Model Discussion - 10th March Onwards

[Lewis]

The models, GFS certainly painting a much cooler flow this weekend, some snow for the Scottish Highlands, and maybe down to low levels at times, a bit of a north/north easterly shot, but no doubt something we was crying out for all winter, amazing really, if that was in December or January, this forum would be in melt down and no doubt the uppers would have been much colder.

Still, it's a fairly potent blast for this time of the year.

April showers springs to mind, all be it a little colder this weekend than usual.

Edited April 10, 2012 by UK Storm Chasers

[NickR]

The bit in bold is contradictory- the main characteristic of a shower is its short duration (relative to organised bands of rain from frontal systems), with 'shower' being the descriptive term.

Almost reads like you're slowly backing away from your original assessment over the weekend that this week was going to be one dominated by persistent rainfall. Now it's "persistent showers".

How long do you want to keep this going?

Sorry but that is a ridiculous post - trying to pick holes in the semantics of a post whose meaning is clear enough and unproblematic enough for everyone else. Is there some sort of hidden agenda going on?

[joggs]

Right can we please stop the hairy fairy nit picking and concerntrate on what we are on here for, this interesting spell of weather forecast by the models

[A.J]

Yet again, for the 40,000th time of asking it seems in this thread, can members please read the thread title and post accordingly....It's not that hard is it?......Report any questionable posts, please don't reply to them in here!

[Bottesford]

Seconded back on topic please or your post will disappear like April showers do after sunset...

[damianslaw]

Remainder of the week - all models agree on the continuation of northerlies, and turning colder more generally by the weekend as we begin to pull in some very cold uppers for the time of year - whole country will be locked in sub 528 dam air by Saturday, and -10 uppers will be knocking on the door of northern scotland. It is a showery outlook and thanks to the slack pressure pattern, any showers that do turn up will be heavy and quite long lasting bringing risk of hail and for high ground in the north sleet and snow down to increasingly low levels by the weekend. Eastern parts are likely to see more showers than southwest parts.

The weekend itself is looking a cold one, especially in the north with air frosts likely and very poor maxima, when showers crop up temps will drop down to low single digit figures I imagine increasing the chance of snow being seen at very low levels in the north.

Next week - some divergence between ECM and GFS, ECM keen in maintaining the very unsettled outlook with the trough continuing to trouble the country and the potential for a deep low pressure becoming slow moving and cyclonic in nature - so potentially some very useful heavy rain, with snow on high ground and poor temps. GFS keener on developing an easterly as we see heights transfer to the NE. ECM was suggesting such a scenario a couple of days ago and is usually the better model in handling the development of easterlies - so remains to be seen. However, as I said yesterday I think the trough will remain in situ for quite some time yet and the ECM output does look very plausible. This April is increasingly looking like being a cold one, and possibly the first proper cold one for quite some time, a far cry from last year.

[Cloud 10]

Seconded back on topic please or your post will disappear like April showers do after sunset...

....unless the shower's are persistent.

Still an unsettled outlook from the model's over the next ten day's or so and probably more.

GFS and ECM ensemble means's,and indeed today's outlook chart from CPC pretty much

singing from the same hymn sheet.

ecm> gfs>

cpc Climate Prediction Center - 8-14 Day 500mb Outlook

[andreas]

I cannot help but have memories of April 1981, when after a mild/warm spell the north/northeasterlies established themselves after mid-month, culminating in 4 inches of lying snow in Cheltenham on the 26th and nearly an ice day.

[bluearmy]

whilst we appear to be headed for a cold 'trough ridge trough' evolution over the next twelve days, beyond that there are strong indications that the flow will become south of west/east and we will see a recovery in temps as we head towards the final week of april. given what we have endured so far this month, a below average return for april would seem a certainty. it wouldn't be ridiculous, however, to see a southerly flow as we enter the final few days of april and that could easily see some very respectable temperatures.

[Polar Maritime]

The bit in bold is contradictory- the main characteristic of a shower is its short duration (relative to organised bands of rain from frontal systems), with 'shower' being the descriptive term. Almost reads like you're slowly backing away from your original assessment over the weekend that this week was going to be one dominated by persistent rainfall. Now it's "persistent showers". How long do you want to keep this going?

Firstly sorry mods but it has to be said.

1) I never said that this week was going to be Dominated by persistant rainfall, please read post's correctly.

I said quote "Pushing bands of showers or longer spells of rain South".

2) I only give a view on what the models are showing,and as most of us on here know they do change detail slightly from day to day. Which is what makes model watching interesting for the majority of us. So if anything the models have backed away (a little) from my last assessment.

3) Im on here to learn as im shure others are, If my assessment of any model i show on the day is incorrect then please inform me in a more polite and informative way.

4) And as for an agenda..... All i have done is disguss the model output, which i fail to see you doing but only targeting every post i seem to make in a very rude and insulting way over the last few days.

Once again Mods & everyone who reads this thread, sorry for this off topic post. I just personaly felt i had to say something regarding weather09 attitude towards me.

regards

PM

Edited April 10, 2012 by Polar Maritime

[lorenzo]

Cold sneakily making its way back as the week unfolds.. looking pretty raw this weekend from up here, not pleasant.

From a model perspective the upper profile this morning that brought around 2 hours of snow showed -4 at the 850hpa level with pools of colder air within at -6 or so, my location 138m or so got a good covering so much nearer ground level than anticipated.

Looking at the above charts some potential for the weekend as that 528 line creeps south, also colder air filtering down the east coast.

The weather certainly rolling the dice as it moves from pattern to pattern, fantastic skies and action today.

Edited April 10, 2012 by lorenzo

[Weather Wizard]

Firstly sorry mods but it has to be said.

1) I never said that this week was going to be Dominated by persistant rainfall, please read post's correctly.

I said quote "Pushing bands of showers or longer spells of rain South".

2) I only give a view on what the models are showing,and as most of us on here know they do change detail slightly from day to day. Which is what makes model watching interesting for the majority of us. So if anything the models have backed away (a little) from my last assessment.

3) Im on here to learn as im shure others are, If my assessment of any model i show on the day is incorrect then please inform me in a more polite and informative way.

4) And as for an agenda..... All i have done is disguss the model output, which i fail to see you doing but only targeting every post i seem to make in a very rude and insulting way over the last few days.

Once again Mods & everyone who reads this thread, sorry for this off topic post. I just personaly felt i had to say something regarding weather09 attitude towards me.

regards

PM

The thing is the GFS precip maps are so inaccurate that pointing them out on here especially past 96h is misleading in itself even though this is the model thread

[Iceni]

I cannot help but have memories of April 1981, when after a mild/warm spell the north/northeasterlies established themselves after mid-month, culminating in 4 inches of lying snow in Cheltenham on the 26th and nearly an ice day.

I remember that w/e very well as my sister got married in bright warm sunshine, honeymooned in the West Country and had to get to the shops to buy warmer clothes than they'd packed. The contrast was one of the most extreme I've ever experienced in this country.

Mind you, it's very nice to see April living up to its name — the cruellest month and April showers etc.

[johnholmes]

With the cold pool at upper levels hanging around and the surface flow decreasing then heavy slow moving showers seem the pattern each day for many areas, thunder is certainly a probability and increasingly snow at the highest levels at first but tending to fall to a fair number of hilly areas into the weekend.

The rainfall prediction charts are always highly suspect even at short time scales but the overall pattern suggests that a lot of places, hit and miss of course with showers, will get a reasonable fall of rain at some time over the next 24-120 hours.

As for the definition of showers then the first part is that the precipitation falls from covective cloud, the second is that they are 'usually of relatively short duration' but the professional meteorologist will sometimes use the word showers may be prolonged and merge into longer spells of rain. As in most things to do with meteorology the waters can quickly become 'muddy' you might say so its best not to be too dogmatic about definitions. The first one is the most important.

[IDO]

The GFS 0z ensembles are very clustered for the next 6-7 days, so high confidence. It looks like a slack northerly for the majority of that time, so in the sun the south may not be far off average temps., though this weekend will be cooler even down here. From T144 the ensembles are varied, with a spread of T850s (London) from +5 to -5c. The cluster at the end of FI suggests a less cool outlook. Fi on this run is again a cooler option with the mean average temps (London) above 10c whilst the Op run hovers around 5c. ECM not dissimilar in the reliable time frame.

So not too bad weather for the next week, average/cool with sunshine and showers. I had one 30 second shower yesterday. After that HP edges closer from the SW and the models are struggling with the knock on effect of that battle, but they are consistent with the lows from the west winning out, and on this run they have a low stalling over the UK for 60 odd hours, as it interacts with the HP. Hopefully, as they do, GFS have over egged this. Ditto from T228 to the end of the run, another slow moving low hovering over the UK as HP blocks squeeze it from the east and SW. By the last week of the month HP has a weak hold on the UK.

Edited April 11, 2012 by i'm dreaming of...

[shedhead]

Once again this morning it's soul destroying to see both the big two trotting out chart after chart that we all craved throughout Winter. Overnight frosts and cold, sleety rain just don't do it for me in April, but as is so often the case in this country we are seeing perfect synoptic setups for extreme weather at the wrong time of year - last month it was heatwaves, this month widespread snow and bitter cold.

[Evening thunder]

Isn't it not that unusual to see northerly's in spring, and big switch arounds from warm weather to cold weather? Just because it's spring doesn't mean the weather will just bring westerly winds with no good 'winter' or 'summer' set ups.. The ECM brings Atlantic lows in again this morning by t+144 after a not particularly long lasting northerly, I bet if it was winter people would be complaining how the Atlantic smashes through without a fight and all that.. I don't find it particularly 'soul destroying' to have spells of below average weather in spring, pretty normal really unlike last spring, it's to be expected.

On a personal note I hope the ECM's later time frames are correct because we could do with some decent rain here.

Just maybe we will get the warmer set ups in summer this year? but then, that might be too much to ask..

[Thundery wintry showers]

It has always been a fact of life in the UK that pronounced "episodes" of northerly, southerly, cyclonic and easterly weather are more likely in spring than at any other time of year, due to the comparitively weak jetstream coming across from the Atlantic. This pattern traditionally continues into early to mid June before the "June Return of the Westerlies" sets in, although as last year's May demonstrated it is still possible to get prolonged "westerly" spells even in late spring.

I am not sure that the upcoming synoptic setup would have delivered particularly widespread snow had it been winter. The airmass presently over us is not particularly cold, and would probably have only delivered a wintry mix of showers had it been winter, particularly around windward coasts. We'd rather be looking at two or three days of sleet and snow showers down the eastern side of Britain (Friday-Sunday) with little or no snow in the west.

Not sure that cold raw and sleety rain really sums up the upcoming weather accurately either- it looks set to be bright and showery for a while to me, perhaps with shower activity easing off towards the weekend after two or three days of heavy showers and hail and thunder.

[snowmadchrisuk]

Some Hot Weather Showing up in FI on the 6z , around the last week of the Month, has shown a few times lately with High pressure over Europe extending Westwards over the UK, Would be great to see if it can get any Closer to time as would be 25-30 deg Widespread . In the mean time , Sunshine and Showers and the odd front travelling West to East across the UK. In the South it would be nice if we could get some slightly warmer 850's in as when the Sun is out in this type of setup it feels very pleasant .

[MP-R]

The GFS is brilliant for standard mixed spring weather. Turning cooler this weekend before a reset to Atlantic conditions next week - probably a band of rain followed by more widespread heavy showers. A rPm spell of sorts is being shown for the 18th-21st which would generally bring more thundery activity than the current spell. Then FI shows it warming up nicely for a few days with 21-24C quite possible, perhaps the odd 25C and heightened thunderstorm chances.

I'd be happy if this run came off as shown.

[Summer Sun]

wow what an end to GFS 06z!

Some very warm temperatures and the potential for thunderstorms not a bad end to GFS 06z, can the 12z keep this up? FI hasn't been bad of late.

[Don]

wow what an end to GFS 06z!

Some very warm temperatures and the potential for thunderstorms not a bad end to GFS 06z, can the 12z keep this up? FI hasn't been bad of late.

That would be typical where yet again our chances of achieving a comfortably colder than average month are scuppered by unseasonal warmth showing its hand at some point! It has been a real struggle to get a below average month since August. That said at least my CET guess could end up being close to the mark!

Edited April 11, 2012 by Don

[Summer Sun]

As you can see above the very warm temperatures on the 06z have been replaced by somthing much cooler.

[andy100]

warm weather and high pressure are boring

[johnholmes]

warm weather and high pressure are boring

that is of course just your view but we are supposed to be discussing the models and what they are showing?