Model output discussion - late November

[tight isobar]

An interesting 6z...pumping out..

The slightest alignment of heights on a more westerly stretch will see a continuation of both prolonging cold injection...and likely deeper/colder overheads=850's..

 

Certainly a seasonal start to the festive month...'nonetheless'!!

And some interesting compare-via suites/and particular outs....from here on in!

On the above regards....^^

Edited November 26, 2019 by tight isobar

[IDO]

Medium-term wise the GFS 06z faster at flattening the NH profile and the tPV more organised earlier. Only one run so no conclusions but the background signals would be akin to this scenario. 

D10: 

This will mean the jet becoming less broken, the cold uppers migrating to the pole and a more zonal NH pattern. The tPV chunk to our north so a cooler zonal more likely.

Will have to see if this is a blip or the signal for a new pattern, but we expect this to occur and hopefully other factors will prevent it being a longer term synoptic.

[Frosty.]

Interesting to note that although the 6z operational gradually introduces milder uppers (850's) next week, surface cold persists for much of next week which would mean quite a lengthy cold spell for many!

Edited November 26, 2019 by JON SNOW

[Weathizard]

IMO what’s showing is a seasonal spell, which is perfect to start December, I’d love that high to stick around and give us a few weeks of dry crisp seasonal December weather, I don’t see a snowy spell possible so that’s the perfect second prize.

Just again shows you how tough it is for a decent ridge or proper HLB to actually set up to deliver proper cold for us, you need the perfect mix of ingredients, just the right LP exit speed, strength and angle, the correct jet position oh and a cold supply to tap into. 

[Tim Bland]

Now that’s what you call cold Zonal! Good for the Scottish ski industry at least 

[MATTWOLVES 3]

I must admit I was a little concerned after viewing the ECM op this morning.... +11 uppers..... Noooooooo... But after checking the extended mean to day 14...that mean comes down quite sharply!! I'm seeing around - 2C for the Birmingham area at this stage. I will stick to my guns here, and say... Only a briefer mild spell. 

[SMU]

Another big step to the ICON

GFS mean 162 where did that atlantic trough come from

Note the continental flow

The result...

A 6 degree reduction of the 850s for london... run V run

Edited November 26, 2019 by Steve Murr

[SMU]

Hum.... This is the full blown trough dig to the south end result

[StretfordEnd1996]

GFS shows that it may actually take a good couple of days after the HP has toppled in next week before we feel the effects on the ground

Well into the next working week we're still seeing very cold temperatures well after the HP toppled through

A perfect cold spell in my opinion minus the lack of snow for the majority of us (though that's still not completely confirmed)

Beyond that out towards 240+ and beyond it does look a tad more mobile and zonal this morning I must say - though little in the way of us being sat right under a huge Azores High (its really not that type of pattern)

The result of which means whilst the uppers are no longer cold they certainly are a long long way off being mild

Have a feeling though that this won't be the endgame the latter half of next week

 

[SMU]

WOW 

3 Sub -10 runs ( inc 1 -11) at 172

:0 :0  PTB 20

 

[Jordan S]

Here's Another update on tonight's potential of very heavy rain for southern, central and Eastern England. 

Gem..

Note the small kink in the isobars to the west of France this is an area of particularly heavy rain. Its likely to track close to or over the south and east of the UK this evening and overnight with the potential for some torrential downpours mixed in. 

For curiosity sake this is the Arome update last night..

Now the 6z this morning..

10pm tonight.. 

Midnight.. 

2am..

4am..

Note the green and yellow blobs.. that shows the potential for some torrential downpours in amongst the already heavy rain I wouldn't rule out this being thundery rain either. If the Arome is indeed correct. 

Not all models agree on this however such as the GFS takes is further east with the heaviest rain confined to the southeast and east anglia. 

Arpege..

Midnight.. 

3am..

9am..

Arpege slightly east than its previous update but a bit of a blend of the Gfs and Arome in bringing it over the southeast and east anglia. 

Whether most of it stays to the east or it pushes into much of the south and east is still open to question but the most likely outcome for now is for this to track through the southeast of England and east anglia fringing into Central parts too with very heavy rain at times. Arome showing 15-25mm widely which because of saturated ground will enhance the risk of flooding not to mention this coming down in a short space of time.

Arome accumulated rainfall.

Arpege 10-20mm shown. 

Even before then this afternoon the risk of heavy thundery downpours are there for the south.  Plenty to keep an eye on.

Edited November 26, 2019 by jordan smith

[SMU]

Last one from me before the 12z runs

For reasons as explained over weekend at this point scrap * ALL * Ensembles past 192 as this trough digging is a pattern changer - enough to impact the zonal flow at 216

Await further runs it could well dig further south creating a cut off High

 

[tight isobar]

I think its fare to say any milder air 'shortlived'...

And the upcoming colder flow ever more highlighted via ens..

The London ones noting the continental flow!!!

 

...

And after a 'probable' milder interlude...it looks only as if the real headache ...as we stand...

Is the direction of cold air transfer ..rather than will it won't it!!!

Edited November 26, 2019 by tight isobar

[MattStoke]

Some severe ground and air frosts to come from this weekend. UKV air and ground temperatures for Saturday morning.

[bluearmy]

23 minutes ago, Steve Murr said:

Last one from me before the 12z runs

For reasons as explained over weekend at this point scrap * ALL * Ensembles past 192 as this trough digging is a pattern changer - enough to impact the zonal flow at 216

Await further runs it could well dig further south creating a cut off High

 

musing about that myself after the ec op

as you say, it could have a number of consequences or it could simply be a blip in the expected pattern to our west 

next few runs should supply the spread of likely options 

[Jordan S]

Gfs keeps cold air in situ over the uk until at least Wednesday 4th now but southern England hanging onto cold air until Thursday 5th with a slack flow off the increasingly cold continent. This would result in hard overnight frosts with perhaps freezing fog in a few places.. This is a mostly dry set up. But a cold and crisp start to December if this is correct.

Overnight temperatures.

3rd..

4th..

5th..

Eventually at the end of next week colder air retreats away slowly back southeast with a milder Atlantic flow coming back in.. This is a ways out so won't necessarily pan out like this and no more detail needed just a snapshot of what the Gfs is showing. 

Edited November 26, 2019 by jordan smith

[Tim Bland]

1 hour ago, Steve Murr said:

Last one from me before the 12z runs

For reasons as explained over weekend at this point scrap * ALL * Ensembles past 192 as this trough digging is a pattern changer - enough to impact the zonal flow at 216

Await further runs it could well dig further south creating a cut off High

 

Certainly fits with the meto thinking as they are still saying cold all of next week with wintry showers. Let’s see if any of the op runs later / tomorrow make more of this 

[Ninman]

Just for fun obviously - CFS 0z shows a possibility of the high shifting out to the NE with eventual undercuts through Dec with some cold uppers at times

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Edited November 26, 2019 by Ninman
removing duplicates

[knocker]

As the Camborne sounding is illustrating it's dry here at the moment with just some medium size Cu courtesy of the instability in the lower layers but the occlusion is currently bringing heavy rain to N. Ireland and southern Scotland which will continue t move slowly north through the rest of today and tonight

This movement is primarily the result of the center of the low drifting east which also means that the wrap around occlusion will also bring heavy rain to south west Wales and England by midnight  At the same time heavy rain will track north across much of south east England effecting all in an area east Midlands to the Humber courtesy of another stray occlusion/ And it will be quite breezy on the boundaries of the circulation

[Snowman.]

GEFS do show interest much later on with a few developing a block NE, about half also show a new batch of disruption to the TPV. All in la la land but we have entered December with worse odds.

[SLEETY]

Icon showing that it should be known as a canon fodder model.Flat as a pancake now,and big difference from last run,another model that obviously over amplifies everything

Need to remember that going forward this winter

 

 

 

 

[swfc]

6 minutes ago, SLEETY said:

Icon showing that it should be known as a canon fodder model.Flat as a pancake now,and big difference from last run,another model that obviously over amplifies everything

Need to remember that going forward this winter

 

 

 

 

I think it shows where fi lies on models tbh.very little come the time anywhere near the forecast ATM .

Edited November 26, 2019 by swfc

[snowray]

6 minutes ago, SLEETY said:

Icon showing that it should be known as a canon fodder model.Flat as a pancake now,and big difference from last run,another model that obviously over amplifies everything

Need to remember that going forward this winter

 

 

 

 

All of the models have been a wind up though, as per usual in winter.

We go from that...game on.      

 

To this...

 

You couldn't make it up, and the cold air is just off our east coast so I guess the forcefield is switched on and working ok,

 

[SLEETY]

5 minutes ago, swfc said:

I think it shows where fi lies on models tbh.very little come the time anywhere near the forecast ATM .

Hopefully it's joined the other models in being too progressive in sinking the high,so we all end up Zonal ,which I despise unless it's NNW Zonal,which can be wintry to low levels

 

[Weathizard]

13 minutes ago, SLEETY said:

Icon showing that it should be known as a canon fodder model.Flat as a pancake now,and big difference from last run,another model that obviously over amplifies everything

Need to remember that going forward this winter

 

 

 

 

I’ve said this all along, it irks me a little when I see people championing it to be honest, it called the easterly 2/3 years ago and since then has basically lived off that reputation. It’s a dreadful model.