Model Output Discussion - The Start Of Winter

[alex12]

I agree with regard to fergie.. We are so lucky to have a member with professional insight, it does however make me feel like I'm watching my team on match of the day and knowing that they have lost... Takes the fun away a little sometimes..

what page is Fergies post? 

[Mucka]

I agree with regard to fergie.. We are so lucky to have a member with professional insight, it does however make me feel like I'm watching my team on match of the day and knowing that they have lost... Takes the fun away a little sometimes..

 

Ha ha I know what you mean but it is great to have a grounded view from a professional as well as the more speculative amateur views on what changes may occur rather than just what is being modeled. It is the best of both worlds and remember the models ALWAYS change their output from day 5 at the latest so anything 10 days+ and out to a month is highly open to change and the forecast along with it.

Even the professionals are speculating at these ranges albeit from a very informed standpoint.

Edited December 6, 2014 by Mucka

[TSNWK]

what page is Fergies post?

09:13 page 37

[Dancerwithwings]

what page is Fergies post? 

https://forum.netweather.tv/topic/81934-model-output-discussion-the-start-of-winter/page-37#entry3081689

[BlueHedgehog074]

Don't want to be a party pooper, but we've had to terminate a post on the previous page that wasn't weather model related (a post about someone's song choice), so just a reminder to try keep this thread to the models please. I know most of you are doing that, but just thought I'd still add in this reminder. Thanks guys and keep up the fab work.

[IDO]

Ha ha I know what you mean but it is great to have a grounded view from a professional as well as the more speculative amateur views on what changes may occur rather than just what is being modeled. It is the best of both worlds and remember the models ALWAYS change their output from day 5 at the latest so anything 10 days+ and out to a month is highly open to change and the forecast along with it.

Even the professionals are speculating at these ranges albeit from a very informed standpoint.

Fergie did add that Shannon is on holiday till after Christmas. So it is probable that there won't be a pattern change in the medium term, confirmed by recent FI output.

[LomondSnowstorm]

GEM keeps it flat through the next 10 days:

 

gem-0-114.png  gem-0-156.png gem-0-240 (1).png

 

The uppers remain -4c or warmer throughout the run and any snow is on Scottish mountains. No Arctic Northerly at the end of next week either?

 

So UKMO at one end of the amplification index, GEM at the other end and GFS in the middle. At least 50% support for something closer to GEM than the GFS op at D6 according to its ensembles, and no surprise that there is no support for the UKMO take (after their last non-Northerly it has to be treated with considerable doubt):

 

Meteociel_-_Panel_GEFS 2.png

 

So still uncertain how much the Atlantic ridge will amplify?

A minor point but the GEM does have a tendency to undercook upper air temperatures, particularly in north/northwesterly flows, while simultaneously having a tendency to overcook Arctic heights. I've seen it do this a few times so far this winter, where even early doors it gives uppers 2-3C higher than the GFS or ECM, and often ending up with bizarre setups that look like classics synoptically but without any cold pool to tap into. Conversely JMA (and to a lesser extent UKMO) are often a bit too keen on the colder uppers, and usually the ECM or GFS ends up the closest for upper air temps within the reliable.

Anyway, reasonably happy with the output so far, with still a decent cold pool coming east on Tuesday night and sticking around for a day or so (and eventually being reinforced from the NW). Where this is centred will determine where has the best chance of lowland snow, and it looks likely that somewhere from Central Scotland to about Manchester has the best shot, but potentially further north/south depending on where the low ends up tracking. After that, a fairly consistent signal for a northerly toppler, potentially not all that cold at first but with the possibility of sub -8C uppers and near -40C 500hpa temps which, in a straight northerly flow, open up the possibility of (whisper it) polar low formation in the NE Atlantic

[snowice]

I agree with regard to fergie.. We are so lucky to have a member with professional insight, it does however make me feel like I'm watching my team on match of the day and knowing that they have lost... Takes the fun away a little sometimes..

I wouldn't worry to much how many times have we see the output change on the models?

[Frosty.]

Not a bad northerly at 156 on gfs but those cold uppers look abit narrow for snow away from the far north. Also still a week away so confidence low at moment.

I don't think confidence is low, the only question is whether it's a bitter northwesterly or northerly blast but either way it will bring snow showers and frosty nights..not just my words..MO predicting cold, windy and showery weather later next week and next weekend and lots of pm wintry weather before then too.

Edited December 6, 2014 by Frosty.

[Mucka]

Fergie did add that Shannon is on holiday till after Christmas. So it is probable that there won't be a pattern change in the medium term, confirmed by recent FI output.

 

He did indeed and it is a fair point but Shannon entropy is really only a measure of uncertainty and he is basically saying that today the probabilities are high for no pattern change but will that be the same in 5 to 10 days?

That is what makes the weather and output so interesting to follow and brings us here virtually every day - after all you will be back tomorrow and  the day after scouring the models for changes with the rest of us. 

[nick sussex]

Is this more attention seeking from the UKMO or will it actually pull out a chart at T144hrs that actually verifies?

 

The UKMO is much better than the GFS both upstream and to the ne but we've been here before over recent weeks in which its over amplified the patterns and backtracked.

 

If the ECM backs it then perhaps its on to something but otherwise I'd certainly have low expectations for the UKMO to actually verify.

 

The ECM doesn't back the UKMO however it develops a different shortwave over Canada, much depends now on whether this phases with the cut off low and stops piling all the energy into Greenland.

Edited December 6, 2014 by nick sussex

[Cloud 10]

Is this more attention seeking from the UKMO or will it actually pull out a chart at T144hrs that actually verifies?

 

 

Yes,it certainly had a severe case of over amplication-itis for yesterday's "Northerly",and stuck with it for a good few runs as well.

 

144 hrs predicted..  actual..

 

At least it has some support this time around from the GFS,and you can generally count on the ECM to provide some extra amplification when needed!

[Snowmad79]

Fergie did add that Shannon is on holiday till after Christmas. So it is probable that there won't be a pattern change in the medium term, confirmed by recent FI output.

Nothing is confirmed until it verifies! To be honest, everyone seems so hung up looking for the Scandi block they are missing the bigger picture and that is frequent incursions of PM airmass via the North and West. Even if we continued in the current pattern it will be a good thing for many and better than last year.

 

Wind at times ? Yes, Wet at times Yes ? Snow showers for many ? Yes. Obviously the models do not currently show a severe and prolonged cold blast via blocking but it is not the be all and end all. Some of us have already had snow but we should not forget that changes to severe cold can often be abrupt.

[johnholmes]

Is this more attention seeking from the UKMO or will it actually pull out a chart at T144hrs that actually verifies?

 

The UKMO is much better than the GFS both upstream and to the ne but we've been here before over recent weeks in which its over amplified the patterns and backtracked.

 

If the ECM backs it then perhaps its on to something but otherwise I'd certainly have low expectations for the UKMO to actually verify.

 

The ECM doesn't back the UKMO however it develops a different shortwave over Canada, much depends now on whether this phases with the cut off low and stops piling all the energy into Greenland.

 

below is the link to show the 500mb statistics for the main models, over the northern hemisphere yes, but it seems unlikely that it is markedly different in our small patch in there? day 6=144h often maligned on here but the facts differ from some of the posts about this model, or so it seems to me.

http://www.emc.ncep.noaa.gov/gmb/STATS/html/new_acz6.html

[Summer Sun]

ECM looking better than GFS keeps the northerly at t168, still no sign of the Atlantic moving in at t192

 

 

Turning colder as well with -9 850's pushing into northern Scotland by Friday, by Saturday the -9's are further into Scotland

 

 

Chance of snow right down to the south west at 9 day

 

 

 

If the above comes off then the risk of snow to lower levels will increase significantly later next week in the north

 

Edited December 6, 2014 by Summer Sun

[nick sussex]

What drama! The shortwave over Canada phases with the cut off low and you can see because this is more amplified it draws the low heights nw and leaves southern Greenland.

 

You can see from the GFS it drives a shortwave east into Greenland and low heights head se.

 

The ECM regardless of what happens here on in is better than this morning, what you're looking for is for the low heights to arc away and with a bit more amplitude with the ECM you might get the high to kick further ne.

 

Amen for some excitement! here we go upstream that jet digging, I'm not sure if we'll get it this time but you can see how the low heights arc away nw around the high.

Edited December 6, 2014 by nick sussex

[Dancerwithwings]

Is this more attention seeking from the UKMO or will it actually pull out a chart at T144hrs that actually verifies?

 

The UKMO is much better than the GFS both upstream and to the ne but we've been here before over recent weeks in which its over amplified the patterns and backtracked.

 

If the ECM backs it then perhaps its on to something but otherwise I'd certainly have low expectations for the UKMO to actually verify.

 

The ECM doesn't back the UKMO however it develops a different shortwave over Canada, much depends now on whether this phases with the cut off low and stops piling all the energy into Greenland.

Plenty of back up there from the ECM for the UKMO to verify it's output... Even better than the UKMO at 144h don't you think!

 

[bluearmy]

Looks like the latter stages of ECM will deliver a depression running nw/se which would deliver snowfall. The feature running along the south coast day 6 looks like it won't influence far enough north to bring anything white.

[Mucka]

What drama! The shortwave over Canada phases with the cut off low and you can see because this is more amplified it draws the low heights nw and leaves southern Greenland.

 

You can see from the GFS it drives a shortwave east into Greenland and low heights head se.

 

The ECM regardless of what happens here on in is better than this morning, what you're looking for is for the low heights to arc away and with a bit more amplitude with the ECM you might get the high to kick further ne.

 

Amen for some excitement! here we go upstream that jet digging, I'm not sure if we'll get it this time but you can see how the low heights arc away nw around the high.

 

 

Yeah it's a nice run and 192 could be a snowy chart in the North but no support at the moment unfortunately.

[Cloud 10]

Pie in the sky at this range,but a very snowy day 8 chart from the ECM this evening with those 2 small LP's wrapped up in established cold air.

 

[Barry12]

If day 9 verified there would be a good chance of snow to low levels as far as the South West. A very cold and wintry run from the ECM tonight, who needs a pattern change?

 

Edited December 6, 2014 by Polar Maritime
To remove off topic comment.

[Nick L]

Pie in the sky at this range,but a very snowy day 8 chart from the ECM this evening with those 2 small LP's wrapped up in established cold air.

 

ECU1-192.GIFECU0-192.GIF

 

Indeed! The ECM precip-type charts show a swathe of snow all the way down to the M4 corridor with that. It's foolish to take such details seriously at this range, but it's still good to see. Very cold for Scotland with temperatures getting down to minus double digits.

Edited December 6, 2014 by Nick L

[nick sussex]

Heres the saviour shortwave over Canada:

 

 

For newbies I've arrowed the direction of energy, the whole thing fluidly moves anti-clockwise, you can see this shortwave will engage the cut off low and it rides in on a more amplified wave upstream, as this phases it helps to pull those low heights nw and allows the high to ridge further ne.

 

The more dig of the jet over the eastern USA the further ne the high will get pushed, it does flatten out somewhat at T216hrs but I wouldn't worry about this just yet.

 

We have to hope for a bit more amplification in future runs, however the key trigger is that shortwave that gets the ball rolling.

 

 

[Hocus Pocus]

Indeed! The ECM precip-type charts show a swathe of snow all the way down to the M4 corridor with that. It's foolish to take such details seriously at this range, but it's still good to see. Very cold for Scotland with temperatures getting down to minus double digits.

What would make that more impressive is the fact we'd be making a silk purse out of a sows ear given the fact that HLB is still not being shown in any of the output, just yet. Something is stirring around  mid month with or without HLB in place.

[blizzard81]

Nick does the word SHORTWAVE give u nightmares from Winters past.....

But this shortwave is not from the dark side of the force!