December 2023 Mid/Long Term Pattern Discussion: Let it Snow!

[PowellVolz]

Trailing energy keeps looking better and stronger.


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[PowellVolz]

If the 12z GFS is right, I think above 3500’ along the Apps might get hammered with the first system. My only issue and maybe someone can chime in here with more knowledge but could orographic lift suppress rate driven dynamic cooling?


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[John1122]

The way things are going now, we may not even get rain in the area from the system.

[Carvers Gap]

The system this weekend has accumulating snows above ~2500' on both the CMC and the Euro.  Both have a backside vortex that gets pulled into the surface low to the east of the Apps.  Very plausible.  Is it right?  IDK.  Like Fountain noted, there will be several more looks before models settle-in due to the semi-complicated look to model.  If the energy in the front is slower or energy in the back is faster....bigger storm for somebody.  As we noted earlier in the week, a storm that strong should have snow somewhere near it, and modeling is "seeing" that now in some regards...not so much the storm dynamics by the low diving in as it departs.  Eastern areas and the mountains probably have the best chance of mood flakes.  Well, the mountains could be much more.

[Carvers Gap]

Euro has 3-9" along the Apps.  That would be huge for the ski slopes, and fits with Nino climatology if true.  Again, with marginal temps, anything is possible - including nothing.

[Daniel Boone]

2 hours ago, PowellVolz said:

If the 12z GFS is right, I think above 3500’ along the Apps might get hammered with the first system. My only issue and maybe someone can chime in here with more knowledge but could orographic lift suppress rate driven dynamic cooling?


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Not where orographic lift cools enough for snow but, on lower the above freezing wind would melt dendrites quicker.  So, in the grand scheme , nothing really noteworthy. 

[Matthew70]

At this rate the higher amounts of rain are disappearing quickly for mid TN.  Beautiful day today. LR looks ho hum.  Rinse & repeat.  Will be interesting if winter really does show up for more than 2 weeks.  Strange how it seems we can’t get a solid 6-8 weeks of winter anymore. The earths wx is really bi polar anymore. 

[Carvers Gap]

From MRX this morning re: eastern areas:

On Monday another strong upper low dives southeast out of Canada and
across the upper midwest and Ohio valley regions. This will be
something to watch as it results in very deep H5 heights and will
bring a reinforcing shot of cold air with it along with some
additional precipitation. Currently it appears it will be cold
enough by late Mon afternoon that snowfall down to low elevations
will be possible. The question is how far south this trough, and
resulting precipitation, make it. Right now the consensus is for
areas north of the I-40 corridor, especially in our VA counties and
far northeast TN mountains, to see some precipitation Monday
afternoon into Monday night. It`s likely this will be in the form of
snow in the higher elevations, but plausible there could be some
light accumulations into the low elevations as well. Details are
fuzzy though, and confidence therefore not high. But it is certainly
something to keep an eye on.

[Carvers Gap]

@Daniel Boone, has the persistent trough on the west coast ever actually materialized.  Maybe modeling is just seeing storms pinwheeling about the HB block?  However, I keep seeing it on modeling in the d10+, and then it doesn't show up as we get closer.  Is it feedback or modeling correcting the MJO as we get closer?  I can't tell, but it is wrecking havoc on LR modeling.  I think what we are actuating seeing are storms just rotating under the ridge in central Canada w/ AN heights between storms vs a static pattern where there is a trough or ridge parked somewhere and not moving.

[Holston_River_Rambler]

End of the RGEM looked nice for upslope Monday but it is the end of a hi res run. 

[PowellVolz]

End of the RGEM looked nice for upslope Monday but it is the end of a hi res run. 

That second wave is in a good location for NW flow but if it would dig more, further west, it could bring the valley into the conversation


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[Met1985]

45 minutes ago, Carvers Gap said:

@Daniel Boone, has the persistent trough on the west coast ever actually materialized.  Maybe modeling is just seeing storms pinwheeling about the HB block?  However, I keep seeing it on modeling in the d10+, and then it doesn't show up as we get closer.  Is it feedback or modeling correcting the MJO as we get closer?  I can't tell, but it is wrecking havoc on LR modeling.  I think what we are actuating seeing are storms just rotating under the ridge in central Canada w/ AN heights between storms vs a static pattern where there is a trough or ridge parked somewhere and not moving.

This has been exactly what I've been wondering.  We're is the ridge out west? When are we going to torch city? I mean daytime highs in the 30s and 40s with nighttime lows in the teens and 20's isn't exactly torch city. I think it's just that. Storms rotating through under the Canadian ridge.

[PowellVolz]

This has been exactly what I've been wondering.  We're is the ridge out west? When are we going to torch city? I mean daytime highs in the 30s and 40s with nighttime lows in the teens and 20's isn't exactly torch city. I think it's just that. Storms rotating through under the Canadian ridge.

The amateur social media Mets are behind a lot of the winter freak outs. Unfortunately their voices are as loud as the experts and they have turned 5 degrees AN into beach weather. At its warmest, it’s been mid 50’s and upper 20’a in Knoxville outside of return flow before a weather event. Obviously that’s not what snow lovers want but that’s not a torch either. Just get the PNA favorable for the east and hopefully we can get lucky with timing.


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[Holston_River_Rambler]

Kind of an aside, but something I noticed beyond the usual SPV talk, is what's modeled to happen over Greenland at 50mb:

temps and anomalies:

heights:

With some of the talk about potential NAO blocking in January, this is something to watch to see if it can percolate down to atmo. levels where it matters more for us. 

Even the GEFS mean is pretty enthusiastic:

 

The Euro isn't quite as enthused: 

 

Obviously this is still way out there, but something to think about down the road. 

 

 

 

 

 

[Daniel Boone]

5 hours ago, Carvers Gap said:

@Daniel Boone, has the persistent trough on the west coast ever actually materialized.  Maybe modeling is just seeing storms pinwheeling about the HB block?  However, I keep seeing it on modeling in the d10+, and then it doesn't show up as we get closer.  Is it feedback or modeling correcting the MJO as we get closer?  I can't tell, but it is wrecking havoc on LR modeling.  I think what we are actuating seeing are storms just rotating under the ridge in central Canada w/ AN heights between storms vs a static pattern where there is a trough or ridge parked somewhere and not moving.

Yeah, it sure looks like what you described is the case to me as well. Hopefully we get that retrogression of that ridge into western Canada.

 We can still work with a central ca ridge if we can get a constant flow of Lps moving up the eastern seaboard and pulling down CA from eastern Canada. That can work oddly enough with a +NAO. the C. Can. H pulling air from the Arctic in tandem with the + Nao pulling it, then insitu 50-50 from training Lps pulling that air into the Eastern US. Not likely to happen but, has and can. 

[Carvers Gap]

35 minutes ago, Daniel Boone said:

Yeah, it sure looks like what you described is the case to me as well. Hopefully we get that retrogression of that ridge into western Canada.

 We can still work with a central ca ridge if we can get a constant flow of Lps moving up the eastern seaboard and pulling down CA from eastern Canada. That can work oddly enough with a +NAO. the C. Can. H pulling air from the Arctic in tandem with the + Nao pulling it, then insitu 50-50 from training Lps pulling that air into the Eastern US. Not likely to happen but, has and can. 

Yeah,  I think Quebec is going to have to be our source for legit cold.  I just can't tell if LR modeling is smoothing out things to the point it just "looks" like a trough his off the West coast(and it is actually a storm rotating through) or what. However, the pattern seems much more progressive than a locked in trough in the eastern Pac.  That would be a very Nino pattern.  I do think the MJO is an issue and modeling not handling it well.  Also, that big block in central Canada is not easy to model.  I think when we get to weather patterns which have so few analogs, that disrupts modeling as I am sure some of the physics (even if it doesn't use analogs in original programming) probably has a biased towards analogs as programing would likely somewhere have analogs at its foundation - either programmers and/or root programming and/or other influences I can't see.  Even with long range seasonal modeling(Euro Weeklies) one can see the analog input w/ the snow input.  It rarely outpaces seasonal norms.

[Carvers Gap]

And I am not going to be track this for two weeks(feel free to if you want...I won't judge!), but modeling is picking up on a storm signal around the 28th or 29th.  You can see it every so slightly in the GEPS/GEFS individual snow maps at 12z.  The actual low placement you can see pretty clearly on ensembles...but there is a bit of a signal now at the surface.  As one of the guys mentioned in the MA thread, the actual shift at 500 may end-up only missing by about 5 days.  As Boone noted and also LC, our cold maybe well come from successive storms which steadily press the bound ward eastward, and then tap that cold in eastern Canada. Again, that is a decent storm signal, and does work given the set-up which Boone mentioned above.

[Carvers Gap]

5 hours ago, Met1985 said:

This has been exactly what I've been wondering.  We're is the ridge out west? When are we going to torch city? I mean daytime highs in the 30s and 40s with nighttime lows in the teens and 20's isn't exactly torch city. I think it's just that. Storms rotating through under the Canadian ridge.

Yeah, you all are in a great spot this winter.  I am thrilled for the ski slopes.  As a poster noted in the MA, the STJ is showing little sign of backing off.  The current storm track during Jan-March is likely big money for you all.  

I do wonder if it(the never appearing eastern Pac drought) has something to do with how modeling is smoothing out features after d10.  For example, a big storm cuts into the West coast.  What is depicted as a trough is more like a deep storm which is transient.  I could easily be wrong, but I just am not seeing evidence that the eastern Pac trough is hitting and holding.

[Daniel Boone]

11 minutes ago, Carvers Gap said:

Yeah,  I think Quebec is going to have to be our source for legit cold.  I just can't tell if LR modeling is smoothing out things to the point it just "looks" like a trough his off the West coast(and it is actually a storm rotating through) or what. However, the pattern seems much more progressive than a locked in trough in the eastern Pac.  That would be a very Nino pattern.  I do think the MJO is an issue and modeling not handling it well.  Also, that big block in central Canada is not easy to model.  I think when we get to weather patterns which have so few analogs, that disrupts modeling as I am sure some of the physics (even if it doesn't use analogs in original programming) probably has a biased towards analogs as programing would likely somewhere have analogs at its foundation - either programmers and/or root programming and/or other influences I can't see.  Even with long range seasonal modeling(Euro Weeklies) one can see the analog input w/ the snow input.  It rarely outpaces seasonal norms.

Yeah, agree. Enso is top ingest, Along with MJO and historical daily data of which would be the Analogue basically . Of course NWS and FAA Station data is also as far as precise Temperature output , a no brainer there, lol.. I , like you man, am sure there's more as well. 

[dwagner88]

1 hour ago, Carvers Gap said:

And I am not going to be track this for two weeks(feel free to if you want...I won't judge!), but modeling is picking up on a storm signal around the 28th or 29th.  You can see it every so slightly in the GEPS/GEFS individual snow maps at 12z.  The actual low placement you can see pretty clearly on ensembles...but there is a bit of a signal now at the surface.  As one of the guys mentioned in the MA thread, the actual shift at 500 may end-up only missing by about 5 days.  As Boone noted and also LC, our cold maybe well come from successive storms which steadily press the bound ward eastward, and then tap that cold in eastern Canada. Again, that is a decent storm signal, and does work given the set-up which Boone mentioned above.

Seems like there is one every year around that time. We've had many years in the past with either winter threats, flooding, or severe weather.

[Carvers Gap]

The original Euro Weeklies are probably going to be closer to the mark than when the Weeklies flipped last week.  Global ensembles are showing this now.  And it makes me wonder if there isn't a hiccup right now in the week 3 range.  And this was really seen across most modeling - CFSv2, CFS seasonal, CANSIPS, and GEFS ext.  I don't think the crazy strong WAR every materialized nor the massive GoA trough.  What has been constant is a HB block.  What modeling did miss at 4-6 weeks was the massive chinook due to BN heights in and around the GoA(but thankfully that feature was not on steroids as shown at one time).  That chinook and the jet extension in the Pac(likely related) are things which just aren't modeled well at range, but they also created many features on modeling which appear less likely to reach fruition in terms of reality.  Now, the WAR signature on modeling does show-up sometimes(even if it doesn't verify) as a precursor to SSWs.  Most likely, 500 maps (which are well below, vertically speaking, 10mb in the atmosphere) start to feel that strat warming, and the WAR shows up as a result.  Again, that probably is an over-reaction on modeling, but it can also wreck 500 maps in the LR.  Maybe we back into a decent pattern before the next MJO rotation hits, and we do it all over again.

[fountainguy97]

The NAM has made a huge shift at 00z in regards to the northern wave behind this system. An absolute beast of a NW event. This piece of energy is not even onshore yet.

[John1122]

It was definitely a Namming. Drops 3 inches on me. I'm hoping for legitimate snow showers. 

I will say this, the ground is nicely chilled. I've been in the low to mid 20s all week in the mornings. Drops quickly to freezing just after dark and with these long nights, we've been spending a good 12-14 hours a night below freezing. My low for tonight is predicted at 33, but it's 31 already. 

[Carvers Gap]

@Holston_River_Rambler the NAM has light the signal fire as you predicted.

[Carvers Gap]

Snow hole is over Kingsport....the NAM run is legit.

[Carvers Gap]

MRX afternoon disco...

On the backside of the Miller A low, lingering low level moisture
and northwest flow will bring light rain Sunday night through Monday
morning. The highest elevations mainly above 3500 feet will see a
changeover to light snow as temps drop. Lower elevations will stay
warm enough to keep rain as the precip type. By Monday afternoon, a
trough digging into the Ohio Valley will enhance POPs, mainly north
of I-40. As temps drop late Monday afternoon, a changeover to snow
or rain/snow mix is likely from the Central Tennessee Valley, Upper
Plateau counties, NE Tennessee and SW Virginia. After sunset, POPs
decrease as the trough passes the region. Monday night, northwest
flow will continue the light snowfall for the higher elevations.
Light snow accumulations below half an inch will be possible for the
lower elevations of NE Tennessee and SW Virginia, East Tennessee
mountain foothills and Upper Cumberland Plateau counties. The higher
elevations of the East Tennessee mountains and SW Virginia, above
3500 feet, may see 1 to 2 inches of accumulation.

 

[Daniel Boone]

Just now, Carvers Gap said:

Snow hole is over Kingsport....the NAM run is legit.

I noticed that, lol. Dang, hopefully the systems strong enough to overcome the downslope enough to work out for there. 

[Daniel Boone]

4 minutes ago, Carvers Gap said:

MRX afternoon disco...

On the backside of the Miller A low, lingering low level moisture
and northwest flow will bring light rain Sunday night through Monday
morning. The highest elevations mainly above 3500 feet will see a
changeover to light snow as temps drop. Lower elevations will stay
warm enough to keep rain as the precip type. By Monday afternoon, a
trough digging into the Ohio Valley will enhance POPs, mainly north
of I-40. As temps drop late Monday afternoon, a changeover to snow
or rain/snow mix is likely from the Central Tennessee Valley, Upper
Plateau counties, NE Tennessee and SW Virginia. After sunset, POPs
decrease as the trough passes the region. Monday night, northwest
flow will continue the light snowfall for the higher elevations.
Light snow accumulations below half an inch will be possible for the
lower elevations of NE Tennessee and SW Virginia, East Tennessee
mountain foothills and Upper Cumberland Plateau counties. The higher
elevations of the East Tennessee mountains and SW Virginia, above
3500 feet, may see 1 to 2 inches of accumulation.

 

We'll see if they up those projected totals in the morning if guidance increases amounts. They're going to be gunshy even moreso than usual particularly because of that last failed snowfall projection I think. 

[Carvers Gap]

9 minutes ago, Daniel Boone said:

I noticed that, lol. Dang, hopefully the systems strong enough to overcome the downslope enough to work out for there. 

With that trajectory, definitely is correct.  14-15 we seemed to inexplicably get every NW flow event to hit us in town.  I felt like I  was living at 5,000'.  LOL.  But nah, that is normal.  Thunder in the mountains....not too far off the mark yet again.

[Carvers Gap]

4 minutes ago, Daniel Boone said:

We'll see if they up those projected totals in the morning if guidance increases amounts. They're going to be gunshy even moreso than usual particularly because of that last failed snowfall projection I think. 

I thought NC did pretty well.  They had to close some place on the  Blue Ridge Parkway(?) to sledding or it could be SNP.  The mountains have been doing pretty well (Apps).  Plateau is less for sure.