Model output discussion - late November

[swfc]

13 minutes ago, Ed Stone said:

Indeed...Though the -10C T850s have disappeared, from EA at least, they've been replaced by a sustained period of -6s; so, cold enough for some sort of wintry precipitation...?

   
 

   

The postage stamps say something too, but I can't find my telescope!

Ed your screen is flashing!so yes jet is up and down like a fiddler's elbow.cold shots and unsettled looks the way but no sustained blocking.at least there's no sign of a cod!!

[Jordan S]

29 minutes ago, Ed Stone said:

Indeed...Though the -10C T850s have disappeared, from EA at least, they've been replaced by a sustained period of -6s; so, cold enough for some sort of wintry precipitation...?

   
 

   

The postage stamps say something too, but I can't find my telescope!

Your links don't seem to be working but minus 6 should suffice for some wintriness to any precipitation that is in the flow. 

Edited November 25, 2019 by jordan smith

[knocker]

The complex trough to the south west

[Frosty.]

Looking at the GEFS 6z there's certainly potential for some colder (wintry) interludes and occasionally stormy periods too..so, yes there's potential for short-lived polar / arctic maritime shots but also some milder Tropical maritime air at times and also some quieter intervals but nothing sustained as far as high pressure is concerned..judging by the mean.

Edited November 25, 2019 by JON SNOW

[Geordiesnow]

1 hour ago, IDO said:

The GFS 06z 100% support for the next 10 days viz the ridge and topple:

T168>>  T216>> 

Cold looking high probability:

Mean T168>> 

So circa 5-day cold spell, with limited opportunity of snow for the majority.

After D10 the 06z op is a variation on the 0z theme of a second cold shot. Downstream more relevant, this time the Russian high is sharper, so the trough is better for the UK to get colder air. Obviously too early for depth of cold or snow chances, assuming it verifies, GEFS not yet on board.

Yes and you should know by now even if you have 100% agreement subtle changes will always alter the longer term outlook, that goes with any weather pattern. 

So looks like a chilly Northerly is on the cards, snow potential looks fairly slim but hard frosts is certainly a possibility especially if that 2nd undercut low stays as far south as possible. 

It only takes slight shifts in the WAA to alter the outlook of a cold blast followed by high pressure toppling in and then sinking to something more colder and sustained as hinted by some of the ECM runs. 

On a side note, the reminiscent of that ex tropical storm takes an interesting track when it approaches Ireland, the centre seems to head northwards and even slightly NW'wards but then ESE'ly, quite odd to say the least. The deeply tightly packed low that the GFS has forecast yesterday has unsurprisingly toned down a bit but I just hope this low can quickly scoot away to pull down that northerly so we get some clearer weather coming in as sunshine wise, this November has been very dull at times to say the least and this week emphasises that with the lack of sunshine forecast. 

[IDO]

11 minutes ago, Geordiesnow said:

It only takes slight shifts in the WAA to alter the outlook of a cold blast followed by high pressure toppling in and then sinking to something more colder and sustained as hinted by some of the ECM runs. 

 

Yes, I have been looking for that. However none of the GEFS suggest this, indicating forces are working against such an outcome. Earlier ECM suggested it as a possibility, but now the runs are coming out of FI, the latter runs are not highlighting this ATM.

Sometimes the mechanics of the pattern simply prevent a sustained mid/high-block, and looking at the NH profile, with a HP cell entering the Atlantic after D7, I am unable to see anything other than forcing to the pattern leading to a temporary flattening of the Atlantic sector, before the UK high retrogresses back to the Azores as it is repelled by the Euro trough.

Usual caveats, but nominal confidence in that outcome based on current modelling.

[SMU]

Afternoon All

Certainly an enjoyable weekend of model forecasting just passed > Things beginning to settle in the models now for a 4-5 cold spell then further amplification post that sees a possible potent Northerly- However lets get clarity first on this atlantic High -

[bluearmy]

EC clusters also showing a well supported northerly option later in week 2

[northwestsnow]

11 minutes ago, bluearmy said:

EC clusters also showing a well supported northerly option later in week 2

I assume this is a response, or assisted by the legacy of troughing making it into Europe week 1 ...

ie pulling the collapsing high into the western Atlantic ..

[knocker]

23 minutes ago, bluearmy said:

EC clusters also showing a well supported northerly option later in week 2

Is this 'well supported' northerly option over a few days blue because any confident shout of a northerly in week two of the clusters rather alludes me at the moment?

Edited November 25, 2019 by knocker

[Snowman.]

32 minutes ago, northwestsnow said:

I assume this is a response, or assisted by the legacy of troughing making it into Europe week 1 ...

ie pulling the collapsing high into the western Atlantic ..

Wouldn’t be surprised if we end up in a repeating cycle of topplers. The strengthening of the vortex seems to continually being overdone in the far reaches of FI on the GFS so I am a little sceptical although I do believe that a zonal spell is inevitable for the start of December. 

Edited November 25, 2019 by Snowman.

[StretfordEnd1996]

ICON gets the cooler air in a tad quicker during this run compared to its previous one - 

Here's midday Saturday on the 0z

And the latest

 

 

[Snowman.]

ICON a bit flatter but a lot more in line with other models, I think we’re finally starting to get some convergence on what the weekend may hold. 

[Man With Beard]

EC Clusters this morning in the mid-term.

T240: looks like a flatter period incoming but potentially drier for the UK

Doesn't last though. T360: ridge anomaly retracted west, troughing established close to the UK or even to the NE. Polar Maritime conditions likely, with temporary cold N / NWlies on the back of passing fronts?

Regardless of which permutation, not looking particularly mild for any prolonged time.

 

[northwestsnow]

3 minutes ago, Man With Beard said:

EC Clusters this morning in the mid-term.

T240: looks like a flatter period incoming but potentially drier for the UK

Doesn't last though. T360: ridge anomaly retracted west, troughing established close to the UK or even to the NE. Polar Maritime conditions likely, with temporary cold N / NWlies on the back of passing fronts?

Regardless of which permutation, not looking particularly mild for any prolonged time.

 

Supportive of Bluearmy post -

[Man With Beard]

1 minute ago, northwestsnow said:

Supportive of Bluearmy post -

I must emphasise though, when I look at the T360 clusters I do not see a northerly actually showing, but rather I see potential for a temporary northerly around the time - just the nature of a PM pattern

[StretfordEnd1996]

11 minutes ago, Snowman. said:

ICON a bit flatter but a lot more in line with other models, I think we’re finally starting to get some convergence on what the weekend may hold. 

Well it's more in line with the GFS and UKMO perhaps but certainly not the GEM or ECM .. 

Here's the +168 ICON view -

The HP looking a tad flimsy and looks as if it'd topple in quicker (it's flimsy in pushing up towards Greenland too)

Also of interest is the small 'break' in colder uppers around that timeframe

By the end it is about to come in over the country

In fact non of the uppers look particularly cold (as in freezing) throughout the run, with -4 to -6 at the most looking more likely.

Pfft - it's only the ICON anyway. It's not like I started dancing when it showed a favourable output the other day. xD

 

 

 

Edited November 25, 2019 by StretfordEnd1996

[northwestsnow]

Just now, Man With Beard said:

I must emphasise though, when I look at the T360 clusters I do not see a northerly actually showing, but rather I see potential for a temporary northerly around the time - just the nature of a PM pattern

Cheers mate

I pondered if the troughing digging into Europe might offer some opportunities of brief northerlies or north westerlies down the line...

It will help coldies longer term hopefully preventing a full on Euro high etc..

 

[MR EXTREMES]

4 minutes ago, Man With Beard said:

EC Clusters this morning in the mid-term.

T240: looks like a flatter period incoming but potentially drier for the UK

Doesn't last though. T360: ridge anomaly retracted west, troughing established close to the UK or even to the NE. Polar Maritime conditions likely, with temporary cold N / NWlies on the back of passing fronts?

Regardless of which permutation, not looking particularly mild for any prolonged time.

 

agreed even a northwesterly flow brings in -4 upper air temps which not bad but not surprising at all the cold bottled to our north.

the pulling out west by the ecm further on looks a likely bet as deep lows swing down to our east and southeast.

differences in depth of pressure gradients outline strong possibility of heights to our west deep lows to our east south east.

 with pattern holding.

[knocker]

I must emphasize, and this is purely just my opinion which I have voiced previously, interpreting the week two clusters is fraught with difficulties. Firstly one has to make the correct surface analysis, and then incorporate this into a five day trend. And if you are in a fairly mobile west > east pattern where phasing of Pm And Tm air masses is going on that aint easy. By selecting one or two days you catch the phasing for that particular day For example I could post this and say a mobile Atlantic which may be correct but a completely unjustified call for the period

But to repeat this is just me and everyone else who is more accomplished at 'reading' these is entitled to disagree

 

Edited November 25, 2019 by knocker

[swfc]

1 hour ago, northwestsnow said:

I assume this is a response, or assisted by the legacy of troughing making it into Europe week 1 ...

ie pulling the collapsing high into the western Atlantic ..

Sorry wrong link

Edited November 25, 2019 by swfc

[StretfordEnd1996]

UKMO looks rather similar to the GFS 6z with HP a tad further East than what we've seen and looks ready to topple through after Sunday

Hopefully we'll see it modelled a tad back West again in the GFS and ECM 12z

[shaky]

Ukmo looks like it might trump gfs and ecm on this occassion!!expect a climb down from ecm at some point!!i do with a few frosty cold days never mind!!

[SLEETY]

At least it looks like turning dry for a while,which is a good thing.

And some frosty weather,with it,if no deep cold going to arrive,frost is better than nothing,at least the ground will look white

[StretfordEnd1996]

GFS shows the cold uppers fading away by D7.

Still the ECM to come but overall today's output is a tad lacklustre to yesterdays - but not overly so; we still have coolish uppers which should give us frosts and some nice cold dry days. Would still just about be cold enough for wintry precipitation should any occur but that looks unlikely at this stage

Still only Monday too so you never know, we may yet see more twists and turns with the HP shunted a tad further W/NW again. 

Additionally - I'll be keeping a tiny lose eye on GFS and GEFS FI post-toppler rolling in..