phil nw.

Model Output Discussions 12z 08/03/17

608 posts in this topic

Posted (edited)

A new thread,and the first of the Spring,to discuss the latest model outputs.

Overall for the next few days there appears to be nothing out of the ordinary expected for mid-March with some Azores ridging between the Atlantic weather fronts,shown by today's fax charts.

fax48s.thumb.gif.b40307e81c378a175909ae389ee60889.giffax84s.thumb.gif.234f9ecebe40b32edad484bc2234365e.gif

so the usual variations around the temperature norms. and surface conditions with some brighter and warmer interludes between the rain bands.

ECM mean though repeating the recent trend of a more pronounced build of the Azores high towards the UK next week,which would bring some quite pleasant conditions more widely,although longevity of this remains uncertain at this range.

EDM1-144.thumb.gif.eb4871bc8dfab404dfb70485cc25c765.gif

Let's see what the next few runs indicate for this.

Ok then please continue discussions below.:)

 

Edited by phil nw.
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How far ahead does FI start these days?  GFS at +120 seems reasonably promising with high pressure building in:

image.thumb.png.90a575b9c6bf92ce4a0a7037f6d7a236.png   image.thumb.png.7c1c5d6bde4cd144f9ff152588b71f33.png

At +144 it's still looking quite settled even if sunshine is in short supply:

image.thumb.png.a270e4cc40b956af7ef0bad4fa239e95.png   image.thumb.png.b7f3f0245e8e906137a7d32fb80f7d2d.png

But at +240 things are predicted to go downhill...   But perhaps this is pure fantasy and will not materialise......

image.thumb.png.dd3b8488910b5d10cf83ea9263977645.png   image.thumb.png.4069ce308ae0c086dac5431f4c2b2131.png

By this time of the month I would prefer to see temperatures rising and sunshine levels improving so I'm hoping that the GFS has a rethink about this particular prediction.....

 

 

 

 

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@Sky Full I would say the GFS is a little bit out with the 6z run:

gefsens850London0.png

Temperature wise it fits quite nicely in the ensemble mean, but rainfall wise it's one of, if not the wettest ensemble member. The rainfall mean is quite low, so I'll say it's an outlier. 12z may tell us more
:)

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GFS 12Z showing a nice arctic northwesterly for a few days later next week :), beforehand just more mild cloudy rubbish i'm afraid with rain at times.

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Posted (edited)

UKMO shows a settled start to next week with the best of the weather the further south and east you are

Rukm961.gifRukm1201.thumb.gif.5f16080835f5b9d283344ca6ecdd8c85.gifRukm1441.thumb.gif.813d2b82f04a613056f2b927be311e41.gif

Edited by Summer Sun
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Looks like a NW/SE split developing on the UKMO run, better the further south and east you head. Mild and perhaps pleasant in any sunny breaks.

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Posted (edited)

Purely academic but interesting that the gfs finds a neat way to bring some inclement weather to southern Europe

gfs_uv250_natl_36.thumb.png.64b63b230723cc08f9629dc00052c083.pnggfs_ptype_slp_eur3_38.thumb.png.ea0638edd7388c3314185717825e7079.pnggfs_t2maf_slp_eur3_37.thumb.png.a5047b7303efb9086701bc97d4088ee3.png

Edited by knocker
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Posted (edited)

1 hour ago, Summer Sun said:

UKMO shows a settled start to next week with the best of the weather the further south and east you are

Rukm961.gifRukm1201.thumb.gif.5f16080835f5b9d283344ca6ecdd8c85.gifRukm1441.thumb.gif.813d2b82f04a613056f2b927be311e41.gif

Yes it looks like a settled spell is the firm favourite for the first half of next week, at least across southern uk..good to see..enjoy the milder temps in the days ahead : - )

Edited by Frosty.
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Posted (edited)

What a lovely end to the Gfs 12z with high pressure dominant and pleasantly warm late march sunshine..no complaints from me if something similar to this happens.

12_360_mslp500.png

 

12_384_uk2mtmp.png

Edited by Frosty.
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Posted (edited)

It's good to see some support for the pleasantly warm anticyclonic end to the Gfs 12z op from the Gefs 12z..hopefully support will grow for a nice late March!:)

13_360_500mb.png

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Edited by Frosty.
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The ecm deconstructs the upper trough and also brings some inclement weather to the Med.

ecm_z500a_5d_natl_11.thumb.png.eb3cf6b32e27b75f05f150f57663d53f.pngecm_mslp_uv850_natl_10.thumb.png.105828adb514da89ba4f515c16d0d37d.png

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Posted (edited)

27 minutes ago, knocker said:

 and also brings some inclement weather to the Med.

What about the uk? Not really interested what happens to the Med.

Edited by Frosty.
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Posted (edited)

2 hours ago, Frosty. said:

What about the uk? Not really interested what happens to the Med.

But actually it does impact on the UK weather if you look at this evening's GEFs and ecm mean anomalies. The position of the trough to the north west, the ridging in the vicinity of the UK and the trough to the south east are all relevant to the direction of travel of any Atlantic systems thus the weather in the UK Although it would appear that NOAA is far more bullish with the ridge And for the record I assume it's okay to comment on aspects of the model output if it is interesting to the poster?

ecm_eps_z500a_5d_nh_11.thumb.png.50378d3d3c5ce6b2fdecf7d5a28ed532.pnggefs_z500a_5d_nh_41.thumb.png.6fe435e05bbe3a816ee424a4c8a74caf.png610day_03.thumb.gif.c5f226fe304118306e5615cdb73db4a8.gif

Edited by knocker
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6 minutes ago, knocker said:

But actually it does impact on the UK weather if you look at this evening's GEFs and ecn mean anomalies. The position of the trough to the north west, the ridging in the vicinity of the UK and the trough to the south east are all relevant to the direction of travel of any Atlantic systems thus the weather in the UK Although it would appear that NOAA is far more bullish with the ridge And for the record I assume it's okay to comment on aspects of the model output if is interesting to the poster?

ecm_eps_z500a_5d_nh_11.thumb.png.50378d3d3c5ce6b2fdecf7d5a28ed532.pnggefs_z500a_5d_nh_41.thumb.png.6fe435e05bbe3a816ee424a4c8a74caf.png610day_03.thumb.gif.c5f226fe304118306e5615cdb73db4a8.gif

Thanks for the detailed reply, I'm sure everyone appreciates it.:)

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Posted (edited)

Just like the Gfs 12z ended on a high note, the 18z does too with a nice spell of late march weather, especially across the southern half of the uk..hopefully the gfs is sniffing out a longer term trend!:)

Early next week looks pleasant too.

18_117_mslp500.png

18_117_uk2mtmp.png

18_141_uk2mtmp.png

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18_336_mslp500.png

18_360_mslp500.png

18_360_uk2mtmp.png

18_384_mslp500.png

18_384_uk2mtmp.png

Edited by Frosty.
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A very brief look at the GEFS anomaly this morning indicates the vortex back near N. Canada with troughs down the eastern seaboard and Greenland extending SE through the UK to the Mediterranean. The det. operates within this context.

gefs_z500a_5d_nh_43.thumb.png.b467b9791dda73fce420a28235eec8b6.png

Essentially the det run for ten days (reasonable time frame) is a variation on a familiar theme of a lot of emery pouring forth from the US and a strong jet, interacting with surges of the warmer Azores air and the phasing of this, complicated to some extent towards the latter part of the period by the blocking high pressure in eastern Europe and deconstruction of the upper trough in the vicinity of the UK and a cut off low over the Med.

So we start with some brief ridging that quickly moves east as weak fronts associated with a low near Iceland traverse the country on Sunday. From here we have a rather classic set up with the upper trough to the north west and the Azores to the south west, a very strong thermal gradient and surface lows being spawned and travelling rapidly east.

gfs_z500a_natl_24.thumb.png.100e18c6e5dd7d3ea437e77451b39c64.pnggfs_ptype_slp_eur3_25.thumb.png.649b2d1499ea1c42df36ba6a0ee87bd3.png

The first one rushes through Scotland early Wednesday but it's the next one that needs to be watched as it deepens quite quickly and is east of Aberdeen 976mb by Thursday 00. Potentially some very strong winds in the north with snow in the mountains, albeit we are talking a week away at the moment.,

gfs_ptype_slp_eur3_29.thumb.png.09681506b5cd2d9da33f870d5ae20d21.png

The depression moves quickly away and the aforementioned upper trough deconstructs setting up the pattern for the scenario to be repeated. with some modifications

gfs_z500a_natl_36.thumb.png.77d2cc13056fdf16e8d79062b3543cfc.pnggfs_ptype_slp_eur3_39.thumb.png.aab64667be0ff0bb49c089fbc6e1ac89.png

So in a nutshell a pretty changeable few days with a bias towards a N/S split with temps initially a tad above average but trending down late on.

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Still differences amongst the anomaly charts but over a flow from about west over the Atlantic seems the most I can glean from them over the past 48-72 hours. The EC-GFS version is quite strong with the idea of Atlantic ridging and troughing into Europe with a flow from north of west. Noaa 6-10 less rdge-trough idea and more of a westerly into the country.

Take your pick, nothing that suggests major ridging from any direction, fence sitting could be the best option for a time!

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Posted (edited)

Enjoy the mild spell, 13-16c in the south this afternoon and 13-15c tomorrow..very pleasant, especially in any sunshine.:)

Mild weekend too

06_57_uk2mtmp.png

06_81_uk2mtmp.png

Edited by Frosty.
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Posted (edited)

ecmwf_T850a_eu_6.png

Behold, our own ring of fire :laugh:

I'm enjoying the tendency for a bit more of a ridge across from the southwest early-mid next week from ECM but GFS remains less enthusiastic - though even it has increased the influence a little, with unsettled conditions a bit slower to return Wed-Thu.

Overall it seems that those seeking a protracted fine spell are having to wait patiently for the polar vortex to either move away from Siberia or weaken sufficiently to put an end to the tendency for the jet stream to return toward a path that heads straight into Eurasia on either a W-E or NW-SE trajectory. The unusually persistent displacement of the vortex made a mess of Feb and is now troubling us as we look toward getting some springlike weather. Thankfully it appears that an inflation of the subtropical ridges will be sufficient to produce at least one day next week of appreciably 'warm' temperatures for the time of year (mid-teens) and dry conditions, to accompany those of this week.

Given the way ECM disrupts the Atlantic trough and drops a low south - represented loosely by the 'ball' of below-normal temperatures in the above image - there looks to be a chance that the progress of the jet into Eurasia will be impeded, in fact a good chance given that UKMO looks primed to produce a similar outcome as of +144.

UW144-21.GIF?09-05

Height rises toward Scandinavia, often beyond initial model projections, has been a theme of recent years from spring right through to autumn (but of course, not so much in winter, when it would be more interesting to a fair few on here - typical eh?). At this time of year, it may have something to do with early snow cover loss and the polar boundary moving way north of what was once typical. Whatever the exact cause - it's something to keep an eye on.

Edited by Singularity
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Posted (edited)

High pressure to start next week, staying fine for longest in the SE but then becoming more changeable / unsettled from midweek but it looks like a nw / se split with the best of the temperatures, fine weather and sunshine the further s / se you are but still with some rain at times and that goes for the further outlook too..all in all, not bad..temps generally near or a little above average with some much milder days here and there but also some chilly nights with slight frosts, mainly further south during quieter spells.

21_120_500mb.png

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21_156_2mtmpmax.png

Edited by Frosty.
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As the longer term output keeps varying so much, let's just have a look at the short to mid term 4-6 day outlook:

Rukm961.gifRukm1201.gifRukm1441.gif

Looks fairly decent for March. Best in the SE closer to the high, slightly windier and a bit wetter in the NW closer to low pressure.

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GFS 12z still trying to slow down the new growth in my garden by bringing on a cold snap in two weeks time.

image.thumb.png.eb8f0075d6b95e7bf4a8c43a18c2f32e.png  image.thumb.png.71a2cf7ed2e4cf82dc5a3d40a5c3ca52.png

Luckily the chances of this prediction verifying even close to this are probably less than 10% and ironically the very fact that the GFS says it could happen almost certainly rule it out completely, based on the disappointing degree of inaccuracy at this time scale shown during the last three months.  Can't be too harsh, though, as it's pretty much impossible to forecast the weather in this country beyond five days, isn't it?

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11 minutes ago, Sky Full said:

GFS 12z still trying to slow down the new growth in my garden by bringing on a cold snap in two weeks time.

image.thumb.png.eb8f0075d6b95e7bf4a8c43a18c2f32e.png  image.thumb.png.71a2cf7ed2e4cf82dc5a3d40a5c3ca52.png

Luckily the chances of this prediction verifying even close to this are probably less than 10% and ironically the very fact that the GFS says it could happen almost certainly rule it out completely, based on the disappointing degree of inaccuracy at this time scale shown during the last three months.  Can't be too harsh, though, as it's pretty much impossible to forecast the weather in this country beyond five days, isn't it?

Doesn't even look cold, more nuisance value than anything even if by some fluke it verified..I would rather see a warm plume than another watered down attempt at cold to join all the failures of the last 3 months.

12_312_uk2mtmp.png

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No indication on last night's analysis, and what's available so far this morning, of any significant changes in the next fourteen days so just straight on to a quick look at the gfs outlook

Some weak fronts traverse the UK Sunday before the Azores ridges strongly north east at the beginning of next week with the jet running SW-NE and the troughs/ cooler air the polar side of this. Thus some settled weather for a few days as the high pressure slowly falls away east bringing dry and quite warm weather to most with the NW perhaps being the exception. As ever in these situations cloud will be the imponderable.

gfs_uv250_natl_19.thumb.png.bf1130fdb96b7939862d8431afbfffd5.pnggfs_ptype_slp_eur3_19.thumb.png.9ca58c1cf13fd0fd7d7ad0a8e2118e5d.png

Friday sees the entrance of the next upper trough from the west, which duly deconstructs, and associated surface fronts followed once more by some brief ridging but this is the signal for the Atlantic to become more involved with the bursts from the Azores being suppressed. Temps still around average.

gfs_z500a_natl_29.thumb.png.1cc8bb9f199d8c25ea8f9dbc5bb08441.pnggfs_ptype_slp_eur3_38.thumb.png.1e35d6f7698554532f70a002c7f1a35d.png

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A settled outlook out to day 6/7 with just one or two trailing fronts to get through..

ECMOPEU00_120_1.png

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