Model output discussion 02/02/20

[Anthony Burden]

All eyes on March signs of low pressure digging south,the percentages beginning to favour a cold spring

and something not seen all winter a pressure rise to the north of U.K. could be on the cards.

[Radiating Dendrite]

20 minutes ago, knocker said:

As far as I'm aware the term as used in meteorology originally applied to a specific event such as the 'Spanish Plume' which, put very simplistically, is the movement of a warm (hot) airmass north from Iberia. From this the word plume has been  plucked to refer, more or less, to any advcetion of warm air from the south. To refer to a cold plume merely adds another expression to the NW glossary

A plume is something that rises by definition, so in this instance, I do not think it is correct to use.

Cold air sinks and generally comes from the north (or east). A submersion of cold might be better

[knocker]

1 minute ago, Radiating Dendrite said:

A plume is something that rises by definition, so in this instance, I do not think it is correct to use.

Cold air sinks and generally comes from the north (or east). A submersion of cold might be better

Yes I realize that which is why I was keen to emphasis 'as used in meteorology'

[Interitus]

1 hour ago, Radiating Dendrite said:

A plume is something that rises by definition, so in this instance, I do not think it is correct to use.

Cold air sinks and generally comes from the north (or east). A submersion of cold might be better

Not necessarily, in fluid dynamics it is possible to have negatively buoyant plumes.

For example, the process of brine rejection during sea ice formation releases colder, denser salt water into the warmer sea water creating a brine plume. It's just the vertical fluid motion of one density material through another, but as pointed out has been used to refer to something in particular in meteorology. Though note in the US it is occasionally used with moist warm air from the Gulf of Mexico etc.

Edited February 22, 2020 by Interitus

[Froze were the Days]

Charts (ECM) starting to look like they did back in November and that's a mess of low pressures on somewhat of a southerly jet stream which will probably equate to chilly conditions and rain...oh joy!

[Northern Sky]

Surely a plunge of cold air is the most apt description?

[Methuselah]

3 minutes ago, Northern Sky said:

Surely a plunge of cold air is the most apt description?

But, so long as the meaning is easily divined, who cares what the 'official' definition be?

[mushymanrob]

1 hour ago, knocker said:

As far as I'm aware the term as used in meteorology originally applied to a specific event such as the 'Spanish Plume' which, put very simplistically, is the movement of a warm (hot) airmass north from Iberia. From this the word plume has been  plucked to refer, more or less, to any advcetion of warm air from the south. To refer to a cold plume merely adds another expression to the NW glossary

I recall on tv back in the 70's i think, when the BBC weathermen started showing satelite photos, a weatherman (might have been Mckelwee) showing us a satelite photo of thunderstoms over northern Spain heading our way. He was the first one i heard use the term "Spanish Plume" and suggested (im sure) that it was because the clouds looked like "plumes" , from above, feather like.

[joggs]

6 minutes ago, Northern Sky said:

Surely a plunge of cold air is the most apt description?

It is,and didn't call me Shirley.

[Zak M]

Still a wet day to come to the UK today. A rash of beefy showers will be in the north, with hail and thunder possible in these showers, and the chance of sleet and snow. Also, there will be some showers in the south, although not as much and not as heavy. 

Saturday morning

On Saturday morning, there will be a scattering of showers, especially in Scotland, Northern Ireland and northern England. These showers have the chance of being heavy, with some hail or thunder, and could merge into longer spells of rain. Some sleet/snow could fall from these showers if they're over higher ground. Elsewhere, bands of rain are possible across southern England, although they shouldn't be heavy.  The only problem is that it could be quite windy in the morning, especially in the north, where gusts of 30-40mph are possible. Temperatures in the south should range from 5-10c, and in the north, they should range from 0-4c. It will feel a bit colder however in the morning due to the strong winds.

Saturday afternoon

On Saturday afternoon, the showers that are in Scotland, Northern Ireland and northern England will still be present with the chance of hail, thunder, sleet and snow. In between these showers, there will be some sunshine. Some rain will continue in the south although it certainly won't be as heavy as the showers in the north. If you don't catch some of this rain, then it will be a cloudy and overcast day. Some strong wind gusts are possible too, gusting up to 30mph in places. Temperatures in the afternoon in the south should range from 7-13c, and in the north, it should range from 2-7c.

Saturday evening/overnight

On Saturday evening/overnight, some rain will start to develop in the SW. This could perhaps be heavy in places, especially over the hills of Wales, where the Met Office has a yellow rain warning in place. The heavy showers over Scotland and Northern Ireland will still be ongoing, with still the risk of hail, thunder, sleet and snow, and they could also merge into longer spells of rain. Some places in the north might see some evening sunshine as it sets on the horizon if you don't have a heavy shower right on top of your head. The rain that is actually arriving from the SW is a warm front, so temperatures won't drop much in the evening and overnight if you live in the south. The temperatures in the south will range from 6-12c, and in the north, it should range from 1-6c. 

Have a good morning!

[Zak M]

2 hours ago, Climate Man said:

I thought that too but looked up definition and it is shape and not direction.

 

1 hour ago, knocker said:

As far as I'm aware the term as used in meteorology originally applied to a specific event such as the 'Spanish Plume' which, put very simplistically, is the movement of a warm (hot) airmass north from Iberia. From this the word plume has been  plucked to refer, more or less, to any advcetion of warm air from the south. To refer to a cold plume merely adds another expression to the NW glossary

 

1 hour ago, Radiating Dendrite said:

A plume is something that rises by definition, so in this instance, I do not think it is correct to use.

Cold air sinks and generally comes from the north (or east). A submersion of cold might be better

 

41 minutes ago, Northern Sky said:

Surely a plunge of cold air is the most apt description?

Oh 

[Dorsetbred]

55 minutes ago, General Cluster said:

But, so long as the meaning is easily divined, who cares what the 'official' definition be?

How will new folk learn the right and wrong language/terms if they are not correctly applied in here. Off topic , yes, important yes.

Edited February 22, 2020 by Dorsetbred

[nick sussex]

Wedge gate !

Both the GFS and ECM now want to develop a wedge of heights to the n/ne around day 8.

The upstream pattern is very complicated because as the original eastern USA storm heads east the flow over the ne  USA reamplifies.

So instead of all that energy barreling eastwards it starts heading se allowing that wedge of heights to develop .

The re amplification is now key and that opens up some opportunities if of course it verifies.

 

Edited February 22, 2020 by nick sussex

[Dangerous55019]

Morning everyone 
Well its been a couple of weeks since I last had a look at the CFS 4 weekly anomaly charts, so time for another quick look. 

Week 1 - 22nd to the 28th of Feb: It looks like the jet stream is right over the top of us, bringing yet more wet and windy weather.
Week 2 - 29th of Feb to the 6th of March: This yet again look low pressure dominated, with yet more wet and windy weather.

Week 3 - 7th to the 13th of March: A complete change! The CFS is showing what looks to be the Azores High drifting in from the Atlantic! 
Week 4 - 14th to the 20th of March: Again, high pressure dominated, with a large area of high pressure sitting just to the south east of us here in the UK!

Now in my last post I noticed that the CFS was wanting to bring a change to high pressure about, and its still hankering after such a change! Now is the CFS right, or its it wrong? I don't know, Only time will tell on that. 
But if the CFS is right (and that's a very BIG if) then I dare say that a bit of spring warmth and drier weather would be welcomed by most on here. 

As ever this is the CFS, and I am but a mere amateur, so please take these charts with the usual gritter load of salt. 

[Methuselah]

11 minutes ago, Dorsetbred said:

How will new folk learn the right and wrong language/terms if they are not correctly applied in here. Off topic , yes, important yes.

Fair point DB!

And, though the details are unimportant at this stage, the dof-end of the GFS 06Z looks interesting: the tPV moves back westwards and the heat continues to build, south of the Med...So, who knows what Spring 2020 will be like? Let alone Summer!

    

PS: What is a **** of cold air advecting into Australia, from the Antarctic called?

[nick sussex]

Surprised this place isn’t a bit busier !

In the UK although northern blocking is always the best option for snow these wedges of heights to the n/ne can still provide that .

As long as you stay on the northern side of the jet and any shortwaves which run east se  are quite shallow you can see snow on the northern flank of those .

As I stressed though in my previous post that re amplification upstream is crucial to help direct the energy se which allows any wedge to develop to the n/ne .

Anyway lets see what tonights outputs produce.

Edited February 22, 2020 by nick sussex

[snowray]

06z ens looking rather chilly for early March, will we get a wedge or a proper block to our north though, that's the big question? 12z runs could be interesting.

 

[PiscesStar]

5 minutes ago, nick sussex said:

Surprised this place isn’t a bit busier !

In the UK although northern blocking is always the best option for snow these wedges of heights to the n/ne can still provide that .

As long as you stay on the northern side of the jet and any shortwaves which run east se  are quite shallow you can see snow on the northern flank of those .

As I stressed though in my previous post that re amplification upstream is crucial to help direct the energy se which allows any wedge to develop to the n/ne .

Anyway lets see what tonights outputs produce.

Does. That include the snow. Starved south east in that  offering Nick? 

[nick sussex]

1 minute ago, snowray said:

06z ens looking rather chilly for early March, will we get a wedge or a proper block to our north though, that's the big question? 12z runs could be interesting.

 

There’s no sign of any proper northern blocking at the moment . I think at the moment the wedge is the best possible outcome from the current set up.

This is an improvement on a few days back which just barreled a load of energy eastwards .

[nick sussex]

1 minute ago, Snowfish2 said:

Does. That include the snow. Starved south east in that  offering Nick? 

That depends on where any shortwaves track and of course how much cold is embedded at the surface before that happens .

Still too early to say I’m afraid , and the most important thing is the upstream pattern plays ball to get that energy se wards .

We have seen these more amplified solutions bite the dust before this winter so best to keep any expectations low until we see this constantly modelled and it ticks down towards the more reliable timeframe .

[shaky]

4 minutes ago, nick sussex said:

That depends on where any shortwaves track and of course how much cold is embedded at the surface before that happens .

Still too early to say I’m afraid , and the most important thing is the upstream pattern plays ball to get that energy se wards .

We have seen these more amplified solutions bite the dust before this winter so best to keep any expectations low until we see this constantly modelled and it ticks down towards the more reliable timeframe .

 

8 minutes ago, nick sussex said:

There’s no sign of any proper northern blocking at the moment . I think at the moment the wedge is the best possible outcome from the current set up.

This is an improvement on a few days back which just barreled a load of energy eastwards .

Shame about jat

 

9 minutes ago, nick sussex said:

There’s no sign of any proper northern blocking at the moment . I think at the moment the wedge is the best possible outcome from the current set up.

This is an improvement on a few days back which just barreled a load of energy eastwards .

Shame about that rise in 850s between 27 and 29th!flatlined around minus 5 couple of days ago!!

[Neil Harris]

43 minutes ago, Dangerous55019 said:

Morning everyone 
Well its been a couple of weeks since I last had a look at the CFS 4 weekly anomaly charts, so time for another quick look. 

Week 1 - 22nd to the 28th of Feb: It looks like the jet stream is right over the top of us, bringing yet more wet and windy weather.
Week 2 - 29th of Feb to the 6th of March: This yet again look low pressure dominated, with yet more wet and windy weather.

Week 3 - 7th to the 13th of March: A complete change! The CFS is showing what looks to be the Azores High drifting in from the Atlantic! 
Week 4 - 14th to the 20th of March: Again, high pressure dominated, with a large area of high pressure sitting just to the south east of us here in the UK!

Now in my last post I noticed that the CFS was wanting to bring a change to high pressure about, and its still hankering after such a change! Now is the CFS right, or its it wrong? I don't know, Only time will tell on that. 
But if the CFS is right (and that's a very BIG if) then I dare say that a bit of spring warmth and drier weather would be welcomed by most on here. 

As ever this is the CFS, and I am but a mere amateur, so please take these charts with the usual gritter load of salt. 

yes please. and short sleeves for Cheltenham!l

[Zak M]

Is spring here yet? 

[nick sussex]

22 minutes ago, shaky said:

 

Shame about jat

 

Shame about that rise in 850s between 27 and 29th!flatlined around minus 5 couple of days ago!!

True but I’d take the rise in 850s for a few days if it ends up delivering the wedge of heights to the n/ne afterwards .

Those colder 850s although good on paper were predominantly PM sourced air.  The wedge could produce less moderated air from the ne meeting any shortwaves.

Anyway it’s just a few runs and we’ve been here before so at the moment low expectations . 

[johnholmes]

2 hours ago, General Cluster said:

But, so long as the meaning is easily divined, who cares what the 'official' definition be?

Highly confusing to any new folk.

Why do some want to use a term that is not in use.? I suspect to sound 'clever' but if you want a sensible term for what adjective to add to 'cold air' then perhaps plunge is the best, certainly not a plume.

In the meantime no real signal for any deep cold air other than very briefly on the rear of deep lows that will continue to sweep across to the NW of the UK. Obviously if a calmer period coincides with a night period then cold and frosty. In over 60 years dealing with the weather I can honestly say I have never see such a long period of disturbed weather.

The upper air pattern, which governs our surface weather is shown in the usual 500 mb anomaly charts. Not all too similar but all 3 shows some kind of strong westerly over the Atlantic into the UK and NW Europe for another 10 days, perhaps longer. Also perhaps a suggestion that Pm type air will be more prevalent than Tm air. This MIGHT decrease the intensity of the storms and also the amount of rain they have been producing as the temperature contrast would be smaller.

Climate Prediction Center - 6-10 Day 500mb Outlook

WWW.CPC.NCEP.NOAA.GOV

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

Edited February 22, 2020 by johnholmes
adding extra sentences