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

[feb1991blizzard]

2 minutes ago, Blizzardof82 said:

Is it just me or is the forecast SSW on GFS always at 300 plus hours?

The warming starts much earlier, there isn't a technical SSW (mean reversal at 10mb 60N) being modelled yet , not consistently any way, if the warming progresses and doesn't fizzle out, we should start to see one being modelled and in a nearer timeframe, this week, jury still out on whether it will do that though.

[booferking]

Enjoy the charts because its the only charts we have, dry up to mid term turning Increasingly Unsettled there after.

[Summer Sun]

Certainly, an upward trend for temps from the 23rd on this evening GFS ens double figures possible in the south

Wetter with it

Edited January 16, 2017 by Summer Sun

[chris55]

So in summary it looks like..... ( as we stand tonight)

Grey and cool to begin the week, bits of drizzle here and there, but if the skies clear then some cold nights and sunnier days.

As we head towards the latter part of the week more of a trend for drier clearer air to move our way from the continent, increasing the likelyhood of some quite cold nights and cool sunny days.

Then a signal for a more mobile, milder pattern, potentially turning cooler but still unsettled.

Overall a changeable next two weeks with a bit of everything thrown in........

Then we look forward to the big February freeze up courtesy of the SSW   (tongue in cheek here) you never know.

 

 

[blizzard81]

Whiff of a pressure rise over scandi after day 10 on the ecm op. Looking to see the ext ens trending colder towards the back end.

Edited January 16, 2017 by blizzard81

[nick sussex]

Well at least the ECM displaces the Azores high. Any earlier differences due to disagreements about some initial energy heading se like the UKMO don't currently effect the medium term.

It looks like turning colder during the week for the UK as the flow turns more se and there is still the chance for something wintry given both the UKMO and GFS attempt to bring some fronts in before the cold is pushed away.

 

[MP-R]

2 minutes ago, chris55 said:

So in summary it looks like..... ( as we stand tonight)

Grey and cool to begin the week, bits of drizzle here and there, but if the skies clear then some cold nights and sunnier days.

As we head towards the latter part of the week more of a trend for drier clearer air to move our way from the continent, increasing the likelyhood of some quite cold nights and cool sunny days.

Then a signal for a more mobile, milder pattern, potentially turning cooler but still unsettled.

Overall a changeable next two weeks with a bit of everything thrown in........

Then we look forward to the big February freeze up courtesy of the SSW   (tongue in cheek here) you never know.

 

 

Wouldn't be surprised if it takes the Atlantic breaking through to get some snow to our shores. The westerly of mid November was colder than the most recent northwesterly.

Well the CFS crystal ball has indeed showed a February freeze for the last week or so but I haven't posted any charts because it's exactly that... A crystal ball!

In the reliable however, something more seasonal over the next few days and into the weekend.

[Seasonality]

31 minutes ago, chris55 said:

So in summary it looks like..... ( as we stand tonight)

Grey and cool to begin the week, bits of drizzle here and there, but if the skies clear then some cold nights and sunnier days.

As we head towards the latter part of the week more of a trend for drier clearer air to move our way from the continent, increasing the likelyhood of some quite cold nights and cool sunny days.

Then a signal for a more mobile, milder pattern, potentially turning cooler but still unsettled.

Overall a changeable next two weeks with a bit of everything thrown in........

Then we look forward to the big February freeze up courtesy of the SSW   (tongue in cheek here) you never know.

 

 

You forgot the horrible mild Greek Euro high.

[ANYWEATHER]

Evening All and Wake Up!!!  Its rather a stagnant non descript outlook this week with high pressure in control. Looking later into the week Spain throws us a colder pool of air from the south into the weekend ......How often do you see that??? After that interesting times....

[Singularity]

A technicality to bear in mind when looking at the ensembles when a fairly strong Euro High - in terms of SLP and 500 mb heights - is being indicated but not necessarily for very long; there will be differences in timing when it's at 6+ days range which will tend to stretch out the period in which there is some form of high pressure to the south.

The effect applies with N. Atlantic-N. European troughs too, and of course is evident to some extent in pretty much any pattern, but with those aligned to the climatological norm tending to display it more prominently.

Couple that with the fact that the lower resolution of ensembles may lead to a tendency to over-simplify the transport of anomalies from the tropics to the mid-latitudes (not enough complications along the way), and I'm not inclined to take the ensemble mean at face value.

Indeed, 'face-valuing' is a common trait among those trying to find their feet in model watching. It should always be discouraged for charts beyond around 6 day's range and sometimes several less days in complicated situations such as we seem to have had far too many of this winter 

So what use are the ensemble means, then, you might be wondering? Well, for starters you can get a broad overview as to how the overall pattern across a several day period is likely to be. The trick is to then imagine an increasing amount of 'uncertain waviness' in the contour lines as you look further and further ahead; this representing the involvement of areas of low pressure moving with the (usually zonal) flow. Just how much uncertainty there is can be gauged from looking at the anomalies and considering how they compare to what you'd actually expect from a setup akin to the mean. In this case the positive 500 mb anomaly is not that strong considering the scenario of WAA through the UK, so it seems there's room for the trough to be further east with us seeing a transition to polar maritime air and the ridge backing west out of Europe. A trough further west looks unlikely due to the strength of the positive height signal over Canada.

For example, in the below we can see that on balance the most likely outcome is low pressure to the NW with us under warm advection on the NW flank of a ridge through Europe, but, as confirmed by the spreads, the trough could be as far east as Scandinavia by this time (while room for adjustments west does indeed appear small). 

  

 

Interestingly the mean shows lower pressure by day 10 than we've been used to for much of the time this winter (with the exception of last Wed-Fri) and heights to our south look no stronger than normal by this point, which makes something close to the ECM 12z - but perhaps not quite as sharp with dropping the trough at the end - look very feasible, albeit with a very wide range of possibilities in terms of the timing of events (in this case, the stretched out nature of the mean trough can tell us this all by itself but I've attached the other two views because, well, I like a good bit  of colour in my posts):

  

[Grimsby Snow Lover]

37 minutes ago, ANYWEATHER said:

Evening All and Wake Up!!!  Its rather a stagnant non descript outlook this week with high pressure in control. Looking later into the week Spain throws us a colder pool of air from the south into the weekend ......How often do you see that??? After that interesting times....

Hi Anyweather. Please explain why exciting times? Thanks

[Man With Beard]

Hmmm - yesterday I said less than 20% chance of lowland snow by the end of January - well strike that. I think we might be heading for a repeat performance of last week's super-cold polar maritime blast by D11/D12. My evidence:

 

The effect of the Canadian High is to draw very cold air into the Newfoundland area off Greenland.

As the pattern moves east, there will continue to be a Greenland feed into the low pressure system for a good while more - unlike from a normal zonal system, which travels in a straight line off Newfoundland and begins to warm over the ocean straight away.

The way the models are underestimating the speed of what comes out of the Atlantic, I would not be surprised to see a low similar to last Thursday's hitting the UK two or three days after these charts, as long as height stay low over Europe (that's the big "if")

Two more weeks into winter and that extra degree colder might just produce something more substantial.

Chances of snow before February back up to 30/40% for me 

 

[blizzard81]

Ecm ext ensembles for debilt look fractionally colder than this morning's suite towards the back end. I expect this trend to continue with only a temporary mild blip around the middle of next week. I feel the best of this winter is yet to come, namely first 10 days of Feb.

[Seasonality]

7 minutes ago, blizzard81 said:

Ecm ext ensembles for debilt look fractionally colder than this morning's suite towards the back end. I expect this trend to continue with only a temporary mild blip around the middle of next week. I feel the best of this winter is yet to come, namely first 10 days of Feb.

There is a term for this period that I can't remember. It refers to the first half February often being the coldest part of winter "the x minimum." Just can't remember what the x is, I keep thinking Maunder Minimum but I know that is something completely different. Can anyone help?

[blizzard81]

Just now, Seasonality said:

There is a term for this period that I can't remember. It refers to the first half February often being the coldest part of winter "the x minimum." Just can't remember what the x is, I keep thinking Maunder Minimum but I know that is something completely different. Can anyone help?

You are right, certain periods of winter tend to be colder than others. I have noticed this over the years. Not maunder minimum though lol, the Thames will not be freezing over

[mulzy]

16 minutes ago, blizzard81 said:

Ecm ext ensembles for debilt look fractionally colder than this morning's suite towards the back end. I expect this trend to continue with only a temporary mild blip around the middle of next week. I feel the best of this winter is yet to come, namely first 10 days of Feb.

The ext eps broadly similar to this morning's run, but maybe the jet axis a little bit further south.  The control run has a few shallow low pressure systems running on a southerly trajectory that may produce marginal snow events over parts of the UK.

Edited January 16, 2017 by mulzy

[winterof79]

JFF,be just our luck really an SSW

Cross Polar Heights

And we end up with this muck

 

[BurwellWeatherWatch]

10 minutes ago, Seasonality said:

There is a term for this period that I can't remember. It refers to the first half February often being the coldest part of winter "the x minimum." Just can't remember what the x is, I keep thinking Maunder Minimum but I know that is something completely different. Can anyone help?

Buchan or Buchanan period if I remember correctly?

[Stu_London]

16 minutes ago, Seasonality said:

There is a term for this period that I can't remember. It refers to the first half February often being the coldest part of winter "the x minimum." Just can't remember what the x is, I keep thinking Maunder Minimum but I know that is something completely different. Can anyone help?

Or maybe plain old "thermal" - this being around the turn of the month

[winterof79]

24 minutes ago, BurwellWeatherWatch said:

Buchan or Buchanan period if I remember correctly?

While it is quiet.....My version THE BRADLEY SPELLS to the right

3. BUCHAN'S SPELLS.

(NB: strictly based on records across south-east Scotland, and specifically Edinburgh.)

Nine periods where put forward by Alexander Buchan in 1867 on the basis of 50 years of observations (though some texts quote only 1857-1866), constituting fairly reliable periods of unseasonal cold (6 cases) or warmth (3 cases).
Note that Buchan himself did not claim these as 'singularities' and it is widely accepted that they have little real predictive merit: they are included here for the sake of historical completeness. (**=shows some correspondence with Lamb etc.)
7th - 14th February: COLD**     Mild
11th - 14 April: COLD                Mild
9th - 14th May: COLD**       Not as mild (Now known as summer)
29th June - 4th July: COLD/COOL Getting milder
12th - 15th July: WARM    very mild and wet
6th - 11th August: COLD/COOL Getting milder and damper
12th - 15th August: WARM**  very mild and wet
6th - 13th November: COLD   Not as mild
3rd - 14th December: WARM/MILD** warm and wet

Edited January 16, 2017 by winterof79

[blizzard81]

19 minutes ago, mulzy said:

The ext eps broadly similar to this morning's run, but maybe the jet axis a little bit further south.  The control run has a few shallow low pressure systems running on a southerly trajectory that may produce marginal snow events over parts of the UK.

Thanks for that update, much appreciated. I was thinking/hoping the control run showed something like that.

[Ali1977]

22 minutes ago, mulzy said:

The ext eps broadly similar to this morning's run, but maybe the jet axis a little bit further south.  The control run has a few shallow low pressure systems running on a southerly trajectory that may produce marginal snow events over parts of the UK.

What time frame are we talking here?

[festivalking]

The block extends a couple of hundred westwards on the 18z at t96

[winterof79]

2 minutes ago, festivalking said:

The block extends a couple of hundred westwards on the 18z at t96

Its resistance is futile

[mulzy]

15 minutes ago, Ali1977 said:

What time frame are we talking here?

12-15 day period.  All deep FI.