Fall 2022 Medium/Long Range Forecast Discussion

[Carvers Gap]

Looks like we are going to see a cutter(unless something abruptly changes) on Friday.  We could still see some snow showers and flurries along the Plateau and mountains.  I would think the valleys have a shot if the Euro is accurate.  The reason for the cutter?  Well, climatology supports that track as Nina is in place.  It also looks like the energy for this storm(to my eyes anyway), is coming out in several pieces with the main energy cutting int middle and west TN.

[Holston_River_Rambler]

Past that system, the GEFS and EPS seem pretty -NAO happy past day 10:

 

 

Canadian ensembles, not so much:

 

 

 

[Holston_River_Rambler]

The GFS has been handling the Friday system weirdly over the past few runs, but the Euro has been more consistent. 

Either way , the main low is pulled west of the TN valley, like Carver's said, but hopefully the Euro has a better handle on the pattern and the GFS is holding the system back too much. It's November, cutters gonna cut. I feel like its always been some version of a cutter, just a question of can the whole shortwave eject out of the SW at once, and how much energy gets pulled in on the back side as it strengthens and pulls away. 

It is East TN and it is a chance for snow, so what can go wrong, may in fact go wrong, lol. Hopefully at least a good upslope for the eastern mts and NC. 

[Holston_River_Rambler]

Out in ye olden tropics, looks to me at least like the MJO wave has moved into 5/6:

 

At that pace it should make it to the more favorable regions in about 2 weeks. Still some convection holding on in the central and western Pac too. I don't have a clue what it is, but there seems to be some favorable aspect to that environment. I will be interested to see how all that looks in a couple of weeks. 

The RMMs suggest that it will do what it did last time and die out:

The above is the GEFS, and the EPS looks pretty similar. But let's remember that the low amplitude treck it just took through the COD produced enough cold to probably even out the temp anomalies in November by the end of the week. 

The EPS and GEFS also want to argue for significant tropical forcing over NE South America and the Caribbean in about 10 days:

 

Not really sure if that is MJO related or something else, but it will be interesting to see how and if that modulates the pattern. 

 

 

[Holston_River_Rambler]

Sorry for the flurry of posts, but just thought of one more thing to add. Well more of a question. Do y'all think there is a relationship between the upper level divergence forecast over NE South America and the Caribbean, and the -NAO that the ensembles are also wanting to build along the same longitude? 

[Met1985]

58 minutes ago, Holston_River_Rambler said:

The GFS has been handling the Friday system weirdly over the past few runs, but the Euro has been more consistent. 

Either way , the main low is pulled west of the TN valley, like Carver's said, but hopefully the Euro has a better handle on the pattern and the GFS is holding the system back too much. It's November, cutters gonna cut. I feel like its always been some version of a cutter, just a question of can the whole shortwave eject out of the SW at once, and how much energy gets pulled in on the back side as it strengthens and pulls away. 

It is East TN and it is a chance for snow, so what can go wrong, may in fact go wrong, lol. Hopefully at least a good upslope for the eastern mts and NC. 

You can say that again.  The GFS has been very inconsistent with this Friday's system.  I have no clue what has gotten into the data set of the gfs but it's been weird. 

[Carvers Gap]

Regarding the NAO, some runs it appears it is headed for an alignment which would benefit us.  On others it is east based which would favor cold for Nova Scotia and the extreme NE.  With the Pacific being hostile (PNA/EPO included), the NAO from what I have seen is only blunting what would otherwise be a record setting torch.  As is, the NAO will keep us seasonal.  Even marginal help out west would create very cold conditions here.  OTH, if the NAO backs off....torch city.  I tend to lean towards a period of moderation during the early half of December, an idea shared by many.  I then think that we see the end of December turn cold before flipping to a potentially winter-ending pattern in January.  Not saying that is a certainty BTW, but that is on the table.  The other option is winter just ratchets down and never warms back up truly.  There is the potential for a modified 95-96 pattern.  In NE TN and the mountains, we are long overdue for that.  14-15 is on the table as well.

[Carvers Gap]

I mean really for MBY, we are five to six weeks away from prime climatology, so even tracking at this time of year(my elevation) is a bonus!  The early snows of the past decade were not something I even saw as a kid at lower elevations.  Now the Apps and Plateau, snow is not uncommon beginning now.

[Daniel Boone]

4 hours ago, Holston_River_Rambler said:

Past that system, the GEFS and EPS seem pretty -NAO happy past day 10:

 

 

Canadian ensembles, not so much:

 

 

 

That evolution of the EPS/GEFS actually looks pretty '95-96 ish. Nw to Se oriented Jet Pattern. Several Clipper's and Miller B to Miller A transfer's that Winter. 

      Not likely to have a Winter near carbon copy of that but,ay e a watered down version. Hopefully, would still be enough to give a decent amount of Snow to the area. 

[Carvers Gap]

It is 384 for kicks and giggles.  That traps the PV.  Blockimus Maximus.

 

[Daniel Boone]

3 hours ago, Carvers Gap said:

It is 384 for kicks and giggles.  That traps the PV.  Blockimus Maximus.

 

Big time Bridge ! 

[Carvers Gap]

Pretty nice run of the Weeklies and looks to really repeat what we have seen during November.  Cold shots followed by ridging....wash, rinse, repeat.  NAO gives way to an EPO ridge later in the run - displaced slightly westward but still will work.   I have seen MUCH WORSE runs than that.  We are almost out of shoulder season, so the "trust factor" of the Weeklies edges upward with each run now.

[Carvers Gap]

Looking at the 0z CFSv2extended/seasonal, 6zGEFS, and Weeklies(careful as today's runs don't look overly similar...), I am beginning to feel more comfortable that a window of cold/wintry weather will make its appearance around mid-December.   And that might be our shot.  That window has been tough to nail down.  Duration is incredibly tricky as well.  This is just spitballing.  The cold could show up anywhere between Dec 7-15th, and maybe last 10-20 days(if pressed I would say Dec 10th...earlier if the 6z GEFS is correct, but it is prob rushed).  Christmas is too far out to say anything with certainty.  Some LR model runs show cold...some not.  The third week in December seems almost universally cold on modeling though.

[Carvers Gap]

12z GFS today has the bridging of the HL PAC and Atlantic blocks now at hour 288, roughly beginning Dec3-4.  Guessing part of the TPV gets trapped and sent southward.  Impressive look.   12z GFS w/ a hold my beer run compared to yesterday's incredible look at 12z.

[Carvers Gap]

12z GEFS does not support the operational after d10.  I think the idea of the next cold shot coming around mid-December looks about right.

[Holston_River_Rambler]

Some chatter about the long range EPS in the MA subforum, so I thought I would post it here. Interesting pattern if it verifies:

[Daniel Boone]

1 hour ago, Holston_River_Rambler said:

Some chatter about the long range EPS in the MA subforum, so I thought I would post it here. Interesting pattern if it verifies:

Hopefully that Nina enhanced Aleutian Ridge nudges East and forms -EPO and ultimately a + PNA along with the bridge blocking. That would git'r done for us . 

[Carvers Gap]

The ensembles are spitting out a pretty nice pattern from mid-December onward.  Cosgrove has been doing pretty well this late fall...he has a nice write-up about it on social media.  How long does the cold last?  TBD.  As John noted, there are some similarities to '89, but there are also some similarities to some winters which saw cold come back after a brief January thaw.  The bridge over the top of HL blocking is a pretty good signal for winter here.  

[Met1985]

1 hour ago, Carvers Gap said:

The ensembles are spitting out a pretty nice pattern from mid-December onward.  Cosgrove has been doing pretty well this late fall...he has a nice write-up about it on social media.  How long does the cold last?  TBD.  As John noted, there are some similarities to '89, but there are also some similarities to some winters which saw cold come back after a brief January thaw.  The bridge over the top of HL blocking is a pretty good signal for winter here.  

Yeah the ensembles,  the CFS, and the telecommunications look really good if you ask me. There are some waffles but hey that's to be expected.  I feel like something is different this season already.  We've had multiple cold outbreaks already which has been a rarity for the past several years. Was reading through that maybe just maybe blocking is making a comeback finally after being sparse for a decade....

[Carvers Gap]

Patterns is very blah after what looked like something promising.  I still think mid-December looks like a good window for the beginning of cold.  Nailing down that timeframe has not been easy.  Certainly looks like the trough will pull into the West in January, if not before.  But really, I have no crystal ball on that.  The Pacific is so hostile, I am not sure the trough can hold in the east at all for more than a few days.  That said, January climatology normally does the trick.  

[nrgjeff]

I don't normally just drop Twitter threads, but this one is legit. Original thread is accessible from my retweet.

 

[Carvers Gap]

The 12z EPS has a MONSTER -NAO.  It is so strong that it nearly overcomes a PAC that is the exact opposite of what we need it.  BN temps still relatively on target for mid-December...could begin during week 2 of December.  Huge grain of salt right now as this is a wonky set-up...could be much colder or much warmer.

[Daniel Boone]

1 hour ago, Carvers Gap said:

The 12z EPS has a MONSTER -NAO.  It is so strong that it nearly overcomes a PAC that is the exact opposite of what we need it.  BN temps still relatively on target for mid-December...could begin during week 2 of December.  Huge grain of salt right now as this is a wonky set-up...could be much colder or much warmer.

The MJO is a problem. Think you and I called the path correctly a couple weeks ago when data was showing it making it to ph 8 and many were buying it, even Masiello. As we discussed also, once those SST'S warm in that area we should be in business, as far a help and not hindrance from it.

       It still has a chance making it past 7 but, probably die off quickly. 

[Holston_River_Rambler]

I don't know, I still think the MJO did a pretty good job delivering cold air here, even with the 8-1-2 in the COD. I DO think the horrible Pac on the long range Ops and Ens. has been impacted by where the MJO is now and has been for the past few days. 

Yuck:

 

On the other hand Satellite looks kind of meh to me. I've seen much worse looks. I'm kind of surprised it registers this as a medium amplitude 7.

 

It would be nice if we can get this NAO block to hold out long enough for whatever the MJO pass gets back to whatever produced this most recent cold snap and the one week long on in October. It was pretty stout. Wiped out + anomalies for the western part of the state and almost did it in the east:

 

 

Now if we get through the next week and a half to two weeks and the Pac still looks awful on day 10+ or so modeling, Nina for the loss! 

 

 

[Holston_River_Rambler]

4 minutes ago, Holston_River_Rambler said:

Now if we get through the next week and a half to two weeks and the Pac still looks awful on day 10+ or so modeling, Nina for the loss! 

In fact, we might want to go ahead and clear janetjanet a place off at the TN Valley weather table:

 

There's that La Nina firehose we all know and love! 

[Daniel Boone]

59 minutes ago, Holston_River_Rambler said:

I don't know, I still think the MJO did a pretty good job delivering cold air here, even with the 8-1-2 in the COD. I DO think the horrible Pac on the long range Ops and Ens. has been impacted by where the MJO is now and has been for the past few days. 

Yuck:

 

On the other hand Satellite looks kind of meh to me. I've seen much worse looks. I'm kind of surprised it registers this as a medium amplitude 7.

 

It would be nice if we can get this NAO block to hold out long enough for whatever the MJO pass gets back to whatever produced this most recent cold snap and the one week long on in October. It was pretty stout. Wiped out + anomalies for the western part of the state and almost did it in the east:

 

 

Now if we get through the next week and a half to two weeks and the Pac still looks awful on day 10+ or so modeling, Nina for the loss! 

 

 

I think I didn't mention in my post that the period we were talking is the period we're in now. Yeah, if it can make it to ph 8 then COD, I think we still may do pretty good. I agree if we get that stout -NAO we should be ok. May even do decent with MJO in warm phases, particularly western and northern sections of the Valley.

       The Nina is a pain for sure. I do wonder had that southern SW System not came along WHEN it did, how the Pattern would of been. It's possible the earlier depiction of the rain to snow scenario would of came to fruition. Timing with that sw vort hurt. 

[Daniel Boone]

1 hour ago, Holston_River_Rambler said:

In fact, we might want to go ahead and clear janetjanet a place off at the TN Valley weather table:

 

There's that La Nina firehose we all know and love! 

Would be nice for a faster cold push and some of that be in the form of Snow 

[Carvers Gap]

Woof at the 18z GEFS.  Looks more like the Canadian and EPS now.  That is a COLD look.

[Carvers Gap]

Temps are cold from the Apps west, northwestward.  That is a strong high latitude blocking signature.  If true, I expect severe cold to ensue.  Pretty easy to see where the storm track battle line is drawn.  As noted above, flooding is a possibility as well as an extended overrunning event in the areas where cold and GOM moisture intersect.  

 

[Carvers Gap]

This is what corresponds to those above...Euro is about 36 hours slower.