Model output discussion 25th Jan - The final third of winter beckons..

[sparky1972]

3 minutes ago, TEITS said:

Possible if the flow veers from a E,ly to a NE/ENE,ly. The temp rise occurs due to the warming effect though the wash. Seen this occur many times.

thanks for the reply, guess that writes off any snow chances, lol.  still here is hoping for change, looking forward to reading peoples views and opinions on the days model output, keep up the great work guys and girls

[nick sussex]

The GFS and ECM are on different planets today. The ECM seems to want to leave the PV over Greenland and the GFS removing this and developing some retrogression. If the MJO is the key driver then the GFS is correct as its evolution and what its been trying to do ties in with the progression of that signal. It could be that we're seeing different views of the PV in terms of re-location after the strat warming but its very unusual to see such vast differences in terms of strat response.

The MJO today on the Macritchie forecast remains rock solid on progression to phase 7 and 8 , so with conditions now helping that signal to impact the NH pattern I'd continue to be dubious of the ECM.

Edited February 6, 2017 by nick sussex

[frosty ground]

The GFS 06Z increases the strength of the wind on this run, there will be a real wind chill even when the uppers get mixed out for a time.

[Gustywind]

4 minutes ago, sparky1972 said:

thanks for the reply, guess that writes off any snow chances, lol.  still here is hoping for change, looking forward to reading peoples views and opinions on the days model output, keep up the great work guys and girls

I remember back in Jan 10 ( I think) the Beeb were calling up to 20cms of snow for SE, but they got rain instead. Steve Murr forecast this in advance I believe.

Upper air temps were sub -10 I think but the long fetch over the North Sea turned dew points the wrong side of marginal.

[snowray]

What we have here is not just a Greeny high setting up but a huge Northern Block going from Greenland, through Iceland and into Scandi. Late February could be memorable, bitterly cold and snow too.

 

T240 

[Ice Day]

At 234 there is a growing cold pool with -8's expanding over the eastern side of the UK with snow showers building in for the north east of England and east coast of Scotland

 

[frosty ground]

Day 10 chart but that cold pool over the UK has really intensified in situ.

[jvenge]

8 minutes ago, nick sussex said:

The GFS and ECM are on different planets today. The ECM seems to want to leave the PV over Greenland and the GFS removing this and developing some retrogression. If the MJO is the key driver then the GFS is correct as its evolution and what its been trying to do ties in with the progression of that signal. It could be that we're seeing different views of the PV in terms of re-location after the strat warming but its very unusual to see such vast differences in terms of strat response.

The MJO today on the Macritchie forecast remains rock solid on progression to phase 7 and 8 , so with conditions now helping that signal to impact the NH pattern I'd continue to be dubious of the ECM.

ECM Op has been terrible for a week or so now. No idea what is going on with it. 

[snowray]

HP over Iceland 10/10. Lots of snow showers packing in now.

[snowray]

Very snowy chart.

[Ice Day]

Almost a nationwide snow event at 276.  Looks particularly good for our friends in the West and Ireland

[nick sussex]

Composites for phase 7 and 8 MJO, to be conservative these are the ones for a lower amplitude. I think you can see the GFS is quite close to this

 

[snowice]

1 minute ago, Ice Day said:

Almost a nationwide snow event at 276.  Looks particularly good for our friends in the West and Ireland

Way out in FI, but with a block  that large not so Fantasy after all! 

[Man With Beard]

37 minutes ago, Iceberg said:

Gfs looks very good, more importantly the small wave that develops for Sunday will imho develop into a meso low at it enters the t96-72 timeframe with warm sector and cold sector. The warm sector should still be cold enough for snow but I can see this giving 2-8 inchs due to the low progression and infeed of moisture from the North Sea. 

 

Yes Iceberg. This feature is being forecasted by models again and again, first by GEM and now by all the others.

I can't see this being a dry feature. 

Snow chances for the weekend on the up imo.

And watch this front on Wednesday. Could turn to snow as it is pushed back.

If these runs come off, it will be like waiting for a bus and 3 coming at once.

Edited February 6, 2017 by Man With Beard

[Sky Full]

GFS 06z now showing a cold easterly setting in as early as +48hrs

and continuing almost unbroken from the same cold direction until the 18th - well into FI.   Getting even colder towards the middle of the month....

This is, I believe, what is commonly referred to as 'getting the cold in'.   Whatever is being modelled today, it Is practically a certainty that most of the U.K. will see snow in some form or another over the next 2 weeks.  Can we begin to hope that something like the situation shown on the 17th February will bring some significant snow to many places?

 

 

 

 

[Nouska]

27 minutes ago, nick sussex said:

The GFS and ECM are on different planets today. The ECM seems to want to leave the PV over Greenland and the GFS removing this and developing some retrogression. If the MJO is the key driver then the GFS is correct as its evolution and what its been trying to do ties in with the progression of that signal. It could be that we're seeing different views of the PV in terms of re-location after the strat warming but its very unusual to see such vast differences in terms of strat response.

The MJO today on the Macritchie forecast remains rock solid on progression to phase 7 and 8 , so with conditions now helping that signal to impact the NH pattern I'd continue to be dubious of the ECM.

The BBC weather men talking as if this is a key ingredient.

 

[Singularity]

13 hours ago, s4lancia said:

Even though it seems a bit backwards, Isn't the fact it is in high resolution exactly why an op can go off on one in certain circumstances. Picks up on a wrong signal early on and exponentially goes awry thereafter. i.e. takes the baton and just runs with it, a path of no return

That said, if it is it is a signal the lo-res aren't going to see quite yet, sometimes its going to be a correct one...

Late responding to this but there may be something in this; more data points could act to amplify any differences - including errors.

However I get the sense that for some reason there's something fundamentally different about the forcing going into the model from the tropics - as if some contradictory phenomenon is being fed in, perhaps something to do with the handling of to what extent convection occurs over the Indian Ocean and how much impact this manages to have. The Indian Ocean Dipole is near neutral which offers little guidance as to what's more likely to take place - but there's enough professional interpretation indicating a prolonged cold spell to permit an assumption -at least for now - that whatever interference ECM is seeing is spurious.

GFS 06z, with it's less cold interlude from the SE Mon-Tue yet still a recovery of a cold flow from the east by next Wednesday, is much as I expected the 00z ECM to pan out when the run was about halfway uploaded. For whatever reason, while GFS sees the jet stream a little south of the eastern Med. helping to maintain a shallow upper trough environment there with the block 'propped up' even as the surface pressures rise across C-S. Europe, ECM seems to be negating this connection, leaving a 'gap' at the upper levels into which the block can 'sink'. This is speculative, though, as I only see the public charts.

Some fascinating weather coming up from a meteorological perspective and perhaps some interest from an observed-weather perspective too 

[bluearmy]

Little time to comment but the extended ens are getting me interested now as they trend towards the Siberian vortex taking charge again and possible dropping troughing  south west towards scandi

the fi gfs ops (both normal and parallel ) headed this way

the mid range still uncertain but the 5/7 day period holds a lot of interest though pinning down exactly where that interest is greatest will prove a problem for the next 72/96 hours !

[Frosty.]

My God these Gfs 6z charts are magical

After last winter's dismal desperate horror show we coldies richly deserve this don't we?..and this is the tip of the iceberg so to speak, it could go on and on and on...

Edited February 6, 2017 by Frosty.

[Summer Sun]

The GFS ens shows it becoming very cold later this week

Into next week it remains cold but real low 850's move away with the UK seeing -2's or so instead of -8's to -10's

[Summer Sun]

Short term GFS ens shows the Op is on the cold side of the mean from the 9th to 13th (though getting closer to the mean around 11th before going colder again) it then goes on the warm side for how long? we'll find out soon

Edited February 6, 2017 by Summer Sun

[Weathizard]

The 6z GEFS are a real mess in the medium term so the mean is skewed, control is very good though following a similar pattern to the op.

Both will be right at the cold end

[frosty ground]

4 minutes ago, Summer Sun said:

Short term GFS ens shows the Op is on the cold side of the mean from the 9th to 13th (though getting closer to the mean around 11th before going colder again) it then goes on the warm side for how long? we'll find out soon

Two groups which gives us a 50/50, The mean is irrelevant as it's one or the other.

Plenty of support for the Op
 

[legritter]

50 minutes ago, Man With Beard said:

Yes Iceberg. This feature is being forecasted by models again and again, first by GEM and now by all the others.

I can't see this being a dry feature. 

Snow chances for the weekend on the up imo.

And watch this front on Wednesday. Could turn to snow as it is pushed back.

If these runs come off, it will be like waiting for a bus and 3 coming at once.

Yes its great that we do have this cold period well in the reliable ,and next weekend or should i say this weekend could see some surprises ,these will of course show up better on fax charts as we go through this week .

for those of a nervouse position including myself ,i have watched many cold spells [over the years ]start dry and a bit boring but surprises do turn up ,and its going to be a forecasters nightmare i think ,lets hope that we are waiting for a bus and three turn up that we can hop onto ,well gang hope all of us see something cheers .

[nick sussex]

Putting aside the difference in 850 values on the GEFS the key thing to take from those is that at T240hrs not a single member backs any sort of Atlantic return. At the moment the GEFS are still finding their way from the Scandi block to how that retrogresses. Game over for the Atlantic don't let the door hit you on your way out!