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Model Output Discussion - The Run In To Christmas


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Unfortunately, there needs to be a recognition that if we share at *this tentative juncture* the exact nature of what we have as Ops Centre guidance, certain individuals will inevitably extrapolate/wa

If the UK can't get cold from an upstream pattern with a negatively tilted troughing setting up over the ne USA , indeed the best set up since two winters ago then I will seriously consider throwing m

The good news just keeps on coming!   Upstream pattern is falling into place to deliver what many people in this thread want to see, NCEP give us the best update since winter 2012/2013,  indeed I'm

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Christmas day is actually colder on the 12z than the 00z

 

ECM0-192.GIF?17-0ECM0-192.GIF?00

 

I'm not talking about the specifics on which is colder on a set day, I mean this last run is less good in terms of potential longetivity on this possible cold spell also on the chances of snow.

 

Look at the latest 216H chart though

 

ECH0-216.GIF

 

By this stage on the 00z run there was uppers of -8 across northern england.

Edited by Harsh Climate
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I'm not talking about the specifics on which is colder on a set day, I mean this last run is less good in terms of potential longetivity on this possible cold spell also on the chances of snow.

You wasn't talking about longevity........ you was talking about how far south the northerly digs in.

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snow event for the North setting up at 216, with polar height field battered with high pressure as well

 

240 will be another cold back edge push

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the low left mid atlantic is going to cause some headaches for the next few days as the models decide how and where it will head ne. it could get cut off completely. not much point in going into detail on the probable solution days 9/12 until we know what happens with that.

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In terms of consistency of what the models are and have been showing for 12z Xmas Day, I am sure somewhere on Net Wx this facility is available so apologies Paul for using this link

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&CONT=euro&MODELL=gfs&MODELLTYP=1&VAR=prec&WMO=&ZOOM=0&RES=0&PERIOD=&PANEL=0&ARCHIV=0&BASE=201412150000%26HH%3D252

It shws that the 12z has given some kind of flow from about NW for several days. If you look at the 00z this has not been the case until the last 2 runs.

The EC output also has not been consistent.

Best to look, at these time scales how each model is showing for the same time ahead, in this case I have chosen Xmas Day.

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Christmas day is actually colder on the 12z than the 00z

 

ECM0-192.GIF?17-0ECM0-192.GIF?00

 

They're almost identical, the only difference is that we're looking at a chart for midday rather than midnight.

Anyway, a bit of a less clean run from the ECM it must be said, but it looks like it'll get the job done, as Nick highlighted the upstream pattern is for once likely to  reinforce the ridge rather than blow it away so perhaps the 'shortwave' drama is likely to be a bit less do or die this time. +216:

ECH1-216.GIF?17-0 ECH0-216.GIF?17-0

 

Just to cause a bit more trouble it puts a dartboard low right over us:

ECH1-240.GIF?17-0

No sign of the Atlantic getting back in from there though so again not all that concerned yet  (not saying it's nailed on by any means yet though), although the GFS evolution looks a bit more plausible IMO. 

Worth remembering too that the ECM has form on creating drama with GHs (as do all the models to be fair):

https://forum.netweather.tv/topic/58097-model-output-discussion/page-13

Edited by LomondSnowstorm
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This comment may get lost in the excitement of the ECM but can I ask, is this modelling output along side the kind of timescales we saw the cold outbreak start to be modelled with the 2010 snow events (I can't remember!) just wanting to get a grip on the situation... Don't want to get my hopes up for it all to go wrong. Thanks.

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You see my first ramp post is met by a miserly ECM T216hrs chart! I think I'll go back to mr sensible. Serves me right for getting carried away.....

 

The ECM T216hrs manages to phase a shortwave to the sw with the one heading south from the north and was devised by Satan himself, the timing for that to happen that way is very unlikely.

 

I wouldn't get too worried about the ECM as its making things overly complicated, lets be positive the upstream pattern is great for cold into the UK.

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http://www.meteociel.fr/modeles/ecmwf.php?ech=72&mode=1&map=1&type=0&archive=0

Uninspiring 216 was expecting better never mind keep going!

Whilst not great on the face of it, the pressure rises throughout the pole shifting the Polar Vortex to Scandinavia is incredibly exciting. It wouldn't take a huge amount of tweaking to get the ECM showing some stunning charts.

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short wave drama?ECM1-216.GIF?17-0

Or battlefield event?

Yes and how far south the northerly digs in will affect the longetivity AND how cold it will be  :rolleyes:

Not really....... The longevity will be dictated by upstream actions not how far a cold push gets south........ think toppler

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The good news just keeps on coming!

 

Upstream pattern is falling into place to deliver what many people in this thread want to see, NCEP give us the best update since winter 2012/2013,  indeed I'm wondering did any cold lover hack the NCEP site!

 

So folks here it is, I've picked out the most important bits:

 

..OVERVIEW...

ACTIVE SPLIT-FLOW PATTERN OVER THE CONUS WILL TRANSITION TO A MORE

AMPLIFIED RIDGE/TROUGH WITH A NEGATIVELY-TILTED TROUGH SETTING UP

OVER THE GREAT LAKES AND MID-ATLANTIC/NORTHEAST REGION(S) AROUND

THE CHRISTMAS EVE TIME FRAME

 

I thought I'd join the festive spirit,we still need to see the detail over the next few days because it might still take a shortwave to head se to bring the deeper cold in.

 

 

 

TIME For Amber alert Nick :cold:  :clapping:

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Forecast challenge for certain, but bear in mind it is better to compare 12z ECM to yesterday's 12z than last night's run, and as many key ingredients in this developing situation are over North America, this may be one time where GFS/GEM (fairly consistent agreement) might have an edge at this point in time. We'll see how that plays out. Would not be very surprised if tonight's ECM goes back to a stronger solution.

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You see my first ramp post is met by a miserly ECM T216hrs chart! I think I'll go back to mr sensible. Serves me right for getting carried away.....

 

The ECM T216hrs manages to phase a shortwave to the sw with the one heading south from the north and was devised by Satan himself, the timing for that to happen that way is very unlikely.

 

I wouldn't get too worried about the ECM as its making things overly complicated, lets be positive the upstream pattern is great for cold into the UK.

 

Couldn't agree more. There's no point getting too hung up on details for charts still 8-10 days away, that kind of thing will change with every run.

 

What cold fans should focus on is what is NOT currently showing for the period between Xmas and New Year; i.e. mild Atlantic driven weather. Every model has some kind of unsettled and cold theme; just different takes on it. That has to be a good sign; the trend is clearly there.

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Don't stress about a uninspiring ecm 216hr chart peeps. We are talking 9 days away after all and as you get told thousands of times don't get elated or depressed with each run.

The trend of building heights towards greenland is there again on the ecm tonight just like it is on the earlier gfs and that is all that matters at the moment. Rome wasn't built in a day.

Edited by No Balls Like Snow Balls
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The ecm is slightly delayed in its progress by the spoiler low!Its just a one run variation .Its not the best on blocking and ridging id suggests given todays output will be gone by tom.Anyone expecting cross model agreement at 7-10 days is going to be off there nut in a week imo

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I wouldn't get too worried about the ECM as its making things overly complicated,

 

thats what the higher res models do as the runs go on. the main reason why the pros will generally ditch the op past day 7 unless it fits what they expect to be the situation at that point and then they will take interest in how the higher res handles the evolution.  ive read a fair bit on how the new gfsp is being described as being likely to generate a more messy verison of the current gfs with no great increase in accuracy.

 

until we see whats going to happen mid atlantic days 5 thru 8, we are just guessing re any detail. at the moment, just take the long wave pattern and be comfortable if it points cold (assuming thats what rocks your boat).

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