Model Output Discussions 06z 04/11/16

[gottolovethisweather]

Argggh, editing post problems. I'm trying to respond to young William's post up thread in as much to say, what happens after Sunday's troublesome low could yet dictate (well, give us several clues at least) as to how cold the rest of November might yet become. A deep undercutting feature diving quickly diving SE'wards in towards France and Germany may provide the perfect trigger for a colder spell of N'rlies and NE'rlies as projected by some of the output. Equally, the WAA advection either side of the trough might not position itself favourably for the UK, and instead, we'll sit in warmer than desired (by me anyhow) airflow. We will know more by the end of the week and into the weekend as to which side of the polar influenced airstream the UK sits. For sure, someone's going to get a fair dumping of snow before the end of November.

[MP-R]

5 minutes ago, gottolovethisweather said:

Argggh, editing post problems. I'm trying to respond to young William's post up thread in as much to say, what happens after Sunday's troublesome low could yet dictate (well, give us several clues at least) as to how cold the rest of November might yet become. A deep undercutting feature diving quickly diving SE'wards in towards France and Germany may provide the perfect trigger for a colder spell of N'rlies and NE'rlies as projected by some of the output. Equally, the WAA advection either side of the trough might not position itself favourably for the UK, and instead, we'll sit in warmer than desired (by me anyhow) airflow. We will know more by the end of the week and into the weekend as to which side of the polar influenced airstream the UK sits. For sure, someone's going to get a fair dumping of snow before the end of November.

Was there not a similar evolution in the final third of November 2012? A period of heavy rain and flooding around the 21st-24th before the northerly floodgates opened in the final week? The models are showing tentative signs of this at the moment. As you say, what happens with the Sunday/Monday trough will have quite a large bearing on what follows. Interesting times indeed.

[bluearmy]

6 minutes ago, Catacol said:

... which is what it is all about. Lots of dissecting of charts at the moment, but T+240 only brings us to 25th November. For the vast majority of lowland Britain it is simply too early for anything other than a transient snow event. I can remember one November only where snow stuck in the south for more than 24 hours and I think I can remember most of my weather watching life since moving to England in 1983 and leaving the glories of Scotland behind....

Wave 2 warming in the medium term followed by a lag of let's say a further 10-14 days tied into what Tamara was saying/hoping yesterday regarding a reload of convection in the pacific maintaining more of a Nino rather than a Nina atmospheric reaction brings us broadly to mid December. I'm not sure to be honest that we will see anything too remarkable until that point. There is a strong suggestion of low pressure to our south and a continental flow more frequently than we might expect it normally - but we need the near continent to cool down further and anything that happens now is a transient bonus. Even a north sea trough and a cold NE feed wont deliver consistently at this time of year.

The key to my eye is to enjoy the model feel.... in other words to spot the ongoing trend for a very disrupted NH pattern with amplification and a vortex on its last legs seemingly before it even learned to walk. Cold in November? bah. Give up on it as a waste of hope and energy. But a cold setup for mid December onwards is a different game, and we look PERFECTLY setup at the moment for that to happen (or at least as reasonably close to perfect as I think we can expect.)

Belay all this above if you live on high ground - enjoy imminent snowfall. But to be honest I doubt if high ground inhabitants get too hung up on this forum about snow for the same reason as I suspect the "We love sunshine" website in southern Spain has a membership of 1.

Let the clock tick and be patient. Keep looking at NH charts (not Atlantic ones...) and keep an eye on the Berlin charts for ongoing strat warming and predictions of the MJO. Continued amplification will be to our benefit if we can secure it. Nice to see a quiet sun too.....

I wouldn't underestimate the possibilities of sub zero uppers in nw Europe and a continental drift ahead of precip running across in a general w-e direction to our south. admittedly the north sea will lift temps if there is a long sea track but a short sse flow across the channel into the south east could be of interest, especially if we have had a period of cold surface temps in an inversion situation..

[Frosty.]

Despite on going model wobbles (for want of a better word) between milder and colder solutions, the medium / longer range trend continues to be for a southerly tracking jet with height rises to the n / nw and temperature wise, generally on the cold side further north with occasional short-lived milder episodes across the south..so, increased energy pumped into the southern arm of the jet whereas the northern arm, which was so powerful and unforgiving in the run up to and including most of last winter, this time looks considerably weaker with the pv going walkabout instead of the monster limpet feature it was late last year / early this year!

Edited November 15, 2016 by Frosty.

[Connor Bailey Degnan]

I've been enjoying reading peoples thoughts today about the upcoming "potential cold" December . 

We have every opportunity for a great December with plenty of snow events given the set up. 

I think the models will bring further eye candy output for early December in the days to come. 

One things for sure, it's the exact opposite of this time last year

[gottolovethisweather]

19 hours ago, Frosty. said:

The GEFS 12z mean does show support for a milder Southerly flow next week, similar to the Gem 12z..time for a slice of humble pie

 

 

 

 

 

 

Not Frosty's post I'm attempting to reply too but MP-R's here.

Not sure, all I know it ended up a cold end to November according to my Davis data but with variable winds, a couple of frosts to finish the month. We all know which recent November proved to be the holy grail for coldies, so something even close to that would be warmly coldly appreciated by most, lol.

 

 

 

Edited November 15, 2016 by gottolovethisweather

[Grimers]

This is a big if, but if the GFS model is correct, then a blizzard is certainly not out of the question for the higher ground of Wales and N England on Sunday.

 

[Cheshire Freeze]

6 minutes ago, Grimers said:

This is a big if, but if the GFS model is correct, then a blizzard is certainly not out of the question for the higher ground of Wales and N England on Sunday.

 

The 6z had a threat of wintryness for lower ground too, although there would certainly be no settling there

Edited November 15, 2016 by CreweCold

[Banbury]

Quote

 

P10 will do just fine

[weirpig]

2 minutes ago, CreweCold said:

The 6z had a threat of wintryness for low ground too 

Yes  this type of scenario always does well for the Midlands and further north  think the uppers maybe a tad too high  but high ground may well do well. One to watch

[Catacol]

30 minutes ago, bluearmy said:

I wouldn't underestimate the possibilities of sub zero uppers in nw Europe and a continental drift ahead of precip running across in a general w-e direction to our south. admittedly the north sea will lift temps if there is a long sea track but a short sse flow across the channel into the south east could be of interest, especially if we have had a period of cold surface temps in an inversion situation..

Yep - agree there is always potential there Blue, but in November I've never seen it happen. The snow I do remember down here in November came from a cold NW flow and the flow remained cold enough for the snow to stick around for 48 hours. 2005 I think it was... But I would certainly love it if 2016 brought a channel runner in November producing snow!

I'm more hopeful this winter of a Feb 91 or Feb 96 setup. Feb 96 was winter wonderland down here from charts that might look fairly inoccuous, but worked solidly off a cold continental feed Those Feb 96 charts look remarkably like the MetO pressure anomaly charts that were posted a day or so ago. This is the one:

 

Couldnt see my numberplate after this went through, and for the rest of the week it looked a bit like this - again very similar to the overal Met anomaly charts:

 

 

Sorry to digress and I think I've posted these charts before so apologies for that too. But going back to my point initially I dont think charts like this will deliver in November 99% of the time.

[Frosty.]

There are some real zingers and several close calls among the GEFS 6z perturbations with stunning potential for a cold / very cold late Nov / early Dec.

Edited November 15, 2016 by Frosty.

[Connor Bailey Degnan]

15 minutes ago, Frosty. said:

There are some real zingers and several close calls among the GEFS 6z perturbations with stunning potential for a cold / very cold late Nov / early Dec.

This could be the December we've been craving for too long... 6 years

[Catacol]

To look at the MJO for a minute we are in phase 8 and heading towards phase 1 again I think. Composite for this from JMA using a very rounded average is this

 

Vortex forecast to end up here in 10 days:

 

My money will be on the ENS stand off mentioned by IanF ending up with the blocked scenario and more of an easterly than a westerly component at the surface. Nothing is ever certain of course....

[Paul]

Matt's latest synoptic guidance blog is now online - lots to look at this week, with an increasingly cold airmass moving south + the threat of a stormy spell this weekend. 

http://www.netweather.tv/index.cgi?action=news;storyid=7773;sess=

[Zakos]

Wow, quite a shift in the output over the last  4 days!

Significant upgrade for the ridging in the atlantic next week.

Excellent mean height anomaly at day 10 from the GFS

As many have noted, no sign of a notably cold airflow yet

However, an even more impressive mean anomaly at 384 - December 1st. Strong signal for heights to our NW, plus low heights deeping over europe, possibly hinting towards a cold airflow from the NE as we enter December, perhaps as a result of a PV lobe dropping over Scandinavia.

Certainly very little sign of the PV forming over Greenland/Canadian Arctic, with a strong signal that its core will remain within siberia.

]

 

Lovely to see any attempt at PV formation over Greenland being swiftly swept aside and replaced with ridging. A far cry from the horror show that unfolded this time last year!

[Ali1977]

First low is bumping into slightly colder air on this run, -4c uppers down to the M4 corridor (I know) AT t96.  Interestingly the 2nd low that followed in the 06z isn't there, this may be aiding slightly colder air as there is more of of Northerly flow behind the 1st low.  Warmer air quickly in as the low hits, high ground up North may still get some white stuff with high ground North Pennines and Southern uplands potentially in a sweet spot for a decent dumping as the low pivots.

Edited November 15, 2016 by Ali1977

[Jonan92]

Quite a difference between yesterday and today

Yesterday 12z

 

Today 00z

 

Today 12z

 

 

[Mucka]

As Fergie pointed out earlier this channel low might be something or nothing but it is finding some consistency in the output across all models now.

 

It is unusual to see the GFS ahead of the ECM in wanting to sharpen up any amplification in the Atlantic sector. 

 

Edited November 15, 2016 by Mucka

[Nick L]

3 minutes ago, Ali1977 said:

First low is bumping into slightly colder air on this run, -4c uppers down to the M4 corridor (I know) AT t96.  Interestingly the 2nd low that followed in the 06z isn't there, this may be aiding slightly colder air as there is more of of Northerly flow behind the 1st low.

Yeah but by the time the precip gets there, dew points are well above zero.

[tight isobar]

The gfs 12z..continues with sharper migration of the Lp...in compare ecm...

Finer elongation 'thus' aiding cleaner WAA into Greenland. ..and this could be the major pinpoint going forwards.....overall! 

Edited November 15, 2016 by tight isobar

[West is Best]

Crikey!

This is getting better and better. I did mention the synoptics were the key thing. If this low tracks along that kind of southerly path then ... well.

[West is Best]

Don't forget we're on the north of the Polar Front Jet. That makes a difference ref. normal rules on upper air temperatures and dew points?

[Grimers]

12 minutes ago, West is Best said:

Don't forget we're on the north of the Polar Front Jet. That makes a difference ref. normal rules on upper air temperatures and dew points?

Not always, as Nick L pointed out, fronts normally bring warmer dew points hence why you sometimes need cooler uppers.

Edited November 15, 2016 by lorenzo
Updated Nick F to Nick L as requested

[Seasonality]

11 minutes ago, West is Best said:

Don't forget we're on the north of the Polar Front Jet. That makes a difference ref. normal rules on upper air temperatures and dew points?

How does the positioning of the PFJ alter the basic physics?