Model output discussion - the beast arrives

[Derecho]

Now that is what I call a swing . Many ensemble members follow the op so quite the contrast. Whereas earlier it looked as though milder air would bring average temperatures, it looks like Sunday could bring an extension of the cold... even down here (maximums slowly creeping up though until another cold blast comes along perhaps due to mixing or solar radiation - imagine if this was December....)

And I thought persistent cold earlier was a long shot...

Edited February 27, 2018 by Quicksilver1989

[JBMWeatherForever]

Looking at the models tonight and I really think this is now looking more and more like a spell which lasts at least two weeks. Lots of opportunities for snow events in the next week or so too. In fact after the slightly less cold (but still cold conditions) make it into the UK from the South, every chance now of renewed very cold air returning from the north east next week. The current very cold air may even hold on in the north, on current trends. 

[Timmytour]

Interesting keeping track of the models for the UK from here in Austria where of all the weeks to be out of the UK Im away this week.

Had very cold days and nights but forecast has been consistent for a long while now about the cold getting pushed away. Today max -16... Friday due to be 8C and rain

Just to show cold air can be shunted away.  Hope what is over UK prevails lo g enough for me to see....

[tight isobar]

 Hardly mild...

In fact this could soon go-complete opposite!!.

@scatter later @but trending

[BLAST FROM THE PAST]

12 hours ago, Ed Stone said:

I'm minded to agree with you there, Fred: the 'warmest' temps I've seen forecast for the early part of next week are mostly 5s and 6s...So hardly warm for the start of March...

As we often like to say on here: It ain't over till Adele sings!

 

And what an interesting morning we start with.  More cold remaining adjustments south and maybe more to come yet.  UKMO colder than 12z up to t144.

 

BFTP

Edited February 28, 2018 by BLAST FROM THE PAST

[That ECM]

Gfs control at t90 t96 t102 is interesting. Not dissimilar to ukmo as a low separates. Control has this heading more east than ukmo. Having looked at the gefs between t90 & T102 there are 10 of the 20 perbs that follow the control. Using my fingers that's about 50%

Edited February 28, 2018 by That ECM

[bluearmy]

Whilst some messing about still occurring pre day 4/5, all the models now pretty well in the same boat in the mid term. 

[SteveB]

26 minutes ago, bluearmy said:

Whilst some messing about still occurring pre day 4/5, all the models now pretty well in the same boat in the mid term. 

Which is?...................

[MR EXTREMES]

14 hours ago, nick sussex said:

Thanks yes I know you prefer that measure rather than the MJO.

So blocked ne Atlantic sounds good. 

And to add to this.

This mornings ECM in fi has blocking pulling back towards Greenland with most of the vortex segments over Scandinavia side.

So northerly and northeasterly perhaps another easterly is always possible extremely messy charts today.

Absolutely bitterly cold today no heating boiler broke typical.

Still have fingers crossed at least for a covering of snow here on the south coast.

[nick sussex]

The ECM ensemble mean keeps the north of the UK with continued chances for snow and the jet still quite a way south.

For areas further south it wouldn’t need a big change in the jet to bring some of that colder air back south.

The ECM op is a big mild outlier for London days 9 and 10.

 

 

Edited February 28, 2018 by nick sussex

[Methuselah]

2 hours ago, BLAST FROM THE PAST said:

And what an interesting morning we start with.  More cold remaining adjustments south and maybe more to come yet.  UKMO colder than 12z up to t144.

 

BFTP

Morning Fred!

What a wonderful sight to wake-up to, eh? Heavy showers, -4C and 4" of fresh snow...

As you say, the further outlook could be problematic; though I'd tend to, unfortunately, expect the milder air to win out - at least in the short-term...

[Derecho]

Just thought I'd update the trackometer this morning before the 06z



Still the cold holding on for all appears to be the slightly favourable option but it looks finely poised. 

[cfbath]

I've been following this thread with great interest. Thanks to all those who take their time to dissect the models for us less so able!

Currently in the process of sending out a communication to all of my staff (Bristol / SW based) regarding the forecast disruption over the course of tomorrow and Friday.

Looks to me as if we may get off lightly down here however...!

 

[Purga]

Anyone seen a similar chart to this FI recently?

The High sinks afterwards but interesting...

[Derecho]

Volatile sums up the latest trend on the ensembles for later in the weekend, with the milder air pushing a bit further north being the trend again.

[stodge]

Morning all

Quiet in here as you might expect with plenty of places seeing snowfall.

Looking further ahead, what are the models seeing beyond the vagaries of this weekend's event and as far as Saturday March 10th:

Starting as always with ECM 00Z OP at T+240:

A cold front is clearing SE removing a brief incursion of much warmer air into the south of the British Isles. A broad but shallow LP is moving slowly ENE into Scandinavia and the eye is drawn to ridging from Greenland and the Azores into mid-Atlantic.

GEM 00Z OP at the same time:

Very different but perhaps less so than on first look. A long trough extends NE from mid Atlantic to the north of the British Isles and into Scandinavia with heights rising from the south across western Europe. This draws in a mild or very mild SW'ly airflow to all areas so pleasant if not benign conditions for most ahead of the next Atlantic frontal system approaching from the SW.

GFS 00Z OP at T+240:

A complex trough sits over or near the British Isles. The main centre to the SW is aligned NW-SE and looks set to head into Iberia. Pressure is rising over Scandinavia and winds over the British Isles are generally light but with a SE'ly in western areas. Uppers are just negative so showers mainly of rain (though snow to altitude). Into FI and the trough edges north toward Greenland but makes little eastward progress as heights rise strongly in response to the NE of Scandinavia leaving the British Isles in potentially a new battleground situation.

GFS 06Z OP at T+234:

A simpler evolution with a stationary deep Atlantic LP squaring off against a strong anti-cyclone over northern Scandinavia. The British Isles is in a SE'ly airflow but with colder air encroaching toward East Anglia and the SE from the east. Further into FI the HP dominates moving SW to sit over the British Isles before declining slowly east and allowing much warmer SW'ly winds to move in with a taste of spring just after mid month.

GFS 06Z Control at T+240:

More complex though actually less so than it looks. It may at first appear we have LP to the north, south, east and west of the British Isles and indeed we do but there are heights over Southern Scandinavia and ridging up from the Azores so the British Isles is in a calm col with a very light N'ly flow. FI hasn't fully rolled out but it looks as though HP will set up over Denmark drawing a SE'ly over the British Isles.

The 06Z GEFS at T+240:

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=240

For all that's there little apparent spread, there are a lot of options on the table. The Mean calls it well with LP to the south-west but oriented more NW-SE so as likely to move into Europe as to come across the British Isles and hints of height rises to the NE.

To conclude, GEM looks an outlier this time and apparently the ECM is on the mild side of its suite so I'm left with the British Isles in a no man's land between LP to the south west and heights to the NE. A new incursion of cold air (though not to the scale of what we have now) can't be ruled out and it may be for all the LP and trough activity the real signal is for heights to rise from the NE and leave us in a SE'ly airflow going into mid month. With uncertainty over events even 72 hours ahead, trying to read the runes to 240 hours is going to be difficult and as I've argued on here over preceding days, the complex conflict between colder and warmer airmasses is far from resolution.

 

  

[Man With Beard]

The lack of traffic in here normally means a major cold/snow is event is in full swing ... also I guess the lack of direction next week makes it hard to get a decent discussion going.

However the ECM ensembles have at least offered us a few clusters in the D11-D15. They're still on the cold side with the jet predominately south - none indicate the monstrous levels of cold of this week but in early March a short northerly, or a little HP wedge to the north can still allow enough cold to filter in for a snow event particularly further north. Clusters at T264 suggest it will be worth watching for a bit:

[Polar Maritime]

No Meto warnings in here please thank you all.

[Neilsouth]

Where's my post gone? I don't give a bleep about the meto warnings, I asked for model updates for tomorrow and friday!

[johnholmes]

The latest 500 mb anomaly charts drew this comment from me into my anomaly file this morning

WED and ec-gfs much as above as is noaa from last eve so another 6 days perhaps of pretty cold wx, ? re snow

for above read as my last post re the 3, anyway below is the usual pair of links for folk to see what they think they show.

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

the 6-10 continues to show a 500 mb flow from the NW and with quite low contour values, also the trough remains in the UK area so not especially settled would seem to be the pattern for 6-10 days? The 8-14 shows a westerly predicted but still no sign of spring.

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

they both show troughing as the main feature, again with fairly low contour values so much the same idea really as the 6-10 NOAA.

We shall see how the actual weather pans out over the coming week.

Cold dense air is rarely shifted as quickly as either human forecasters or models suggest, no matter from which direction it tries to arrive. 

Obviously after 24-48 hours the incredibly deep cold air will be gone so temperatures at ground level will be higher than now, so thawing is likely with any lying snow.

 

Edited February 28, 2018 by johnholmes

[bluearmy]

6 hours ago, SteveB said:

Which is?...................

bye bye snow ............................

(away from the scots of course but they are used to it )

there is a cluster which brings the snowline back south to the n midlands but whether that survives a few more runs is the question. still downwelling waves to take into account

Edited February 28, 2018 by bluearmy

[johnholmes]

1 hour ago, Ayrshire weather said:

Sorry I'm new to this so is this goof for more cold and Snow in Scotland and the UK?

I'll try to explain them simply

At 500 mb the pattern is usually (stress that word), easier to get right than the bottom 500 mb. Too complex to go into here but please trust me. Aside from the even more complex word, teleconnections, you might ask one of the experts in that to chat to you? The anomaly charts can if they are consistent both with one another and over 2-3 days, give a good indication of what the average lines on the chart (they are called contours and are lines of equal height at 500 mb, again too complex for here to explain that),. Given that then we can usually be fairly cionfident of where the air, both at that height and, as an average, at the surface also is going to come from in their time scales, 6-10 days and with NOAA 8-14 days. This can be a big help in deciding what our weather may be in that particular time scale. Basically is the air from a cold source or a warm one, roughly either north or south but again much more complex than that.

So these charts over the past week have consistently shown deep cold likely to affect the UK, this in spite of GFS etc showing somewhat different at times.

What they are now 'starting' to suggest is that beyond about a week then our weather is going to start coming in from the Atlantic rather than east of the UK.

It is a very simplistic explanation but hiopefully it may help you. I am always happy to try and answer any questions via pm rather than clog up the model thread so please take up the offer if you wish

John

[doghouse]

1 hour ago, bluearmy said:

bye bye snow ............................

(away from the scots of course but they are used to it )

there is a cluster which brings the snowline back south to the n midlands but whether that survives a few more runs is the question. still downwelling waves to take into account

Crude generalisation which masks a very important truth. The central belt  of scotland ( I am two miles from Glasgow city centre )are certainly not used to the weather we are currently experiencing.... absolutely epic and on par with both 87 and 91. The point being we probably have more in common with other densely populated areas in the south east but these particular weather patterns deliver spectacularly for areas  both north and south dependent on ridiculous amount of good fortune

[Lynxus]

8 minutes ago, mrmonopoly said:

Not a single flake has fallen in my area in south wales  in fact this beast from the east has given us some brilliant sunshine for ages

We have had a few showers, but nothing of major note here in Gloucester.

I was pegging my hopes and dreams on tomorrow but i think friday is now my only chance with rain on sunday.

 

Friday seeing some snow. Probably of the wetter variety.

 

 

 

If only the system went east by 200 miles.

Edited February 28, 2018 by Lynxus

[lassie23]

2 minutes ago, Lynxus said:

We have had a few showers, but nothing of major note here in Gloucester.

I was pegging my hopes and dreams on tomorrow but i think friday is now my only chance with rain on sunday.

 

Friday seeing some snow. Probably of the wetter variety.

 

 

Do the models agree that the cold spell vanishes by the weekend