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Early run up to Winter 2020/2021 discussion


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That's all we (okay I...) want; high pressure somewhere to the North of the UK. Northwest or Northeast preferably both.

What we don't want are cold plunges in Eastern Canada as this seems to rev the Atlantic up into positive oscillation and then gets stuck into delivering the UK Westerly after Westerly for weeks on end. High pressure should in theory stop the Atlantic from getting too lively and stop those storm inducing cold plunges in the West Atlantic as that area would see more Southerlies.

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Just a post for any newbies who have just joined. Musings and posts you WILL regularly come across in the months ahead and going into a winter: 1. October: 'This winter will be front loaded or ba

Says it up top 02/10.   Hot off the press Met office seasonal update OCT 20 for NDJ Considerable changes in favour of a colder Front loaded winter. Gone is the negative low pressur

Good Evening - An enjoyable period of model watching this past 24 hours as we begin to see high pressure develop over the pole in the 10-15 day outlooks - Whats interesting to me is whils

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I seen on some websites saying that the troposphere over high latitude has dramatically shrunk over the past year due to lower UV irradiance. Does this mean colder, dryer weather at high latitudes and high pressure likely across high latitudes?

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17 minutes ago, power77 said:

I seen on some websites saying that the troposphere over high latitude has dramatically shrunk over the past year due to lower UV irradiance. Does this mean colder, dryer weather at high latitudes and high pressure likely across high latitudes?

Any links to sources? 

(Sounds a bit like my woollens after a hot wash...) 

Ta. 

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14 minutes ago, Steve Murr said:

Updated ECM NDJ forecast from 01/10..

Much much better...

BFF3712D-0E5A-49D8-A67A-C0F0E193CE80.thumb.jpeg.a8793a0c28ea22b06ec3d5190ff513a8.jpeg

would like Glosea to look similar mate.

Next update due soon i believe.

Looks like the strength of nina could be important...

Edited by northwestsnow
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11 minutes ago, northwestsnow said:

would like Glosea to look similar mate.

Next update due soon i believe.

Looks like the strength of nina could be important...

Due 12/10

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1 hour ago, Steve Murr said:

Updated ECM NDJ forecast from 01/10..

Much much better...

BFF3712D-0E5A-49D8-A67A-C0F0E193CE80.thumb.jpeg.a8793a0c28ea22b06ec3d5190ff513a8.jpeg

A three month mean isnt easy - whilst that higher anomoly exists se of greeny,  it shouldn’t be missed that there is also higher slp south of the U.K. .......just for once, could we get slower slp and heights to actually establish to the south of us for more than a few hours ......

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2 minutes ago, bluearmy said:

A three month mean isnt easy - whilst that higher anomoly exists se of greeny,  it shouldn’t be missed that there is also higher slp south of the U.K. .......just for once, could we get slower slp and heights to actually establish to the south of us for more than a few hours ......

Yep, not liking that higher SLP anomaly to our S there...Would like to see Scandi troughing a little further W too.

To me, past December there looks to be strong hints of a mid Atlantic HP with the jet rolling around the top of it. This would be mild and drizzly at the surface for the UK potentially. 

Before then, however, Nov and Dec do hold some promise- perhaps a signal for Polar NW'lys which will increasingly do the business for some into December.

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10 minutes ago, CreweCold said:

Yep, not liking that higher SLP anomaly to our S there...Would like to see Scandi troughing a little further W too.

To me, past December there looks to be strong hints of a mid Atlantic HP with the jet rolling around the top of it. This would be mild and drizzly at the surface for the UK potentially. 

Before then, however, Nov and Dec do hold some promise- perhaps a signal for Polar NW'lys which will increasingly do the business for some into December.

The kind of synoptics we have now staying in situ until end of the year would return a cold anomaly.

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1 hour ago, Steve Murr said:

Updated ECM NDJ forecast from 01/10..

Much much better...

BFF3712D-0E5A-49D8-A67A-C0F0E193CE80.thumb.jpeg.a8793a0c28ea22b06ec3d5190ff513a8.jpeg

will be very cold and snowy here if heights set up as per this 

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4 hours ago, General Cluster said:

This just found me via Google... Maybe I am losing it but, really?

 

 

Ooft. That is definitely a boardroom decision where none of the staff had the confidence to tell their superiors that this is a terrible idea.

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7 hours ago, CreweCold said:

Yep, not liking that higher SLP anomaly to our S there...Would like to see Scandi troughing a little further W too.

To me, past December there looks to be strong hints of a mid Atlantic HP with the jet rolling around the top of it. This would be mild and drizzly at the surface for the UK potentially. 

Before then, however, Nov and Dec do hold some promise- perhaps a signal for Polar NW'lys which will increasingly do the business for some into December.

I would add the caveat that an ebbing/flowing mid atlantic ridge could continue the trend for the trough to dive south and keep systems to the west of the U.K. which would keep us away from warm sectors with sou’easterly flow ahead of the precip.  I think it’s the best hope coldies have for early winter judging by the early autumn patterns (and assuming we don’t see any big changes which we probably will!). 

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14 minutes ago, bluearmy said:

I would add the caveat that an ebbing/flowing mid atlantic ridge could continue the trend for the trough to dive south and keep systems to the west of the U.K. which would keep us away from warm sectors with sou’easterly flow ahead of the precip.  I think it’s the best hope coldies have for early winter judging by the early autumn patterns (and assuming we don’t see any big changes which we probably will!). 

I fear a SE undercut in December might not be cold enough, especially early on when conditions on a macro scale might be more primed.

From the long rangers, I think our best bet is a Christmas day 2004 kind of flow.

Let's hope la nina develops more favourably for us as time progresses from here.

Edited by CreweCold
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1 hour ago, CreweCold said:

I fear a SE undercut in December might not be cold enough, especially early on when conditions on a macro scale might be more primed.

From the long rangers, I think our best bet is a Christmas day 2004 kind of flow.

Let's hope la nina develops more favourably for us as time progresses from here.

Crewecold sounds like from your recent posts your slowly going away now from a cold Winter now as before you where quite excited ? 

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I think the pot at the end of the rainbow scenario this season would be early cold due to enhanced North Atlantic ridging under La Niña conditions followed by a split vortex and downwelling anomalies produced by a Euro High, Aleutian Low combo that does appear to be a possible setup through December. This would mean a cold December, more likely an average January and then - if the split plays ball - a cold February.

But lots of water to flow under the bridge before then, and that pot of gold is not a forecast by the way........

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13 minutes ago, Catacol said:

I think the pot at the end of the rainbow scenario this season would be early cold due to enhanced North Atlantic ridging under La Niña conditions followed by a split vortex and downwelling anomalies produced by a Euro High, Aleutian Low combo that does appear to be a possible setup through December. This would mean a cold December, more likely an average January and then - if the split plays ball - a cold February.

But lots of water to flow under the bridge before then, and that pot of gold is not a forecast by the way........

A cold February certainly goes against most of the LRF's I've seen - which seem to suggest the best chances of anything are November/December?

The latest ECM October forecast certainly looks full on +NAO zonal by then, with strong subtropical highs and lower pressure to our NW that we saw pretty much all of last winter.

image.thumb.png.797f5ee371fa4bee9cb446a79b490806.png
 

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16 minutes ago, mb018538 said:

A cold February certainly goes against most of the LRF's I've seen - which seem to suggest the best chances of anything are November/December?

The latest ECM October forecast certainly looks full on +NAO zonal by then, with strong subtropical highs and lower pressure to our NW that we saw pretty much all of last winter.

image.thumb.png.797f5ee371fa4bee9cb446a79b490806.png
 

This would always be my favoured outcome for winter! Early cold, frost or snow potential making Advent and Christmas feel just right!! I do like snow in January to liven up what is otherwise quite a dull month and then I like a milder February to start an earlyish Spring and get cracking in the garden and sowing seeds etc!!!😁😁

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20 minutes ago, weathergeek said:

This would always be my favoured outcome for winter! Early cold, frost or snow potential making Advent and Christmas feel just right!! I do like snow in January to liven up what is otherwise quite a dull month and then I like a milder February to start an earlyish Spring and get cracking in the garden and sowing seeds etc!!!😁😁

After last "winter" I would take a snowy month in Dec, Jan, Feb or March this year! 🙂

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10 hours ago, CreweCold said:

Yep, not liking that higher SLP anomaly to our S there...Would like to see Scandi troughing a little further W too.

To me, past December there looks to be strong hints of a mid Atlantic HP with the jet rolling around the top of it. This would be mild and drizzly at the surface for the UK potentially. 

Before then, however, Nov and Dec do hold some promise- perhaps a signal for Polar NW'lys which will increasingly do the business for some into December.

To me all that shows is that the model is suggesting weaker than average zonality over that period. A weaker Icelandic low and maybe the Azores displaced further north. Note there is no lower than average pressure anomaly to the south in the Azores area. 

The trouble with anomaly charts is that it does not necessarily mean high pressure but higher than average pressure. So say the Icelandic low is on average 990mb and a model forecasts a +10hpa pressure anomaly in that same area, it just means an Icelandic low averaging around 1000mb 

Edited by Weather-history
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59 minutes ago, mb018538 said:

A cold February certainly goes against most of the LRF's I've seen - which seem to suggest the best chances of anything are November/December?

The latest ECM October forecast certainly looks full on +NAO zonal by then, with strong subtropical highs and lower pressure to our NW that we saw pretty much all of last winter.

image.thumb.png.797f5ee371fa4bee9cb446a79b490806.png
 

Let's aren't exactly 100% reliable though are they and much still to be resolved in terms of la nina strength, how much the north Pacific will cool (which it is at the moment, QBO situation etc.

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11 minutes ago, Premier Neige said:

Let's aren't exactly 100% reliable though are they and much still to be resolved in terms of la nina strength, how much the north Pacific will cool (which it is at the moment, QBO situation etc.

Absolutely - they aren't reliable at all...but it looks like a classic Nina style pattern that they are expecting. We will see!

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Here's a daily run of GLOSEA featuring an average of 60 ensemble members for December.

EjuHaKsXsAMJFgK.thumb.png.905148dc45b6e5afe5c6834500dc4211.png

And here's a plot featuring the last 5 runs for December against model climate on the left.

EjvWIk0XcAALQGP.thumb.jpeg.7efe487a097ec3699d360681021d38f5.jpeg

Not too shabby! I wouldn't expect the public monthly update to be quite as exciting, but it's certainly something of note! ECM/Meteo-france and to an extent GLOSEA all signalling for a colder, blocked start to winter. Certainly fits the theme of a La Nina front loaded winter. 

Interestingly, the GFS/CFS continue to forecast a below average strat to begin this winter season.

u10serie.thumb.png.6e33c84cbd893e2e4e612977918cc899.png

I'm at this stage, quietly confident we'll see something better than last winter, at least during the first half.

 

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8 minutes ago, Met4Cast said:

Here's a daily run of GLOSEA featuring an average of 60 ensemble members for December.

EjuHaKsXsAMJFgK.thumb.png.905148dc45b6e5afe5c6834500dc4211.png

And here's a plot featuring the last 5 runs for December against model climate on the left.

EjvWIk0XcAALQGP.thumb.jpeg.7efe487a097ec3699d360681021d38f5.jpeg

Not too shabby! I wouldn't expect the public monthly update to be quite as exciting, but it's certainly something of note! ECM/Meteo-france and to an extent GLOSEA all signalling for a colder, blocked start to winter. Certainly fits the theme of a La Nina front loaded winter. 

Interestingly, the GFS/CFS continue to forecast a below average strat to begin this winter season.

u10serie.thumb.png.6e33c84cbd893e2e4e612977918cc899.png

I'm at this stage, quietly confident we'll see something better than last winter, at least during the first half.

 

Thanks for this! 

I'd tend to ignore the blue CFS strat runs - they have a known weak vortex bias. The purple bias corrected ones are a much better guide - but even these as you say show a slow start to the PV gaining strength. November could be an early treat this year! A cold and frosty bonfire night would be nice!

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2 minutes ago, mb018538 said:

Thanks for this! 

I'd tend to ignore the blue CFS strat runs - they have a known weak vortex bias. The purple bias corrected ones are a much better guide - but even these as you say show a slow start to the PV gaining strength. November could be an early treat this year! A cold and frosty bonfire night would be nice!

Those purple runs are trending towards a stronger than average PV through December though, although too far away to really worry about at this stage.  I think much hangs on the La Nina strength this winter.

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