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Model Output Discussion 29th December - Into mid-Winter.


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As expected the 6z OP was probably the coldest of all the members. Hopefully nobody will start being equally as crazy and saying 'massive downgrade' 'letdown' and the like if the 12z OP ends up being one of the milder members.

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Evening All For those of us who have been here for a long while there is times when you know you have to throw in the towel on chasing cold & times ( very rare ) when you 'just know' that the

Boom goodnight vienna

People being a bit harsh on Steve Murr, at least he has the balls to try and read and predict what may happen from his viewpoint rather than just posting what charts show.

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3 minutes ago, easton888 said:

That HIRLAM chart has way less rain coming through from the west than what's actually falling right now. 

It's extremely high res - I can confirm it's dry in my office ! 

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7 minutes ago, Snowmaiden said:

Annnnnnnnd with an easterly so shall I return to the forum!

all my beautiful posts have gone! Eeeeeek, but never mind!! I've been following the winter solely on the Meto updates (since 2011!), but got the impression something was afoot from their almost unprecedented forecasts of quite cold. Surprised by the current output is an understatement, thrilled is not an understatement, being in the front line for easterly action as I am here in a chilly Norwich. Looking through the models and if I can remember how to read them (!) looks like the main danger will be shortwave activity over the top and possible sinking of the coldest weather into Europe, but this does not look favourite on the 00 suite and the 06. Very little, actually zero, danger of a Scandiberian (TM snowmaiden 2009) locking us out on the mild side. Hope you are all in good spirits, I see a lot of you haven't gone anywhere in the last 5 years! Good :)

Welcome back. Nice to see someone else from the beginning. Just need to get Mr Crazy Snowfan posting now.

On Topic, Models firming up on the most significant cold weather event since March 2013. As for snow, I think there's a lot of marginality in the short term and it may be rather dry in the more medium term, so there might be disappointment for some. As ever the evolution in the modelling has been fascinating though.

 

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From what I have read regarding HIRLAM, it is highly respected along side ECM with regards high resolution for wind data. (If I can find the link I will share) watching the precip charts from HIRLAM over the past few months I'm not overly impressed tbh. Arpege high resolution seems to do OK, for what it is worth tonights charts from ARPEGE & HIRLAM some difference in regards to precip events country wide. Lets see what happens.....

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1 hour ago, ghoneym said:

From what I have read regarding HIRLAM, it is highly respected along side ECM with regards high resolution for wind data. (If I can find the link I will share) watching the precip charts from HIRLAM over the past few months I'm not overly impressed tbh. Arpege high resolution seems to do OK, for what it is worth tonights charts from ARPEGE & HIRLAM some difference in regards to precip events country wide. Lets see what happens.....

 

HIRLAM already has a successor called HARMONIE which is better but HIRLAM still beats GFS for local weather, don't know any sites except weerplaza that show HARMONIE though

 

http://www.weerplaza.nl/weerkaarten/harmonie

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In terms of the milder blip over the weekend I'm still wondering whether this will get fully across the UK or will be shortened in duration.

Although its just the USA model the NAM having checked through its last 3 runs including the 12hrs has from the 00hrs run become a bit more amplified each time with the jet leaving the ne USA.

Because of the set up any more amplification we can squeeze out upstream will likely develop a better cut back in the jet near the UK. Its not terrible if we don't see that NAM trend picked up by the global ops because even with the current modelling hopefully with no dramas the milder blip should just be that before it turns much colder into next week.

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10 minutes ago, Bristle boy said:

To put it bluntly Nick this current cold couple of days, starting today with cold rain and wet snow for some (other than our Northern contingent) is a bit of a damp squib. Now we move on to next week i guess, which at the mo seems to be about a cold, but dry, easterly. Hmm...

To be honest BB I was always a bit more interested in next week being founder member of Coldies Against Slushy Snow (CASS)! lol

This week was always looking a bit of a messy picture because of the depth of cold and modification, something which would be less of an issue with a more continental type flow.

As for it being dry, I think we need to reserve judgement for the timebeing because this far out the strength of the flow, what the southern Europe low does and the track of those lows around the block is still open to change.

If we can keep the cold for a decent amount of time then things could pop up.

Edited by nick sussex
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An interesting diversion will be to see if, as we enter the next few runs, we start to see any North Sea convection streamers developing given the general agreement on the direction of weather. It moves from forecasting the general to looking out for specifics from t72-96 inwards.

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2 hours ago, Alexis said:

The 528 dam line is of no significance with a continental flow. It's not even very useful in a polar maritime - I've seen 100% rain at levels well below 528dam.

 

Thanks for the reply Alexis, lets hope we see the 510 heading in from the east on future runs :)

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For those in the West Country, missing out on events further east, the 12z Arome model continues to suggest some light snow showers crossing the West Country during the early hours of Friday morning;

aromehd-1-13-0.png

aromehd-1-14-0.png

This timeframe has been a consistent thought in high res modelling for some flurries.  Question is, who is dedicated enough to stay awake at said timeframe on the off chance of seeing a light snow shower?

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Is it just my imagination or have many of my fellow cold enthusiasts from Eire gone somewhat quiet these past few days. Understandable I suspect as a greenie high would be more beneficial to us rather than a Scandi high resulting in something tasty from Siberia for the majority of you guys, especially for those further towards the southeast. All I dare say we can best hope for is a seriously watered down version by the time any continental flow reaches our shores. Would this be an accurate assessment I wonder of where things stand right now?

Edited by Newberryone
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46 minutes ago, snowflakey said:

 

Thanks for the reply Alexis, lets hope we see the 510 heading in from the east on future runs :)

on the contrary, with a continental flow you can have snow at 540 dam.  however, if you want the cold to drive convection then you do need the deep cold associated with very low dams

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I hate the word downgrade but looking at ops alone this evening then nothing more than high pressure next wk with the cold air staying over the channel. Pole opposite from the 06z that's for sure. But means nothing really because it's valid for a whole 6 hours!

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Not sure this run will verify for Southern Europe so I'm out on the 12z

 

 

No scientific reason but I cannot see or remember that depth of cold down there.

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But then looking at UKMO who knows

Edited by winterof79
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1 minute ago, mulzy said:

Very poor (against expectations) 12z runs so far.  Everything further south - we're back in UK high territory.

UN144-21.GIF

 

Not really the very best runs have only just brought in cold uppers, tonight's runs agree with each other (ECM withstanding)

We are looking at some cold and hopefully clear weather next week, maybe a spot of drizzl for the south east

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