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

[Matthew70]

9 minutes ago, John1122 said:

GFS still honking wide spread frozen events over the next week. Basically the entire forum will see some kind of frozen precip over the next 7-8 days and the cold will be stiff. At one point there's snow falling with Temps in the upper single digits and low 10s. Exactly where will not likely be determined until it's falling. Especially the freezing rain/sleet possibilities. But the cold is almost always further south and east than modeling indicates when they happen. 

When does it start for middle TN?  Is the snow dome staying strong?

[Matthew70]

1 minute ago, John1122 said:

Long duration and slow buildup is the worst case scenario. 

I take it rest of state is in cold rain while that happens?

[John1122]

1 minute ago, Matthew70 said:

I take it rest of state is in cold rain while that happens?

Actually fairly warm rain. It's a very sharp divide on either side of the front. 

[Matthew70]

Just now, John1122 said:

Actually fairly warm rain. It's a very sharp divide on either side of the front. 

Appreciate.  Flooding rains in order possibly. From all indications the pattern flips to warm solidly in couple weeks.  After another disappointing minor snow events I am ready. 

[John1122]

The snow and ice lines will move back and forth and likely won't be known until within 24-48 hours if even then. But there's a lot of cold and a lot of precip flying around over the next 10-14 days. 

[John1122]

2 minutes ago, Matthew70 said:

Appreciate.  Flooding rains in order possibly. From all indications the pattern flips to warm solidly in couple weeks.  After another disappointing minor snow events I am ready. 

 

If the GFS comes to pass we may all be ready. Still has highs in the single digits and teens and lows below 0 for many in the region for days on end.  

[Matthew70]

2 minutes ago, John1122 said:

The snow and ice lines will move back and forth and likely won't be known until within 24-48 hours if even then. But there's a lot of cold and a lot of precip flying around over the next 10-14 days. 

Well looks like Nashville and Chatty get the middle finger lol.  

[John1122]

2 minutes ago, Matthew70 said:

Well looks like Nashville and Chatty get the middle finger lol.  

Possibly, but to me that just shows the potential of the pattern being modeled. The exact snow amounts and ice amounts and locations are a long way from being known. That said, both get 3-5 inches from that run. I doubt anyone would turn it down!

[Matthew70]

I feel sorry for the forecasters this week.  Sheesh.  The GEFS mean seems to be trending colder again.  Now most of state is in more ice.  What a cluster to try and forecast.

[BNAwx]

27 minutes ago, Matthew70 said:

Well looks like Nashville and Chatty get the middle finger lol.  

It’s always possible but take these outputs with a grain of salt.  It’s simply going to depend where the arctic boundary sets up shop.  Ice for someone is almost a given.  Models will struggle until we get much closer.

[John1122]

The Euro and GFS remain on separate planets regarding the upcoming cold or no cold. One will have to flinch soon. The GFS move to cold begins in less than a week. 

[John1122]

The 06z GFS is insane. 

 

[weathertree4u]

34 minutes ago, John1122 said:

The 06z GFS is insane. 

 

That is not good. That would cause serious hardship for days across the region 

[Looking to the skies]

Those same signals were here on the Gulf coast  less than 36 hours ago. That is how far the cold has been shoved back and warmth pushed up per models thinking. 
 
How many times will this continue? Models sgnal an Arctic outbreak then poof it is magically gone or shoved so far back north it should be counted as their Normal winters

[Shocker0]

2 minutes ago, Looking to the skies said:

Those same signals were here on the Gulf coast  less than 36 hours ago. That is how far the cold has been shoved back and warmth pushed up per models thinking. 
 
How many times will this continue? Models sgnal an Arctic outbreak then poof it is magically gone or shoved so far back north it should be counted as their Normal winters

Yeah it is crazy. Eventually it's gonna be pushed back so far that the "cold" will finally arrive in June when it's way too late. 

[Holston_River_Rambler]

 

Regarding the Euro's  depiction of the arctic front, here are some gifs that compare the new parallel Euro (left) to the current operational Euro. 2m temps/ 24 hour snowfall/ MSLP (no 500 mb charts available for the para). Looks like the parallel is a compromise between the far western Euro solution and the more easterly GFS 

 

 

 

  

 

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[Kentucky]

3 hours ago, John1122 said:

The 06z GFS is insane. 

 

Suppose I'll go ahead and that generator ready today.

[Carvers Gap]

I don't think the Euro is modeling this front well.  I see some posts on other forums where Arctic air is often modeled too quickly and overdone.  Indeed, that is often the case, and I don't disagree.  However, there are times(because cold air is relatively low to the ground) that modeling misses the southerly extent of the cold air.  Ditto to BNA above in saying that modeling is struggling with the Arctic front.  When models can't reach consensus 12 hours from now, they don't have the late week pattern nailed down either IMO.  The pattern has the potential to support a big overrunning event.  I am just going with prior knowledge and not modeling...there should be an event.  It is going to depend on whether the cold gets hung up on the Plateau(very plausible) OR seeps into the eastern valley and banks against the west slopes of the Apps.  So, my guess is that western forum areas get hit with 1-2 ice/snow/mix systems(one significant) and then the from presses east towards the eastern valley.  I think the 6z GFS may be on to something.  Now the really question for me is whether a system remains to run the cold when it moves into the eastern valley.  So for now, I am not swaying with model runs...just think this has a reasonable chance of occurring.  We spotted this evening's system a couple of weeks ago by recognizing the pattern and knowing that a storm was possible.  That doesn't mean we get snow tonight BTW, but it has been something to track and the NWS has issued winter weather products for various locations.  

[Carvers Gap]

That is no knock on the Euro BTW.  It is a fantastic model, but it is shoulder season time, and that model is very mortal when seasons begin to change.  All modeling is bouncing all over the place right now with this boundary and even with this current storm.  I don't really have a "go to" model at this point.  I think we are just going to have to rely on pattern recognition for a while.  So, the real answer I am going to be looking for is the how strong the cold front will be later this week, its speed, and location.  In other words, we needs its vector...victor.

[Carvers Gap]

Kind of an interesting test today....the NCEP/MJO plots show the MJO heading for 8 or COD just under the 8 plot(meaning background phases of MJO are cold).  Let's see if modeling follows suit today.

[Carvers Gap]

The 16 day run of the 6z GFS.  It is going to be the zero or the hero. LOL.   Of course the Euro had something similar as well just a few days ago.  Of course, a lot of this is ice - so be sure to make that distinction. That would be a really big pattern for this entire subform.  This is the potential for the pattern if the cold presses like the 6z GFS had.

 

 

[Carvers Gap]

9 hours ago, BNAwx said:

It’s always possible but take these outputs with a grain of salt.  It’s simply going to depend where the arctic boundary sets up shop.  Ice for someone is almost a given.  Models will struggle until we get much closer.

Worth saying about 1000x.

[Bigbald]

Will the cold front push through the plateau is my big question.  It seems like recent modeling is hanging it up on the rim and creating that diagonal axis that gives the west, KY, etc.  

[Carvers Gap]

4 minutes ago, Bigbald said:

Will the cold front push through the plateau is my big question.  It seems like recent modeling is hanging it up on the rim and creating that diagonal axis that gives the west, KY, etc.  

Very realistic and has occurred many times in the past....my guess it that is does bank against the Plateau(if the cold indeed pushes that far).  Then a couple of fronts will likely press it onward.  But the setup on modeling is a classic old school set-up for ice in western sub-forum areas.  Used to happen like that when I was a kid and lived in Knoxville(70s). I share this often, but I used to think our cold came from due West, because Memphis was always coldest first w/ ice.

[Daniel Boone]

Mjo I think could be the clear answer here as far as how far the Arctic Front pushed. Problem is, will it have enough umph due to its Amp.

[Carvers Gap]

For reference, here is the 6z GEFS 10 day snow map beginning on Wednesday so as to eliminate tonight's shenanigans.

[Carvers Gap]

3 minutes ago, Daniel Boone said:

Mjo I think could be the clear answer here as far as how far the Arctic Front pushed. Problem is, will it have enough umph due to its Amp.

Yeah, agree.   Need it moving towards 8 or COD and then we get enough help from the Pac to push the cold eastward.  

[Daniel Boone]

4 minutes ago, Carvers Gap said:

Yeah, agree.   Need it moving towards 8 or COD and then we get enough help from the Pac to push the cold eastward.  

It kind of looks like the Euro in particular is basically wanting to present a phase 7 pattern of sorts. Like u alluded, need that phase 8 then cod. That's what's being projected by mjo mods so, will learn GFS .

[Carvers Gap]

For comparison, here is the 0z EPS for the 10-20th.  Not a great signal but a weak signal.  That does not take into account ice I don't think.  So, one might wonder if the southern extent of that is indeed icy.  Biggest takeaway I have is how far south the extent of frozen precipitation is....

[Bigbald]

Not much discernable difference to me through 90 for 12z gfs when compared to 6z.