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Model Output Discussion - Into Autumn 2020.


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Good evening! 😀 1st ever post! 1st of many I hope. Love this forum.   ECM: Tonight Matthew, I’m going to be... The GFS from yesterday!     A real tease, shame the OP only

ECM indicating a return to some settled weather end of next week however a few showers & the flow becoming Northerly so the potential for some frost developing- Nice & seasonal.

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38 minutes ago, Sky Full said:

FI GFS is predicting a week of high pressure over the UK from the 18th to the 26th November:

39626063-598A-4E5E-93BA-81621B9BC59A.thumb.gif.cbb709d33412ddac6975916dbe3cec4d.gif

Initially mild but cooling down towards the end of the period:

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but rainfall almost absent according to this sequence....

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A period of settled weather looks likely but I very much doubt it will be as dry as depicted.  
December is now the most likely month for any real wintery weather to appear but nothing’s written in stone yet!

Looks like we've got some very different options at day 10 now:

Going from most settled, somewhere in the middle, to more unsettled:

GFS                                                              GEM                                                            ECMWF
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Have to check the GFS and ECM ensembles to see the bigger picture here I think!

GFS a bit of an outlier as you'd expect:

image.thumb.png.d47c47fa0acecd2cc34ba7da0243120f.png
 

Edited by mb018538
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11 minutes ago, mb018538 said:

Looks like we've got some very different options at day 10 now:

Going from most settled, somewhere in the middle, to more unsettled:

GFS                                                              GEM                                                            ECMWF
image.thumb.png.e32acc2f7335d26e3465323a79faf106.pngimage.thumb.png.37a9b44992e08ab103fd100c3aa93b84.pngimage.thumb.png.e7cf34b3da6efc7691cdb30bd9731a27.png

Have to check the GFS and ECM ensembles to see the bigger picture here I think!

GFS a bit of an outlier as you'd expect:

image.thumb.png.d47c47fa0acecd2cc34ba7da0243120f.png
 

Yep.  Quite a bit of variation there - it’s all about the positioning of the high which looks likely to develop to our south west.   I would like to see a cool high dominate out weather at the end of November - which could bring some increasingly rare early winter frosts and fog to some parts - but I thing the ECM is more likely closest to reality here.

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7 hours ago, SLEETY said:

Gfs slowly getting there. Cold start to December on the cards? 

That’s basically what the MO have been suggesting in their extended output for some time now, and the text hasn’t really changed, so perhaps not surprising we’re seeing it in the output. Loooooong way out though.... plenty of time for it to go wrong 😆

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apologies I know its off topic but i have no idea where to ask - when does the GLOSEA 5 ( UK Met) model update for DJF time period , I thought the Met posted monthly updates on its website? Does it shoe any interest?

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54 minutes ago, southbank said:

apologies I know its off topic but i have no idea where to ask - when does the GLOSEA 5 ( UK Met) model update for DJF time period , I thought the Met posted monthly updates on its website? Does it shoe any interest?

Hi Southbank, they do indeed get posted/updated monthly. The charts can be viewed down below. Different parameters you can play around with such as the 2 meter temperatures, 500hPa height anomalies, pressure, precipitation and more: 

climate-averages-hero.jpg
WWW.METOFFICE.GOV.UK

Ensemble-mean fields up to six months ahead. Updated monthly,


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Looks like they get updated around early to mid-month. Suspect the new update for the December/January/February period will be updated tomorrow seeing as the last update was on 11th October. 

From what it’s been showing on the October update for the DFJ period, using both the 500hPa and Pressure charts:

D5A0C0FB-3620-4302-86EE-0F5980849E57.thumb.png.4e7a63cd8be97ae71c1d83f37cb0ea19.png43E47588-6DE9-4C57-BF0D-589AFA1CE51B.thumb.png.58603ce1cff7e09c4c854855661f8de9.png

 

looks like generally some High Pressure and high upper heights close by to the UK to our East. Some upper height rises to the North of the UK too. But it does also show Low Pressure to our North-West in the Atlantic at times.  Despite the upper heights showing some promise of blocking over and to the East and North of the UK, looks like it would be generally drivern by a fairly positive North Atlantic Oscillation (NAO) pattern. So probably not the best pattern for colder weather. Ideally could do with some stronger positive pressure and height anomalies (yellows and oranges) over central/Northern Scandinavia and the Greenland regions. Certainly on the Sea Level Pressure anomaly chart. So be interesting to see what the next update delivers.

Wouldn’t consider myself to be an expert on these and some might disagree with my analysis. Also worth saying, that with this being a 3 month average, it won’t necessarily mean all the months will be like the above. Could get one month of strong Greenland Highs and 2 months of strong low pressure over that region to still give that chart a bit of a positive NAO feeling to the 3 month average. 
 

Hope this is of some help 🙂

Edited by DiagonalRedLine
Changing Pressure to Sea Level Pressure
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Interesting! BOM website has updates ENSO charts from various model guidance. Looks like we could be stabilizing within wintertime ONI betwen -1.3 to -1.6 which gives these as best ENSO analog sets - 1955/56,1975/76.1998/99,1999/2000,2007/08,2010/11. Have a look at the blend of these years Nov-Feb with comparison to latest GEFS evolution. Uncanny similarities. Poleward Aleutian high/neutral NAO/mid Atlatic-western Europe ridge and Sceuro througing.  

1CQs9ClI.jpg

YEgZnyHc.jpg

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image.thumb.png.d665232d06de30ccd5246112849b872a.pngimage.thumb.png.a35eabb4282a5996a8ee8d01e0ef1a0e.png

ECM Op was a big outlier at the end for SLP and 500mb heights - indicating it being too aggressive with the low pressure influence. Mean stays above 1025mb, indicating high pressure is a good bet.

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2 hours ago, Jon Snow said:

This would be a very powerful anticyclone for late November on the Gfs 0z operational...very impressive if it happens..and for what it’s worth, I believe we will see an anticyclonic mid / late November!😜

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Looks like the high we had in mid January when some places broke pressure records... it was a lovely spell of weather in an otherwise boring month. Would be nice to see it transfer to the northeast.

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Worth barring in mind that the ‘October Fog Index’ is based on the theory that fog is caused by high pressure over the UK and a high over the UK in Autumn has a fair chance of moving to a favourable position in winter to create a block. I’d be more than happy to have some fine weather to see out this lockdown and then a cold December with hopefully some snow!

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51 minutes ago, jules216 said:

Interesting! BOM website has updates ENSO charts from various model guidance. Looks like we could be stabilizing within wintertime ONI betwen -1.3 to -1.6 which gives these as best ENSO analog sets - 1955/56,1975/76.1998/99,1999/2000,2007/08,2010/11. Have a look at the blend of these years Nov-Feb with comparison to latest GEFS evolution. Uncanny similarities. Poleward Aleutian high/neutral NAO/mid Atlatic-western Europe ridge and Sceuro througing.  

1CQs9ClI.jpg

YEgZnyHc.jpg

DWD (German model) was showing this in October - positive heights just to our north west, so a certain possibility - and that could mask some cold shots.

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