Jan Medium/Long Range Disco: Winter is coming

[Ralph Wiggum]

3 minutes ago, Weather Will said:

About the same....slightly less snow mean at 18Z.

In fairness you should compare the valid 12z Sunday maps.

[NorthArlington101]

What I've been trying to track is the 50th percentile on the ens... so the median vs. the mean. If I remember my STAT 101 (I might not) it's a better control for outliers, both positive and negative.

that said, here is the 18z. It's better than 12z in the metro, little worse out west, but it's mostly just been oscillating back and forth.

[psuhoffman]

11 minutes ago, WinterWxLuvr said:

Comparison to prior?

The changes are noise, its virtually the same 

[StormyClearweather]

[NorthArlington101]

Just now, StormyClearweather said:

I'm giving this a "true, but misleading" like Snopes. If you check the next 6 hr interval (so looking at 132 at 18z), it's trended colder run over run. Can cherry pick these little shifts anyway ya really want to at range.

[Terpeast]

1 minute ago, StormyClearweather said:

Not sure it’s necessarily trending warmer, but rather just moving things faster

[AtlanticWx]

2 minutes ago, StormyClearweather said:

the trend for a faster storm is pretty evident here

[StormyClearweather]

1 minute ago, NorthArlington101 said:

I'm giving this a "true, but misleading" like Snopes. If you check the next 6 hr interval (so looking at 132 at 18z), it's trended colder run over run. Can cherry pick these little shifts anyway ya really want to at range.

Thanks, you're right. I wasn't thinking about the speed-up. 

[psuhoffman]

2 hours ago, umdterps29 said:

Thanks! I’m torn between heading out to Deep Creek for the weekend or hanging home and seeing what happens here. Feels like Deep Creek is the more sensible bet if i don’t want to risk disappointment

If it trends north/west I will head out to either Snowshoe, Timberline, or maybe Seven Springs in PA.  Wish Blue Knob had lodging anywhere near the mountain, its a decent little spot but impossible to get to in a storm.  That was my go to when I was at PSU.  

2 hours ago, Ji said:

This could be a season saving storm. Without out we are looking at 2 cutters and no snow by January 15z.

This storm is critical. We could be at above average snow on Monday for the season

It’s like your fantasy rb scoring a td in the first quarter if it happens

Don't sleep on late Jan into Feb regardless of what happens this weekend.  I still think our best stretch is after Jan 20th.  Jan 20th seems to be a sweet spot in similar years that showed up.  1966, 1987, 2016 all produced big snow around or just after Jan 20th and just about nothing before.  

2 hours ago, CAPE said:

Storms would track NW with the trough in that position though.

This is where it would really get good for the MA as advertised. More mature NA block with lower heights shifting into the 50-50 position, and the Aleutian low is in a better spot with a ridge building towards the western US. If this is real the latter part of Jan is gonna be interesting.

I am really starting to like the January 20th on period.  The GEFS needs to get a clue but the EPS and GEPS are setting us up nice for the end of January.  Fits nino climo also...I know everyone is focused on Feb, and thats possible 1958 and 2010 are in the analogs, but 66, 87, 2016 all had the best stretch the end of January so I'm not ruling that out.  IMO the reason Feb looks so much better in the means than Jan on a nino composite is because often the first 1/3 of January is a shit show and skews the pattern look worse than if you just look at Jan 15 on.  To be the money period is Jan 20 through Feb.  March is a wildcard, 58, 78 were awesome, 2003 but most others faded by then.  

2 hours ago, nj2va said:

IMO snow depth maps are talked about too much.  Just one tool to use but too much emphasis placed on those.

I am reducing my seasonal total from 4" to 1" because of the depth maps 

1 hour ago, Stormchaserchuck1 said:

A few days ago there wasn't a primary low in Kentucky. You guys can say it's trending better but PSU actually posted something good about where the thermal boundary is. I think in future trend, the cold air may get cutoff. It would be different if there was a low pressure in the N. Pacific ocean, and for snowstorms in the Mid Atlantic, that is a major piece. I've seen this pattern set up a lot over the last few Winters, and we are still far ways out (5-6 days), and they almost always trend warmer to verification. Over the PNA/GOA region, especially lately, you need a Low , not a High. It has downstream effects not completely estimated in the model at this range (5-6 days) from what I've seen. 

I am not dismissing your concerns. if we do fail this would be the most likely way, BUT the compressed flow between the western trough and the 50/50 make this more favorable than normal.  Sometimes regional geographical features can offset the hemispheric ones.  Without that compression between those features you're right this would not be much of a threat.

[Jebman]

Seven Springs webcam https://www.7springs.com/the-mountain/mountain-conditions/mountain-cams.aspx

[cbmclean]

2 minutes ago, psuhoffman said:

I am really starting to like the January 20th on period.

I just saw Webb mentioning that it appears that another high was targeting central Asia which would in turn lead to another EAMT+ event which would then lead to another jet extension.  Have you seen anything about that?  That turned my blood cold.  The continental thermals are just starting to try and heal from the mauling of that last pac puke.

[psuhoffman]

4 minutes ago, cbmclean said:

I just saw Webb mentioning that it appears that another high was targeting central Asia which would in turn lead to another EAMT+ event which would then lead to another jet extension.  Have you seen anything about that?  That turned my blood cold.  The continental thermals are just starting to try and heal from the mauling of that last pac puke.

We want a jet extension just not as strong as the last one. 

[clskinsfan]

4 minutes ago, cbmclean said:

I just saw Webb mentioning that it appears that another high was targeting central Asia which would in turn lead to another EAMT+ event which would then lead to another jet extension.  Have you seen anything about that?  That turned my blood cold.  The continental thermals are just starting to try and heal from the mauling of that last pac puke.

At least we have some colder air on this side of the hemisphere now. We should be able to withstand a short pac puke episode. 

[psuhoffman]

23 minutes ago, StormyClearweather said:

 

21 minutes ago, Terpeast said:

Not sure it’s necessarily trending warmer, but rather just moving things faster

It’s sped up about 6 hours in the last 4 runs. 

this isn’t perfect but these frames are a better comparison when the storm is at a more similar spot in its pass which matters more. The change is noise imo. 18z looks slightly colder but with the 6 hour adjustment now it’s maybe an hour behind 0z so it’s a wash imo. The eps has been holding with only noise changes run to run today. 

[wxdude64]

2 minutes ago, psuhoffman said:

 

It’s sped up about 6 hours in the last 4 runs. 

this isn’t perfect but these frames are a better comparison when the storm is at a more similar spot in its pass which matters more. The change is noise imo. 18z looks slightly colder but with the 6 hour adjustment now it’s maybe an hour behind 0z so it’s a wash imo. The eps has been holding with only noise changes run to run today. 

I-81 and west takes this in a heartbeat. 

[psuhoffman]

4 minutes ago, clskinsfan said:

At least we have some colder air on this side of the hemisphere now. We should be able to withstand a short pac puke episode. 

We want the jet to extend enough to push the ridge back into western N America and establish a trough in the N Pacific.  We just don't want it to go crazy like the last one.  The reason we might get a relax and a cutter next week is because the jet retracts too much and we end up with nina like pacific forcing for a short time.  

[clskinsfan]

Its actually quite a bit colder up into PA. Which is a good sign I think. 

[Terpeast]

13 minutes ago, psuhoffman said:

 

It’s sped up about 6 hours in the last 4 runs. 

this isn’t perfect but these frames are a better comparison when the storm is at a more similar spot in its pass which matters more. The change is noise imo. 18z looks slightly colder but with the 6 hour adjustment now it’s maybe an hour behind 0z so it’s a wash imo. The eps has been holding with only noise changes run to run today. 

Awesome, thanks for putting that together. If this does verify, its going to be a nailbiter out here. 

[nj2va]

We can start extrapolating the NAM this time tomorrow. 

[Eskimo Joe]

2 minutes ago, nj2va said:

We can start extrapolating the NAM this time tomorrow. 

Thank the gods

[Stormchaserchuck1]

1 hour ago, jnis said:

Hi Stromchaserchuck1...,

I appreciate your's, and everybody's analysis as  we close in on a potential snow threat. You seem to be interpreting some the data differently then a lot of the other experienced and knowledgeable contributors. Could you please elaborate on the meteorology regarding your last two statements. I'm hoping to expand my meteorological knowledge. Thanks! 

Hello, Thanks. I have been observing weather models almost daily since 2016, and I have found them to underestimate the amount of surface-layer warmth of a -PNA pattern more times than not. If you look at a historical composite of DCA or BWI snowstorms, the strongest feature with a 50/50 low is a GOA/Aleutian island trough. On the models we have that needed trough digging into the West Coast US, instead. Here is a 500mb correlation map with January N. Pacific:

https://ibb.co/sJPTkdB

https://ibb.co/10d2BGN

As you can see, that N. Pacific region posts a +0.53 500mb correlation over DCA/BWI at that time. Here is the 500mb map of 1 day before the storm moves NE. The cold air is pretty cutoff. 

 

https://ibb.co/tsF0xLh

 

In my experience, places along I-95 do not do well in these setups because the surface temperature ends up reaching 35-36 degrees. I know we are getting closer to where the entire N. Hemisphere pattern is of less concern, but it is still 5-6 days away, which I find is still valid for a trend away from snowstorm (I-95). I'm just saying this same scenario has happened that way 9/10x recently, so watch for the same model error/adjustment. I would say mostly rain to <1" for Balt/DC. 

[aldie 22]

4 minutes ago, Terpeast said:

Awesome, thanks for putting that together. If this does verify, its going to be a nailbiter out here. 

It hasn't really snowed much since you have been back has it? Leesburg is definitely a tad better than Ashburn. After I left Leesburg I ended up in Lansdowne and it was always just a little less. It will be interesting how Aldie is as I'm south but more west. This could be a fun one

[Terpeast]

18 minutes ago, aldie 22 said:

It hasn't really snowed much since you have been back has it? Leesburg is definitely a tad better than Ashburn. After I left Leesburg I ended up in Lansdowne and it was always just a little less. It will be interesting how Aldie is as I'm south but more west. This could be a fun one

I’ve only seen measureable snow twice and both were half an inch or less. Leesburg or west of 15 is probably better than Ashburn, but coming from Vienna, Ashburn probably will do better in i-95 fall line setups like this one

[WEATHER53]

2 hours ago, psuhoffman said:

We had this discussion many times over the years.  I hate when it becomes an argument over definitions.  I could care less what we call them.  The problem is for the "purists" that define any transfer as a miller b, we then HAVE to differentiate between northern stream dominant SW's that transfer and STJ dominant transfer storms.  The best definition system I've seen classifies the later as "hybrid" systems.  And by that definition system our best storms are almost all hybrids.   

Pure miller a storms usually are trucking and moving too fast to dump prolific totals.  The transfer process actually slows down the system some, plus often when a primary west of the apps transfers its because its blocked to some extent.  We also run the risk of being too far west for a pure miller a.  They sometimes end of coastal scrapers for our area and nail NYC, especially in a Nina!  A primary into the TN valley pretty much guarantees we don't miss out on the party, so long as it transfers in time for us to stay cold enough.  Additionally getting the wave to amplify to our SW opens the door to prolific WAA snows before the storm even gets going.  Our really big storms are when we get a foot of snow from overrunning before the coastal even gets going.  

Miller a/b hybrids are actually our best storms.  But the people that classify everything as A/B scare the crap out of some when they classify them as miller b and they suddenly think of every NS jump storm that screwed us over and hit New England.  

I know you know this, we've had this conversation before...but thought it was time to bring it up again for all the new members since the last time we got to actually go over this...since its been so freaking long since we actually got to discuss a legit snow threat in this kind of detail.  

This is great  info and you are right about getting nervous in transfers. I love how you break the difference in the nature of transfers down to NS vs low moving from south into TN and then transferring , Did I get that right? Thsnks 

[87storms]

Hello, Thanks. I have been observing weather models almost daily since 2016, and I have found them to underestimate the amount of surface-layer warmth of a -PNA pattern more times than not. If you look at a historical composite of DCA or BWI snowstorms, the strongest feature with a 50/50 low is a GOA/Aleutian island trough. On the models we have that needed trough digging into the West Coast US, instead. Here is a 500mb correlation map with January N. Pacific:
https://ibb.co/sJPTkdB
https://ibb.co/10d2BGN
As you can see, that N. Pacific region posts a +0.53 500mb correlation over DCA/BWI at that time. Here is the 500mb map of 1 day before the storm moves NE. The cold air is pretty cutoff.    https://ibb.co/tsF0xLh   In my experience, places along I-95 do not do well in these setups because the surface temperature ends up reaching 35-36 degrees. I know we are getting closer to where the entire N. Hemisphere pattern is of less concern, but it is still 5-6 days away, which I find is still valid for a trend away from snowstorm (I-95). I'm just saying this same scenario has happened that way 9/10x recently, so watch for the same model error/adjustment. I would say mostly rain to

We need to adjust the slope of the regression line towards zero to account for the weekend rule.

I’m kidding, but I do think there’s been times where cad (assuming that’s in play) has been under-modeled. That, along with a quicker arrival of precip, might offset some of the initial temp issues.

[Ji]

18 minutes ago, Terpeast said:

I’ve only seen measureable snow twice and both were half an inch or less. Leesburg or west of 15 is probably better than Ashburn, but coming from Vienna, Ashburn probably will do better in i-95 fall line setups like this one

that rain snow line has shifted since the 80's quite a bit. I used to be comfortable living in Herndon...then i think it went to ashburn and now its just wests of Leesburg ... scary

[jnis]

36 minutes ago, Stormchaserchuck1 said:

Hello, Thanks. I have been observing weather models almost daily since 2016, and I have found them to underestimate the amount of surface-layer warmth of a -PNA pattern more times than not. If you look at a historical composite of DCA or BWI snowstorms, the strongest feature with a 50/50 low is a GOA/Aleutian island trough. On the models we have that needed trough digging into the West Coast US, instead. Here is a 500mb correlation map with January N. Pacific:

https://ibb.co/sJPTkdB

https://ibb.co/10d2BGN

As you can see, that N. Pacific region posts a +0.53 500mb correlation over DCA/BWI at that time. Here is the 500mb map of 1 day before the storm moves NE. The cold air is pretty cutoff. 

 

https://ibb.co/tsF0xLh

 

In my experience, places along I-95 do not do well in these setups because the surface temperature ends up reaching 35-36 degrees. I know we are getting closer to where the entire N. Hemisphere pattern is of less concern, but it is still 5-6 days away, which I find is still valid for a trend away from snowstorm (I-95). I'm just saying this same scenario has happened that way 9/10x recently, so watch for the same model error/adjustment. I would say mostly rain to <1" for Balt/DC. 

Thank you for the more detailed response. I appreciate you time. I see what you mean based on the last map you posted. Hopefully, there will be enough cold air for 95 east to get in on the action, but a rain/ snow line setting up near the  95 corridor seems fairly typical. Happy New Year.

[psuhoffman]

21 minutes ago, WEATHER53 said:

This is great  info and you are right about getting nervous in transfers. I love how you break the difference in the nature of transfers down to NS vs low moving from south into TN and then transferring , Did I get that right? Thsnks 

Yes, there is a HUGE difference between a wave coming at us from the southwest tracking into the TN valley before transferring to a coastal and a northern stream SW diving out of the NW that develops a coastal storm.  

[Fozz]

Just now, psuhoffman said:

Yes, there is a HUGE difference between a wave coming at us from the southwest tracking into the TN valley before transferring to a coastal and a northern stream SW diving out of the NW that develops a coastal storm.  

Was Feb 10, 2010 a purely NS-driven storm? Or did it phase with any STJ component?

[Ji]

If we didnt have this storm....where is the next threat coming from? Nothing really stood out looking at the long range? Maybe the 12th/13th?