Model output discussion - 1st December onwards

[Gavin Hannah]

2 minutes ago, radiohead said:

Staggering difference between the UKMO and GFS over Canada at T144

Woah... that's a disagreement and a half!

[radiohead]

Well there's potential there...High pressure squeezing up to Greenland. I'm looking forward to the ECM already.

 

Edited December 8, 2015 by radiohead

[bradymk]

As others have said, big disagreements still between the models and fairly early in the runs too. When you have such disagreements, you're always in with a shout i believe.

GEM, GFS and UKMO attached all showing something different at 144....

[Ali1977]

4 minutes ago, radiohead said:

Well there's potential there...High pressure squeezing up to the Greenland. I'm looking forward to the ECM already.

 

Yes, actually quite similar to the last run with regards high pressure towards southern Greenland, not quite as extreme but still cold enough for a spell of proper winter weather, although maybe only for a day or so. Not to far away from linking with the Arctic high neither!!

Edited December 8, 2015 by Ali1977

[Mucka]

Certainly not the first time a battle ground scenario has been shown between cold air attempting to dig in from the North and warmer air pushing up from the SouthWest - if that came into the reliable things would get very interesting re frontal snowfall. Too far out and wishful to paint pretty piuctures right now though

 

[Snowman.]

Pressure continuing to build over Southern Greenland

 

 

[Dreamnine]

13C in Edinburgh at 6 this morning - there have been a few days like this. I see nothing in the models to show any cold for the forseeable future, just a slight and brief cooling down coming over the weekend.

[Man With Beard]

Ahh...the ensemble means debate.

The ensemble mean, for me, gets more useful the further away from average it is. A mean which is significantly one way or another indicates a bias for clustering, and therefore a better guide of the likely outcome.

Recent example - mean charts at the end of October had a 1030mb High over Eastern Europe at T300. Now that's a serious deviation from the average. It indicated both the likely strength and size of the block. Furthermore, they were consistently at this level for several runs. From those mean charts, it was easy to predict that in the first 14 days of November, the UK would be on a boundary between High and Low, with a warm SWly feed. In fact, the block was slightly weaker than the mean had predicted, but it was still strong - in other words, there was still a difference between the mean at T300 and the actual at T0, but the initial mean variation was so strong that we could be confident that even a deviation in the mean would still result in a decent block, and therefore fairly similar weather.

A mean which simply tracks the average, though, is not as helpful, for the reasons already well stated by Nick and others - it doesn't reveal if the members are all close to the mean, or if the members have a large scatter but equally weighted on both sides.

[Iceberg]

Gfs was always going to end up like that thanks to the t144 jet. 

Still very far from certain and only a possibility but hopefully it puts to bed the it only happens in fi and never gets any closer brigade. 

Meto does not agree with gfs, although far from perfect the meto isn't bad. But a southerly jet exit at t120-t149 does  a greeny high make. 

[northwestsnow]

Some very encouraging outputs this evening with GFS wanting to bring in a northerly and some very seasonal weather in the run up to christmas.:)

[Mucka]

4 minutes ago, bradythemole said:

As others have said, big disagreements still between the models and fairly early in the runs too. When you have such disagreements, you're always in with a shout i believe.

GEM, GFS and UKMO attached all showing something different at 144....

 

 

GEM is cannon fodder, not worth considering unless we it shows clod and we are desperate

The promising thing is that though GFS and UKMO are very different and therefore not to be taken too seriously, they both show the promise of some colder weather developing. UKMO would likely look very nice at 192 IMO.

[Daniel*]

Well it seems we'll be losing those long drawn south westerlies with winds from a N/W vector. Average to just below average the wider scope. 

+180 is quite interesting with that storm possible helping in squeezing and reinforcing a weak ridge to Greenland. There are reasons to be quietly satisfied if you're a coldie.

[Gavin Hannah]

 

Is there something brewing in the GFS cauldron.... this would produce some insane amounts of snow at the "battleground" mark.

The key difference between the 06Z and this is the strength of the low of Scandi. It's more organised and a single low rather than two cluster lows.

Edited December 8, 2015 by Gavin Hannah

[Man With Beard]

5 minutes ago, Mucka said:

Certainly not the first time a battle ground scenario has been shown between cold air attempting to dig in from the North and warmer air pushing up from the SouthWest - if that came into the reliable things would get very interesting re frontal snowfall. Too far out and wishful to paint pretty piuctures right now though

 

And now for a current models post! Yes, serious battleground Mucka

That little gap between low in the Atlantic and low over Scandi would result in very cold on the east side and very mild on the west side. Possibilities of cold for NE areas seem to be growing - SW areas might need to have a  thick coat handy as well as a BBQ, Knocker!

Now, if the two lows could combine and cut the High off, then coldies would be in serious, serious business...

Edited December 8, 2015 by Man With Beard

[Ali1977]

If the ECM backs this up maybe we have a rapid and quite unexpected change coming in, still hard to believe we can even get a freebie high in such a strong PV - however this is the new very powerful GFS so maybe it knows best!!!! Or not.

[chrisbell-nottheweatherman]

3 minutes ago, Man With Beard said:

A mean which simply tracks the average, though, is not as helpful, for the reasons already well stated by Nick and others - it doesn't reveal if the members are all close to the mean, or if the members have a large scatter but equally weighted on both sides.

As usual, someone else sums-up my point in 2 lines when I needed 2 paragraphs! 

 

 

[knocker]

The gfs has the first low tracking into Ireland before turning east. It then tracks the second low up by Mon. 00z before moving it NE. Hopefully the rain associated with them doesn't hang around although the rainfall amount/distribution wont really be sorted until the analysis is nailed down more later in the week.

 

[ItNeverSnowsInWindsor]

Fascinating watching the GFS 12z emerge which trends similarly to the 6z until T144 where the earlier run develops a shortwave near Iceland which the 12z doesn't and allows an earlier plunge of pM air over the UK.

Too close to call on this run with the UK sitting right on the COL with a battleground situation emerging between cold Arctic air and mild tropical maritime air.

Look forward to seeing the ECM's take on things later.  The crucial timeframe could be around T120 to see whether the low coming off the US coast moves South East to merge with the low in the mid Atlantic by T156. We need to see more energy going into the southern jet stream otherwise low heights around Greenland / Iceland would prevail as shown on the GEM.

Edited December 8, 2015 by prolongedSnowLover

[carinthian]

7 hours ago, carinthian said:

Good Morning, a colder end to this week for most of British Isles. The model charts for Sunday are showing some uncertainty. The warm front looks like making limited progress NE wards this time with perhaps Northern UK holding on to colder air mass for a bit longer. Perhaps snowfall may come into the forecast later into next weekend, especially further north and east with height. Whether this is transitional will be determined how quickly the colder air ahead of the front is over ridden. The timing and speed of movement of this front is now open to some debate and we await further updates as the upper air push is now weakening from this direction.

 C

Now with a bit more information, it looks like the UKMO wants to progress the warm front  NE over the weekend but timing is still not certain in its forecast. The latest model difference between GFS and the UKMO shows GFS to be more progressive with its frontal clearance over the weekend, whereas, the UKMO less so. Here lies the problem if the fronts slow down, lots of rain likely and again looks like NW England could see the brunt.  I think we have to see how the weekend pans out before a more define cold/ mild battle boundary devolves.  Should make for some interesting model watching during this transition.

 C

Edited December 8, 2015 by carinthian

[Captain Shortwave]

Good effort from the GFS in respect to developing that high between Iceland and Greenland, not far off from developing a potent and potentially prolonged spell of cold weather if that came off. The Temperatures at day 9 range from below freezing in the north to scraping mid-single figures in the south.

One must not get too caught up in the moment though as huge uncertainty remains and of course one one issue we continue to see is the above average heights over Iberia and the eternal struggle to shift them.

GFS

Snow for Scotland, especially the north east, mild air still hanging on over Cornwall and Devon with outbreaks of rain and back edge snow over the hills of South Wales and and nearby English counties.

The GEM however develops differently as expected with the mid range shenanigans.

Cold lovers dream or cold lovers nightmare in two charts almost, with near enough every other solution in the mix, though stormy conditions look less likely as the pattern looks rather sluggish from the end of this week and beyond.

The first attempt to build a mid latitude high looks unlikely to succeed (timing this weekend), but a second attempt is increasingly showing on the models and holds a little more potential as a deeper trough exits north America and tries to undercut this ridge. No guarantees on the end result of course (Wintry, cold and dry, another unlucky mild solution). 

Edited December 8, 2015 by Captain Shortwave

[Ravelin]

OK, the GFS has officially gone off it's rocker in FI...

[Snowman.]

Pub run came early?

[gottolovethisweather]

Cross model suite confusion still as has been the case over many recent days and at as early as D6 then, speaks volumes for me. Sadly, there are much more pertinent discussions to be had around the next few days' rain and further flooding potential. Beyond this weekend, it is with growing confidence that I see next week as a turning point in the UK Winter. I'm not predicting entrenched bitter cold air lasting for days upon end or for equally Blizzards in Barnet but I do see a change a-coming, one that coldies and/or those seasonal types amongst us will enjoy. Not much difference Northern Hemispherically speaking from this post except that things might start ramping up in here should these prospects remain in the outputs come the early part of next week.

 

Personally, I still stand by what I said here.

On 07/12/2015 at 10:03 AM, gottolovethisweather said:

My interest is piqued as with many folk in here by looking beyond the immediate more predictable timeframes into those mid to longer range timescales. Well, from the 13th December onwards, I still believe some form of pattern change (Should you be located in the NW or Scotland you'll be shouting Hoorah be gone flooding rains and winds at this stage) is on its way for the second half of December. Here is part of my reasoning based upon these 850s charts from the ECM 0z aforementioned.

 

On 07/12/2015 at 10:03 AM, gottolovethisweather said:

Also, again, the period from the 17th December as hinted at by the ECM does at least appear to be of interest to us coldies. 

 

 

 

[Ali1977]

3 minutes ago, Ravelin said:

OK, the GFS has officially gone off it's rocker in FI...

I said it may link with the Arctic high.....wishful thinking hits reality.....Come on ECM, follow suite please.

Edited December 8, 2015 by Ali1977

[feb1991blizzard]

This 12z GFS is turning into one of the great runs of all time hemispheric wise, unfortunately with the lack of support and poor run to run consistency, I don't think it has much credence, if it was to veryify though, we could be looking at a really long winter, with further attacks on the Strat vortex likely, it could be a long road to any daffodil growing weather!