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Model output discussion - after the beast, what next?


Paul
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THE BEAST - THE SEQUEL AND BEYOND

After losing almost all the content of this post earlier today just prior to submitting it, I decided to have another go! Thank you to all the supportive PMs that I received which were much appreciated and encouraged me to re-write it.

In this post I will briefly review the last few days, then assess the current set up and the incoming very cold wave. How cold might it get, how snowy can we expect it to be and how long long will it last? I will look further ahead and examine the broader patterns.

Last Week and This Week So Far:

My last review was on March 6th (on page 5 of this thread) and I shall pick up where I left off. During last week we saw the milder air finally push up into Scotland so that the whole of the UK saw a thaw. The deep cold over much of Europe was slowly pushed back into northern Scandinavia, north-east Europe and western Russia. The jet stream remained generally far to our south and this left the UK under the influence of fairly slow moving LPs with a succession of fronts. This produced pretty unsettled conditions with some quite large rainfall totals. This and thawing of any remaining snow produced some flooding. It has been considerably milder than recently with temperatures on several days reaching well into the teens. There were some brighter and less mild interludes and some parts still saw one or two frosts where skies cleared overnight. We currently have another push of LP from our west. This is the current set up:

                   Live Pressure                           8 hours to 15th March 2230 GMT             ECM  12z 15th March 1300  T+0               Met O Fax 15th March 1800                   GEFS 12z 15th March 1300  T+0     

pression2_eur2.png   tempresult_blz3.gif  ECH1-0.GIF  20180315.1856.PPVA89.png  gensnh-0-3-0.png

The live chart should update every 10 minutes so you can return and check on the progress (sometimes you might need to refresh the page of press F5 to give it a nudge). In the 8 hour chart (the 24 hour chart facility had a glitch today) you can see the LP to our west starting to stall as HP is building steadily into northern Scandinavia. In the ECM chart you can see that this HP extends all the way down from the North Pole. There is LP over western Russia and through eastern Europe down to the Black Sea.with a north-north-easterly flow pushing down through eastern Scandinavia. The fax chart shows stalling occluded fronts over south-west England and north-east Scotland. The main branch of the jet stream remains  well to our south on a west to east trajectory through Spain and the Mediterranean. There is a weakening streak looping through the UK north-westwards towards Iceland and returning south-eastwards into Scandinavia.

             Live 2m Surface Temps                  8 hours to 15th March 2240 GMT               Surface Temps at 1450 GMT          GEFS 12z 15th Mar 1300 T+0 2m Temps   GEFS 12z 15th Mar 1300 T+0 850Temps         

temp_eur2.png   tempresult_tta4.gif   temp_eur2-15.png   gensnh-0-4-0.png      gensnh-0-0-0.png

The cold block which had been pushed back into central and northern Russia for much of the last week has started to advance south-westwards again into Scandinavia and north-east Europe. There is a large expanse of intense  surface cold with sub -40s over Siberia. This is a 1300 chart so should represent somewhere close to maximum temps! There are sub -32s appearing over northern and north-western Russia. Sub zero temps are extending into much of central and northern Europe. There are some extremely low 850s (for mid-March) over the same areas. There is a  small pool of sub -28s over northern Russia and a much larger area of sub -12s, -16s and -20s stretching into north-east Europe and Scandinavia.

The Next 3 Days:

     Met O Fax Friday 16th March 1200        Met O Fax Saturday 17th March 1200      Met O Fax Sunday 18th March 1200           GEFS 12z 18th March 1300  T+72     

  20180315.1621.PPVE89.png    20180315.1710.PPVI89.png    20180315.1806.PPVK89.png    gensnh-0-3-72.png

By midday tomorrow the fronts have stalled completely over England and a cold front is pushing back into Scotland introducing east-south-easterly winds. The HP has intensified further and is now resident right over Scandinavia. By midday on Saturday there have been rapid developments. The HP has re-orientated from a north/south to an east/west axis. A broad easterly air stream sourced all the way from Siberia has pushed right through Europe and the UK. The fronts have all but cleared the far south-west of England. A quasi stationery trough (the one with the toothed edges) has already formed in the North Sea. This is a snow streamer running from the north of the Netherlands into Lincolnshire. By midday Sunday, this through has pushed through into the Midlands. Another trough is showing in south-east England which looks like a Thames streamer. There is a wave shown on the front to our south and a small area of LP may even develop over north-west France. This type of synoptic development will be incredibly difficult to nail down in terms of intensity, position and timing but this is what some of the forecasts of a possibly more significant and widespread snowfall over southern England are based on. By Sunday, the main branch of the jet stream has dived even further south into North Africa.  A small northern loop is encircling the Scandi HP with a small returning east to west streak pushing through central and northern England.

 2m Temps:         GEFS 12z 18th Mar 1300 T+72                            GFS 12z 18th Mar 0100 T+60                         GFS 12z 18th Mar 1300 T+72  

                        gensnh-0-4-72.png           60-580UK.GIF?15-12           72-580UK.GIF?15-12 

850 Temps:           GEFS 12z 18th Mar 1300 T+72                           GFS 12z 18th Mar 0100 T+60                         GFS 12z 18th Mar 1300 T+72  

                        gensnh-0-0-72.png           60-7UK.GIF?15-12           72-7UK.GIF?15-12 

Dew Point Temps:                           GFS 12z 18th Mar 0100 T+60                            GFS 12z 18th Mar 1300 T+72  

                                                  60-101UK.GIF?15-12           72-101UK.GIF?15-12

Ground Temps:                               GFS 12z 18th Mar 0100 T+60                         GFS 12z 18th Mar 1300 T+72  

                                                 60-543UK.GIF?15-12           72-543UK.GIF?15-12

GFS seem to be suggesting that some parts may see an "ice day" on Sunday. Given the intensity of the cold air arriving all the way from Siberia and the strength of the easterly winds, this is a possibility in parts which remain relatively cloudy. Any areas that see some sunny intervals for a reasonable period are likely to see temps climb several degrees above zero. We have nearly reached the spring equinox and the sun is much higher in the sky with increasing strength. We shall also see some more exceptionally low 850s (for mid March). Much of the UK will see sub -10s with sub -13s in the south-east and East Anglia. Several model runs have shown even lower values than this. These temps will once again be highly conducive to considerable low level convection. All coasts exposed to the easterly winds will see frequent snow showers developing through Saturday and with some significant accumulations by Sunday. Given the strength of the wind, many of these snow showers will be carried well inland and some will filter right through to the west. With troughs and possible minor disturbances some parts may see more organised bands of snow. The south of England and particularly the Channel islands look most likely to see this but this will be subject to short range and nowcasts. 

The dew points are also very low and the air moving out of the continent is extremely dry. Much of the snowfall is once again likely to be the dry powdery type. Now a word of caution. I have included the "ground temp" charts. In the last cold spell we saw several days of sub zero temps prior to much of the snowfall arriving. The ground was frozen solid to a depths of a few centimetres. This time around the very cold iar is arriving much more directly and quickly. In fact, the south-west will only be falling below 5c during Saturday. The ground temps even early on Sunday are shown to be around 3c to 5c in southern England but do fall away steadily to more like 1c to 2c during Sunday and some areas further north are below zero. Even powder snow may struggle to settle initially with some melting but this should be less of a factor later on Sunday.

Sea Surface Temperatures (SSTS): 

  Global SST Anomalies 14th March                        14th March 2018                                      7th March 2018                                      14th February 2018                                   14th March 2017

sst_anom.gif  sstuk.gif  2018-03-07uk.gif  2018-02-14uk.gif 2017-03-14uk.gif 

The first chart shows the current SST anomalies compared to the (1971 to 2000) 30 year mean. Unusually, the UK is almost surrounded by below average temps - the first time since March/April 2013. The lowest SSTs in our waters general occur around early to mid March but can be several weeks earlier or later than this depending upon weather patterns, prevailing winds and air surface layer temps. The lowest temps this winter were on March 7th at the end of the last cold spell. They have barely recovered since then. Just compare these values to those a month ago just prior to the on set of the cold surface flow. Not surprisingly the SSTs are considerably lower now than this time last year. The current SSTs are low enough to only modify the easterly slightly as it crosses the North Sea and the English Channel but they are high enough to assist with considerable low level convection.

How Long Will It Last?

When I wrote this report the first time this morning (before losing it all this afternoon) this was a lengthy section with a cross model analysis for day 10 and beyond, comparisons to several other March cold spells and loads more charts. I will greatly abbreviate this now, so that I can post this tonight.

Most of the models show a fairly quick breakdown to the very cold easterly flow with the Scandi HP moving over us and then to our west or north-west before sinking into a ridge from the Azores. This would allow less cold Atlantic air to circulate around the top of the HP. Areas that have a deep snow cover may see some unusually severe frosts for mid March under any calm clear nights early next week. The flow will back to the north for a while. I've just shown how low the North Sea temps are right now. These should help to maintain at least rather cold conditions for a while longer. I note that the jet stream is predicted to remain mostly to our south, albeit further north than recently, with the UK still mostly on the cold side of the jet. With this fairly weak jet, I feel that the breakdown to less cold conditions shown in most of the model runs is rather too progressive. 

Looking further ahead, most of the models that go to day 10 or further out, are suggesting a fairly cold pattern from a northerly quarter. This would be very much in line with what I concluded last week in my last report on page 5. Although the impacts from the sudden stratospheric warming have weakened to some extent, there is still a generally reversed and blocked signature on the northern hemisphere patterns. We only have to go back to March/April 2013 to see how a prolonged colder regime can be maintained. The SSW then occurred back in January. There is talk of a fairly early "final warming" in the strat occurring imminently and impacting in the coming days. This is likely to have far less influence but might help to maintain the cold for rather longer. I still favour more of a north-easterly to northerly flow, perhaps following a few less cold days with pretty cold conditions continuing for a while. Judah Cohen and several others, also favour this outcome with a cold trough dropping into Scandinavia within the next week or so. I've noted several references on here to March 1965. Some have pointed out how cold that month was but this is not entirely accurate. Like this March it started off with a very cold and snowy spell with the British minimum March record temp being set with -21.7c. Again like this March, there was a milder interlude for a week or so before another very cold spell. What has not been mentioned is that March 1965 ended with a heatwave and a record March maximum temp of 25c! I will not show the archive charts for that month but here's a link to the Met Office's Monthly Weather Report which makes for fascinating reading:    https://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/o/f/mar1965.pdf

Now I am not saying that this year will replicate March 1965 or March/April 2013, just that I feel there's enough evidence to support further generally cold weather for a few more weeks. I'll end with, perhaps, some better news for those wishing to see some much more springlike weather. The La Nina is continuing to weaken and the ENSO state is likely to be more or less neutral within a few weeks. This stage of that cycle at this time of the year is often associated with fairly blocked patterns and weak jet streams. The continent starts to warm up rapidly as we move further into the spring season. it is quite likely that we may see a quick transition during April from cold to much warmer, drier and settled conditions. Nothing is certain but one to look out for.

This is likely to be my final winter model thread post for 2018 I will be making occasional posts on the MOD and the south-west regional threads during the summer half of the year but my main focus will be to further develop the "Teleconnection Learning Thread".  I posted on there yesterday with an update on some exciting developments. I invite anyone who's interested in learning more about some of the teleconnections and key drivers that influence our weather patterns to visit the thread from time to time. You will be made to feel very welcome. Here's the link:  https://www.netweather.tv/forum/topic/89161-learning-about-teleconnection-science-and-background-signals/?page=6

or just click on the chart below:

 

Edited by Guest
Correct typos and check charts & links
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Posted
  • Location: Mytholmroyd, West Yorks.......
  • Weather Preferences: Hot & Sunny, Cold & Snowy
  • Location: Mytholmroyd, West Yorks.......

Will somebody confirm that I've had input here , both over the beast, and now son of beast to call off the bot saying i've had nowt to say???

jaffa cakes poor synoptics for the BFTE II with it obviously veering ever south with each tun .....and it's March!

The fading of the polar night jet as it undergoes it's end of season 'final warming' ( even though its off centre position places half of it in direct sunlight for over a week???) so no help there?

We are in a time of extreme LRF forecasts due to the basis of such forecast running at the extreme of there programming.

The last output just pulls away any moisture from the UK leaving Lincolnshire and Norfolk, along with the SE the only places to see anything other than pretty , sunlit, vflurries???

Edited by Gray-Wolf
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Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire

ICON pulls the Sat night/Sunday front further N...Midlands and Wales could see a fair bit of snow

icon-2-51.png?16-00

icon-2-54.png?16-00

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Posted
  • Location: Manchester
  • Weather Preferences: Sunny and warm in the Summer, cold and snowy in the winter, simples!
  • Location: Manchester
34 minutes ago, CreweCold said:

ICON pulls the Sat night/Sunday front further N...Midlands and Wales could see a fair bit of snow

icon-2-51.png?16-00

icon-2-54.png?16-00

The corrections back North will give much more opportunity for widespread snow, as you say central and Southern regions could do very but areas further North and West now not excluded.

UKMO a couple of days ago and today. So much better for snow chances further North and convection.

I might even get more snow from this mini beast than his big brother but then that wouldn't be hard.

UW96-21.GIF?14-00UW48-21.GIF?16-05

Also the cold will be around a little longer than the models were originally predicting.

 

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Posted
  • Location: Coastal Northumberland
  • Weather Preferences: Snow, heatwaves and anything extreme
  • Location: Coastal Northumberland

Slightly annoying that the media are referring to this as the mini beast. By the model output and snow potential it differs very little from beast 1, I think many average folk will be surprised by this over coming days. Its a beast its going to be pretty exceptional and something to remember again.

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Posted
  • Location: st albans
  • Location: st albans

The faxes and raw ec data show Saturday nights potential snow in the se to be less impactful though further west the threat remains for Sunday. Ec has consistently shown parts of the West Country (n Somerset, n Devon and s Wales especially) to be a sweet spot). 

getting closer to being able to make a call on snowfall although as the change in fax convergence troughs overnight show, this is different every run!  Euro 4 likes lincs and e Yorks!  still a lottery! 

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Posted
  • Location: Cobham Surrey
  • Weather Preferences: clear skies , hard frost , snow !
  • Location: Cobham Surrey
35 minutes ago, J-Man said:

Slightly annoying that the media are referring to this as the mini beast. By the model output and snow potential it differs very little from beast 1, I think many average folk will be surprised by this over coming days. Its a beast its going to be pretty exceptional and something to remember again.

Seems a fair description in relation to what the models are showing - a short less intense version of what many had at the turn of the month - the uppers and DAM values are higher this time round ice days will be a struggle with the mini beast for many this time round compared to the big beast. We might get some impressive low minima for the time of year though Sunday night if things go clear !

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Posted
  • Location: Middlesbrough
  • Location: Middlesbrough
1 hour ago, tight isobar said:

Also for :add..

Gfs..

Compare; wants south^south east- with dumpage!..

Frontal persistant snow.

Moving west/south west:

Game on ....

18031812_1600.gif

18031800_1600.gif

This looks good for the NE again. Could be in the sweet spot like last time out. 

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Posted
  • Location: st albans
  • Location: st albans

just a note that the ec 46 update continues to show almost whole Europe below av T2 out to end April. se corner escapes which says that low slp will continue to our south on average 

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Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth

My view this morning is that there's still a large scatter in possibilities. I would forecast most areas seeing snow falling, and probably more than 50% of the UK seeing a covering, but it's still very much a nowcast on the totals. I do agree that the threat to the SE seems less at the moment, troughs more likely to form further west and perhaps not so cold for the Thames streamer, but still time to run in this.

We've seen a small shift north in the past 24 hours, but wouldn't be surprised with a small shift back south over the next 24, seems often the way?

Edited by Man With Beard
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Posted
  • Location: Springfield, Chelmsford, Essex 30Mtr ASL
  • Weather Preferences: snowy or sunny but not too hot!
  • Location: Springfield, Chelmsford, Essex 30Mtr ASL
9 hours ago, IPredictASnowStorm said:

Look how dark that pink is ?

IMG_0501.PNG

Good Morning everyone.

I realise that the pink colour denotes snow, but not being that versed in this type of thing could someone please advise me of the following. 1) Is it the total amount that falls from the sky or accumulations on the ground? 2) Darker pink presumably means more snow, but is there a key indicating what each shading equates to?

Many thanks

Dave

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Posted
  • Location: Bexhill-on-sea, East Sussex (11.8M ASL)
  • Weather Preferences: Thunderstorms, snow, and wind storms
  • Location: Bexhill-on-sea, East Sussex (11.8M ASL)
1 minute ago, claret047 said:

Good Morning everyone.

I realise that the pink colour denotes snow, but not being that versed in this type of thing could someone please advise me of the following. 1) Is it the total amount that falls from the sky or accumulations on the ground? 2) Darker pink presumably means more snow, but is there a key indicating what each shading equates to?

Many thanks

Dave

I believe that is snow falling, and the key can be found where it comes from: https://www.netweather.tv/charts-and-data/gfs then select 'UK precipitation type'. Hope that helps!

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Posted
  • Location: Cobham Surrey
  • Weather Preferences: clear skies , hard frost , snow !
  • Location: Cobham Surrey

Mmm the northward shift is taking London and SE out of the game - if I was up north  would be feeling more confident -heavy disruptive snow across the conurbation looking less likely this morning

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Posted
  • Location: Orpington Kent
  • Weather Preferences: Snow freezing rain heat waves
  • Location: Orpington Kent
13 minutes ago, Badgers01 said:

Mmm the northward shift is taking London and SE out of the game - if I was up north  would be feeling more confident -heavy disruptive snow across the conurbation looking less likely this morning

Really we here this all the time when colder spell/snap is on way south east will get nothing..:rofl:

F6DEECA7-B520-4969-9159-7F8A871C238E.png

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Posted
  • Location: uxbridge middlesex(- also Bampton oxfordshire
  • Weather Preferences: blizzard conditions. ice days
  • Location: uxbridge middlesex(- also Bampton oxfordshire

Just quickly;...

Almost anywhere down the spine of the country-backing east...is likely to bear fruit from the evolving beast.

Although even westward of above mentioned- can and will likely show up....

This is a short  SHARP- shock incursion.

And will do damage......then leave!!!!

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Posted
  • Location: Rotherhithe, 5.8M ASL
  • Location: Rotherhithe, 5.8M ASL
19 minutes ago, Badgers01 said:

Mmm the northward shift is taking London and SE out of the game - if I was up north  would be feeling more confident -heavy disruptive snow across the conurbation looking less likely this morning

There has been a northward shift but not only that wind direction has veered more easterly rather than ene but that is incorrect to suggest so. Some models while minority clobber London and SE the HIRLAM was best with snow last time, so I take note it’s interested in 10cm and excess fairly widely. I think the far southeast may be challenged not a great sea track to work with, nonetheless a fairly strong signal for an area of persistent snowfall looks to move up. And then work from east to west.

92D61BDA-6C26-4CD2-8B18-2310EB20B780.thumb.gif.c1a30543c23abcf74ffdd7d931aa3f6e.gif15BD6027-A543-4D89-8365-E89F691673AE.thumb.gif.87e734e2b829e0fc925e4dfcb0e1d974.gif

Edited by Daniel*
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Posted
  • Location: Peterborough N.Cambridgeshire
  • Location: Peterborough N.Cambridgeshire

Have to be honest rather underwhelmed with the snowfall predictions in the model output for my location. If I was honest the Arpege, Hirlam have been posted this morning but personally I have always found the Euro 4 to be most reliable.

The locations that seem to hit the jackpot is Lincs to Northumberland. The problem for my location and others is the lack of a N,ly element to the E,ly flow. I have seen the wash streamer mentioned but this will not occur from a direct E,ly flow.

I will add even for the far SE the Euro 4 only suggests light snowfall.

18031800_1600.gif

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Posted
  • Location: Cobham Surrey
  • Weather Preferences: clear skies , hard frost , snow !
  • Location: Cobham Surrey
7 minutes ago, abbie123 said:

Really we here this all the time when colder spell/snap is on way south east will get nothing..:rofl:

F6DEECA7-B520-4969-9159-7F8A871C238E.png

And many in the south east last time got very little snow ... there has been a northward shift if heavier snow and the convergence “twig” line on the fax which has the human input has gone ... so the snow risk for the south east is not as good as it was.

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Posted
  • Location: portsmouth uk
  • Weather Preferences: extremes
  • Location: portsmouth uk

It's amazing we have cold and wintry weather incoming.

How many of us really know where a shower is going to form ?

And what strength and depth will that shower deliver ?

Does these wintry showers have labels on them no they dont.

Not until the showers form and deep echoes are picked up on weather models.

Then we know where when and how much roughly but not 100 %.

Even human input from the met office can be a little out.

09/10 winter was classic for extremely late warnings so surprises are more than definitely likely.

If this was a frontal snow event then things are easier to report.

I live in Portsmouth but 10 miles north might get a dumping even the isle of Wight can get plastered and were snow free.

So nothing to do with weather especially snow and storms ect is 100%.

I think that this spring could be a on of cold Spring.

Background signals would suggest this.

As for who when and where,

It's case of radar watching. 

 

Edited by MR EXTREMES
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Posted
  • Location: Orpington Kent
  • Weather Preferences: Snow freezing rain heat waves
  • Location: Orpington Kent
18 minutes ago, Badgers01 said:

And many in the south east last time got very little snow ... there has been a northward shift if heavier snow and the convergence “twig” line on the fax which has the human input has gone ... so the snow risk for the south east is not as good as it was.

 I remember last cold spell last minute change gave me around 5-10 cm south east London so I’m just going to keep eye on the radar and Steve murr updates..

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