Model Output Discussion

[frostyjoe]

Ooooh a very interesting GFS run, of course we will have to take it at face value but one can still hope it comes of. After a rather boring March with a distinct lack of snow (one day here with snow cover) I personally would love one last snowy spell. As we head into April the sun should be strong enough for some really heavy showers, these showers would pack a punch with very heavy hail, sleet or snow and even lightning. Temperatures would be below average but nothing unusual (4-6.c), -5 850's can't really deliver temperature wise in April.

Favourite chart, 4 inches of snow for Wales .

oh!!! just in time for easter but it will just get pushed back and downgraded to 10c!

[Bristawl Si]

"Goodbye cold, slushy snow, sleet, cold rain, whatever....hello, warm, sunny days!"

Well, that's what i'd prefer to be happening now and into April.

Not much of a fan of 'late cold, snowy outbursts'.

Models seem to be hinting at such an event for some - hopefully they'll backtrack and the last we'll see of cold weather until November

[Thundery wintry showers]

I used the term Raw and Sleety a few days ago.

Just want to clear any confusion, i was referring to a particular Easterly setup that was showing at the time.

I wasn't referring just to you- we often get a fair number of posts that use terms to that effect at this time of year to describe anything cold (I remember some disagreements over what that particular easterly would've brought but in fairness any downgrade to the very cold uppers ECM showed on that run would certainly have given something fitting that description). Bristle_boy's post above indicates the kind of "spun" stereotypes of warm and cold weather that prevail at this time of year- the automatic association of warmth with sunshine is the other one that I omitted to mention!

Just checked out the UKMO and ECMWF and those charts show something more moderate as a result of the secondary lows cutting off the cold northerly flow- probably unsettled and cool but with snow reserved for northern hills if those two runs come off. I think agreement on it turning average to rather cold is increasing but the wintry showers scenario remains odds against away from perhaps the northern half of Scotland.

[mushymanrob]

While people are entitled to lose interest in cold and snow as soon as meteorological spring begins, I get very tired of the usual delusions about what wintry weather in Spring entails. Yes, persistent snow cover becomes rare once we reach this time of year, but to say that all wintry weather in spring is "raw and sleety", "horrible wet slushy stuff" or even "cold rain" is pure confirmation bias of the form "I don't want wintry weather in Spring because it's useless, and it's useless because I don't want it". In particular those northerly/north-westerly regimes with towering Cb cells, shafts of snow and hail, and dramatic temperature fluctuations hold a lot of appeal for some.

If I am being referenced here, there is a distinction between matters of preference and matters of misconception. The misconception that cold/wintry weather in spring means raw sleety muck, slush, cold rain, or a result that's useless for all, is no better than the misconception that mild weather in winter means overcast skies and drizzle, and it often serves as means of dismissing other people's excitement over northerlies through use of negative spin on them. I've seen numerous projections for stonewall "sunshine and snow showers" northerlies- including the aforementioned one in April 2008- labelled as "dull raw and sleety" over the years, purely because many people didn't want them.

.... and when was the last time snow in april produced anything lying?... 1968 lad thats when! :lol: here anyway... ok my misconception might be that people want snow because they like seeing it, all settled and pretty, and i might not be aware that hoards of weather fans like sunshine and snowshowers although obviously you do... fair play! im not averse to dramatic skyscapes. but lets face it.... snow from here on in IS useless 99% of the time if you are looking and hoping for a 'wintry scene', snow in spring IS horrible wet slushy stuff and very rarely produces what snowfans want...a covering.

[Cheese Rice]

.... and when was the last time snow in april produced anything lying?... 1968 lad thats when! here anyway... ok my misconception might be that people want snow because they like seeing it, all settled and pretty, and i might not be aware that hoards of weather fans like sunshine and snowshowers although obviously you do... fair play! im not averse to dramatic skyscapes. but lets face it.... snow from here on in IS useless 99% of the time if you are looking and hoping for a 'wintry scene', snow in spring IS horrible wet slushy stuff and very rarely produces what snowfans want...a covering.

Lets not forget March and April 2008, prime example which produced lying snow in the center of London in April.

Looks like 5cm of snow there at a guess.

Edited March 23, 2010 by 10123

[Rollo]

The problem for most if not all low ground is that any snow that falls very quickly turns slushy and ruins all the new growth. Snow in late March and April whilst looking great for a short time is normally only a nuisance. As to higher levels I suppose a good fall has something going for it.

[The PIT]

ECM having none of the cold spell in FI preferring the more changeable mild outcome that GFS showed earlier this week.

[ANYWEATHER]

An unsettled,mild theme for the next few days, but gfs has a cold sting in its tail for the latter part of the weekend, into early next week as cold Artic air moves south over the UK. Certainly would provide some interesting weather ,a cold pool of air aloft, strong Spring sunshine and an unstable Artic Maritime air mass would certainly give us some impressive sky scapes, and some strong Wintry showers ,hail, sleet and snow and perhaps thunder and lightning, basically the kitchen sink. Temps at two and half thousand feet look good for a covering of snow as far south as the Brecon beacons and Black mountains in South Wales......[bUT] wait, gfs shows this ,Ecm has other ideas with low pressure to our North with surface southwest winds.,seems this was what the idea of the gfs had a few days ago now gfs is showing what the ecm was showing a few days ago and ecm is showing.....oh well you know what Im saying ,Take your pick!! :lol: :excl:

[MR EXTREMES]

Lets not forget March and April 2008, prime example which produced lying snow in the center of London in April.

Looks like 5cm of snow there at a guess.

yep portsmouth snow lying april 08 made a snowman melted fast but it happened.

:lol:

[Thundery wintry showers]

ok my misconception might be that people want snow because they like seeing it, all settled and pretty, and i might not be aware that hoards of weather fans like sunshine and snowshowers although obviously you do... fair play! im not averse to dramatic skyscapes. but lets face it.... snow from here on in IS useless 99% of the time if you are looking and hoping for a 'wintry scene', snow in spring IS horrible wet slushy stuff and very rarely produces what snowfans want...a covering.

People want snow for reasons that differ from individual to individual, and for some, soft fluffy flakes falling from the sky have an appeal regardless of whether they provide accumulations on the ground, as do associated dramatic skyscapes and fluctuating temperatures, and from those perspectives snow in spring is not useless. "Snow in spring IS horrible wet slushy stuff" is only an opinion, yet many are expressing the "snow in spring is bad" as fact rather than opinion- the implication is that either people who disagree don't exist, or are wrong.

It's like saying that warmth in spring is useless if it's accompanied by cloud and drizzle. Most people would probably agree with that (warm sunshine being the usual preference), but some do not, and they're allowed their opinions, so why the double standard?

[Paul]

Is there any danger of this becoming the model discussion thread rather than the 'what weather do you like' thread please??

[cooling climate]

The difference between the GFS and the Euro models lies in what happens around the

t120 time frame. On the GFS an area of high pressure ridges north from the eastern

seaboard to link with the Greenland high thus trapping the low in over Baffin Island this

then allows better ridging in the atlantic and a better block.

On the Euro models the low breaks out into the Atlantic thus not allowing ridging and

blocking to form.

I must just add its so tedious to read this endless waffle about spring and what people

expect and also how they describe the weather. Each to their own is what I say, whats exciting

for one could be boring for another and there are no stedfast rules on how one should describe the

weather. It really is painful to keep reading the same old stuff over, and over and over and ...

Edited March 23, 2010 by cooling climate

[Cheese Rice]

yep portsmouth snow lying april 08 made a snowman melted fast but it happened.

If the synoptics then provided snow so far south then the GFS would defiantly bring snow. -5 850's can deliver widely at this time of year, more so at night but even during the day, last April there was several hours of snowfall during the day.

[Thundery wintry showers]

-5C 850hPa can deliver snowfall at this time of year but showers under that scenario will usually be a wintry mix with any accumulations of snow being short-lived and, during the afternoon, restricted to the heaviest showers. The 8th April 2006 provided a good example of snowfall with 850hPa temps around -5C which gave brief accumulations, but apart from that one heavy shower, the others fell as rain, sleet or graupel.

In frontal setups, with persistent cloud cover, the same caveats apply as they do in the middle of winter, but with the added complication that even if it does snow, unless heavy snow continues through the afternoon temperatures are likely to rise then resulting in a thaw- while light snow will also permit a temperature rise turning precipitation back to sleet or rain and any snow cover to slush.

GFS would definitely bring snow but most likely not on the scale of 6th April 2008- that northerly was unusually potent with 850hPa values of around -10C at one point.

[Eugene]

.... and when was the last time snow in april produced anything lying?... 1968 lad thats when! here anyway... ok my misconception might be that people want snow because they like seeing it, all settled and pretty, and i might not be aware that hoards of weather fans like sunshine and snowshowers although obviously you do... fair play! im not averse to dramatic skyscapes. but lets face it.... snow from here on in IS useless 99% of the time if you are looking and hoping for a 'wintry scene', snow in spring IS horrible wet slushy stuff and very rarely produces what snowfans want...a covering.

LOL, you and bottesford really come across as people who really hate cold weather, i'm glad im not like you two, comes across as kind of like the christmas grinch, being miserable at other peoples happiness.

'

April can deliver snowcover even if brief, i'm sure in October you wouldn't care if warm setups only produced temps of 20C by day instead of the more intense heat in the summer.

Edited March 23, 2010 by Eugene

[Northernlights]

Not really about the models but snow in spring fom an arctic northerly here can be really dramatic due to the intensity of the light highlighting snow covered hills, the coldness of the sea, the blueness of the sky and the colours of the the snow shower clouds which you never get in midwinter although mid December 2009 produced some very good contrasts between cloud, sky and land. Showers of grauple during the day are more frequent and falling on usually dry ground usually settle if air temperatures are low enough, quite often to be followed by a fall of proper heavy snow. Many times around my birthday in the first week of April I remember lying snow and on the farm we never really budget for winter ending completely until the third week in April, when hopefully there is fast enough growing grass to put the cattle out. Just now it has changed colour from brown to green but no appreciable growth yet to feed livestock. And yes Easter "68" had around 7 days of lying snow which only melted on the roofs during the day and was topped up during most sub zero nights for that week. Only have black and white photos from then but they show up to 8 inches of lying snow.

[Thundery wintry showers]

Still chances of Aberdeenshire getting the scenario described above if the GFS 18Z is to be believed. In general northern Scotland is the one region where I wouldn't say a showery northerly is odds against.

Friday continues to hold interest for those looking for storms, with a classic returning polar maritime airflow. There is some talk over in the convective discussion thread about possible storms on Thursday, but I think the frontal system that is set to move north that day is more likely just to give heavy rain, although the intensity could be quite dramatic in places and there will certainly be storms over northern France. The showers following behind are progged to be associated with high CAPE over south-west England for Friday:

http://charts.netweather.tv/gfsimages/gfs.20100323/18/69/ukcapeli.png

The 12Z scenario for late in the weekend and early next week is repeated on the 18Z:

http://charts.netweather.tv/gfsimages/gfs.20100323/18/144/h500slp.png

http://charts.netweather.tv/gfsimages/gfs.20100323/18/144/ukprec.png

Significantly the cold Arctic air does not fully establish except in Scotland before the fronts arrive. Thus the assessment is much the same as for the 12Z, sunshine and wintry showers (hail, snow) for Scotland but probably just "cold rain" from that system for the Midlands southwards. However the GFS is almost certainly vastly overdoing that low, and given the rather different UKMO/ECM outputs, this scenario is by no means certain to arise. It's worth keeping an eye on to see what happens in future runs. As with the 12Z the northerly plunge then heads south across the rest of the country out into early FI giving sunshine and wintry showers.

[johnholmes]

Looking at the 6 day verification on the major 3 tonight (T+144) I'm not sure, even though two are not dissimilar, that much faith could/can be put on any of them. This in spite of a rather odd comment from NOAA about 'STRONGLY PERFORMING EUROPEAN CENTRE GUIDANCE' the performance of all 3 has nose dived to barely 0.6 compared to averages of .82 for GFS to .86 for ECMWF.

No idea what they are having so much trouble getting to grips with but they sure are not performing well according to the bald statistics on the NOAA check site.

[Cheese Rice]

Really hope the GFS is onto something, atm I can't say which of the models is right.

A little "ramp" from me

[BlueHedgehog074]

According to that precipitation map, I'm just about on the on the line between the snow and sleet (lol).

It does seem like that this update is slightly more favourable for snow, with some higher snow risks and still with some good 850 hpa high-up temperatures, although I kind of agree about the fact that perhaps the GFS Models and Maps are over exaggerating the low. It does seem a bit sudden that some places would be getting 30 or more mm's of precipitation on Tuesday with a highish snow risk, though I suppose it's not impossible.

What I find amazing is that I think it was either yesterday, or the day before that the GFS Models and 10 day Netweather forecasts showed more of a warmer spell for next week, yet the Met Office showed the possbile snow risk extending to more Southern areas in their outlook. I understand that the forecasts and that can change alot, especially after 7 days, but still kind of interesting with the predictions.

Perhaps the GFS Models and Maps have detected a new trend, which the other forecasts have not picked out, although admittedly I could be wrong, since I'm still trying to become more and more familiar with all the models. I suppose should the various forecasts and models keep showing different things, we might end up getting just a cool spell with the odd spell of wet wintry weather, but still with the Northern parts having the highest chance.

Edited March 24, 2010 by Rainbow Snow

[SP1986]

As far as I can see the GFS is still the only one hinting at this cold, snowy situation although all models follow a similar potential evolution. I personally think the euros are more likely given the mobile setup of current

[SteveB]

GFS still going for a cold spell from Sunday onwards. Has good support from its ensembles too.

[mushymanrob]

huge discrepancy between the gfs and ecm this morning, in fact i dont think they can be more opposite past t120... a cooler interlude is probable, and normal.

[karyo]

huge discrepancy between the gfs and ecm this morning, in fact i dont think they can be more opposite past t120... a cooler interlude is probable, and normal.

Yes, but the difference so far today, is that the UKMO has moved much closer to the GFS scenario!

Karyo

[Mole]

Yes, but the difference so far today, is that the UKMO has moved much closer to the GFS scenario!

Karyo

Yes its the same old story,lol, in that we can never get cross model agreement on a cold spell.Still its 2vs 1 and Ecm has a tendency to flip flop a lot as was seen during the winter