December 2020 Medium/Long Term Pattern Discussion.

[Carvers Gap]

Looking out in time a bit.  I really like the GFS extended that has been added to WxBell's model suite.  Basically it show the pattern degrade around mid-month, relax for about ten days, and then return....huge grain of salt at that range please.    Was looking at teleconnections this morning, the general gist is that the AO and NAO are going to be slightly negative with the EPO going slightly negative - all of that varies slightly depending on model and run.  Going to be interesting as the MJO has trended towards a warm(weak) phase look.  Is the MJO going to camp out in those phases or move quickly around and/or will weak(but favorable teleconnections) balance out any MJO mischief.  Makes me think that the base pattern will still have a Nina look, but that cold may well move eastward from time to time, and thus, give us some chances.  Lots of uncertainty right after Christmas as one might expect...but sort of we didn't expect uncertainty as I pretty much felt like January was going to be warm - not nearly as much of a certainty as once thought.

[Carvers Gap]

On a quieter(less newsworthy note),  the 12z GEFS(post 300h) is not looking warm.

[Carvers Gap]

12z GEFS d11-16 (5) day mean at 500 so TIFWIW.  I like the -EPO which is showing up.  We are going to need something to counter the upcoming MJO convection in warm phase regions(hoping it is low amplitude and fast if it goes into warm phases).  Definitely a possibility this pattern(shown below) retrogrades/trends into the West as the EPO slips a bit westward off the coast of western NA.  Scandinavian Ridge connecting ever so slightly with the EPO.  That should open up the gates for cold air to head into the Lower 48.  Huge caveat...this is basically what was shown during November that headed into the West - occurred twice.  The MJO is a thorn here, but there are times when we do overcome the unfavorable MJO phases with a pattern similar to this if memory serves me correctly.  Maybe the winter of 14-15?  One of those went through the warm tour and it stayed cold.  Anyway, just worth a look.  Everyone knows the rules about taking LR ensemble stuff as gospel.

[John1122]

28 minutes ago, Carvers Gap said:

12z GEFS d11-16 (5) day mean at 500 so TIFWIW.  I like the -EPO which is showing up.  We are going to need something to counter the upcoming MJO convection in warm phase regions(hoping it is low amplitude and fast if it goes into warm phases).  Definitely a possibility this pattern(shown below) retrogrades/trends into the West as the EPO slips a bit westward off the coast of western NA.  Scandinavian Ridge connecting ever so slightly with the EPO.  That should open up the gates for cold air to head into the Lower 48.  Huge caveat...this is basically what was shown during November that headed into the West - occurred twice.  The MJO is a thorn here, but there are times when we do overcome the unfavorable MJO phases with a pattern similar to this if memory serves me correctly.  Maybe the winter of 14-15?  One of those went through the warm tour and it stayed cold.  Anyway, just worth a look.  Everyone knows the rules about taking LR ensemble stuff as gospel.

If we can get an EPO ridge where that one is depicted we tend to mute then MJO to a large extent. The EPO can he epic or stink though. It it's west based at all we get the SE Ridge. 

[Carvers Gap]

Just now, John1122 said:

If we can get an EPO ridge where that one is depicted we tend to mute then MJO to a large extent. The EPO can he epic or stink though. It it's west based at all we get the SE Ridge. 

Thanks, I thought I remembered that the EPO "could" mute the MJO.  Definitely both scenarios(epic or spin) in play at this range IMO...Have seen some LR modeling that retrogrades the ridge a bit too far and the SER pops.  Past 24 hours worth of model runs have looked better.  

[Carvers Gap]

12z GEPS follows suit with the GEFS d10+....still a true threat the trough could retrograde back West.  But two seasonable to cold model runs for much of the lower 48 east of the Rockies.   Been a while since I have seen a full latitude trough verify during winter...so I am always suspect.  That said, better than staring at what we did during much of this month(November).

[John1122]

1 hour ago, Carvers Gap said:

Thanks, I thought I remembered that the EPO "could" mute the MJO.  Definitely both scenarios(epic or spin) in play at this range IMO...Have seen some LR modeling that retrogrades the ridge a bit too far and the SER pops.  Past 24 hours worth of model runs have looked better.  

I think it was February 2015 when the EPO drove us into Polar Vortex land and it just blasted MJO, +NAO and all that into near meaninglessness. 

[Daniel Boone]

Feb. 2015 was epic and was going against the grain, so to speak.

[nrgjeff]

Took last week off and totally checked out. I'm so far behind in this thread that it's hopeless. However I guess that's a good thing if the pattern is worth discussing.

ECMWF weeklies followed the CFS with now a third cold week, counting this week, week 2 and week 3. Now we are in -ABNA with some +PNA which is cold. 

MJO is in a decent phase. While we have a week TC attempt near Sri Lanka in the Indian Ocean, the vast majority of convection is in colder phases of the West Pac.

[Carvers Gap]

15 hours ago, nrgjeff said:

Took last week off and totally checked out. I'm so far behind in this thread that it's hopeless. However I guess that's a good thing if the pattern is worth discussing.

ECMWF weeklies followed the CFS with now a third cold week, counting this week, week 2 and week 3. Now we are in -ABNA with some +PNA which is cold. 

MJO is in a decent phase. While we have a week TC attempt near Sri Lanka in the Indian Ocean, the vast majority of convection is in colder phases of the West Pac.

Thanks for the update and welcome back!   Hope you had some great time off.  We are busy switching our running gear from summer to winter.  LOL.  

[TellicoWx]

Think our middle TN folks would call it winter complete with that 00z GFS run for the end of the week lol..

[Holston_River_Rambler]

Out in fantasy land the Euro looked interesting days 8 - 10:

Not a lot of cold air around, so we would probably be waiting on a the N. stream to catch up to the southern one, even though the s. stream energy takes a sweet track.

0z EPS 24 hour snow plots look like scattershot, so not much agreement there for anything (though there is a little support for less than an inch around Memphis with the storm later this week). 

Long range EPS still liking the time near mid month for an even colder pattern, after a brief warm up:

Like Cravers has said, this looks very very similar to what models showed at range, this time of the year, only to turn into a trough in the SW that only slowly and inconsistently pushes east.

GEPS looks similar for a while, but in a change from some previous runs, it gets rid of EPO ridge over AK and plops a trough:

That would produce the old Pac Puke

GEFS looks like a split between the two, but leaning a little towards the GEPS:

 

In terms of MJO/ tropical convection, not much to add to what Jeff said yesterday.  So it seems a little weird that the GEFS and GEPS seem to have bit on a look that seems more MC convection based.

The EPS does see a little more suppression/ confusion for how the MJO will evolve and Ventrice's plots seem to favor more western Pac convection towards week 3 (EPS, GEFS, and Ventrice's OLR plots, in that order):

 

 

Actual convection doesn't really seem to reflect a big MC MJO event to me, but admittedly I have no clue what the MJO looks like on satellite, other than a mass of convection. Sure there is some convection there, but I have seen much worse. I've been watching it for a while this year and it just seems anemic each time it gets to the MC so far. Hopefully I haven't jinxed it now, lol. And there's convection out near the dateline,. Maybe the cyclone in the Bay of Bengal is messing with the ensembles depictions of how tropical convection will evolve to impact the N Hemisphere pattern? 

 

 

Apologies if I have misrepresented anything others have said. 100% not my goal. 

 

 

 

[Carvers Gap]

Don't sleep on the 0z GEM for this weekend....was close to a decent storm for the eastern valley.  Euro was just an open wave that amounted to nothing.  6z GFS was close.  More of an outside shot, but the Canadian gets a bit more weight than usual as it did decently with this last system.  I mean the 0z GFS as @TellicoWx mentioned, was decent for middle TN.  Last year, we kind of didn't have enough cold with the HB block.  This year, we have barely enough, but as last night shows...the cold doesn't have to be overwhelming to get snow.  Right now, only the Euro(and that is an important piece) is without a snow solution for someone in the TN Valley forum area.

In the LR, definitely a pattern breakdown on the 0z GEPS and 6z GEFS at 500.  The 0z EPS is pretty solid.  Basically modeling is calling for that really deep trough mid-month to lift into Alaska.  Plenty of option on the table which also include and EPO in that area.  Right now, I would lean towards that trough lifting out for the last third of the month, but am not confident in that at all.  I do think there is potential for cold/snow to return in January(if it indeed leaves).  The Cansips this AM has flipped to a cold SE for DEC.  It pulls the cold back in January, but based on its 500 look...seems like their is room for cold to move out of the Rockies into the SE...

[Holston_River_Rambler]

For us strat junkies, despite the wxtwitterverse occasionally seeing something to get excited about, I'm not seeing much yet, but there are some perturbations (as they say in the old country) toward 50mb. But up at the top, the SPV looks pretty stout (gif shows heights at 50 mb, but ends on heights at 10 mb):

 

Lawrence's 3D vortex reflects that:

 

[Holston_River_Rambler]

3 minutes ago, Carvers Gap said:

Don't sleep on the 0z GEM for this weekend....was close to a decent storm for the eastern valley.

Yeah, this made me decide to go look at the UKMET.....and......:

 

not an awful look at all

[Carvers Gap]

2 hours ago, Holston_River_Rambler said:

Yeah, this made me decide to go look at the UKMET.....and......:

 

not an awful look at all

Just watching the 12z GFS out to 90, very similar set-up to the UKMET from this AM.

[Carvers Gap]

Sure enough, by 102 the GFS has decent snow in SE KY and SW VA - think that is Boone's local.  Would not surprise me to see that solution become a bit more robust in terms of scope.

[Carvers Gap]

Basically seeing the 12z ICON and 12z GFS develop a low on the front and bring a system NNE from the Panhandle of Florida.  Has the potential to be a really big interior NE snowstorm(northeast of here), but will be interesting if someone can get enough marginal, cold air to wrap into the storm to get some snow early in its development.

[Carvers Gap]

Interestingly, both the GFS and ICOn both wrap bring some light snow showers after that system departs.  

[Carvers Gap]

12z GEM takes a fairly organized SLP from the panhandle.  Snow is middle TN at 102.  Even though that has marginal cold, that track will work - especially if that system is that organized.  Trending towards something that needs to be watched closely.

[Carvers Gap]

I am generally suspicious of systems following up a previous system with a similar look...but the set-up is eerily similar to yesterday.

[Carvers Gap]

Regarding the 12z suite....That is now the ICON, GFS, and now GEM with systems coming out of the GOM just after hour 84.  Again, cold source is lacking...but that track (SE to NE) can be snow in the NW quadrant at this time of year.  

[Holston_River_Rambler]

12z UKMET is in:

 

[Carvers Gap]

Euro is a big change towards a halfway consolidated low in the Piedmont.  EPS concurs.  Nice 12z suite.  

[Carvers Gap]

Also beginning to see the pattern breakdown late in week 3 on both the EPS and GEPS with the trough lifting towards Alaska and the SER waiting in the winds as the EPO retrogrades into the Aleutians.  Long way off and that could change, but is a very persistent signal on modeling and Weeklies runs.

[Holston_River_Rambler]

NAM is trying to do some kind of odd ball, last minute phase on the weekend storm:

 

[Carvers Gap]

I know I sound like a broken record, but there is a load of energy about to come together this weekend on the EC.

[Carvers Gap]

D14+...Just looking at the MJO, that is some weak sauce stuff.  Maybe it trends stronger like last year, but it can barely get out of the COD.  And it looks like modeling wants to get it into cooler phases quickly if it goes into the warmer phases at some point - which looks low amplitude at this point.  Might be tough to get this trough out of the East...maybe we get the pattern where the cold extends from western Canada and into the nation's mid-section with bouts of cold in the East.  Primary storm track is a cutter into the Ohio Valley with secondary up the coast?  Are we going to go with a "Dec 1989 Lite" look with a flip to warmth for the rest of winter or maybe a "95-95 Lite" look?  I have no idea.  The ensembles in the LR seem sort of split on the matter.  Those are cold maps around d10+ off the top of my head.  Been a long time since we have seen a full latitude trough...of course we could just go zonal.

Until then, we might have some more things to track for the next 2.5 - 3 weeks.

[Holston_River_Rambler]

RGEM out to hour 84 verbatim would be a heart breaker, but I suspect, if this were to verify, there might be more fun after hour 84:

 

 

[Carvers Gap]

37 minutes ago, Holston_River_Rambler said:

RGEM out to hour 84 verbatim would be a heart breaker, but I suspect, if this were to verify, there might be more fun after hour 84:

 

 

Whole lot of energy running around on that map.   Looks like a phase just east of the area to quote a good friend.  That said, the trough over TN is about to go negative tilt.   As we learned with this last storm, phases are finesse deals.  Most modeling just "figured out" today that a storm was possible.  Have to think no solution is locked in...  That said, I would be feeling pretty good in the NE with that look.  We really need to be pulling for that energy to go neg tilt slightly earlier.  The 18z GFS was well west of the RGEM and is on the others side of the envelope.  Kind of like being in the middle of two solutions at this point.  LOL.  Great share.  Illustrates the complexity and coolness of following winter storms.  Bunch of 1s and 0s make a pretty neat map and solution.