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Model Output Discussion 01/09/17


phil nw.

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Posted
  • Location: Gillingham, Kent
  • Weather Preferences: Snow, Thunderstorms,
  • Location: Gillingham, Kent

Much better separation of energy between the shortwave and the PV lobe across Canada on this run. Moving towards the ECM/UKMO

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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
1 minute ago, shaky said:

Gfs 18z edging towards euros here!!shortwave being released more freely at 96 hours!!backtrack begins....i think!!

And you thought right, not saying its going to be an ECM but its a better run guaranteed than its previous.

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Posted
  • Location: Hoyland,barnsley,south yorkshire(134m asl)
  • Weather Preferences: severe storms,snow wind and ice
  • Location: Hoyland,barnsley,south yorkshire(134m asl)

A lot better:)

gfs-0-114.png?18gfs-0-120.png?12

 

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Posted
  • Location: Nr Chelmsford, Essex
  • Weather Preferences: Hurricanes, Thunderstorms and blizzards please!
  • Location: Nr Chelmsford, Essex

Houston, we have lift off (I think!) at 120hrs

gfsnh-0-120.png?18

Looking miles better than the 12z at the same time....

gfsnh-0-126.png?12

Edited by Ice Day
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Posted
  • Location: Dousland, South Dartmoor 205 m/asl
  • Weather Preferences: The fabled channel low
  • Location: Dousland, South Dartmoor 205 m/asl

Ha the GFS falling in line? Now watch the ECM back track. Thats how these things work surly?:rofl::diablo:

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Posted
  • Location: Scouthead Oldham 295mASL
  • Location: Scouthead Oldham 295mASL
3 minutes ago, tinybill said:

just watched  the news  24 weather  for  the week cold  for the weekend    .monday should  be windy  and  wet with winds  coming  from the west   turesday onwards should back to biting northly winds bring wintry  showers  with night frosts    should last all of  next week!!!

 

:yahoo:

My optimism is increasing again ...18z has moved towards EC :cold:

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Posted
  • Location: Hull
  • Weather Preferences: Cold Snowy Winters, Hot Thundery Summers
  • Location: Hull

The 18z going along the right path this time, just 6h slower then the UKMO and ECM, here is a comparison with the 18z (left) and 12z (right) at the same time

GFSOPEU18_120_1.png GFSOPEU12_126_1.png

The 18z shows more support for heights to the NW, especially when that low moves south across the UK. Great stuff and a step in the right direction at close range too!

Edited by Quicksilver1989
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Posted
  • Location: Wildwood, Stafford 104m asl
  • Weather Preferences: obviously snow!
  • Location: Wildwood, Stafford 104m asl
1 minute ago, northwestsnow said:

:yahoo:

My optimism is increasing again ...18z has moved towards EC :cold:

Have read on here that the 12Z is the most progressive of the 4 GFS runs? 18Z can be a bit too amplified a bit like ECM sometimes

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Posted
  • Location: Hoyland,barnsley,south yorkshire(134m asl)
  • Weather Preferences: severe storms,snow wind and ice
  • Location: Hoyland,barnsley,south yorkshire(134m asl)

A definate backtrack from the gfs at 120, the main three, more oomph up to the NE on the gfs:shok:

gfsnh-0-120.png?18UN120-21.GIF?22-18ECH1-120.GIF?22-0

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Posted
  • Location: Hull
  • Weather Preferences: Cold Snowy Winters, Hot Thundery Summers
  • Location: Hull

Also someone mentioned the lack of cold uppers.... well at T144 we can see unstable air develop near Svalbard and uppers drop very quickly, major steps forward today :D

GFSOPEU18_147_2.png

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North
8 minutes ago, tinybill said:

just watched  the news  24 weather  for  the week cold  for the weekend    .monday should  be windy  and  wet with winds  coming  from the west   turesday onwards should back to biting northly winds bring wintry  showers  with night frosts    should last all of  next week!!!

 

That sounds just like the Ecm 12z ensemble mean..Booooom:bomb::clapping::cold:

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Posted
  • Location: Hoyland,barnsley,south yorkshire(134m asl)
  • Weather Preferences: severe storms,snow wind and ice
  • Location: Hoyland,barnsley,south yorkshire(134m asl)

This is much better from the 18z,heights punching into greenland on this run at 144hrs

talk about a backtrack,i would have thought that it would show this on Sunday lol.

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Posted
  • Location: Nr Chelmsford, Essex
  • Weather Preferences: Hurricanes, Thunderstorms and blizzards please!
  • Location: Nr Chelmsford, Essex

Out to 162 and it's keeping the fun going.  Tremendous stuff today from ALL the models!

gfsnh-0-162.png?18 gfsnh-1-162.png?18

Cold few days coming up with promise of much more down the line.....maybe.

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Posted
  • Location: Manchester
  • Weather Preferences: Sunny and warm in the Summer, cold and snowy in the winter, simples!
  • Location: Manchester
19 minutes ago, Allseasons-si said:

Wait:D

the 18z and the 12z

gfs-0-102.png?18gfs-0-108.png?12

height going up now.

I was on about a kink in the isobars in the northerly flow intimating unstable air, should have been clearer. :santa-emoji:

Maybe it will turn up in a future run and give an organised band of snow showers from the North, maybe.

 

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WINTER 2017/18 REPORT No. 1 WITH NOVEMBER 22nd INPUT

Hello everyone, I’m back! I have been following all the activity on this thread for a few weeks and I wasn’t intending to post any more due to major time constraints but I’ve been sucked in again! Last winter I produced weekly full reports as well as various ad hoc posts. These were often very long (too long for some readers) and took many hours to prepare. This winter I am busier than ever running my business and I have just decided to produce very occasional posts. These will not be as extensive as before and I will cover only a few of my regular features. I will endeavour to avoid repeating some of the general model output, charts and comments which are given excellent coverage by many posters on here. Instead, I will focus on particular “model related” topics and try to add something to the overall discussion.  Like many of you, I am a serious “coldie” but I do attempt to provide some balance in my comments.

I have noticed numerous comments regarding the lack of any significant cold and not low enough 850s despite some excellent synoptics.  Today, I will examine this issue in relation to the current model output. As I always say, I am certainly not an expert although I have been a keen “weather enthusiast” for well over 50 years.

Some Great Synoptics but Little Significant Cold Showing – Why?:

We have seen some very promising output on many recent model runs but a real lack of low enough temperatures to produce little if any lowland snowfall. The surface and the 850 temperatures are not really low enough. There are a whole host of reasons for this. This includes, the source of the cold and depth of the cold at that source; how long the airstream lasts; the modification of the airstream over its journey to our tiny country and the length and direction of that route. The time of the year – late November is not deep mid-winter. High sea surface temperatures. Near record low Arctic sea ice extent and well above average temperatures there. No deep cold over most of Europe.  This list is by no means exhaustive. I shall go through some of these now

Selection of Current Model Output for T+144 (Tuesday, November 28th):

PRESSURE:           UKMO                                      ECM                                             GFS                                          GEM

                UN144-21.GIF   ECH1-144.GIF?22-0   gfsnh-0-144.png?12?12  gemnh-0-144.png

850s:                       UKMO                                     ECM                                              GFS                                          GEM

            UN144-7.GIF  ECH0-144.GIF  gfsnh-1-144.png?12?12  gemnh-1-144.png

These generally show Arctic airstreams of sorts. Some more direct than others. The 850s over much of the UK are mostly around -2 with a few closer to -4. Today’s ECM 12z (rolling out as I’m writing this)  looks great again but is still struggling to get to -4. Even in the coldest GEFS ensembles (not shown), the lowest values are around -4 to -5 (several perturbations show this at T+144). I’m sure that there must be some colder ECM perturbations.

If the Arctic airstream lasted long enough and/or intensified, it is possible that rather lower 850s might reach our shores. Renewed bouts of Arctic incursions (or reloads) might also see rather lower values later on. In recent winters, even the seemingly more potent (albeit brief) Arctic incursions have struggled to deliver significant cold. Despite all this, I do believe, that with various factors falling into place, it will still be possible to see colder conditions. There have been very few examples of early winter (or even late Autumn) cold spells during the last 30 years but we only have to go back to 2010 to see that it is possible. That was of course an extreme example and the coldest and earliest start to a British winter since 1890. That might well have been a once a century occurrence but for most of the time the air arrived via a polar continental rather than a direct Arctic flow – so not a good comparison for several reasons (at this stage).

Back in the 1960s and 1970s there were a number of early winter cold snaps with Arctic airstreams and quite widespread lowland snowfall(s). These were all from memory – amazing how I recollect these but my memory of more recent events is poor these days. Let’s compare several of these to the current (predicted) colder spell.

PRESSURE                 19/11/1962                              30/11/1965                                  7/12/1967                                 29/11/1969

                     archives-1962-11-19-0-0.png  archives-1965-11-30-0-0.png  archives-1967-12-7-12-0.png archives-1969-11-29-12-0.png 

850s                             19/11/1962                              30/11/1965                                  7/12/1967                                 29/11/1969

                     archives-1962-11-19-0-1.png  archives-1965-11-30-0-1.png  archives-1967-12-7-12-1.png  archives-1969-11-29-12-1.png

These are all taken from the excellent “NCEP Reanalysis Archives” website. For those of you who have not visited it before, here’s the link:  

http://www.meteociel.fr/modeles/archives/archives.php?day=1&month=12&hour=0&year=1967&map=7&region=&mode=2&type=ncep

You can select any date back to 1871 and set rolling 15 day periods.

All these earlier examples were at times when the Arctic sea ice extent was almost twice the current levels. There were generally rather lower 850s compared to today’s but not hugely so.

Arctic Sea Ice News and Analysis:

The last full monthly report was published on November 2nd. This shows that the Autumn recovery in ice growth has been slow and the overall ice extent is currently very close to the record low levels of 2012. Here’s the link for the latest report and updates:

N_daily_extent.png   N_daily_concentration_hires.png  N_iqr_timeseries.png

http://nsidc.org/arcticseaicenews/

These charts shows the current extent of the sea ice (as on November 21st) in relation to the 30 year means.

Source: National Snow and Ice Data Center (NSIDC)

Arctic Current Sea Surface Temperatures (SSTs):

         SSTs  November 21st                                      SST Anomalies November 21st                         SSTs UK November 21st

  color_newdisp_sst_north_pole_stereo_ophi                                   color_newdisp_anomaly_north_pole_stereo_                         2017-11-21uk.gif

The anomaly chart shows that there is a wide area of open water in the Arctic with well above surface temperatures. The SSTs need to be below the -1.5c threshold (the purple colour). Sea water will start to freeze when it is below -2c but that is for normal salinity. There is slightly lower salt content in the Arctic (mainly due to ice melt) and the threshold is nearer to -1.5c. There are some areas with SSTs well above freezing and the current anomalies are widely 4c to 6c above average and up to 8c above in places. These higher SSTs are a legacy of the 2015-16 winter when the Atlantic Jet Stream powered well into the Arctic for much of the first half of winter. This shifted much warmer than average currents right up to the edge of the ice sheet. This strong anomaly has persisted for 3 years and is exceptional and comes on top of the already generally warming Arctic. Unless the SSTs reduce substantially, the anomalies might be carried through to next summer and into a fourth winter.  There is a small area of the North Atlantic, mostly south-east of Greenland with a negative anomaly.

Northern Hemisphere Current 2m Surface Temperatures:

  GEFS ens mean 12z T+0 - Current                    GEFS ens mean 12z T+144 for Tuesday, November 28th:

      gensnh-0-4-0.png                                                            gensnh-0-4-144.png 

If you compare the current and T+144 charts the main area of deep cold is over Siberia, with less widespread and less intense cold in North America. There is little change over Greenland and in most of the Arctic Ocean. Quite honestly, there is far too much of the Atlantic and Arctic to our north that is warmer than average. It will be difficult to see much deeper cold heading our way on a direct Arctic airstream during at least the next week or so.

Svalbard Daily “Maximum” Temperature Forecast for 10 Days:

Here are the links to the 3 Svalbard stations that I monitored last winter together with a summary of D1, D5 and D9 values:

Central/West Svalbard – Longyearbyen 28 m asl:   

http://www.yr.no/place/Norway/Svalbard/Longyearbyen/forecast.pdf

November 23rd  -6c;        November 27th    -7c;        December 1st  -4c.

North-West Svalbard – Ny-Alesund:  

http://www.yr.no/place/Norway/Svalbard/Ny-Ålesund/forecast.pdf

November 23rd  -6c;        November 27th    -10c;        December 1st  -5c.

Central South Svalbard – Sveagruva:   

http://www.yr.no/place/Norway/Svalbard/Sveagruva/forecast.pdf

November 23rd  -5c;        November 27th    -12c;        December 1st  -9c.

Please note that the links above will update automatically at frequent intervals throughout the day. They are the Norway met office’s predictions. We need to be aware that these are only a forecast that is subject to change and I am told that the Arctic surface temperature forecasts are not completely reliable even at quite short range. 

The temperatures were above freezing for a week or so earlier this month but they, at last, fallen well below freezing for the last week or so and are set to remain at these levels for at least the next 10 days. Nevertheless, temperatures are well their 30 year means. To put the above figures into context, here is a link to the main Longyearbyen site:  

http://www.yr.no/place/Norway/Svalbard/Longyearbyen/statistics.html

mnd.eng.png    aar.eng.png    

Tabular view for temperature and precipitation per month
Months Temperature Precipitation Wind
Average Normal Warmest Coldest Total Normal Highest 
daily value
Average Strongest 
wind
Oct 2017 0.5°C -5.5°C 7.7°C Oct 23 -5.8°C Oct 25 27.4 mm 14.0 mm 18.9 mm Oct 24 5.1 m/s 13.2 m/s Oct 23
Sep 2017 4.9°C 0.3°C 13.3°C Sep 26 -0.7°C Sep 1 20.8 mm 20.0 mm 5.3 mm Sep 19 4.9 m/s 16.3 m/s Sep 23
Aug 2017 6.1°C 4.7°C 11.6°C Aug 2 0.2°C Aug 27 16.2 mm 23.0 mm 7.4 mm Aug 29 4.7 m/s 14.6 m/s Aug 16
Jul 2017 6.9°C 5.9°C 13.1°C Jul 18 2.7°C Jul 4 20.4 mm 18.0 mm 6.5 mm Jul 14 5.5 m/s 13.6 m/s Jul 14
Jun 2017 4.6°C 2.0°C 9.0°C Jun 11 -0.2°C Jun 5 5.6 mm 10.0 mm 1.9 mm Jun 17 4.3 m/s 11.6 m/s Jun 29
May 2017 -3.9°C -4.1°C 7.3°C May 31 -11.5°C May 9 5.3 mm 6.0 mm 1.7 mm May 15 4.1 m/s 13.9 m/s May 15
Apr 2017 -8.3°C -12.2°C 2.9°C Apr 29 -21.3°C Apr 1 6.2 mm 11.0 mm 2.5 mm Apr 28 5.5 m/s 15.0 m/s Apr 5
Mar 2017 -11.8°C -15.7°C 2.5°C Mar 14 -23.5°C Mar 18 15.8 mm 23.0 mm 2.8 mm Mar 7 5.6 m/s 15.6 m/s Mar 26
Feb 2017 -6.6°C -16.2°C 5.9°C Feb 6 -21.3°C Feb 18 45.4 mm 19.0 mm 10.6 mm Feb 8 6.5 m/s 21.0 m/s Feb 21
Jan 2017 -10.3°C -15.3°C 2.2°C Jan 16 -21.1°C Jan 31 24.6 mm 15.0 mm 8.7 mm Jan 19 6.3 m/s 17.9 m/s Jan 17
Dec 2016 -6.0°C -13.4°C 4.8°C Dec 21 -18.5°C Dec 8 22.7 mm 16.0 mm 3.4 mm Dec 20 5.9 m/s 24.8 m/s Dec 29
Nov 2016 -0.7°C -10.3°C 6.4°C Nov 8 -11.1°C Nov 27 58.0 mm 15.0 mm 41.7 mm Nov 8 5.7 m/s 16.5 m/s Nov 8
Oct 2016 3.2°C -5.5°C 10.1°C Oct 7 -3.8°C Oct 15 57.0 mm 14.0 mm 18.3 mm Oct 15 5.7 m/s 17.8 m/s Oct 8

This shows monthly means and actual highest/lowest temperatures recorded during the last 15 months. Svalbard has been seeing “maximum” temperatures often running at 8c to 10c above their long term average throughout most of the last 4 years. This is reflective of the warming Arctic and the near record low sea ice cover.

Overall, it is not difficult to see why it is so hard to achieve prolonged cold and wintry weather from an Arctic airstream these days. Let’s see if the current synoptic pattern is sustained for long enough to achieve something more memorable. I do feel that the better route to cold, even in late November, is to have an Arctic or Siberian blast over mainland Europe and/or Scandinavia and then to import this cold into the UK with winds from either a north-easterly or easterly direction. I will looking for the Arctic airstream to veer into that direction and set up a pattern more akin to 2010.

When I have time to write another report, I’ll look at Asian (well above average) and European (very little right now) snow cover as well as temperatures in those regions.

 

Edited by Guest
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Posted
  • Location: Netherlands close to the coast
  • Location: Netherlands close to the coast
58 minutes ago, Daniel Smith said:

 

 

This is exactly why the ensemble means are useless and I don't put much credence into them. 

The mean would have you believe there's solid support within the ensembles at day 10 for a continuation of blocked and cold, the individual members above tell a completely different story.

(Day 10 is miles away and until we get the shortwave sorted for this weekend, isn't really worth worrying about)

When you see a clear signal in the mean it is usually pretty significant but when you don't see any clear signal it doesn't mean nothing is happening, so you need to look at spread and individual  ensemble members 

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Posted
  • Location: sheffield
  • Weather Preferences: cold ,snow
  • Location: sheffield

Better 18z for sure altho not as good as ecm of earlier.all looking good for a cool-cold snap.hopefully laying the foundations for later in december

 

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