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Paul

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Posted
  • Location: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl

Some understandable sense of frustration from cold seekers wrt the Operational outputs today which still continue to shy away from true Arctic blocking,more particularly around Greenland where the vortex continues to show on later frames.

I thought i would revisit some medium range data and so called background signals to see where we might be going.

First of all a view of the 12z Mean Outputs-rather than the Ops-for days 8-10.taken from ECM and GFS.

post-2026-0-22605400-1328476931_thumb.gi

Now the MJO forecast showing entering phase 8 in a few days and it`s composite NH pattern.

post-2026-0-58158800-1328477014_thumb.gi post-2026-0-18785400-1328477145_thumb.gi

See the similarity with the mean chart above-not quite there but time for minor changes to that 500hPa pattern as we are looking at week 2 for this.

Now a look at tonights 500hPa mean hts anomol forecast for days 6-10(automated at weekend)which has been remarkably steady for days.

post-2026-0-95546500-1328477408_thumb.gi

Again compare that with the previous images-all the same approximate pattern-Heights to the North,Lower to the South.

It doesn`t scream zonal in any way as we go further into the 10 day period.

Finally from the Strato.data and on the left mean zonal winds show a reversal at high latitudes indicating a complete disruption of the vortex and the other 2 images are forecasted pressure patterns at the lowest level ie100hPa of the Stratosphere taken from both the ECM and NCEP(GFS) sites.

post-2026-0-27331200-1328478804_thumb.gipost-2026-0-39714400-1328478811_thumb.gipost-2026-0-54483400-1328478827_thumb.gi

We can see the vortex split with troughing indicated over Scandinavia and Canada and the gap for heights over the Greenland area.

These are all indications for a cold blocking pattern in high latitudes around the approximate Greenland /Iceland or mid Atlantic (north) area in 10-14 days.

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

totally agree with that post phil-the 500mb pattern has been pretty solid from about 17-29 January if my memory is correct. I normally have all the charts saved but was on holiday and just copied them to paper, once I got back and saw that the first 5 days back simply carried on that pattern I threw them away!

Prior to that date they had been not too much in agreement from day to day or with one another. Even though the Stratosphere ideas by then were already suggesting what we have now.see below for my 'snapshot' view using the 30mb temperature

post-847-0-97877200-1328482260_thumb.jpg

Even before I went away though there were signs of a suggested building of heights at 500mb, although at that stage well west, see below

post-847-0-64624600-1328482364_thumb.jpg

so the 'signals' have and continue to be for blocking not mobility. I simply do not understand, other than for some the enjoyment of deep analysis of every model run, why there is this obsession with 4x2 and 2x2 outputs each day. Fun to look at and maybe compare and discuss but not terribly scientific I feel at the risk of upsetting some folk.

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

24 hours and things can look a bit different!

Taking a closer look at 'things' this morning.

The 30mb temperature is now diving down below average. The AO is pedicted to rise well above the zero line, while the NAO has not really changed from 4 or 5 days ago. The MJO has suddenly moved further from the origin than it has been for many weeks, currently in 6/7 so still suggesting blocking. Its forecast to return to near the origin and be close to 8/1, so not so blocked is my take on that.

The 500mb anomaly charts are not that close to one another in the past 24 hours. ECMWF and NOAA seem the closest with GFS showing some difference. Indeed this morning ECMWF and GFS deal with things rather differently. GFS maintains its block shape in the UK area, ECMWF shows a flatter type and they disagree on the two main troughs, shapes and positions and depths; the European and that over NE America.

So having been convinced up to last evening that everything continued to suggest major blocking well into February I am now not so sure. Certainly a cold week to come and into the weekend. beyond that then things may be starting to change to a more mobile type of upper pattern but that is a long way off. We have to watch the links I've mentioned over the next 5 days or so.

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Posted
  • Location: Reading/New York/Chicago
  • Location: Reading/New York/Chicago

Thanks John. I like your updates because they are almost the UK equivalent of the NOAA forecasts regularly posted by Nick (albeit written in plain English). Nice to have an idea of the thoughts of the Met Office forecasters as they prepare their output!

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

some may like to read through this-its an attempt to show what the models are showing without any personal bias at T+144, 240 and other indicators further out.

Will it stay cold or will it get less cold and more unsettled?

Models as of 7 feb 12.pdf

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Posted
  • Location: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl

some may like to read through this-its an attempt to show what the models are showing without any personal bias at T+144, 240 and other indicators further out.

Will it stay cold or will it get less cold and more unsettled?

Models as of 7 feb 12.pdf

Thanks John.I think you picked a tricky time to do this one.Some differences recently with the 500hPa patterns,Certainly as you suggest not clear cut on cold or milder towards day 10.

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Posted
  • Location: Farnham, Surrey
  • Weather Preferences: Cold, Sunny and Dry with a Hard Frost.
  • Location: Farnham, Surrey

"Certainly as you suggest not clear cut on cold or milder towards day 10." ...to be honest I don't think there is any clear cut from the weekend. I don't buy into the ECMRWF evolution from 96 to 120 hrs because the position of the High to the west just looks wrong..particularly at this time of year. Mind you I'm hardly enamoured by the middle term GFS projection either! We will see some major changes again on several models as we go towards Friday. At the moment it looks like a change signal is in the early evolutionary stage which is throwing out some odd pressure placements on a few of the models. That doesn't necessairily indicate mild weather either...

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Posted
  • Location: Farnham, Surrey
  • Weather Preferences: Cold, Sunny and Dry with a Hard Frost.
  • Location: Farnham, Surrey

And what on earth is happening with FAX plus 84 hours...some very off jumps and an evolutionary speed of a fleeing zebra....

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Posted
  • Location: Sunderland
  • Weather Preferences: cold
  • Location: Sunderland

MJO and GWO still seem to favour HLB n/ of UK. Strat still warm and some reversal in zonal winds and all the characteristics for local wave breaking events to occur. Alas, where is the NWP response to this? Coming I say, patience still.

Up to +48 it seems that high pressure will be over the UK in some way or another, allowing some potentially harsh frosts and sunshine for most. The high pressure cell in the mid-atlantic attempts to transfer it's blocking heights to Greenland via a ridge, but ultimately fails, and thus bringing a close to any persistant arctic cold at +72. At UKMO, the +96 shows a better chance as the blocking heights have moved into S Greenland, and WAA is very much apparent, however, the HP cell is too far south-west, just west of the UK allowing milder air from the mid-atlantic to interrupt the flow, giving mild nw/n'lies to western parts while the eastern parts miss much of the cold action that occurs in Denmark/Benelux.

UKMO +120 gives up on the ridge, and the trough sinks, giving the UK temporary NE/N'lies, allowing colder air to seep in to the east.

By +144, the PV is back in action, the Atlantic high moves into the azores, and despite the trough sinking, it appears we are too far west as the high gives us mild nw'lies.

Preferably, we want good WAA up w greenland, a stronger ridge, firstly the heights more strong towards Greenland/Iceland and the HP cell further north-west. Next, we want the trough to first move W towards the benelux/n sea so much of the UK enjoys a potent northerly, and then, sink preferably, allowing height rises to the north, shunting away any vortex attempts, and creating a spell of NE/E winds.

Entirely possible when looking at the teleconnections. Patience.

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Posted
  • Location: Ribble Valley
  • Location: Ribble Valley

Don't mention that word to cold and snow lovers in the west, they might say its about time it bloody delivered!

Yes but come May all this patience will pay dividends. :lol:
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Posted
  • Location: Llanwnnen, Lampeter, Ceredigion, 126m asl (exotic holidays in Rugby/ Coventry)
  • Location: Llanwnnen, Lampeter, Ceredigion, 126m asl (exotic holidays in Rugby/ Coventry)

My regionally selective take on the next 7 days

Weather guide Sunday 12th to Saturday 18th February (west Wales and central Midlands specific)

Headline: Milder with plenty of dry weather

The cold spell is on it's way out now, having brought heavy snow to the East this week, and with last night temperatures as low as -18c over the snow fields of Eastern England. Although winds are coming from a generally North-westerly direction this coming week, the air is greatly modified and it will not be cold.

The cold hangs on tonight with another hard frost for the Midlands. Sunday sees high pressure moving west across the UK, but with weak frontal systems within this. It's a similar picture for Monday too, with the high ending up to the west of Ireland. Bands of cloud will be tracking south across England and Wales on these two days, and perhaps bringing a little light rain or drizzle in places, with some sunny intervals too, especially later on Monday. There may be a touch of frost by night if skies are clear enough. Feeling chilly in the NW breeze, but temperatures reaching close to the February average of 6 to 8c, so much milder than the past week! Tuesday should be a dry, bright day but with a chilly north wind.

During Wednesday and Thursday the high pressure is positioned well south- west of Ireland, and the feed of air, although still from the NW, has tracked all around the high from the mild Azores region of the Atlantic, so that in spite of the wind direction, it will be a fairly mild couple of days. Due to the lengthy sea track of the air, it will be a rather cloudy spell this, but with a few sunny intervals, and frost is unlikely mid week, with afternoons reaching 8 to 10c. Dry for most, bar a spot of drizzle at times for west Wales.

By the end of the week, it looks like a low pressure passing close to Iceland and then into Scandinavia will influence us, the high edging further south-west into the Atlantic and away from the UK. A more unsettled theme for Friday and the weekend then, with bands of rain and some showers affecting the UK, most of the showers over west Wales. Although turning colder, temperatures are not far from average, reaching 5 to 8c, so any sleet or snow will be confined to the higher ground of Wales. Slight frosts will occur by night given clearances.

For supportive charts see here:

http://forum.netweather.tv/topic/72509-wales-cymru-weather-discussion-part-5/page__st__460

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Posted
  • Location: Sleaford, Lincolnshire
  • Weather Preferences: Whatever we get.
  • Location: Sleaford, Lincolnshire

I'm just an observer of the model threads, but I do like the objective style of TonyH's post. I hope this thread will develop like that, without the subjective qualifications such as 'poor', 'upgrade', 'downgrade' etc. applied to models according to the posters particular bias.

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

That is the general idea for when it gets totally frantic in the model thread some of us will post in here with, we hope, a none judgemental view on the models and any marked differences they show. Along with our view on how we feel the weather may turn out.

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Posted
  • Location: Llanwnnen, Lampeter, Ceredigion, 126m asl (exotic holidays in Rugby/ Coventry)
  • Location: Llanwnnen, Lampeter, Ceredigion, 126m asl (exotic holidays in Rugby/ Coventry)

Ah somewhere out of the limelight :acute:

My regionally selective take on the week ahead:

Headline: Becoming very mild. Changeable with some rain at times. Exceptionally mild on Thursday and Friday, especially the Midlands

Unless the next few months are very wet, then water shortages beckon for the Midlands this Summer, as the Winter has failed to produce adequate rainfall after the very dry 2011. The rest of February will only see small amounts of rain for Warwickshire once more.

High pressure over us tonight gives a frosty start to Monday, although this may be lifting by dawn over west Wales as a milder breeze spreads in. A dry, bright day for the MIdlands, but clouding over for west Wales, and drizzle possible late in the evening.

From Tuesday, a deep fetch of air originating from the tropical Atlantic, feeds in increasingly mild winds from the south-west or west.

Mostly cloudy and mild on Tuesday and Wednesday with rain and drizzle at times, most for west Wales; drier spells for Midlands. although even here there will be a spell of light rain late on Wednesday. Fresh to strong south-west winds.

Thursday and Friday will be mostly dry, bar the odd spot of drizzle for west Wales (typical!). Sunny spells are likely for the central Midlands meaning exceptionally mild days, reaching as high as 15 or even 16c. Even for cloudier west Wales, 13 or 14c is attainable on Thursday. These figures are not often reached in February and are 6 to 8c above the average. Still a fair bit below the record of 19c reached in the Midlands in February 1998 though.

A mainly dry looking set up for next weekend, although weak troughs may threaten a little rain in places. Should skies clear by night then slight frosts would occur.

For supportive charts please visit Wales:

http://forum.netweather.tv/topic/72646-wales-cymru-spring-weather-discussion/page__gopid__2273923#entry2273923

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Posted
  • Location: Llanwnnen, Lampeter, Ceredigion, 126m asl (exotic holidays in Rugby/ Coventry)
  • Location: Llanwnnen, Lampeter, Ceredigion, 126m asl (exotic holidays in Rugby/ Coventry)

Weather guide Sunday February 26th to Saturday March 3rd (west Wales and central Midlands focused)

Headline: Mild to very mild and mostly dry. Disappointingly cloudy for west Wales.

Spring is making an early appearance this year! On Thursday Coleshill, Warwickshire, was the warmest place in the UK, reaching an amazing 18.7c, this 11c above normal, and close to a February all time record. Nothing so spectacular in west Wales, although Llanwnnen managed 14c.

Winter has been on the dry side for the Midlands, only 120mm falling at Rugby in the past 3 months, compared with 383mm for Llanwnnen which is close to the average. A fairly mild Winter overall- especially for west Wales, few of us seeing even a single day of snow cover.

This week sees more Springlike weather, more unseasonably high temperatures for February mid week, and with high pressure close to the south or south-east predominantly dry, at least for the Midlands.

High pressure is close to southern England Sunday to Monday, although fronts will cross more central and northern parts bringing bands of rain there. Mostly cloudy for west Wales, with a little light rain or drizzle at times Sunday evening and during Monday. The central Midlands staying generally dry, even with a little sunshine. Quite windy on Monday, and mild at 11 or 12c maxima.

During Tuesday and Wednesday the high gradually transfers east into the near Continent with very, even exceptionally mild, sub Tropical air wafting over us again. Unfortunately for Ceredigion it is a moist air flow off the Atlantic once more, so although very mild (maxima 12 to 14c), plenty of cloud will threaten the odd drizzly shower. For Warwickshire, the cloud breaks to give sunny spells, with temperatures challenging this weeks, reaching 15 to 18c on Tuesday and Wednesday. Less breezy mid week.

On Thursday it looks like a weakening trough of low pressure moves into the high, bringing some rain, especially to west Wales, and it will be a cooler, cloudier day for the Midlands, although probably not much rain again. A long way off, but it may be clear enough behind this trough to give many places a ground frost on Thursday night.

A more unsettled look to the end of the week charts, although Friday could well be mostly dry and bright. More active fronts attempt to bring rain bands across all areas next weekend, however, it could be that high pressure asserts to our south once more to kill this off yet again for the MIdlands, so we'll see!

For supportive model charts:

http://forum.netweather.tv/topic/72646-wales-cymru-spring-weather-discussion/page__st__20__gopid__2276054#entry2276054

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Posted
  • Location: Llanwnnen, Lampeter, Ceredigion, 126m asl (exotic holidays in Rugby/ Coventry)
  • Location: Llanwnnen, Lampeter, Ceredigion, 126m asl (exotic holidays in Rugby/ Coventry)

Ah alone with my thoughts...again!

My take on the coming week albeit biased to west Wales and the central Midlands:

Weather guide Sunday 4th to Saturday 10th March

Headline: Cold and probably wet Sunday, dry early next week, then changeable with some rain, but mild

Most of us saw some pleasant Spring weather at times last week, and on Friday Ceredigion was the warmest part of the UK, Llanwnnen reaching 15c, some 6c above the early March average. We are not likely to see temperatures as high in the coming week. Some much needed rain probable for the Midlands tomorrow.

Small lows heading for the South-west approaches of the UK are notoriously difficult beasts to forecast. They often contain locally very wet weather, and tend to drag colder air around their northern flanks. Due to margins of error with the modelling of their expected tracks, forecasts are liable to go wrong even a few hours ahead! At this time of the year, if the low tracks across southern England or Wales, then these areas get a very wet spell, perhaps even with some snow eventually, but should the low track a mere hundred miles or so further south over northern France then the much of Wales and the MIdlands would end up with a dry day. So ,let's see how Sunday pans out!

It is exactly this scenario that we are faced with on Sunday (a forecaster's nightmare or was that challenge!).

My stab is that the low will cross the far south of England during Sunday, with heavy rain extending up across south and mid Wales and much of the Midlands. North Wales and the far north Midlands will see a cloudy but mostly dry day, apart from perhaps a little rain at times. It will be a cold, raw day, temperatures reaching just 5 or 6c, and with colder northerly winds digging in behind this feature then the rain may turn to sleet or wet snow during the afternoon, especially over high ground such as the Brecon Beacons and the Cotswolds. Such are the margins of error, that Warwickshire could get anything between 5mm and 20mm of rain tomorrow, the difference between a damp day and a really wet one! The precipitation will probably clear west Wales by mid afternoon, but persists into the evening for Warwickshire.

Sunday night will see clearing skies leading to a ground frost, especially west Wales. The low is close to the east coast on Monday so quite a cold day with a fresh north wind, sunny spells and perhaps a few showers. Temperatures struggling to reach 8c.

Frosty on Monday night, with Tuesday being a pleasant, mostly sunny and dry day, temperatures a bit higher at around 10c. Atlantic fronts bring cloud and rain overnight Tuesday and first thing Wednesday. Brighter Wednesday afternoon with some showers, especially for west Wales, and a cool west wind.

For the end of the week, high pressure is tantalising close to our south- though perhaps not close enough to prevent weak troughs bringing bands of cloud and a little rain at times. So Thursday to Saturday seems breezy and milder but fairly dry, temperatures reaching 11 to 13c with no night frosts.

Supportive model charts here:

http://forum.netweather.tv/topic/72646-wales-cymru-spring-weather-discussion/page__st__60

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Posted
  • Location: Llanwnnen, Lampeter, Ceredigion, 126m asl (exotic holidays in Rugby/ Coventry)
  • Location: Llanwnnen, Lampeter, Ceredigion, 126m asl (exotic holidays in Rugby/ Coventry)

Weather guide Sunday 11th to Saturday 17th March (for west Wales and the central Midlands)

Headline: Mostly dry and very mild, or warm even! Variable cloud, sunny spells, especially mid week. Rain possible Friday to Saturday, and cooler

March has came in like a Lamb this year once more...funny how our best weather has often occurred during Spring over recent years. Even better conditions for all this week with a large high dominating, until the threat of some rain comes from Friday.

On Sunday high pressure has edged up and sits over southern UK for the first half of the week. The first 3 days of the week are dry and very mild, even warm depending on sunshine. It looks as though this high could be containing plenty of cloud within it, so variable and perhaps large amounts of cloud but with some good sunny spells locally also. Light and variable breezes, very mild for March up to 14c to 16c widely, and potentially even warmer given decent amounts of sunshine. Probably the cloud preventing overnight ground frosts from forming for the most part, although morning mist or fog could be a bit of a feature through to mid week.

post-2595-0-66727800-1331402802_thumb.gi post-2595-0-15374100-1331402822_thumb.pn post-2595-0-68011700-1331402837_thumb.gi

On Wednesday and Thursday the high slips east into the near Continent, it continues dry, and with a southerly breeze it is warm with more in the way of sunshine. Temperatures higher, reaching 16c to 19c, very high for mid March! It may, however, cool off across west Wales later on Thursday as the wind turns more south-westerly bringing cloudier skies.

post-2595-0-12416900-1331402866_thumb.gi post-2595-0-98845100-1331402883_thumb.pn post-2595-0-32770200-1331402905_thumb.gi

The end of the week is cooler with SW to west winds. Cloudier with some sunny intervals, also some rain or showers about perhaps? Maximum temperatures down closer to average between 11c and 13c.

post-2595-0-77370900-1331403113_thumb.pn post-2595-0-43698900-1331403282_thumb.gi post-2595-0-61725700-1331403298_thumb.pn

Edited by TonyH
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Posted
  • Location: Llanwnnen, Lampeter, Ceredigion, 126m asl (exotic holidays in Rugby/ Coventry)
  • Location: Llanwnnen, Lampeter, Ceredigion, 126m asl (exotic holidays in Rugby/ Coventry)
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