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Model output discussion - 20th Feb onwards

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33 minutes ago, PolarWarsaw said:

One thing seems notable this morning - the strength and consistency of a proper Greenland high as been watered down, quite significantly.

that shouldnt be a surprise, as the noaa 500mb charts has never supported a strong greenland high linking with the azores high. any such ridge was always a transitory feature as the upper flow looks quite strong on the northern flank of a strong azores high.

 

610day.03.gif

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3 hours ago, karlos1983 said:

I'd pay a premium to see those charts :shok: bet there wouldn't be many other sites that could compete with that.

 

I was thinking exactly the same thing Karlos1983, would def pay a premium to view those as I am sure others would :)

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29 minutes ago, mushymanrob said:

that shouldnt be a surprise, as the noaa 500mb charts has never supported a strong greenland high linking with the azores high. any such ridge was always a transitory feature as the upper flow looks quite strong on the northern flank of a strong azores high.

 

610day.03.gif

Yes i have to agree with that Mushy.

Although we are seeing -ve ht anomalies over the pole we still have a problem with the remaining Canadian pv segment.

The Atlantic ridging this coming week is partially effective in tandem with a Scandi trough in producing a cold flow but it is not modeled to last.A look at the day 8 mean charts from both

gfs192.thumb.png.67e1bdaa8431acdff22d091npsh500.192.thumb.png.2d49e3ffa2fbb27656

shows it toppling as we lose the Scandi trough leaving the way open for the Azores high to nose in.

Effectively we do see a colder week with uppers of -6 to -8c heading south but currently little sign of any widespread precipitation whether it be rain or snow.

Warks ens -uppers and rainfall.

56c9a15b0e312_warksuppers.thumb.png.671fprec.thumb.png.304294a60fd6d154ca309287b

and the combined London temp.ens.

ensemble-tt6-london.thumb.gif.5938af88a5

The problem, as it has been all Winter, is the lack of an Arctic block giving a lasting deeper cold feed south.

What we are currently expecting is a northerly from a transient period of Atlantic ridging which gives us a shorter and somewhat modified spell of Arctic air,enough to send daytime temps into single figures and produce some night frosts. 

 

 

 

Edited by phil nw.
to add another image

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12 hours ago, Karl. said:

Isn't it great that we are discussing potential accumulations of snow! The models look really interesting with a colder spell arriving next week from the north..let's get the cold air in place and see where this goes...I think somewhere in the UK is going to get a significant dumping next week.:)

You were saying........ :)

The story of this winter for me.....  a lot of promise with no verification.  Are we about tp embark on another episode?

That said..... if it's one run out of eight that promises narnia, we'll remember that one run not verifying, not that seven that maybe did!  

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3 minutes ago, fergieweather said:

Temperatures are about to start a decline to below average and expectations are for quite a few weeks of that situation remaining, with cold/bocked weather dominating. It could last well into March. Longer range products have only just started reacting to the MJO phase 7 (which tends to have instantaneous response in outcome here) due to lag. Now we can see the direction becoming clearer in GloSea5 and EC Monthly, we await the operational model centres to catch-up. Storm track is expected to become ever more southerly in next 1-3 weeks, with inherent prospect of these passing to S-E of UK and resultant risk of wintry hazards. It's total chalk and cheese change versus winter so far and evidence is now compelling for most protracted period of below-normal temperatures seen for some time. It matches exactly the UKMO Seasonal Team assessment for this winter, but only now is the model evidence becoming well aligned. 

Is The GEFS and EC EPS rise in temperature towards the end of the end of the run being discarded?, it looks to me like a return to zonality of sorts on both those models although I obviously have only seen the later in London graph form.

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17 minutes ago, fergieweather said:

Temperatures are about to start a decline to below average and expectations are for quite a few weeks of that situation remaining, with cold/bocked weather dominating. It could last well into March. Longer range products have only just started reacting to the MJO phase 7 (which tends to have instantaneous response in outcome here) due to lag. Now we can see the direction becoming clearer in GloSea5 and EC Monthly, we await the operational model centres to catch-up. Storm track is expected to become ever more southerly in next 1-3 weeks, with inherent prospect of these passing to S-E of UK and resultant risk of wintry hazards. It's total chalk and cheese change versus winter so far and evidence is now compelling for most protracted period of below-normal temperatures seen for some time. It matches exactly the UKMO Seasonal Team assessment for this winter, but only now is the model evidence becoming well aligned. 

Thank you as always, Ian. 

My view has long been that March will be an anticyclonic month but that we might start with the HP centred to the south of the UK leaving us in a mild or very mild spell and we might have 10 days or so of what I call "false spring" with well above average temperatures. The HP then moves north or north-west and we come into a much colder airflow from the northerly or easterly quarter with resulting wintry risk to the south.

Given the size of the British Isles set against the size of the northern hemisphere, I think it more than possible the final positioning and orientation of the HP might not put us in as good a position as fans of cold weather hope - at least initially. 

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36 minutes ago, Timmytour said:

You were saying........ :)

The story of this winter for me.....  a lot of promise with no verification.  Are we about tp embark on another episode?
 

I was discussing the Gfs 18z which was a snow fest, and I also said let's get the cold air in place first and then see what happens next. I'm pleased to see we are on track for a colder than average spell which could last well into march which at least increases the chances of snow!:)

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29 minutes ago, feb1991blizzard said:

Is The GEFS and EC EPS rise in temperature towards the end of the end of the run being discarded?, it looks to me like a return to zonality of sorts on both those models although I obviously have only seen the later in London graph form.

That's for London - the rest of the country, as far as we can see on the IMO charts, has a cold 850 ensemble mean right through the extended period - eg. T+312.

ec-ens_millikort_mslpmean_t850mean_t850s

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5 minutes ago, Nouska said:

That's for London - the rest of the country, as far as we can see on the IMO charts, has a cold 850 ensemble mean right through the extended period - eg. T+312.

ec-ens_millikort_mslpmean_t850mean_t850s

My only slight gripe though is that because its one cluster, are there any decent variations and in any quantity where the high gets further up into Greenland?, mind you it looks like it would (even the mean!) if it went any further and baring in mind its a mean, I suppose one cant really grumble.

Edited by feb1991blizzard

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The major difference between what we've seen modelled thus far and now is the predicted euro heights over the upcoming fortnight. With a fairly significant low anomoly centred n Germany and the Azores ridge remaining mid Atlantic week 2, no reason to think that the period will see anything other than lower than average temps - perhaps much lower. 

Problem at this time of year is whether that can deliver widespread lowland snowfall. we still need some luck for that. 

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Although perhaps not as cold and snowy outlook as some of us on here may be craving, the upcoming period looks probably coldest period particularly in terms of longevity for almost 3 years (March 13) 

ECM dry cold and sunny mid week before becoming cloudier Friday and over the weekend but staying cold. Would feel very cold in the quite strong north easterly breeze by end of the weekend in the south. Staying dry though.......for now. As BA says above though, time is not in our favor if its lowland snowfall in the south you want. Sooner the better!

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10 minutes ago, bradythemole said:

Although perhaps not as cold and snowy outlook as some of us on here may be craving, the upcoming period looks probably coldest period particularly in terms of longevity for almost 3 years (March 13) 

ECM dry cold and sunny mid week before becoming cloudier Friday and over the weekend but staying cold. Would feel very cold in the quite strong north easterly breeze by end of the weekend in the south. Staying dry though.......for now. As BA says above though, time is not in our favor if its lowland snowfall in the south you want. Sooner the better!

Should just add , if the NEly develops

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1 minute ago, Banbury said:

Should just add , if the NEly develops

yes true, was just talking purely on the ECM run in my post there as it was the only run i had seen. Looking at GFS, 00z had it, 06z didnt so we'll see. Either way, long period of colder weather coming up.

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A slight change in the wind direction for Wednesday on the 12z GFS generates some showers in the Irish sea and they push on as snow over northwest England and north Wales, the into the midlands. It shows that once you have the cold air in place opportunities can arise.

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3 minutes ago, karyo said:

A slight change in the wind direction for Wednesday on the 12z GFS generates some showers in the Irish sea and they push on as snow over northwest England and north Wales, the into the midlands. It shows that once you have the cold air in place opportunities can arise.

Very light in nature with no accumulations I would suspect though.

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Looking like a really good run here, this at 132

gfsnh-0-132.thumb.png.6b263290012a489009gfsnh-1-132.thumb.png.dd510cf3750b0bebe8

Much improved over the 6z

 

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4 minutes ago, feb1991blizzard said:

Very light in nature with no accumulations I would suspect though.

Those troughs coming down the Irish sea often pep up as we approach the event. In other words, the precipitation charts tend not to pick them up well.

For example, previous GFS runs had hardly any precipitation although the 0z UKMO had a trough coming down from the northwest at the same time.

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