Model output discussion - mid-winter

[andymusic]

5 minutes ago, Bazray said:

Yes lets have a south correction, Northerners get enough snow - need to share ot out a bit. Last decent snow event I remember here was Jan 2010, got pasted, cant remember what caused it? Easterly, nw? Would be interested to know if anyone rembembers that far back?

severe north easterly flow with attacks from the west if I re-call - someone might b able to get the archive charts up though

[ICE COLD]

2 minutes ago, shaky said:

What is w signal?

Westlys signal shaky . He basically  saying Westlys are unlikely after day 10 ?. Well that's what I think ?? Hope he's right ?

[Chesil View]

3 minutes ago, shaky said:

What is w signal?

I would assume westerly signal. In otherwords we will probabaly be looking north or northeast. Thats how I read it anyway.

[tight isobar]

5 minutes ago, andymusic said:

severe north easterly flow with attacks from the west if I re-call - someone might b able to get the archive charts up though

Correct a few snaps from the period..

2010-..

North/north easterly..easterly components...

Edited January 12, 2018 by tight isobar

[Snowjokes92]

13 minutes ago, andymusic said:

looks a bit blizzardy lol

I know its out of reliable timeframe but thats something else and out of this world for these parts at just 6 days

Edited January 12, 2018 by Snowjokes92

[tight isobar]

10 minutes ago, shaky said:

What is w signal?

Westerly flow..zonal/mobility...

Crap- in other words..?

[MR EXTREMES]

1 hour ago, Steve Murr said:

If we look now ( as opposed to last night ) the low pressure is becoming more elongated ... 

still think it might split-

That's good chart the only way that low could possibly go is southeast.

We have weak heights north of Greenland and high pressure to our northeast!

if the heights grow to the north of Greenland and stick for bit longer to our northeast around Scandinavia,

then it's looking like a win win situation as the low can't go northeast because of the block.

Certainly a building block in the right direction and certainly not blow torch southwesterly.

Interesting stuff.

[Paul]

Please can we stick to model discussion in here, I get the excitement about the prospects of snow, but this isn't the place for simply asking and chatting about the chance of snow in certain locations etc. 

The regional threads are great for local snow risk discussion:
https://www.netweather.tv/forum/forum/142-regional-discussions/

And the banter thread is the place for ramps, moans and emotional reactions to the models (eg stuff like the 'snow risk charts are amazing for [insert place here]')
https://www.netweather.tv/forum/topic/86721-model-moans-ramps-and-banter/

It's likely to get very busy in here during the coming days, and those who keep posting off topic stuff in here are likely to find their accounts being restricted, so please don't let that be you, and think about what you're posting where, before hitting submit. 

 

[SMU]

I’m off now till later

 

one things clear- especially for the E/NE/SE if we want an extension of the cold spell to include some form of NE incursion then a ridge being thrown directly north about day 8-10 ( somewhere in there ) is crucial

Try PTB 2

 

Edited January 12, 2018 by Steve Murr

[karlos1983]

Not a huge number of mild members in the extended, looking pretty chilly out to D15.

Back to keeping my eye on these now in the D10-15 period. 

Edited January 12, 2018 by karlos1983

[tight isobar]

Just now, karlos1983 said:

Not a huge number of mild members in the extended, looking pretty chilly out to D15.

Tbf the gfs 6z london ens are as good as iv'e seen for a good while!!!

[Frosty.]

Looking at the GEFS 6z mean, and this is no exaggeration at all, it shows a prolonged cold cyclonic wintry spell from early next week onwards, especially potent further north with ice days as well as a good chance of snow for most days of the run together with plenty of frosts and ice..hopefully a return of proper wintry weather, it's looking good!

[Singularity]

47 minutes ago, radiohead said:

Yikes. At least there'd be more open space for sledging afterwards .

 

Interesting input from GP regarding MJO signal as it crosses 4-5. Sounds like the knock-on effects of earlier developments should override it.

[CK1981]

Doesn’t look all that special, especially in the south. Temperatures are slightly below average and according to the latest GFS they remain above zero down here at night. I’m so glad I’m off to the Baltic’s next weekend for some proper winter weather!

Edited January 12, 2018 by CK1981

[SLEETY]

1 hour ago, tight isobar said:

Yep your correct i viewed/commented on the composite posted...not the views!!

Quick over-reaction on my part!!!

Edit;..

however  that scenario cant be ignored..however unlikey.

Whenever their is a chance of the Westerly returning,expecting it not to happen is not the best option.You CANNOT ignore the facts that the Westerly nearly always seems to win out,in all the outputs in the long range ,they show the Westerly winning out at the moment.

Trying to get a decent Easterly or North Easterly seems almost impossible to achieve now in winter

Edited January 12, 2018 by SLEETY

[Man With Beard]

56 minutes ago, radiohead said:

Not just P1

            

could have posted more 

on the ECM ensembles for next Thursday, about 20 out of 51 have a notable gale or worse but most go through the English channel

[Glacier Point]

18 minutes ago, Singularity said:

Yikes. At least there'd be more open space for sledging afterwards .

 

Interesting input from GP regarding MJO signal as it crosses 4-5. Sounds like the knock-on effects of earlier developments should override it.

More appropriately, whereas the MJO and GWO were in sync for the Indian Ocean passage, they seem to be out of sync for the uptick in angular momentum likely.

MJO for phases 4/5 compared to phases 3 and 4 of the GWO:

 <<MJO (look familiar to 06 GFS op?)

<< GWO

Edited January 12, 2018 by Glacier Point

[bluearmy]

1 hour ago, ShortWaveHell said:

I read that as GP saying signals for W signal are false 

Agreed 

the euro ridge will be overdone in the extended ens modelling if he is right 

[MattTarrant]

Just going to do a quick analysis/overview of the likelihood of snowfall next week, using a series of parameters. 

This will focus on; 500mb Heights, 850hpa Temperatures, Dew Point & Dam Air Thickness. Credit for base knowledge goes to; https://ukweather.wordpress.com/weather-guides/basic-snow-forecasting-guide/

All charts are from the GFS at 108hrs.

500mb Heights:

A general rule of thumb is for this to be at or below -27 Degrees Celsius. 

That is a tick for essentially all of UK mainland (Approaching -40 in parts). 

850pha Temperatures:

For snow to sea level -7 uppers are generally required. 

-5 uppers widely across UK mainland (-6 & 7 further north). Sea level snow marginal with highest chances in Scotland & Northern Ireland. 

Dew Point:

0c generally needed for snow to settle, marginally above requires substantially heavy falls. 

 

Tick! 

Dam Air Thickness:

Generally below the 528 value. 

Tick for majority of UK mainland. 

Overall Conclusion:

Overall parameters look on the favorable side, with uppers being the most marginal (fine for inland snowfall). A key word of caution though is significant moderation of the boundary layer, due to the large westerly component and resulting larger fetch. This is the cause behind the rather uninspiring 2m Temperatures, hence why snow would seem favorable overnight in contrast to daytime, especially further south. The requirement for heavy precipitation should be stressed, allowing for marked temperature swings during shower cycles. 

Temporary settling is possible almost anywhere, especially north of the M4 . Though noteworthy is likely restricted to the North West, Northern Ireland & Scotland (Hence warning out from the Met Office for Northern Ireland & Scotland).

 

Edited January 12, 2018 by MattTarrant

[Daniel*]

 

[Methuselah]

And one more thing: try not to get too carried-away when members post the coldest ensemble members...They're about as likely to approach reality as a forecast for snow in the Sahara Desert...

Oh, hang on!

[Bobafet]

It is certainly an exciting time ahead with the Models firming up on a period of cold weather for all, and hopefully further down the line we can expect even better prospects for everyone.

There have been some excellent analysis today and this helps people like myself get a better understanding of how to interpret the charts so thank you for your input.

I personally feel that we are on the cusp of a possible noteworthy spell of cold weather that we have not seen since 2013 (especially for us southerners!!)

Roll on 3.30pm for the next round of model output and hopefully further upgrades will be incoming!!

[Frosty.]

In a nutshell, if you're not a fan of mild weather you should be happy with the latest model trends which clearly show an increasingly cold zonal cyclonic pattern on the way next week which may then veer to an even colder arctic maritime with plenty of opportunities for snow as well as lots of frosts including sharp / severe frosts over the snow fields at times, especially further north..this could turn into a very rewarding january for coldies, hopefully that goes for february too!!❄❄❄❄❄❄❄❄

Edited January 12, 2018 by Frosty.

[Methuselah]

2 minutes ago, Frosty. said:

In a nutshell, if you're not a fan of mild weather you should be happy with the latest model trends which overall show a cold cyclonic pattern on the way next week with plenty of opportunities for snow as well as lots of frosts including sharp / severe frosts over the snow fields at times, especially further north..this could turn into a very rewarding january for coldies, hopefully that goes for february too!!

Indeed Frosty...even a growing hint of a straight northerly!

[Guest]

FONT SIZE ISSUES - A GOOD OLD BRITISH COMPROMISE

I have noted the various mixed views and comments regarding font size.This is from both the MOD thread as well as the new "Learning All About Teleconnections" thread that I launched last night. I will try to remember to reduce my font size just before I press the "submit" button. I had no idea that I would cause such a "mixed" reaction and I apologise to everyone (including the moderators) for seemingly disrupting the thread at a busy time which would never be my intention. I pride myself on the use of good English and presentation skills and this matter really concerns me. There is something of a dilemma which I want to post here as it's extremely relevant to many who post anywhere on this forum. I am deliberately ensuring that @Paul will read this and I will also be sending him a PM about a particular aspect of it shortly. I will also see if he or someone in his team can edit my last 5 posts (one on page 27 of the MOD thread and 4 on the new thread) to reduce the font size to what I outline below.

Part of the problem is that some of the posters (like me) work from our trusted desktop PCs and some use their laptops. I now understand that many use mobile apps, perhaps even a majority these days and the viewing is very different. It is not just a generation thing as my brother dispensed with his desktop several years ago and, unlike me, he is far more in touch with the outside world! I asked him this morning to give me a demonstration of the problem. I was quite shocked just how little of the text shows up even when he did that finger movement thing to varying the size on the tiny screen. I can also see how difficult it is to use the mobile app for posting oneself and I can see why we have an abundance of short posts and some "part view" charts and with a vertical view when they appear on here. This is one side of the coin but please read on.

Although my general eye sight is very good, I have been wearing reading glasses for the last 15 years or so and (I just had my last annual eye test and there was no deterioration - but coming up to age 65, I need to have regular checks). It is difficult for me to read very small print and anything from font size 12 and below is a real struggle. I use "varifocals" for when I'm working on my desktop computer. I write everything in a much larger font size so that I can edit it easily and correct typos and spelling errors etc. With the new 15 minute editing time restriction, I find it hard to check everything (including all the links and charts) on my long posts. I have partially overcome this by proof reading everything several times prior to submitting the post. I will try to ensure from now on that my final action prior to submitting any type of post is to reduce the font size from the 16 to 18 (or even 20 for titles) that I have been using down to size 14 for standard text and only 16 for titles and headings - just like on this post, This is effectively meeting some of you halfway and I sincerely hope that this really helps. Sometimes in this world of increasingly polarised views, a good old British compromise might still be the best way forward and I hope that most of you agree.

Finally, although I hope that the moderators will allow this post to remain on here (and also in the Teleconnections thread), I feel that if you have any points to make on this matter either way, that you simply PM me or send a sticky note message. I do not wish to be accused of clogging up the thread again. Oh, I just remembered to reduce this from font size 18 to size 14!

Just a reminder of the new thread (just click on the chart below):