Potential Big Dog Snow Event February 15th

[ShawnEastTN]

It doesn't cut from what I can tell, it simply goes right over the Smokies. At 120 the low is at 996 right in the middle of North Carolina.

Right over the Smokies makes me sort of discount that a bit.  Not very normal to track directly over the high country like that historically.  Its going to go east or west of the spine, but which?

[weathertree4u]

Heck. I'm not even sure what it does. This is the map at 120 from Tropical. The map from wxbell shows it sitting on top of Snowshoe Mountain in West Virginia at the same time.

 

Odd very odd, this may be one of those systems that modeling doesnt get a handle on until 36 - 48 hours before showtime. 

[Carvers Gap]

12z Euro.......Snow axis runs from SE Mizzou to Cleveland. It is actually north of the Ohio river. Minus the UKMET, all models continue northwest. Think w TN might get a front end thump but everyone quickly goes to rain. Kentucky gets very little snow. Another 300 mile northwest jog. Looked to me like the low got hung-up in the arklatex and it slowed down. Looks weird, but the GFS basically did the same thing. Low tracks into middle TN then into E TN. At that point a low is over WVA and another is forming over WNC. Be interesting to hear wpc discuss it.

[John1122]

12z Euro.......Snow axis runs from SE Mizzou to Cleveland. It is actually north of the Ohio river. Minus the UKMET, all models continue northwest. Think w TN might get a front end thump but everyone quickly goes to rain. Kentucky gets very little snow. Another 300 mile northwest jog. Looked to me like the low got hung-up in the arklatex and it slowed down. Looks weird, but the GFS a basically did the same thing. Low tracks into middle TN then into E TN. At that point a low is over WVA and another is forming over WNC. Be interesting to hear wpc discuss it.

 

I guess my hope for no model madness was too much. These 300 mile jogs on every run is enough to make a man drink. Not sure what's going on with the WVA vs NC primary low either. I've never seen a 997 LP with a 996 LP 150 miles away. I don't really think I've seen many systems ride the spine of the Apps either but maybe it will.

[John1122]

The Euro may have corrected properly with how quickly it shot precip out ahead of the system. WPC took it entirely out of it's forecast package last night. 

 

It based its forecast on the EPS mostly with the GFS mixed in, said the EPS was handling the system the best right now.

[weathertree4u]

I guess my hope for no model madness was too much. These 300 mile jogs on every run is enough to make a man drink. Not sure what's going on with the WVA vs NC primary low either. I've never seen a 997 LP with a 996 LP 150 miles away. I don't really think I've seen many systems ride the spine of the Apps either but maybe it will.

There has to be an atmospheric reason why modeling continues to shift with each run we are just not seeing it yet.

[ShawnEastTN]

The next couple of major runs 0Z and 12Z tomorrow will be critical.

[Carvers Gap]

Several good mets really like the Ohio River track.  Seems to me when you see the energy dig just a shade too far into the Arklatex...the energy slows down and strengthens.  That forms a strong low and it ejects into the TN Valley.  Really need the energy to keep moving in that area.  Not sure if it is a feed back error, but I have definitely seen storms dig like that while sending out overrunning moisture.  Then, finally the whole system kicks out.  Normally don't see that happen w/ the northern stream, but w/ something coming out of the southwest.  The snowfall map looks like a "V."  Highly doubt that verifies.  It may go to the Ohio, but that was one strange run.  It really seems like the Euro is stuck w/ one foot in and one foot out when it comes to the track.  I full expect to see two groupings of lows.  The UKMET gives me some hope.  But the Canadian and GFS all shifted northwest a bit.  Models all winter have underestimated the southern stream when it gets involved and have overestimated the cold.  If indeed some variation of that verifies, that is a result of the Nino.  If tonight's model runs go to the Ohio, might be ballgame.  Seems like the 12z suite really wanted to go to the Ohio River solution w/ many of the models having trouble getting the energy around the corner.  Still, at this time...I lean towards a Miller A, but barely.

[John1122]

Several good mets really like the Ohio River track.  Seems to me when you see the energy dig just a shade too far into the Arklatex...the energy slows down and strengthens.  That forms a strong low and it ejects into the TN Valley.  Really need the energy to keep moving in that area.  Not sure if it is a feed back error, but I have definitely seen storms dig like that while sending out overrunning moisture.  Then, finally the whole system kicks out.  Normally don't see that happen w/ the northern stream, but w/ something coming out of the southwest.  The snowfall map looks like a "V."  Highly doubt that verifies.  It may go to the Ohio, but that was one strange run.  It really seems like the Euro is stuck w/ one foot in and one foot out when it comes to the track.  I full expect to see two groupings of lows.  The UKMET gives me some hope.  But the Canadian and GFS all shifted northwest a bit.  Models all winter have underestimated the southern stream when it gets involved and have overestimated the cold.  If indeed some variation of that verifies, that is a result of the Nino.  If tonight's model runs go to the Ohio, might be ballgame.  Seems like the 12z suite really wanted to go to the Ohio River solution w/ many of the models having trouble getting the energy around the corner.  Still, at this time...I lean towards a Miller A, but barely.

 

 

The odd thing is the OP runs keep being on the Northern edge of their ensembles. The Euro has been especially bad with that during the last couple of days and the GFS is too. The Canadian was also well north of it's ensembles at 12z. WPC keeps saying that any track west of the Apps doesn't add up and that models trying to cut west are too quick in trying to move the Arctic airmass out. They mention that is often a bias on every model suite.

[Stovepipe]

12z GGEM ensemble mean:

 

[John1122]

I'd say we might get this one nailed down by Saturday with the current model waffling. 

 

I am going to really really hope for the 00z type solutions from last night but getting historical level snows are rare and those would be historical in many areas. 

 

Right now I'm going to guess the Ohio River track is closer to reality and hope we can get a front end few inches due to stubborn Arctic air.

[1234snow]

This run was a big hit to our snow chances. Not a nail in the coffin by any means but it wasn't good. I knew by looking at the 500mb maps first it wasn't going to be hot. I would like to say that these warmer and northwest runs are bogus but I have an increasing feeling they will be right. I just don't see anything in the NE and up into Canada to block this and keep it on a preferred track thru Georgia, South Carolina, and North Carolina. The front running energy separating and running into the Great Lakes is not good for us. But there is not much confluence to stop that either. There is some confluence there but that energy that runs into the Lakes shunts it out quickly. There are going to have to be some big changes for us. I think we need to be rooting for a quicker arrival of the precip and the storm in general. The longer the low hangs back the easier it will be for the cold air to say adiós amigos.

[Carvers Gap]

This run was a big hit to our snow chances. Not a nail in the coffin by any means but it wasn't good. I knew by looking at the 500mb maps first it wasn't going to be hot. I would like to say that these warmer and northwest runs are bogus but I have an increasing feeling they will be right. I just don't see anything in the NE and up into Canada to block this and keep it on a preferred track thru Georgia, South Carolina, and North Carolina. The front running energy separating and running into the Great Lakes is not good for us. But there is not much confluence to stop that either. There is some confluence there but that energy that runs into the Lakes shunts it out quickly. There are going to have to be some big changes for us. I think we need to be rooting for a quicker arrival of the precip and the storm in general. The longer the low hangs back the easier it will be for the cold air to say adiós amigos.

 

That is the key.  I am trying to see why that low does not keep motoring right along.  Now, we have all seen overrunning events where the main low doesn't kick-out right off the bat, but that usually happens w/ energy originating from the southwest.  The energy "should' swing right through the trough, down through the deep South, and up through the Piedmont.  But that little hesitation in the Arklatex...when the energy "pauses" there, the low has almost always cut.  When it slides smoothly through that region, it puts the snow axis over the Apps.  Almost like a three to six hour hesitation.  That is all it needs to strengthen and then cut.  But really the models are not that far off.  It is the angle that exaggerates the problem much like a hurricane making landfall at an angle.  Just many more options when things are approaching at an angle.

[Carvers Gap]

The odd thing is the OP runs keep being on the Northern edge of their ensembles. The Euro has been especially bad with that during the last couple of days and the GFS is too. The Canadian was also well north of it's ensembles at 12z. WPC keeps saying that any track west of the Apps doesn't add up and that models trying to cut west are too quick in trying to move the Arctic airmass out. They mention that is often a bias on every model suite.

 

Head scratcher for sure.  But overall, the 12z trends have been northwest by 50 miles or 500 miles depending on the model.  The ensembles will tell the story. 

[franklin NCwx]

I posted in the se forum about the Gfs ensemble mean being faster than the op is something you don't see too often. At hour 120 the gefs is closer to the ukie than the Gfs.

[Carvers Gap]

I posted in the se forum about the Gfs ensemble mean being faster than the op is something you don't see too often. At hour 120 the gefs is closer to the ukie than the Gfs.

 

You have a gefs clown map?

[franklin NCwx]

You have a gefs clown map?

Just the individuals. I did see the 6z para ensemble mean and it's south of i-20 to a 95 runner. Good track.

[John1122]

You have a gefs clown map?

The 12z mean is much more snowy that the 12z op. 17 of the 20 members are more snowy than the OP.

 

The mean is 2-3 inches for most of Middle Tennessee and the Central and Southern Valley, 4-5 for the Plateau and northern tier over to NE Tn, 6+ in SWVA. 1.5 or less in Northern Alabama and West Tennessee

[Carvers Gap]

Just the individuals. I did see the 6z para ensemble mean and it's south of i-20 to a 95 runner. Good track.gefs_snow_ens_east_26.png

 

Thanks, franklin.  Not sure what happened w/ the Euro.  Most other models(to varying degrees) support an inland runner like the GEFS.

[franklin NCwx]

The 12z mean is much more snowy that the 12z op. 17 of the 20 members are more snowy than the OP.

The mean is 2-3 inches for most of Middle Tennessee and the Central and Southern Valley, 4-5 for the Plateau and northern tier over to NE Tn, 6+ in SWVA. 1.5 or less in Northern Alabama and West Tennessee

what's the mean have for sw NC? Is it snowier than the 6z?

[John1122]

The EPS and control are looking far far superior to the OP.

[John1122]

EPS mean is similar to the 00z EPS mean, heaviest snow between 40 in Tennessee and 64 in Kentucky 4-5 inch average in those areas. EPS control has  it's major snow axis from Nashville to Lexington. 6+ for most of middle Tennessee with some 10+ areas. 4-6 other areas.

[John1122]

Eyeballing the main cluster of lows, looks like the mean track is similar to the Canadian 12z track.

[John1122]

what's the mean have for sw NC? Is it snowier than the 6z?

The mean actually does look more snowy at 12z than it did at 6z for SWNC.  Looks like 4-7 for that area.

[Jed33]

Thanks John. You are right on top of this one buddy! Appreciate the updates! EPS sounds a lot like the other ensembles. Probably still wise at this point to use the ensembles for more weight than the ops

[Runman292]

Here's MRX's AFD:

BEGINNING SUNDAY EVENING MODELS

BRINGING ANOTHER SYSTEM INTO THE TN VALLEY SUNDAY NIGHT AND EARLY

MONDAY FROM THE NW WITH LIGHT SNOW THEN A MUCH STRONGER SYSTEM

APPROACHING FROM THE WEST AND SOUTH LATE MONDAY AND MONDAY NIGHT

THROUGH TUESDAY. THE FORECAST FOR THIS PERIOD IS STILL UNCERTAIN AS

THEIR ARE MODEL DIFFERENCES IN TIMING...THE VERTICAL TEMPERATURE

PROFILE...AND PRECIPITATION TYPE AND DURATION FOR THIS EVENT.

MODELS GENERALLY SHOW THE PRECIPITATION STARTING AS ALL SNOW WITH

THE FIRST WEAK SYSTEM SUNDAY NIGHT INTO EARLY MONDAY...FOLLOWED BY

WARMING TEMPERATURES MONDAY SO THAT THE SNOW CHANGES OVER TO RAIN

OVER MUCH OF THE AREA. THEN AS THE SYSTEM DEEPENS AND MOVES NE

MONDAY NIGHT AND TUESDAY CHANGES BACK TO ALL SNOW SOMETIME BETWEEN

MONDAY NIGHT AND TUESDAY NIGHT. THERE STILL LOOKS LIKE A POTENTIAL

FOR MIXED PRECIPITATION MONDAY DEPENDING ON THE TRACK OF THE SYSTEM.

THE ECMWF...CANADIAN AND GFS ALL SHOW A SURFACE LOW OVER THE LOWER

MS VALLEY MONDAY THAT MOVES EAST ACROSS THE SOUTHEAST STATES TO NEAR

OR JUST SOUTH OF THE FORECAST AREA BY LATE MONDAY NIGHT OR JUST EAST

OF THE APPALACHIANS TUESDAY MORNING AND DEEPENS BEFORE MOVING NE

ALONG THE ATLANTIC COAST TUESDAY. THE STRENGTH AND TRACK OF THIS

SYSTEM WILL GREATLY INFLUENCE THE AMOUNT OF WARMING AND

PRECIPITATION TYPES MONDAY THROUGH TUESDAY. AS COLDER AIR WORKS IN

TUESDAY INTO WEDNESDAY MORE SNOWFALL IS LIKELY. ESPECIALLY MOUNTAINS

AND NORTHEAST. HAVE KEPT LOWS AND HIGHS BELOW GUIDANCE FOR MONDAY

THROUGH WEDNESDAY BUT CURRENT FORECAST MAY NOT BE LOW ENOUGH.

PLEASE STAY WEATHER AWARE THIS WEEKEND...AND MONITOR THE LATEST

FORECAST INFORMATION FROM THE NATIONAL WEATHER SERVICE REGARDING

THIS STORM SYSTEM...ESPECAILLY IF YOU HAVE TRAVEL PLANS!

[John1122]

MRX AFD was understandably vague. Hard to comment on any exact details with so much uncertainty. Keep in mind the wave that will cause this is not too far from Japan right now.

[John1122]

Basically all of East Tennessee/SE KY/SWVA are in the WPC 50-70% chance of greater than .25 frozen for day 4. That's pretty high for that far out.

[Vol Man]

John, do you think the little system tonight and tomorrow is affecting any of the models? Its just seemed to strengthen a little over the last 24 hours or so....

[franklin NCwx]

12z Gfs para is closer to the ukie