Jump to content

Met Winter 20-21: Pattern Drivers & Evolution


Recommended Posts

  • Replies 4.4k
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Popular Posts

While there's reasonable agreement on a -AO and -NAO persisting into early January, there is some uncertainty WRT whether or not the Pacific side offers any help or not. The EPS develops a +EPO into e

I'm starting to get a little more excited for early-mid December. It looks like the Pacific jet will retract significantly, which is the real reason for the retrograding Alaskan LP. Upper level diverg

I think that we are going to see a pretty impeccable 500mb pattern after January 10th.    The -NAO originally forced by wave breaking (which is occurring in the very near future) will become

Posted Images

18 minutes ago, Nchaboy said:

Dose it matter how long it last? 

Good question, I would assume it would prolong/enhance the effects, but I was mostly just pointing it out because it is an impressive tidbit. It's not too often that the zonal flow is reversed for such a long period!

Link to post
Share on other sites
3 hours ago, Webberweather said:

Of the storms I showed in an animation yesterday, this is the most quintessential example of what many would deem a crappy/garbage N Pacific pattern coinciding w/ a historic east coast blizzard.

 

Seems like I've been beating a dead horse here but, you'll virtually always have a legit chance to get a really big storm on the I-95 corridor when there's a giant west-based -NAO involved.

 

compday.lwq9ElFspi.gif.4898bc0ed84d133d7f7e8ab14cfdd019.gif

 

19780205-19780207-5_78.jpg.bc0a9a059600f7b20f964437bdadbfef.jpg

 

 

Yeah it helps that west based -NAOs are practically on top of the east coast and so it has a lot more control over the pattern than a more distanced -EPO. Sure -EPO can keep the Pacific air away and pump up the PNA making the area colder, but there's a lot more a west-based -NAO can do to a storm near the east coast:

 

- can make 50/50 lows stall around the 50/50 area, ensuring cold air flow into the region

- it can deter the formation of offshore high pressure that causes warm southerly flow, instead favoring high pressure to the north that supplies colder air

- the point above also suppresses lows from going too far north, we're even seeing this happen soon with cutters getting shredded and transferring offshore

- the nature of the block slows storms down letting them last longer and thus can cause bigger snow totals

 

and that's just what I can think of off the top of my head lol. In January, as long as the PNA isn't as negative as it is now, just a west-based -NAO can help load the chances in favor of some pretty epic snowstorms if things go right, for the above reasons

 

@Webberweather great job handling the events as of late! You and others are helping me learn a lot about how these sorts of things work

Link to post
Share on other sites
12 minutes ago, CCB! said:

Lot of great contributions in here this morning. Just two additional visuals to add. The well discussed massive -NAO block is coming & should be well positioned. This is becoming clearer moving up in time. What's also becoming clearer is that the PAC improvements are starting to show up on NWP too, partially attributable to the aforementioned block itself as @PB GFI& others in here have been stating. There's a bit of retraction, but the height field extending poleward from the west coast up through W-Canada is particularly notable. 

 

ecmwf-ens_z500a_npac_fh192_trend (1).gif

 

The ensemble mean tells the bigger story here, but the OP is more robust in showing this since smoothing is not an issue, especially out to day nine.

 

ecmwf_z500a_npac_fh216_trend (1).gif

 

 

 

Wow, so we could expect the pattern to shift a little earlier than we thought if the retrogression and Pac shakeup is trending faster

Link to post
Share on other sites
6 hours ago, Webberweather said:

Of the storms I showed in an animation yesterday, this is the most quintessential example of what many would deem a crappy/garbage N Pacific pattern coinciding w/ a historic east coast blizzard.

 

Seems like I've been beating a dead horse here but, you'll virtually always have a legit chance to get a really big storm on the I-95 corridor when there's a giant west-based -NAO involved.

 

compday.lwq9ElFspi.gif.4898bc0ed84d133d7f7e8ab14cfdd019.gif

 

19780205-19780207-5_78.jpg.bc0a9a059600f7b20f964437bdadbfef.jpg

No storm has come close to that storm up here in RI. I was 17. We had 3 feet of snow in the street. 20+ foot drifts all over the neighborhood. Even higher in downtown Providence around buildings. 4 days before they even began to clear the streets. We've had plenty of big storms QPF and wind wise but none have made anyone around here say that matched the blizzard of 78. Always it was a good one but didn't top 78 blizzard!!!

Link to post
Share on other sites
3 minutes ago, Nick Psomaras said:

 

Wow. I apologize for undermining you hahaha

Not at all! I went the simple route b/c it was indeed that beautiful. But great commentary is always favored :) 

Link to post
Share on other sites
On 12/29/2020 at 11:11 PM, Grace said:

 

East Asia Rule suggests a trough in east somewhere in the JAN 6-10 time frame. 6-10 day correlation from the 30th

20201229_230557.jpg.7043f3df06093de2a308737601109867.jpg

 

 

More in context of your comments, East Asia Rule suggests another trough somewhere in the JAN 13-17 time frame, which is close to the timeframe you're suggesting. 

 

20201229_230532.jpg.db1c2811e06b81aacecb509e84a29deb.jpg

 

Another teleconnection I use suggest the same as EAR. These teleconnections have performed so much better than the models have. 

 

Check this out.

12z Euro East Asia, Dec 30-JAN 1

20201231_125902.thumb.jpg.36ea17523c1585ba0b9171373a04e671.jpg

 

12z Euro JAN 9-10 East U.S.

20201231_125805.thumb.jpg.f8ecfb60bbf8b3d1813e59b380bcfe9e.jpg

 

Not bad...lol. 

 

 

 

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...