January 2021 Medium/Longterm Pattern Discussion.

[Carvers Gap]

The GEFS Extended from yesterday shows the reversal which is modeled to occur over Canada.  This reversal has been accurately modeled for a couple of weeks.  The cold lifted out of Canada last weekend, but check this out.  First image is the 13-20th.  Second image is 24-31st.  Very cold air spills into western Canada.  I think Holston's SSW previous discussions have merit.  If those two maps verify, IMHO that is the direct result of the SSW.  I am seeing ensembles move to this look at 12z today, especially the GEPS and GEFS.  The SSW has basically displaced lots of cold off the pole.  I agree with John that the NAO is likely being augmented by the strat stuff.   Modeling has been trending towards this look for about the past 36 hours.  

[Daniel Boone]

13 minutes ago, Carvers Gap said:

The GEFS Extended from yesterday shows the reversal which is modeled to occur over Canada.  This reversal has been accurately modeled for a couple of weeks.  The cold lifted out of Canada last weekend, but check this out.  First image is the 13-20th.  Second image is 24-31st.  Very cold air spills into western Canada.  I think Holston's SSW previous discussions have merit.  If those two maps verify, IMHO that is the direct result of the SSW.  I am seeing ensembles move to this look at 12z today, especially the GEPS and GEFS.  The SSW has basically displaced lots of cold off the pole.  I agree with John that the NAO is likely being augmented by the strat stuff.   Modeling has been trending towards this look for about the past 36 hours.  

Now that is 95-96 looking. Nw to SE orientation. That'll get r done ! Miller B transfer A hybrids . Although , NAO block is a little displaced further south than 95-96. "50-50" displaced south as well. IF this comes to fruition , don't know what difference that will make in storm tracks compared to 95-96. I'm thinking maybe better for areas further south and west.  Great for all actually.

[John1122]

The Euro has now moved some pretty cold air into our region inside of D10. Looking back from around January 1st, I'm actually more surprised we've seen several wintery chances from then til Jan 15th or so than I am that the cold looks to be moving in around January 20th and beyond. I expected much less favorable weather during these past couple of weeks and modeling was showing that at the time. But as we approach verification time the NAO tends to remain negative and we stay on the cool/warm roller coaster with embedded snow/wintry chances based on timing. We have a good cold shot coming with another wintry chance in a few days.

[Carvers Gap]

25 minutes ago, John1122 said:

The Euro has now moved some pretty cold air into our region inside of D10. Looking back from around January 1st, I'm actually more surprised we've seen several wintery chances from then til Jan 15th or so than I am that the cold looks to be moving in around January 20th and beyond. I expected much less favorable weather during these past couple of weeks and modeling was showing that at the time. But as we approach verification time the NAO tends to remain negative and we stay on the cool/warm roller coaster with embedded snow/wintry chances based on timing. We have a good cold shot coming with another wintry chance in a few days.

Yeah, good find.  When the EPS is cold after d10, that would likely verify much colder if true.  BN temps in Jan are cold!  Certainly looks like the strat stuff is showing up.  Modeling has a tendency to change quite quickly once those effects get to our latitude.  Guessing this is as a result of the early Jan SSW but not certain.  I “think” there is another perturbation(think that is a word?) later this month, so modeling could be sensing that.  But with the GFS last week really getting this cold back into Canada, makes me think this is due to the early Jan SSW.  With such a sudden reversal in the lower 48, really seems like SSW stuff...now, let’s just hope this stuff doesn’t hold in the West like what occurred in Nov.  I think this time around the -NAO likely forces the flow into the East this time after if first ventures into the West. 

[snowmaker]

When cold starts showing up inside day 10 it gets alot more realistic that it may be latching onto something. Hopefully it will continue and expand in the next few days of runs. If we are truly going to get colder and get that full latitude trough in late january we should start to see models converge on that idea pretty soon. Watching the DT video this morning he thinks a overrunning situation is in the cards as we move into late January.

[John1122]

NAM has some good looking snow showers moving across the area and another clipper poised to follow at the end of it's run. 

[John1122]

GFS has nearly forum wide accumulations. 

[John1122]

Long range GFS fridigity. 

[Daniel Boone]

  Apparently, some on air Mets don't keep up to date on latest guidance . A couple local Stations Mets obviously going by earlier model data..  They're doing the same as they have with every snow potential event so far this Season.

    I wonder if anyone calls them on that. Why do they not learn ? Oh well. I always was a stickler for accuracy. Tbh, some are just there for the Job. 

[John1122]

UKIE has two systems in the next 5 days that do pretty well  for a lot of the area. 

[snowmaker]

Yes, this would be a nice pickup for west and northern middle tn. And get us ready for what the rest of the month brings, hopefully everyone in tennessee will be getting some good action as we get into later Jan and early Feb.

[John1122]

MRX really downplaying any accumulation outside of where banding sets up Friday night into Saturday but says accumulation will happen under the bands. Which for some reason they say are more likely in NETN/SWVA (which I don't really see why they say that other than that they always say that with any potential event)  but they feel short term/hi-res models will likely be the only thing that sniffs them out once the event is very close.. . Regardless, the GFS was particularly nice at 06z with the potential on the 1st wave. 

[John1122]

Both systems on the 06z GFS by midnightish Monday.

[Holston_River_Rambler]

Ukie, RGEM, NAMs all show some squally type snow showers:

 

 

The 6z NAM 3km almost has a squall line moving though east TN overnight Friday into Saturday. I will be interested to see if radar looks anything like this when it happens:

I found one band with a 37 dbz return. Look at the forcing into the DGZ:

 

Sorry Stovepipe, I couldn't resist:

 

 

[Holston_River_Rambler]

For you SREF freaks (yeah I'm talking to you!) who've always wanted to see that one member:

ARW core:

 

NBM core:

 

The bottom larger images are the control for each run (right) and mean (left)

[fountainguy97]

29 minutes ago, Holston_River_Rambler said:

Ukie, RGEM, NAMs all show some squally type snow showers:

 

 

The 6z NAM 3km almost has a squall line moving though east TN overnight Friday into Saturday. I will be interested to see if radar looks anything like this when it happens:

I found one band with a 37 dbz return. Look at the forcing into the DGZ:

 

Sorry Stovepipe, I couldn't resist:

 

 

Very good consensus for a pretty large NW event. Just waiting for the high res to get in range. GFS is very bullish still. 
 

 

[Holston_River_Rambler]

I'm getting a little more interested in the second piece of energy (now at the end of the NAM run):

 

It almost has that "traditional" clipper look to it:

 

Upper/ mid Mississippi valley to TN valley. 

RGEM is less aggressive with precip. development:

But, @John1122 I seem to remember you saying that models sometimes have a hard time with these systems. Honestly, I haven't been looking at models long enough to know how these things can play out. (seems like it's been since I was in highschool (late 90s) since we had one)

[Holston_River_Rambler]

 

His tweet was aimed more at the midwest, but I suspect some of that applies in the TN valley too. 

[Carvers Gap]

One rule of thumb is that clippers really like to pull north as the event gets closer.  There are certainly notable exceptions to the rule, but normally we want that clipper going well south.

[Daniel Boone]

2 minutes ago, Carvers Gap said:

One rule of thumb is that clippers really like to pull north as the event gets closer.  There are certainly notable exceptions to the rule, but normally we want that clipper going well south.

    Yeah, and typically a sharp cutoff on southern boundary.  Hopefully, blocking will aid in the southward path. 

[tnweathernut]

1 minute ago, Carvers Gap said:

One rule of thumb is that clippers really like to pull north as the event gets closer.  There are certainly notable exceptions to the rule, but normally we want that clipper going well south.

Lots or ridging in southern Canada to Greenland.  Hopefully this will help us.  I think it's pretty much a lock for snow showers from the system Saturday.  The first system sets up a brief 50/50, so maybe this will also keep the second system far enough south to bring some energy through the TN Valley.

It might be wise to start a thread for the Saturday deal.  May even want to lump early week in with it since these events look relatively minor and both northern stream dominant.  This way, we can keep the longer range discussion separate.

Anyone feeling lucky?

[Holston_River_Rambler]

Just now, Holston_River_Rambler said:

Here's to hope:

 

1 hour ago, tnweathernut said:

Anyone feeling lucky?

I went for it. Jan 2021 Squallicane

[John1122]

3 hours ago, Holston_River_Rambler said:

I'm getting a little more interested in the second piece of energy (now at the end of the NAM run):

 

It almost has that "traditional" clipper look to it:

 

Upper/ mid Mississippi valley to TN valley. 

RGEM is less aggressive with precip. development:

But, @John1122 I seem to remember you saying that models sometimes have a hard time with these systems. Honestly, I haven't been looking at models long enough to know how these things can play out. (seems like it's been since I was in highschool (late 90s) since we had one)

We had an ultra clipper a few years ago that models just downplayed til the end besides the rgem, which began to catch on about 48 hours out.  Border counties from the mid-state east got 3-6 inches. I believe 2-4 was fairly wide spread elsewhere. Model totals rose to the very last run and most never caught up. 

[John1122]

4 minutes ago, Blue Moon said:

Was that the January 15-16, 2018 snowfall that slid from W KY to East Tennessee?

This was in the January 2016, 19th or 20th. 

[John1122]

That said, the biggest difference in that event and this one was that one was extremely cold. Models busted like crazy on that aspect. 72 hours out the NAM had heavy precip but had it as rain or freezing rain over a lot of the area. By event time temps were between 19-24 and it was all snow. 84 hours out models were showing 1-3 inches with a few dollops. At 48 hours the RGEM had started showing some 4-6 inch totals. During the event the HRRR started showing the 5-6 inch totals.

[Daniel Boone]

24 minutes ago, John1122 said:

This was in the January 2016, 19th or 20th. 

Oh yeah. Remember that one well John. Models had south west/central KY  getting up to 8" then rapidly diminishing as system trekked eastward.

        I recorded 4.7" at my home in Jonesville then. Western Lee, Claiborne had reports of 6 to 7 inches of which were verified by pictures.

[John1122]

8 minutes ago, Daniel Boone said:

Oh yeah. Remember that one well John. Models had south west/central KY  getting up to 8" then rapidly diminishing as system trekked eastward.

        I recorded 4.7" at my home in Jonesville then. Western Lee, Claiborne had reports of 6 to 7 inches of which were verified by pictures.

Looking back at the thread, there was some mixing in some areas but it was way colder than inituallly forecast. MRX had valley highs in the upper 30s. No one seemed to make it above 27. 2-6 inches plus ice/sleet underneath were common here. That may have been the last great clipper we've had here in winter. 

[Daniel Boone]

36 minutes ago, John1122 said:

Looking back at the thread, there was some mixing in some areas but it was way colder than inituallly forecast. MRX had valley highs in the upper 30s. No one seemed to make it above 27. 2-6 inches plus ice/sleet underneath were common here. That may have been the last great clipper we've had here in winter. 

Yep. Then the big East Coast Storm hit the 23rd. That one varied big time in the area. Mixing, Downsloping issues in parts of area. Wound up with just 4" from It. Well below forecasted amounts. 

[Shocker0]

4 hours ago, John1122 said:

This was in the January 2016, 19th or 20th. 

We got around 9-10 inches here in January 2016 but it was on January 22nd in Crossville. I do remember a couple days before that we only got about two or three inches from the one you're talking about and areas east of here got a lot more I think. It must've been warm on the 21st because I remember almost all of it had melted by the time the big storm hit on the 22nd.

The 22nd we were supposed to get 2-4 inches but it changed over from rain several hours earlier so we got a lot more than expected. It's the most snow I've had since moving to Crossville in 2012.

[Shocker0]

3 hours ago, Daniel Boone said:

Yep. Then the big East Coast Storm hit the 23rd. That one varied big time in the area. Mixing, Downsloping issues in parts of area. Wound up with just 4" from It. Well below forecasted amounts. 

Yep and most midstate areas received much more than forecast. Nashville eastward was common 8-12 inch amounts and then it trickled off some once you got east of the Plateau I believe