Model output discussion - heading into 2018

[karyo]

Not many comments today about the further outlook just talk about where the slush is going to be!

I was pleased to see the 12z GFS and ECM yesterday as they were showing continuous cool zonality but today things have take a turn for the worse. The jet axis is expected to change after midweek with the southwesterlies returning.

[Weather-history]

34 minutes ago, JBMWeatherForever said:

Latest UKMO fax charts looking more interesting though !

It might help if you post a link and explanation of why it is interesting,

[Polar Maritime]

15 minutes ago, nytram43 said:

Am I reading these charts wrong or is the snow line above 1000 Feet?

GFS shows snow down to around 200m NMM down to 100m, Detail will change over the next 2 days without a doubt, But interesting to watch/follow all the same as much as it is a short lived event.

Edited December 23, 2017 by Polar Maritime

[bluearmy]

1 minute ago, feb1991blizzard said:

How do you mean, the inputted starting conditions (thought they were the same for every model) or the output just formatted differently?

The data that goes into the models is not the same !!  Ecm has more starting data than gfs. I believe some time ago gfs was run with ecm starting data and it performed a little better

back to this potential ‘slider’. This is more complex than last time. The push against the system comes ostensibly from the  Pacific ridge into the pole and the Asian vortex lobe being pushed more towards Scandi rather than being able to traverse as usual to Canada. Watch the NH view to see the movement of everything. 

the models are unlikely to have the finer details worked out on that yet and the final destination could be quite a long way from what currently is being shown 

[feb1991blizzard]

8 minutes ago, bluearmy said:

The data that goes into the models is not the same !!  Ecm has more starting data than gfs. I believe some time ago gfs was run with ecm starting data and it performed a little better

back to this potential ‘slider’. This is more complex than last time. The push against the system comes ostensibly from the  Pacific ridge into the pole and the Asian vortex lobe being pushed more towards Scandi rather than being able to traverse as usual to Canada. Watch the NH view to see the movement of everything. 

the models are unlikely to have the finer details worked out on that yet and the final destination could be quite a long way from what currently is being shown 

Right, I thought it was all collected via WMO from planes, weather stations etc, I thought yes the ECM has more imputed data because its higher resolution thus more grid cubes to input data into, obviously I must have got it wrong.

Maybe that's why the GFS is worse than the ECM then, perhaps its not the mathematicians / physicians that program it then - its the data.

Edited December 23, 2017 by feb1991blizzard

[knocker]

Place your bets. A wet evening in God's Little Acre

[blizzard81]

11 minutes ago, karyo said:

Not many comments today about the further outlook just talk about where the slush is going to be!

I was pleased to see the 12z GFS and ECM yesterday as they were showing continuous cool zonality but today things have take a turn for the worse. The jet axis is expected to change after midweek with the southwesterlies returning.

Couldn't agree more. To be honest, a few hours of snow which melts within hours  I suspect doesn't really cut the mustard for many on here, especially after the last few winters. The 00z runs are a marked downgrade on last night's 12z runs. The mean uppers now back up to 5 degrees in London at the turn of the year. We should almost be used to this though after the last 7 years. I still hold out hope for the second half of January with things still bubbling in the strat for early Jan. 

[johnholmes]

32 minutes ago, feb1991blizzard said:

How do you mean, the inputted starting conditions (thought they were the same for every model) or the output just formatted differently?

Best you ask Paul but Net Wx outputs are based on GFS data with software belonging to Net Wx as far as I know?

 

[Methuselah]

One good thing from the 06Z: there might be enough rain to wash the vomit off the pavements:

[TEITS]

9 minutes ago, Ed Stone said:

One good thing from the 06Z: there might be enough rain to wash the vomit off the pavements:

This mornings output is making me sick.

[bluearmy]

Just looking at the eps clusters and there is a decent chance that the flow stays pretty flat across the Atlantic rather than pivot sw/ne as per the current direction of travel. As the suite progresses it becomes quite bipolar with a strong azores ridge covering much of the w Europe which eventually drifts to become almost sceuro by day 15 (with a capital E rather than S) as against a moderate westerly upper flow continuation 

hence the mean is pretty useless on the 00z suite in the extended as it struggles to cover both bases. 

[Summer Sun]

Any snow which does fall in the south next week will soon melt always colder in Scotland and at times northern England

[tight isobar]

Highlighted-london6z ens...

Our massive 1/2 day cold snap ?

After its back to basics.../mobile wet windy!!!

Although into new year still a few things to be keeping an' eye on.

Preety drab all in all though this morning.

Over to the 12z for some upgrades.

'Hopefully'!

[Dennis]

see the south path of the Jetstream first days next week

[joggs]

2 hours ago, JBMWeatherForever said:

Latest UKMO fax charts looking more interesting though !

Have you got them?.

[bluearmy]

Just now, joggs said:

Have you got them?.

They aren't a secret - they came out before 7am !

[northwestsnow]

9 minutes ago, bluearmy said:

They aren't a secret - they came out before 7am !

Chris Fawkes tweeting about potential for heavy snow across the pennines late boxing day to the 27th this morning-

Not sure this is related to the slider discussed this morning tho Blue

[Snowy Hibbo]

Quote

 

Now I am going to proceed to elaborate a little bit on that. So yes, we are going to Phase 4 GWO. 

Okay very important action occurring...

The EAMT is going to go positive in the next 24-48 hours.

Note the high and low gradient over Tibet and the Himalayas, thanks to the descending Siberian anticyclone.

This generates a +EAMT, this adds "fuel" to the East Asian Jet.

 

The westerly momentum generates some interesting wave activity. Which ultimately reinforces the -EPO/Alaskan High pattern, and keep the good period for snowfall in the Eastern US.

 

Eventually, we might also see a +MT over the Rockies, thanks to the forecast events. That would increase the AAM, and potentially send the GWO into Phase 5. Phase 4 in the meantime, will be held by an increase in frictional torque.

 

 

Quote

 

So the GWO is heading over to Phase 4 (ignore GFS AAM bias please!). This phase of the GWO is associated or correlated with troughing over the Eastern US. It might be there for a while.

 

Slightly old GWO Phase space.

AAM now increasing....

 

Thanks to....

 

Slight Mountain Torque increase.

• East Asian Mountain Torque slightly positive.
• Rockies Mountain Torque continues to be negative.

Frictional Torque increasing now (main factor triggering move to Phase 4 of the GWO).

Interesting times for the Momentum budget....

 

I made these posts on a US forum. I believe they may be of broad relevance to this forum. The charts are a day old.

Anyway an elaboration.

Frictional Torque looks to be slowly increasing from negative over the next couple of days (from current charts). But it should go stay in the negative phases IMO, as a response to a strong world +MT.

A +EAMT event is currently present, and a +NAMT event is soon to start in the medium term. Both of those events should bring the GWO across from it's current GWO Phase 2/3 to Phase 4, then progressing to Phase 5. This will take Worldwide MT to a strong positive signal, and increase the AAM. What happens after, few people know.

The +EAMT is widely expected to extend the NP jetstream in the short term, and contribute to the strong -EPO block (which therefore contributes to the TPV in Eastern Canada, that may have an effect on West NAO domain). Then we are forecast to get a +AAM, GWO Phase 5.... By correlation, that GWO Phase means a ridge for the UK, so not great....

 

 

[nick sussex]

Not exactly crunchy snow and ice days but in the UK any snow is welcome for  coldies.

The fact we're even discussing the possibility shouldn't be sniffed at given some of the earlier model projections for the coming week.

[bluearmy]

25 minutes ago, northwestsnow said:

Chris Fawkes tweeting about potential for heavy snow across the pennines late boxing day to the 27th this morning-

Not sure this is related to the slider discussed this morning tho Blue

It is the same feature - just further north as gfs and ukmo 

[Man With Beard]

1 hour ago, bluearmy said:

Just looking at the eps clusters and there is a decent chance that the flow stays pretty flat across the Atlantic rather than pivot sw/ne as per the current direction of travel. As the suite progresses it becomes quite bipolar with a strong azores ridge covering much of the w Europe which eventually drifts to become almost sceuro by day 15 (with a capital E rather than S) as against a moderate westerly upper flow continuation 

hence the mean is pretty useless on the 00z suite in the extended as it struggles to cover both bases. 

Yes agree with the assessment of the extended - and your comment last night about their lack of a clear signal post  new-year - I do feel a bit nervy making a forecast based on the clusters when the anomalies are small. 

The best guess I still think is slack westerly conditions with breaks between troughs, though those Euro heights seem a bit more prominent today which, if they verify, could shift the UK from the "average" to the "mild".

Next week is an example of how if low pressure can be centred at least level with the UK or even just slightly east, you're always in a with a chance of something wintry developing for a short time. That said, it will be a complete fluke if lowland snow comes off based on these synoptics!!

Edited December 23, 2017 by Man With Beard

[Frosty.]

1 hour ago, Ed Stone said:

One good thing from the 06Z: there might be enough rain to wash the vomit off the pavements:

Post of the century, much better / funnier than Ian Brown's!

The models are certainly taking a turn towards unsettled but there should be some wintry interest next week, after the 25th, especially further north and higher up.

Edited December 23, 2017 by Frosty.

[johnholmes]

I'm not sure about having slack westerlies based on looking at 500mb anomaly charts. All look to have a fairly strong westerly flow into the UK and Europe in the next 2 weeks. Some surface lows are going to be pretty deep with gale force winds associated with them, especially in the NW'ern third of the country. But, yes, ridges behind these systems may give 24-48 hours of colder conditions, even with snow in places, largely higher ground in the northern half of the UK but some might get lucky elsewhere. There is no sign, to me, though of anything that could lead to any deep cold of several days or more at the moment.

Edited December 23, 2017 by johnholmes
spelling and adding a it more!

[bluearmy]

14 minutes ago, johnholmes said:

I'm not sure about having slack westerlies based on looking at 500mb anomaly charts. All look to have a fairly strong westerly flow into the UK and Europe in the next 2 weeks. Some surface lows are going to be pretty deep with gale force winds associated with them, especially in the NW'ern third of the country. But, yes, ridges behind these systems may give 24-48 hours of colder conditions, even with snow in places, largely higher ground in the northern half of the UK but some might get lucky elsewhere. There is no sign, to me, though of anything that could lead to any deep cold of several days or more at the moment.

As week two ticks by, any westerly upper flow looks to lose a little impetus John. Agreed that slack isn't the right description although compared to the speed at which systems are racing west to east later this week, it does look a little more relaxed.

[MR EXTREMES]

Not very good charts again well especially for the south.

Pretty wet windy not especially cold in the south but won't feel pleasant.

Further north is where the action is and some pretty large accumulations further north you are.

All rather uninspiring we need a lucky break.

I keep thinking maybe the vortex might stay displaced of the pole and more over this side rather than Canadian side.

Still I keep watching it's painful but I can only hope.

Just goes to show la Nina really does not fill me with confidence.

Even though 63 was la Nina it must of been a freak event.

Anyway winter marches on but pretty disappointed so far.