Winter 2021/2022 January Thread

[Holston_River_Rambler]

18z Euro compared to 12z Euro:

I can't tell if it has ticked slightly west, or if the trough is more positively tilted. 

 

 

[Mr. Kevin]

Carver, did the 12z eps look cold also further in lala land? I heard it did but wanted your opinion also. Also, the way to continue or redevelop the cold pattern moving forward is to get the Pacific jet to extend instead of retract. 

[Holston_River_Rambler]

Looks like the 18z Euro really tried to pop a low in the Gulf:

 

Next frame it transfers to off of Cape Canaveral, but it is at least there. 

[Silas Lang]

A low in the gulf would really help us out. This evening seems to indicate more of a Gulf element. Hopefully it continues! 

[WinterWonderland]

Robert Gamble's (WxSouth's) preliminary take...

[Carvers Gap]

The 18z GFS is loaded for bear after the cutter.  Gradient pattern with a cold and an active pattern.

[Holston_River_Rambler]

Ye olden NAM at range was pretty tasty:

 

 

 

 

 

[Holston_River_Rambler]

I mean, still not quite where we in east TN want it, but looking better. 

[Carvers Gap]

Truly one of the more impressive runs of the NAM(even for the NAM!) that I have seen.  It brings snow howling all of the way to the Florida/Georiga border.  I have my doubts that it can get the Atlantic feed back this far, but a historic blizzard on the EC certainly seems plausible.  

[Silas Lang]

Looking a heck of a lot better than what it was to start! We were never going to get the brunt of this storm, but just a few more small adjustments in our favor and I will be satisfied. 

Curious to see if the GFS follows the NAM like 18z...anyone here staying up to watch? 

[Utvols235]

Truly one of the more impressive runs of the NAM(even for the NAM!) that I have seen.  It brings snow howling all of the way to the Florida/Georiga border.  I have my doubts that it can get the Atlantic feed back this far, but a historic blizzard on the EC certainly seems plausible.  

I went to school in south GA. In 2014 we were under a WSW and projected to get 3-6 inches in bulloch co. Meanwhile the valley wasn’t supposed to get but an inch or two if any. My parents ended up getting 5 inches in west knox and we didn’t get a single snow flake in so GA. Turned out to be an ice storm from us to Augusta. Sounds like a similar set up although I didn’t follow the wx as close as I do now. Not sure if anyone remembers that storm system.


.

[Silas Lang]

Annddd the 0z GFS takes a step back from the 18z.

[Bigbald]

9 minutes ago, Silas Lang said:

Annddd the 0z GFS takes a step back from the 18z.

Not a great run for anyone except far Northern New england.

[BlunderStorm]

06z GFS Has possibly the coldest air of the entire winter following a vicious App cutter next weekend could be a good deal plateau and west. The associated trough is a lot less positive. Canadian seems to be on board as well but will see if it continues the trend later this morning. 0z Euro was too west for everyone.

(9/10 days out take with a grain of salt)
24hr Kuchera https://www.pivotalweather.com/model.php?m=gfs&p=snku_024h&rh=2022012606&fh=210&r=us_ov&dpdt=&mc=
2m Temps https://www.pivotalweather.com/model.php?m=gfs&p=sfct&rh=2022012606&fh=246&r=us_ov&dpdt=&mc=

Edit: Holy #### Check out the GFS clown in the 300 range. Practically forms a "Tenntucky" Ice Sheet.

[Weathertree2]

Great eye candy on the 6z run of gfs, my new screen saver

[Carvers Gap]

12z Euro has that system as well, but further to the west.  I am guessing that is going to be a cutter for the Plains, but it has trended better for middle and western areas of the state.  If it comes to pass, the GFS nailed this from d16.  I think there is a pic of it in the banter thread.  Regardless of that storm, the pattern that comes after that looks really good.  That 6z GFS run looked a lot like last winter's overrunning event.  

The GFS has some DGEX DNA in it.  It has been over-amping stuff this year in crazy ways, but generally getting the placement of the features reasonably correct on a large scale.  It seems to have feedback issues when a slp turns to the NE or when it phases.  It has done that all winter.  I will say this though as a counterbalance to that last opinion, February systems tend to over-perform in my book.  Modeling often overestimates how far south those storms will be suppressed and underestimates the strength and precip.  

In the LR, modeling(ensembles and operationals) look really good.  What looked to be a pattern change, now looks like an EPO ridge which has ideal placement.  I am a little wary of this flip back to a colder look(after several days of a flip to warm after Feb2).  If you remember back during late December when we flipped cold, for a time modeling only had the monster cold front on Jan3rd, and then turned warm after the front.  In reality, that was a pattern change.  We had a slight warm-up after that front, and then the hammer dropped for good.  Right now we have a similar (but opposite) look where a strong cold from drops into the West during early February.  At first, modeling had that as the pivot to a warmer pattern over the East.   For the past 3-4 days, modeling has trended much colder for the East as it rolls that trough out of the west right back into the East, and then locks it into place.  The 6z GEFS is now a complete flip to a very cold look, and its look is one that could deliver a very cold air mass into the US.  The 0z CMC has something similar.  The EPS has been a few days behind @Mr. Kevin, but it is almost there.  The EPS has been less than consistent in the LR.  Again, GREAT looking pattern.  And again, I am wary of modeling perpetuating the current pattern.  

For you LR model watchers, does that pattern after the cutter look like a return of the current pattern or is it a new pattern?  It looks to me like a variation of the same family of EPO ridges, but the center of the ridge looks further south than the previous pattern.  The reason I ask, the current pattern is due to break 4-6 weeks after Jan 3.  That would mean that look in the LR is very temporary.   If it is a new-is pattern, we may see much of February get cold.  

[Holston_River_Rambler]

6z NAM, just looking at the southwest shortwave, looks like it is holding back quite a bit of energy as compared to the its 18z run and the 6z Euro looks like it is holding back more than 0z (but not much). GFS is holding back a tick more than 0z. So are we tied now wrt this weekend? GFS 1, Euro 1? 

HRRR is going to have tun a 2 point conversion for someone. 

 

[Weathertree2]

31 minutes ago, Carvers Gap said:

12z Euro has that system as well, but further to the west.  I am guessing that is going to be a cutter for the Plains, but it has trended better for middle and western areas of the state.  If it comes to pass, the GFS nailed this from d16.  I think there is a pic of it in the banter thread.  Regardless of that storm, he pattern that comes after that looks really good.  That 6z GFS run looked a lot like last winter's overrunning event.  

The GFS has some DGEX DNA in it.  It has been over-amping stuff this year in crazy ways, but generally getting the placement of the features reasonably correct on a large scale.  It seems to have feedback issues when a slp turns to the NE or when it phases.  It has done that all winter.  I will say this though as a counterbalance to that last opinion, February systems tend to over-perform in my book.  Modeling often overestimates how far south those storms will be suppressed and underestimates the strength and precip.  

In the LR, modeling(ensembles and operationals) look really good.  What looked to be a pattern change, now looks like an EPO ridge which has ideal placement.  I am a little wary of this flip back to a colder look(after several days of a flip to warm after Feb2).  If you remember back during late December when we flipped cold, for a time modeling only had the monster cold front on Jan3rd, and then turned warm after the front.  In reality, that was a pattern change.  We had a slight warm-up after that front, and then the hammer dropped for good.  Right now we have a similar (but opposite) look where a strong cold from drops into the West during early February.  At first, modeling had that as the pivot to a warmer pattern over the East.   For the past 3-4 days, modeling has trended much colder for the East as it rolls that rough out of the west right back into the East, and then locks it into place.  The 6z GEFS is now a complete flip to a very cold look, and its look is one that could deliver a very cold air mass into the US.  The 0z CMC has something similar.  The EPS has been a few days behind @Mr. Kevin, but it is almost there.  The EPS has been less than consistent in the LR.  Again, GREAT looking pattern.  And again, I am wary of modeling perpetuating the current pattern.  

For you LR model watchers, does that pattern after the cutter look like a return of the current pattern or is it a new pattern?  It looks to me like a variation of the same family of EPO ridges, but the center of the ridge looks further south than the previous pattern.  The reason I ask, the current pattern is due to break 4-6 weeks after Jan 3.  That would mean that look in the LR is very temporary.   If it is a new-is pattern, we may see much of February get cold.  

I was thinking same about the overrunning likely will be different next run but as you pointed out indicating the pattern general 

[Carvers Gap]

Stellar write-up by MRX.  I am going to post all of it.  Great discussion about the short and medium range.  Of note, read the last two sentences of the last paragraph @Weathertree2.

Key Messages:

1. A mix of rain, snow, and possibly sleet on Friday will changeover
to light snow Friday evening with heavier rates in the highest
elevations. Accumulations are most likely in the mountains, northern
Plateau, southwest Virginia, and possibly portions of northeast
Tennessee.

2. Well-below normal temperatures are expected Friday night through
Saturday night with wind chills possibly near or below 0 in the
higher elevations. A gradual warmup will follow.

Thursday through Saturday

At the start of the period, a shortwave will be moving out of the
Rockies with surface high pressure centered over New England. This
approaching shortwave will be the focus for much of the extended
period with the initial setup yielding more seasonal and dry
conditions locally. Heading into Friday, the aforementioned
shortwave will dig significantly with cyclogenesis expected in the
western Atlantic ahead of the developing nor`easter. This will
result in significant height falls and increasing low-level
convergence. Cross sections from the latest NAM/GFS show notable
ageostrophic upward motion, well above the dendritic growth zone for
much of the area. However, the column does look to be fairly dry in
the lower levels at the onset of precipitation in the first half of
the day. This will likely inhibit precipitation reaching the ground
initially, but the later timing of precipitation suggested by the
latest model runs has raised potential for more of it to fall as
light snowfall, even outside the mountains. In any case during the
overnight period, focus will be on the mountains for more notable
accumulation potential as 25+ kts of N/NW flow is expected to
persist at the 850mb with continued low-level saturation. With all
of these factors in mind and more aggressive snowfall accumulation
indications from the NAM and many GEFS members, confidence is high
enough for inclusion of wording in the HWO. The focus for better
accumulation potential will be in northeastern portions of the area
where there is better overall moisture, in addition to the higher
elevations of the Plateau, mountains, and southwest Virginia.

Then, heading into Saturday, the focus will be notably cold
temperatures following significant CAA and far below normal 500mb
heights. For places that do see accumulating snowfall, overnight
temperatures may fall to the single-digits as surface high pressure
will promote subsidence/radiational cooling on Saturday night. With
all of these factors in mind, much of the area is likely to remain
below freezing from Friday evening until mid-day on Sunday, perhaps
longer in some locations. Additionally, synoptically-driven winds
early on Saturday when the MSLP gradient increases could produce
wind chills in the teens to near 0 degrees, especially in the higher
elevations. Below 0 wind chills are looking increasingly likely in
the mountains.

Sunday through Tuesday

By Sunday, the mid/upper trough will have moved to our east with
height rises expected into early next week. This will promote a
gradual return to near normal temperatures with drier weather also
expected during this timeframe. At the very end of the period,
deterministic and ensemble models suggest notable troughing in the
central U.S. to begin ejecting eastward. This will likely allow for
a return of a more active pattern at the end of period and beyond.

BW

[Carvers Gap]

Just now, Weathertree2 said:

I was thinking same about the overrunning likely will be different next run but as you pointed out indicating the pattern general 

Yeah, details at this range will be scarce.  I tagged you int he post above.  I thought it interesting to see MRX make a note of that active pattern in their morning discussion.  Originally, I really felt like the system after the Nor'Easter would cut west of the entire forum area.  I think modeling is adjusting to the idea that maybe trough in the west could be quite temporary and the cold front may push eastward more than LR modeling had to begin with...I think a large scale overrunning event looks plausible for folks to my west, but huge cone of probability at this point.  

[Holston_River_Rambler]

39 minutes ago, Carvers Gap said:

For you LR model watchers, does that pattern after the cutter look like a return of the current pattern or is it a new pattern?  It looks to me like a variation of the same family of EPO ridges, but the center of the ridge looks further south than the previous pattern.

I'll take the easy way out and say maybe its some sort of combo of what we had in December and now. 

We kind of have that this weekend with the Aleutians ridge and a PNA ridge. The PNA is rolling forward as it breaks down and the Aleutian is trying to build back in:

 

So let's put this into motion, as the weather folks say:

and the Euro:

 

Watch where the waves break; sometimes over the Aleutians and sometimes closer to the Gulf of Alaska. When it is closer to the Gulf of Alaska, the downstream trough takes a more favorable track for the TN valley. When it is closer to he Aleutians, you get a variety of cutters. 

These wave breaks are modulated by the jet, which is modulated, in part, by tropical forcing. Blocking can modulate the trough and ridge axes as well, but that seems to be hard to come by in the NAO region since December. 

So the jet it is for now.  

Euro:

 

GFS:

 

So we want an upper level Aleutian low to cause the waves to break near Hawaii. When it is near the Okhotsk Sea/ Kamchatka, the waves break too far west.  So watching these animations, it looks to me like the pattern kinda wants to do both lol. I guess this is what they mean by mixed signals, lol. MJO signals are mixed. BOM and Euro want to mess around in the COD, suggesting the mixed signal above, while the GFS wants to do that for a bit, it finally kicks it out into the dreaded phase 4, but the GFS only goes out so far. The BOM shows something similar, but rolls it back to around 7/8 by late February. 

 

I mean, to be honest, I think you probably summed it up a lot more succinctly than my mess above, now that I think about it. Bottom line looks like we are going to have to just time a wave along a front just right. But it does kind of seem like a mix of the two patterns we've seen this winter, to me. 

[Holston_River_Rambler]

I'll add one more thing. As cynical as I am right now, the fact that we are in a Nina (seems like an actual Nina this winter) and it it looks like the pattern can't quite decide what it wants to do in February is probably a good thing. 

[Carvers Gap]

2 minutes ago, Holston_River_Rambler said:

I'll take the easy way out and say maybe its some sort of combo of what we had in December and now. 

we kind of have that this weekend with the Aleutians ridge and a PNA ridge. The PNA is rolling forward as it breaks down and the Aleutian is trying to build back in:

 

So let's put this into motion, as the weather folks say:

and the Euro:

 

Watch where the waves break; sometimes over the Aleutian and sometimes closer to the Gulf of Alaska. When it is closer to the Gulf of Alaska the downstream trough takes a more favorable track for the TN valley. When it is closer to he Aleutians, you get a variety of cutters. 

These wave breaks are modulated by the jet, which is modulated, in part, by tropical forcing. Blocking can modulate the trough and ridge axes as well, but that seems to be hard to come by in the NAO region since December. 

So the jet it is for now.  

Euro:

 

GFS:

 

So we want an upper level Aleutian low to cause the waves to break near Hawaii. When it is near the Okhotsk Sea/ Kamchatka, the waves break too far west.  So watching these animations, it looks to me like the pattern kinda wants to both lol. I guess this is what they mean by mixed signals, lol. MJO signals are mixed. BOM and Euro want to mess around in the COD, suggesting the mixed signal above, while the GFS wants to do that for a bit, it finally kicks it out into the dreaded phase 4, but the GFS only goes out so far. The BOM shows something similar, but rolls it back to around 7/8 by late February. 

 

I mean, to be honest, I think you probably summed it up a lot more succinctly than my mess above, now that I think about it. Bottom line looks like we are going to have to just time a wave along a front just right. But it does kind of seem like a mix of the two patterns we've seen this winter, to me. 

The reason I ask....I usually put a "clock" on weather patterns.  Rare to get a pattern to last past 6 weeks.  That said, just because the pattern changes does not mean it goes to a pattern which is worse(I am kind of conditioned to that line of thinking though, meaning it gets worse!).  Initially, it looked like a flip on LR modeling.  Then, it kind of looked like new pattern.  However, what the GFS just produced was almost identical to what we say it advertising for the Jan 20-30th time frame - centered slightly west of where it is now.  That would bring the storm track onto the eastern seaboard and park it there verbatim.  Storm tracks look something like 2/3 cuts west of the Apps, but 1/3 take the low road.  That is a very traditional storm track or La Ninas IMHO.    So, just trying to figure out if we are stealing a couple of more weeks with the same pattern or is this a new look.  I can't honestly tell.  There are aspects, as you note, which are slightly different.  

@John1122, sure looks like the "cold November" correlation may verify this year....

[Coach B]

1 hour ago, Carvers Gap said:

..... I will say this though as a counterbalance to that last opinion, February systems tend to over-perform in my book.  Modeling often overestimates how far south those storms will be suppressed and underestimates the strength and precip.  

....For you LR model watchers, does that pattern after the cutter look like a return of the current pattern or is it a new pattern?  It looks to me like a variation of the same family of EPO ridges, but the center of the ridge looks further south than the previous pattern.  The reason I ask, the current pattern is due to break 4-6 weeks after Jan 3.  That would mean that look in the LR is very temporary.   If it is a new-is pattern, we may see much of February get cold.  

I did some rudimentary monthly snowfall numbers for Nashville several years ago. While January was the snowiest month, it was only a slight edge. So slight in fact, that if you divided the monthly average by the number of calendar days, that February actually averaged slightly more snow per day. It just likes to snow in February even though the average temp is going up and days are getting longer. I suspect it has to do with the longer wavelengths and slightly less chance of a cold and dry pattern. 

As far as the LR pattern, I'll let those of you who know more break it down. However, to me it looks like the trough wants to set up a touch farther west, which should give us more chances than we've had this week. Question is, will it set up too far west and give us rainy cutters that benefit Oklahoma and Missouri, or potentially give us a shot at some over running wintry precip followed by serious cold. 

[nrgjeff]

East Asia pressure charts are bullish for the Southeast US.

ADDITION: @Carvers Gap longer post this page is rock solid. February is more susceptible to the NW jogs (esp La Nina) with SER attempts. Sharp blocking would keep such SER attempts modest. Honestly don't want any SER for southeast Tenn. Just the seasonal jet stream less South (Jan pattern in Feb) would help.

From https://psl.noaa.gov/map/clim/glbcir.quick.shtml

[Bigbald]

12z gfs is a cutter parade until hr 320, ya know, the sweet spot of all modeling, which blanks west tn but hammers the east.  Of course this will be gone by 18z.

[Weathertree2]

Huge model swings  from  run to run  for sure! 

[Holston_River_Rambler]

I hate to say this, but once the next storm cuts, I kinda think we're going to back to watching to see if the shortwave can kick out of the southwest again. If it does in time, somebody gets some snow, if not, cutters gonna cut. If it had kicked out more at 12z, we'd be back to a snow after, but as it played out, we had to wait until the next cutter to pull through. IMO all that depends on the strength and position of the ridge off or on the west coast. 

A couple of pattern obs. though.  1) Big bomb storm could do some oddball temporary blocking and 2) at least the shortwaves that get stuck in the southwest aren't getting sheared out like they are now, regardless of when they eject. 

 

[Carvers Gap]

12z Euro pushing that next front even further into the forum area.  Nice look at 210.

[Holston_River_Rambler]

6 hours ago, Carvers Gap said:

 If it comes to pass, the GFS nailed this from d16.  I think there is a pic of it in the banter thread

Happy hour GFS run from Jan 19, for Feb 2 - 4:

 

 

 

12z Euro for Feb 2 - 4, lol:

Thankfully no apocalyptic totals though: