monday and lowered temps. Waiting on AFD


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[PowellVolz]

Overrunning = no warm nose so good for our south siders as a rule. 

I feel like the depth of the cold could hold its ground either way.


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[John1122]

3 minutes ago, PowellVolz said:

I feel like the depth of the cold could hold its ground either way.


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Our Chattanooga guys and gals want it 27 and 850s at -5c to be sure. 

[Silas Lang]

Interesting changes today. Almost feels like the models/ensembles want to give us snow, but still don't know exactly how it will happen, if that makes sense. 

[Holston_River_Rambler]

This may end up being very similar to what others have said, but I'm just now getting time to type something up. With that caveat, here are Holston's 2 cents. This is mostly just about the moving parts, so I'm just using the 12z Euro for illustrative purposes. I am not implying it has the solution.

 

We start at hour 0:

 

We have some blocking at H5 in the NAO and AO domains, illustrated here by the red squiggles. Underneath that we have a broad anticyclonic circulation over most of Canada. On the lower fringes of this we have two stout shortwaves, here usefully labelled as Cutter A (the storm from yesterday) and Cutter B (Friday's storm). Now watch as these systems evolve. I can't control when these gifs start and stop, so you may have to watch it a few times to see all the interactions:

 

The first storm rotates up and through the Canadian maritimes as the overall broad anticyclonic rotation continues. But also notice just how many stout shortwaves there are over Canada rotating in that broad circulation. It almost takes on the look of a star at one point, with a nice shortwave at each point. Watch especially the two over Yukon and British Columbia. They kinda sorta try to phase at the end. All the while our cutter does what we expect and cut up through the OH Valley. 

A snapshot of all this at hour 48:

Cutter A has added to what I'm very scientifically labelling a "Fujiwara mess" and a tall ridge just off the west coast and into AK. I know most people here know this, but if not (it's ok) the fujiwara effect is when two cyclones kind of dance around each other. Three huge midlevel, cuttoff cyclones all interacting, meandering, and spinning over Canada, as the ridging over Greenland and that off the Pac coast try to pinch it off. 

 

As this mess evolves over the next 48 hours, the two cyclones over western Canada get more strung out and evnn interact with the Friday cutter, creating a long ribbon of vorticity looping from norther Alaska, down into norther Missouri, and then across the Ohio valley and into the Canadian maritimes. 

While all that is going on, the shortwave that first interests us is coming onshore around hour 87 in N. California. the other thing I would ask you to notice in this is a shortwave associated with the subtropical jet out in the Pacific, southwest of California and associated vorticity extending across Mexico and into the Gulf.

 

The shortwave I have labelled "Part A" is going to swing under that huge vorticity ribbon and aim directly at the TN Valley:

A little vorticity advection, a little flow backing for a smidge of Gulf moisture, a healthy dose of frontogentic forcing I'm guessing with the arctic air and you get the flat, overunning precip event:

So we have that and in some ways its not too complicated. Now let's turn back to that ribbon of vorticity left out from the fujiwara sheared mess:

In the above picture the shortwave that was producing the overrunning anafront stuff is now shearing out under the pressure from basically a piece of the tropospheric PV over St. James Bay. It's the resolution of the fujiwara mess that's getting interesting now. Look at that shortwave diving down through the Rockies. There's also a new shortwave coming on shore in CA and what's left of the STJ energy i mentioned above. 

It's this shortwave over the Rockies that's producing the "almost" Miller A solutions:

It dives down, some of that STJ energy gets involved and we shoot for Florida panhandle cyclogenesis:

There is a lot more to dig around in here, but that is all I have time for, for now. All kinds of moving parts, so it is astounding that models have been as consistent as they have been with some sort of system from as far out as they have seen it. 

 

[Uncle Nasty]

Our Chattanooga guys and gals want it 27 and 850s at -5c to be sure. 

Sent from my SM-S916U using Tapatalk

[PowellVolz]

Interesting changes today. Almost feels like the models/ensembles want to give us snow, but still don't know exactly how it will happen, if that makes sense. 

The good news is it feels like there’s multiple ways for us to get some snow out of this when typically there’s multiple ways for this to fail.


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[PowellVolz]

This may end up being very similar to what others have said, but I'm just now getting time to type something up. With that caveat, here are Holston's 2 cents. This is mostly just about the moving parts, so I'm just using the 12z Euro for illustrative purposes. I am not implying it has the solution.
 
We start at hour 0:

 
We have some blocking at H5 in the NAO and AO domains, illustrated here by the red squiggles. Underneath that we have a broad anticyclonic circulation over most of Canada. On the lower fringes of this we have two stout shortwaves, here usefully labelled as Cutter A (the storm from yesterday) and Cutter B (Friday's storm). Now watch as these systems evolve. I can't control when these gifs start and stop, so you may have to watch it a few times to see all the interactions:

 
The first storm rotates up and through the Canadian maritimes as the overall broad anticyclonic rotation continues. But also notice just how many stout shortwaves there are over Canada rotating in that broad circulation. It almost takes on the look of a star at one point, with a nice shortwave at each point. Watch especially the two over Yukon and British Columbia. They kinda sorta try to phase at the end. All the while our cutter does what we expect and cut up through the OH Valley. 
A snapshot of all this at hour 48:

Cutter A has added to what I'm very scientifically labelling a "Fujiwara mess" and a tall ridge just off the west coast and into AK. I know most people here know this, but if not (it's ok) the fujiwara effect is when two cyclones kind of dance around each other. Three huge midlevel, cuttoff cyclones all interacting, meandering, and spinning over Canada, as the ridging over Greenland and that off the Pac coast try to pinch it off. 
 
As this mess evolves over the next 48 hours, the two cyclones over western Canada get more strung out and evnn interact with the Friday cutter, creating a long ribbon of vorticity looping from norther Alaska, down into norther Missouri, and then across the Ohio valley and into the Canadian maritimes. 

While all that is going on, the shortwave that first interests us is coming onshore around hour 87 in N. California. the other thing I would ask you to notice in this is a shortwave associated with the subtropical jet out in the Pacific, southwest of California and associated vorticity extending across Mexico and into the Gulf.

 
The shortwave I have labelled "Part A" is going to swing under that huge vorticity ribbon and aim directly at the TN Valley:

A little vorticity advection, a little flow backing for a smidge of Gulf moisture, a healthy dose of frontogentic forcing I'm guessing with the arctic air and you get the flat, overunning precip event:

So we have that and in some ways its not too complicated. Now let's turn back to that ribbon of vorticity left out from the fujiwara sheared mess:

In the above picture the shortwave that was producing the overrunning anafront stuff is now shearing out under the pressure from basically a piece of the tropospheric PV over St. James Bay. It's the resolution of the fujiwara mess that's getting interesting now. Look at that shortwave diving down through the Rockies. There's also a new shortwave coming on shore in CA and what's left of the STJ energy i mentioned above. 
It's this shortwave over the Rockies that's producing the "almost" Miller A solutions:

It dives down, some of that STJ energy gets involved and we shoot for Florida panhandle cyclogenesis:

There is a lot more to dig around in here, but that is all I have time for, for now. All kinds of moving parts, so it is astounding that models have been as consistent as they have been with some sort of system from as far out as they have seen it. 
 

That’s great info.


.

[Carvers Gap]

12z is on the left and 0z is on the for comparison.  Notice that the SLP is much more defined and closer to the coast.  Nice looking storm.  This is the sequence of the storm as it climbs the EC.  12z was much slower.  When a storm gets inside of Hatteras that is a good signal for E TN.  Let's see if the trend holds.

 

 

 

 

[Carvers Gap]

30 minutes ago, Holston_River_Rambler said:

This may end up being very similar to what others have said, but I'm just now getting time to type something up. With that caveat, here are Holston's 2 cents. This is mostly just about the moving parts, so I'm just using the 12z Euro for illustrative purposes. I am not implying it has the solution.

 

We start at hour 0:

 

We have some blocking at H5 in the NAO and AO domains, illustrated here by the red squiggles. Underneath that we have a broad anticyclonic circulation over most of Canada. On the lower fringes of this we have two stout shortwaves, here usefully labelled as Cutter A (the storm from yesterday) and Cutter B (Friday's storm). Now watch as these systems evolve. I can't control when these gifs start and stop, so you may have to watch it a few times to see all the interactions:

 

The first storm rotates up and through the Canadian maritimes as the overall broad anticyclonic rotation continues. But also notice just how many stout shortwaves there are over Canada rotating in that broad circulation. It almost takes on the look of a star at one point, with a nice shortwave at each point. Watch especially the two over Yukon and British Columbia. They kinda sorta try to phase at the end. All the while our cutter does what we expect and cut up through the OH Valley. 

A snapshot of all this at hour 48:

Cutter A has added to what I'm very scientifically labelling a "Fujiwara mess" and a tall ridge just off the west coast and into AK. I know most people here know this, but if not (it's ok) the fujiwara effect is when two cyclones kind of dance around each other. Three huge midlevel, cuttoff cyclones all interacting, meandering, and spinning over Canada, as the ridging over Greenland and that off the Pac coast try to pinch it off. 

 

As this mess evolves over the next 48 hours, the two cyclones over western Canada get more strung out and evnn interact with the Friday cutter, creating a long ribbon of vorticity looping from norther Alaska, down into norther Missouri, and then across the Ohio valley and into the Canadian maritimes. 

While all that is going on, the shortwave that first interests us is coming onshore around hour 87 in N. California. the other thing I would ask you to notice in this is a shortwave associated with the subtropical jet out in the Pacific, southwest of California and associated vorticity extending across Mexico and into the Gulf.

 

The shortwave I have labelled "Part A" is going to swing under that huge vorticity ribbon and aim directly at the TN Valley:

A little vorticity advection, a little flow backing for a smidge of Gulf moisture, a healthy dose of frontogentic forcing I'm guessing with the arctic air and you get the flat, overunning precip event:

So we have that and in some ways its not too complicated. Now let's turn back to that ribbon of vorticity left out from the fujiwara sheared mess:

In the above picture the shortwave that was producing the overrunning anafront stuff is now shearing out under the pressure from basically a piece of the tropospheric PV over St. James Bay. It's the resolution of the fujiwara mess that's getting interesting now. Look at that shortwave diving down through the Rockies. There's also a new shortwave coming on shore in CA and what's left of the STJ energy i mentioned above. 

It's this shortwave over the Rockies that's producing the "almost" Miller A solutions:

It dives down, some of that STJ energy gets involved and we shoot for Florida panhandle cyclogenesis:

There is a lot more to dig around in here, but that is all I have time for, for now. All kinds of moving parts, so it is astounding that models have been as consistent as they have been with some sort of system from as far out as they have seen it. 

 

With the system flattened, when that trailing edge of the cold front hits the GOM - boom.  With it being flatter, it gives time for precip to work into the system.   Also, the front halfway stalls.  We really want that front to sag slightly southeast of our region and stall....draped from the GOM to Hatteras.  

[Stovepipe]

MRX update:

Quote

Confidence is increasing for potential accumulating snow during
the Monday to Tuesday timeframe. Exact values are uncertain, but
this could be an almost area-wide snowfall.

Quote

Monday through Wednesday

With respect to our area, cold air from the Arctic high will
gradually expand from the northwest with the main question being
about precipitation potential during this timeframe. There is still
uncertainty about how the exact pattern will transpire during this
time. Most sources are suggesting an Arctic front to be setting up
across the area with divergence aloft early next week. With the
depth of cold air expanding from the northwest, it is likely that
most precipitation would fall during this time would be frozen. The
GFS, CMC, and ECMWF all show precipitation in the area during this
time with the ECMWF being more towards Tuesday and as more of a
Miller A development. The ensembles continue to focus potential
snowfall totals further north in the area. Based on QPF outputs of
0.25 inches to near 0.50 inches, resulting accumulations given
enough cold air would be notable across even the lower elevations.
All sources are then suggesting extremely cold air to set in Tuesday
to Wednesday. This is illustrated by 850mb in all sources to reach
-15 Celsius or lower, values approaching record daily values for
this part of the country. It is also increasingly possible that
resulting wind chills may be sufficient for products in the higher
elevations.