January 2021 Medium/Longterm Pattern Discussion.

[Daniel Boone]

1 hour ago, 1234snow said:

Certainly another sneaky system that has the chance to over-perform for us. NAM isn’t as enthused.

They all except the last system overperformed here. I'm at 17.05" for the season. Probably be about half that if most models had been right , and that within 24 hrs of events. 

[Holston_River_Rambler]

33 minutes ago, Blue Moon said:

The fickle MJO might exit its prolonged weak phase for phase 6. That isn't good, but several members forecast it heading toward the phases we like after that. I'm not sure what verdict that will have on our winter and how that might mitigate the Eastern Pacific being a bully, since I am so green at this.

 

Webb's saying that the RMMs are showing something other than a true MJO wave:

 

 

Now, is that good for us? I have no idea. I'm still not sure what the differences are between Equatorial Rossby Waves (ERs) (maybe that thingy I noted early this AM south of Baja?? which seems to have already dissipated), the "Low", or a Kelvin Wave, and the MJO. 

The MC region has a flare up again N. of the equator, though:

[Holston_River_Rambler]

The Euro stalls in 7, in its RMM depiction:

[Holston_River_Rambler]

I mentioned this in banter earlier, but looks like we're going to ride in the SSW rodeo again:

 

 

If the GFS is correct in its depiction of the MJO RMM plots/ convection/ whatever is going on, that would line up with a warming triggered over Siberia. Another High descending, another mountain torque, another jet extension, this time with a more La Ninaish N Hemisphere state (of course with a -NAO too):

 

 

Of course that is medium to long range, so it could change. 

Like Carver's said though, I am a more of a fan of how the EPS control bumps a ridge over the west coast as the Gulf of Alaska low rolls backwards over the Bering Sea

 

 

 

 

[Carvers Gap]

41 minutes ago, Holston_River_Rambler said:

I mentioned this in banter earlier, but looks like we're going to ride in the SSW rodeo again:

 

 

If the GFS is correct in its depiction of the MJO RMM plots/ convection/ whatever is going on, that would line up with a warming triggered over Siberia. Another High descending, another mountain torque, another jet extension, this time with a more La Ninaish N Hemisphere state (of course with a -NAO too):

 

 

Of course that is medium to long range, so it could change. 

Like Carver's said though, I am a more of a fan of how the EPS control bumps a ridge over the west coast as the Gulf of Alaska low rolls backwards over the Bering Sea

 

 

 

 

Saddle up.  Just remember these SE ridges that connect briefly to high latitude blocking do a number on the SPV.   Then modeling goes to crap, and we have to wait a few days for the dust to clear.  I “suspect” that recent trends towards more favorable outlooks past D10 on the EPS and GEPS are likely tied to this.  Would also likely mean the NAO is going nowhere.  Commerce model mayhem. 

[Carvers Gap]

The 12z GEPS at 500 past d10 is a beauty.

[Icy Hot]

18 minutes ago, Carvers Gap said:

The 12z GEPS at 500 past d10 is a beauty.

Sounds a lot like last year. The cold was always 7-10 days away. :( Maybe it will finally happen.

[Holston_River_Rambler]

IMO If we can just keep the flooding away at this point, it's a win. 

[Holston_River_Rambler]

18z Euro for NE sections:

 

 

 

[Carvers Gap]

2 hours ago, Icy Hot said:

Sounds a lot like last year. The cold was always 7-10 days away. Maybe it will finally happen.

Nah.  Definitely is much different than last year.  We have had a lot more snow in our area.  We have a -NAO.  Pacific like last year is not cooperating.  Atlantic is nearly perfect.   I am not a fan of the SSW stuff.   I feel like that works for us sometimes.  This year, those SSWs fouled what was a good pattern.   Honestly, this year I didn't expect much.  Think my winter forecast is in the winter spec thread.  I normally don't bang my own drum, but was pretty clear that we would have long pauses between events.  Moderate Ninas are a pain.  Now, do I think we eventually get some more cold?  Sure.  I will try to link that forecast here.  Give me just a sec.... 

[Carvers Gap]

I think you all need to dig back through the winter spec thread.  Lots of great thoughts there by many posters! I think most of us were super clear about the difficulties of moderate Nina winters.  I don't always get a seasonal forecast correct, but this has worked out pretty well so far regarding temp and pattern stuff.  Precip idea is too dry.  Those ideas were posted during June.  Here are some excerpts.  Can't say you weren't warned well in advance...

"Best chances for snow will occur late November into early January.  Expecting a big thaw in January this year, BUT I do think we see bouts of serious cold this winter despite my AN temps forecast.  I was really bullish at the end of last winter regarding the upcoming winter being a dud.  And it may well be.  Strong to moderate La Nina's are generally a non-starter IMBY.  The good news, as I have stated before, is that we really need the Pacific to cool down some, and it has been some time since we have seen a strong La Nina.  Winters that have followed strong La Ninas can be pretty good in MBY, so I will suffer through a strong Nina event if need be this winter..."

"....As for snow, everybody wants to know how much we are going to get.  The answer is that it is absolutely impossible to know.  I think our best chances will be early.  After that, one would think that January and February will provide some very long timeframes between chances.  That said, it just "seems" the weather pattern from the past two years right is switching up. We are out of shoulder season which fooled me into thinking the pattern had broken early last winter(the pattern being a little pocket trough forming ad nauseam over the Mountain West in the front range).  With some big heat already being felt in the Mountain West and a transient ridge reforming every few weeks there...makes me think we are seeing a transition.  So, I am less negative about the upcoming winter.  My gut says it will be better than I describe above, but my brain says to beware of moderate to strong Nina patterns - they are generally hostile to winter in the SE.  So, I will go with BN snowfall, but maybe closer to normal than many will forecast, but better than last winter.  Short and sweet with no graphics."

 

 

[Carvers Gap]

Honestly, I have shared privately that we might have 2-3 legit windows this winter.  So far we have had one right around Christmas - maybe another minor window to begin January.  I suspect we get one more good one.  Wavelengths will shorten up during February.  I don't really sweat the "it's always at d10" stuff.  We all know how that works.   And again, when we are talking about the MJO, usually the pattern is not good.  

[Carvers Gap]

The last two times we have seen significant cold predicted(and did not occur) was for early Jan and now late January.   Those two "busts" by modeling are likely (but not totally) attributed to SSW events that have thrown off modeling which occurred during those time frames.  The good thing is that we still had chances as modeling eventually trended back to a moderated cold shot.  I suspect we see this again.

[Holston_River_Rambler]

To be fair:

On 11/15/2020 at 2:39 PM, nrgjeff said:

Let's go a head and issue a Slight Risk for Grumpy Bunch of Posters. Upside is Moderate but maybe we can still salvage basketball.

Actually the ensembles are Enhanced Risk already. 

We gonna upgrade to "Moderate Grump" and issue a product to boost morale:

 

...GRUMPY POSTER WARNING IN EFFECT FROM NOW UNTIL FEB !4
* WHAT...Grump expected. Total grump accumulations of 1 to 3
  grumps, with locally higher amounts possible.

* WHERE...,TN Valley locations

* WHEN...From NOW until FEB 14

* IMPACTS...Plan on slippery models and flooding potential on the ensembles

* ADDITIONAL DETAILS...Grump will be heaviest during the 6z runs through SREFs at 1445 UTC. Grump may melt and
  refreeze on happy hour runs, which may cause sad/ happy spots.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while looking past 7 - 10 days on models, especially the KMA and ICON.

The latest model conditions for the region please see Tropical Tidbits snow maps (10:1 only)

[John1122]

Currently at 31 with blues popping up on the radar to the west of me.  Hopefully I can pull off a little bit of front end snow. 

[John1122]

Not sure how long it will last. But it's snowing. 

[John1122]

Now very heavy sleet mixed with snow. I expect to hit rain before too long. Temp is up to 33. 

[Holston_River_Rambler]

GEPS still looks good this AM:

 

EPS not too shabby either (I'm personally a fan of the blue colors near Yucatán, not for any meaningful reason, other than I always want to see a low form around the Bay of Campeche). 

 

 

and maybe we can live in the land of make-believe for a minute and hope it's picking up on a shortwave, dropping down across the plains to meet that energy:

 

GEFS isn't too far off from either, but sees less ridging along and off the west coast.

[Daniel Boone]

Wound up with a quarter of inch of snow and sleet. Roads were terrible this morning !

[Holston_River_Rambler]

Euro Control 500 mb was interesting. Yeah, yeah, I know waaayyy out in time, but it has some OP support and for all intents and purposes, 10 - 15 days seems about as certain as days 4 - 5 sometimes, so why not? 

 

That EPO/WPO or whateves (circled thingy at the start of the gif) it is, is  a big feature and could def. help drive some of that Siberian cold down into N. America. Notice how at its end (a lot more uncertain than there just being a bid ridge in the N. Pac), it helps create a flow at 500 mb from Siberia into W Canada. Fun little disturbance (circled at the end) added free of charge. 

6z GEFS (12z hadn't populated yet on weatherwodels) as an example of a similar evolution: 

 

All that's waayyy out there and likely to change, but such a big anticyclone (shown below in an anomaly map) is likely to have implications for how energy shifts and flies around, downstream. I think if such an anticyclone develops and rolls over the pole, it is a big storm signal, somewhere, maybe not in the TN Valley (lol). But, if we hypothetically take what the models are showing here, it would inject more cold into the pattern and, at least temporarily force some energy south. 

 

First storm cuts (at least as far as it can with the -NAO), maybe around Feb 4 - 5 and then a few days later would be a better shot for the TN Valley, MA and or OH Valley. 

And yeah, again I know it's a bunch of ifs ands AND buts....

But if I could accurately predict the future I'd use my powers to get UTK a good head football coach, fuhgetabout the lottery, lol! Weather wouldn't be any fun if we knew the outcome. 

 

 

 

[Carvers Gap]

This is the d10-15 5day mean from the 12z EPS.  Weeklies aren't bad...get really good around mid-Feb.  That said, I think the transition to a better pattern was actually sped up on the 12z run.  12z was a substantially better run.  Again, this is a 5d mean.  D15 basically drops the core of BN 500 heights into the Plains and spreads eastward.  Classic cold air delivery mechanism for winter.  Notice the trough building into the west.  It is possible the trough could even split like we had during December.  

[Carvers Gap]

Beginning to spitball a major trough amplification over North America late during the first week of February.  Could easily change.  That said., the 12z EPS actually splits the western NA trough around 240.  That has moved up in time quite a bit.  Fits with the operational quite well.  Trough retrogrades into Canada, ridge builds in the West and sends a lobe of BN into the SE around d10.  Eventually the AK vortex slips SE into the nation's mid-section.  Makes me think that the MJO is maybe going to slip over into 8 or COD by late in week 2.   Honesty, the last few hours of the EPS are the best look we have had all winter.  Not a lot of skill at that range for the model, so will just refer to the 5d mean above.  Just picture the bluest shaping places with the light blue for d15. 

[BNAwx]

Maybe we’ll buck the Nina trend and have a decent 2nd half of the winter.  If the Nina is weakening, maybe that’ll help as well.

[John1122]

I'd love to tap some legitimate cold with the   -NAO around.  Hopefully we can get a 2-3 week period with both.  Even if it was February 10-March 7th that is great climo for snow here if we can get the Pacific on board.  In 2015 we managed to basically get the entire valley involved during the last 12 days of February and first few days of March.  I believe the March event was a West Tennessee blizzard. 

[Carvers Gap]

You know, that 18z GFS storm at 162 is super close to being a big storm for E TN.  Big high over the stop and nearly perfect placement.   If it turns the corner and trends slightly NW(which is entirely possible...boom.

[Carvers Gap]

Pretty interesting to see the 18z GEFS "cave" to the 12z EPS re: the position of the ridge in the eastern Pac.  The GEFS has been stubborn in pushing that ridge well of the coast and allowing the trough to run well into the west.  At 18z, the GEFS now has the trough up against the coast...and bang, EPO ridge just after d10.  All of that can change at this range, but good trends.

[John1122]

0z GFS was a little further west with the snow shield in about 5-6 days.  Webb keeps comparing it to the March 1927 event. That one saw several inches as far back as Nashville with 8-12+ inches across the eastern valley. A foot in Chattanooga for instance. 

[Holston_River_Rambler]

Ukie looked ok for NE sections. Best pic I have right now:

[fountainguy97]

1 hour ago, Holston_River_Rambler said:

Ukie looked ok for NE sections. Best pic I have right now:

Yeah i think only Eastern mountain areas will be in the ball game for this one and even they may see a pretty minor event.  Just not much cold to work with west of the Appalachians as is common in this setup.  Hopefully some other guys to our east can cash in.

[jaxjagman]

Looks like we are going to see a potential big warm up into the first of Feb as the heights are being shown to spike up in East Asia followed by  trough finally in East Asia.Have to wait and see what the teles look like the next few days.Right now it seems, there could  be a decent squall line to come though