Model Output Discussion - Autumn 2018

[lassie23]

1 hour ago, blizzard81 said:

Late October fog = cold snowy winter. Simple as!

Another convert to the OFI October Fog Index

[Mike Poole]

1 hour ago, CreweCold said:

What a pretty picture...

A tri-pronged attack on the trop vortex and a tanking AO

One messed up vortex!  But at the same time another strengthening vortex, in the stratosphere, here zonal mean zonal wind at 10hpa:

Now poking it's nose above average and GFS taking it higher.  So as we enter November and progress towards winter proper, it looks the two vortexes are almost totally disconnected.  I think this gives the potential for some interesting cold weather early into winter or maybe before, depending on location (won't get IMBY in this post!).  

On the other hand, a disconnect between the trop and strat vortexes won't continue indefinitely so this will need to be watched #FrontLoadedWinter

 

[mb018538]

Good post mike - this is why when people were getting a bit giddy in early October with a slight dip in the strat, I wasn’t overly interested.....it can and quickly has accelerated. Equally you shouldn’t now get too downbeat that it has picked up! 

[Cheshire Freeze]

3 minutes ago, Mike Poole said:

One messed up vortex!  But at the same time another strengthening vortex, in the stratosphere, here zonal mean zonal wind at 10hpa:

Now poking it's nose above average and GFS taking it higher.  So as we enter November and progress towards winter proper, it looks the two vortexes are almost totally disconnected.  I think this gives the potential for some interesting cold weather early into winter or maybe before, depending on location (won't get IMBY in this post!).  

On the other hand, a disconnect between the trop and strat vortexes won't continue indefinitely so this will need to be watched #FrontLoadedWinter

 

Indeed...and it must be noted that most of the legendary winters featured an early Canadian warming...

 

9 minutes ago, lassie23 said:

Another convert to the OFI October Fog Index

Larry, this is not the place for 'inane drivel' 

[Cheshire Freeze]

Looking at the forecast zonal winds plot above, my main concern is that going forward as soon as the general trop pattern de-amplifies sufficiently, we'll end up as we were a couple of years back. We ended up (after a promising start) with a displaced Scandi high which became an annoying Sceuro feature, with heights not able to lower to our S and SE. 

[Mike Poole]

5 minutes ago, CreweCold said:

Looking at the forecast zonal winds plot above, my main concern is that going forward as soon as the general trop pattern de-amplifies sufficiently, we'll end up as we were a couple of years back. We ended up (after a promising start) with a displaced Scandi high which became an annoying Sceuro feature, with heights not able to lower to our S and SE. 

Hopefully not that front-loaded! 

I take it you are recalling Dec 2016, MO contingency planners forecast really going for cold and, to be honest it started well... and then gave up the ghost about Dec 7th?  That one? 

Surely 2018 that year of weather giving, will do better!

[Cheshire Freeze]

2 minutes ago, Mike Poole said:

Hopefully not that front-loaded! 

I take it you are recalling Dec 2016, MO contingency planners forecast really going for cold and, to be honest it started well... and then gave up the ghost about Dec 7th?  That one? 

Surely 2018 that year of weather giving, will do better!

Yes that one!

Shudder!

I knew it was all over as soon as that Greenland HP failed to manifest in latter November- a tell tale sign the trop pattern was about to be overrun.

Edited October 16, 2018 by CreweCold

[mpkio2]

Its brilliant to see so many posters come out of their Summer Hiberanation, gearing up during this Autumn and to the coming winter!

This place is buzzing tonight!!!

But who can't get excited when your a coldie and the ECM teases you with this....

All fun and games of course just for now, cause we all know how fate likes to tease us and when it looks all too good to be true, its snatched away before our very eyes!

But there is much to be optimistic about this year! Let the roller-coaster that is model watching, commence!

[damianslaw]

44 minutes ago, mb018538 said:

Good post mike - this is why when people were getting a bit giddy in early October with a slight dip in the strat, I wasn’t overly interested.....it can and quickly has accelerated. Equally you shouldn’t now get too downbeat that it has picked up! 

Didn't we have a notable strat/ trop disconnect through last winter.. helping to produce some cold shots..

[feb1991blizzard]

Nice Northerly would ensue if this run went further.

[SMU]

2 hours ago, Snowy Hibbo said:

With all due respect, you are wrong. A -EPO's downstream effects often create a Eastern trough. That is what it is known for doing, disturbing the polar jetstream up to Alaska, and bringing cold down to the Eastern Half of the United States. A -EPO if it stretches down towards the West Coast of America often gets called a joint +PNA and -EPO. So the assertion that a -EPO must go with a -PNA or vice versa is entirely misleading.

Well - Actually with respect dont turn up here & preech to me when you are wrong.

In this case when you associate the context of the post by Catacol referring to Roger Smiths post & going with the forecast of a possible 'default' loading patter for Winter - associating the September pattern with a downstream trough is 100% incorrect. - especially when the reanalysis chart proves otherwise.

But if you think its just my opinion here again is the 500 height anomaly for the record breaking high pressure over Alaska across early september.

In this scenario its 100% clear to see the troughs located in the Northern plains uo to central & you have a fat ridge on the east coast

Whilst your post has some credibility in the fact that the margins of a -EPO high & +PNA high overlap - the loading pattern for a +PNA ridge is a much better teleconnector to an East coast trough than the -EPO ridge as the latter is located further west.

Here is the October loading pattern for the PNA

Which has a trough in the EPO position.

The overlap can occur when the EPO ridge sits in a position which is east of the loading pattern centre point where the PNA is positive & the EPO is negative -

However when your looking for clarity & identity in terms of teleconnections - if you have a classic alaska centred EPO ridge the PNA will be neutral or Negative. & You will have a downstream ridge over the E/SE coast. This is totally different to a classic +PNA pattern.

vis a vee please dont turn up here & preech to me when the loading pattern & NOAA firmly indicate you are incorrect.

Edited October 16, 2018 by Steve Murr

[SMU]

@Snowy Hibbo

Even the teleconnection data shows your wrong

Reanalysis 28 Aug - 10th sept

Huge -EPO RIDGE in a classic Alaska location

Not an east coast trough in sight...

PNA metric

NOAA data shows huge -EPO & -PNA pattern traversing to +PNA / +EPO pattern.

So dont take my word for it- take the NOAA if you like.

Edited October 16, 2018 by Steve Murr

[bluearmy]

Gfs playing around with a week 2 n Pacific typhoon .......... never a bad thing to be sticking ex tropical air into the high lats into November .........

[ItNeverSnowsInWindsor]

Hoping the latest ECM run is a mild outlier!

Edited October 17, 2018 by prolongedSnowLover

[Paul]

New threads now live:

Model discussion - the hunt for cold

General model discussion