December 2020 Medium/Long Term Pattern Discussion.

[tnweathernut]

2 minutes ago, Carvers Gap said:

0z GFS is rolling....probably still going to see 2-3 more runs of volatility and then see models begin to lock-in by early Saturday.  

I’m just mainly looking for trends at 500.  Feels good to be back tracking something with the crew.......

[Carvers Gap]

Out to 90.  Does not look like a consolidated slp coming out of the GOM.  Looks like energy transfer will happen at some point.  

[Carvers Gap]

Stronger slp out to 108 which pulls everything just a bit west compared to 18z.

[Carvers Gap]

Is also a bit faster with a sharper gradient.  Snow showers in place by 114 over middle TN. 

[Carvers Gap]

Gonna be a decent upslope event for NW facing slopes if this were to verify.

[tnweathernut]

There is more interaction between the northern branch and southern branch, and with that “dance” a further west solution.

[Carvers Gap]

That storm is sub 990.  Whew.

[tnweathernut]

Just now, Carvers Gap said:

That storm is sub 990.  Whew.

Crazy.  Looks like 1950 all over again, just a bit further north...

[Carvers Gap]

Going to leave some room potentially for the next storm to come north - if there is more separation due to quicker speeds of storm one(assuming storm two has not also sped up.).

[Carvers Gap]

Just now, tnweathernut said:

Crazy.  Looks like 1950 all over again, just a bit further north...

And with a storm potentially that big, I bet things are not worked out quite yet.  Going to depend on the all important timing of the phase.

[Carvers Gap]

Man, just crazy to see a storm sit there at that strength and spin nearly in the same place for a couple of time intervals.

[tnweathernut]

Mountain snows would be huge if this plays out as shown on the 0z GFS.

[tnweathernut]

The next piece of energy is robust, but not much separation at 150.  Let’s see how the monster vortex in the eastern US tangos with that piece...

[Carvers Gap]

Storm is stuck in Ohio.  Entered at 123 and still there at 153.  That stall is reducing separation.  Might force that next system way down there.

[tnweathernut]

3 minutes ago, Carvers Gap said:

Storm is stuck in Ohio.  Entered at 123 and still there at 153.  That stall is reducing separation.  Might force that next system way down there.

System in the southwest stays closed and almost stationary as if to say........  woah, good buddy just do your thing.  I’ll hang out here for a while”

[Carvers Gap]

IMHO, the GFS is having issues with steering currents under that big block.  Have to think the next run is going to be fairly different.  

[Carvers Gap]

Well, the 0z Canadian and GFS just go hog wild with all kinds of slp solutions for storm 2.  

[Carvers Gap]

At 306 in fantasy land, that is just a massive PNA ridge, goes well north of Alaska.

[John1122]

The Canadian just destroyed Arkansas and West Tennessee that run on wave 2. I imagine our western Valley folks would cash in on that 10-12 inch event for the whole winter. 

[Carvers Gap]

So, overnight runs weren't great...but then arrives the 6z GEFS.  The slp members are east of the 0z run.  Thus, the mean has increased compared to 0z.  The EPS is basically has the system run the spine of the Apps.  The 6z GEFS is east of that track in western North Carolina.

[Carvers Gap]

Check that...the western edge of central NC.  Probably 100-150 jog eastward.  

[Carvers Gap]

The 6z GEFS is a rain changing to snow for parts of E TN, SE KY, and SW VA.  That is a big move.  Let's see if other modeling follows suit.

[Holston_River_Rambler]

Overnight Euro jumped west again. Looks a lot like the UKMET has for the past couple of days. 6z GFS now looks more like the Euro did yesterday. 

The UKMET, which has been pretty steady the past few days with a cutter over Nashville has now, you guessed it, become the most easterly of the OPs with its depiction of the surface low (shown below for dramatic effect, lol) 

 

 

The UKMET has the northern stream system is slower, so the cold air is late to the party

Not sure how the UKMET does when streams cross though. 

 

 

 

 

 

 

 

 

 

[Carvers Gap]

The 0z GEPS is also well east of both models.  Seems to me like the 6z GFS might actually be a nice compromise....Dangerous ground to stand on going against the Euro, but it well west of the other global ensembles.

[Holston_River_Rambler]

Sorry got a little carried away with gifs on that one and forgot to add that the EPS has jumped west some, but is not as far west as the OP. This close to the day of, it may be expected that the ensembles, run off the west OP, would jump some. 

 

[Carvers Gap]

The 6z off-run of the Euro and EPS will run here in a bit...will be interesting to see the trend.   The GEFS and GEPS are now east of the Apps with their tracks.  The UKMET and Euro have a decent bias of being overly wrapped-up as we are still roughly 4 days from the event IMBY.  Good day to watch some trends.

[Carvers Gap]

The 0z GEPS is so far too the East that it that the main precip shield almost whiffs on middle TN.  

[Holston_River_Rambler]

 

Here are the GEFS member lows for comparison to the EPS above:

 

[Carvers Gap]

Decent jump SE of the axis of precip now on the 6z ICON when compared to 0z.

[Carvers Gap]

Can see the same slip eastward of the precip axis in the Midwest with the 6z GEFS compared to its 0z run.  Looks like the NW jog on those models has halted.  Are they right?  No idea.