Model Output Discussion

[Tim Bland]

GFS ensembles continue to look encouraging http://www.netweather.tv/index.cgi?action=charts;type=ens;sess= If anything the 12z op was on the mild side for the important part (mon / Tue) not a single member getting above -5 850s for the foresasble. I would rather take a gamble on a marginal situation than the usual N / NE incursion that leaves 98% dry and sunny. Interesting week to come next week, think most will see deep snow, sleet and rain at some point. Only place that may miss out will be the extreme south and South west IMO.

[Snowyowl9]

Does anyone remember the snowy spell we got in early January across Midlands southwards? Low pressure driving down from the north and another low pressure developing to the south. The forecast 4 days away was saying more like rain for the south with most of the snow potential over the weekend.

http://sussexyorkie.files.wordpress.com/2010/01/copy-of-snow-january-2010-002.jpg

In the end most of us got the heaviest snowfall since 1962. 20cm-40cm. Snowed all evening, through the night into the next day and into the evening.

The setup was very similar.

One of the best events of the winter heaviest snowfall incl previous week heavier snow since 1982 though.

As for this week I don`t think I`ve witnessed a HP for week in this position before just to the NW,to the north yes to give a straight E-ly,but this high certainly has come much further south to what was shown last week.

http://www.wzkarten3.de/pics/brack2.gif

[Cheese Rice]

I'm looking forward to the upcoming northerly, I fully expect the high to shift further east in coming runs, nothing too dramatic but enough to deliver the goods for most.

It looks like most of the UK will experience snow, especially northern England/Ireland and Scotland, I expect the south (South West/East/central south) to see some very marginal conditions at time with alot of wintry weather (rain sleet snow). There is likely to be some mild sectors associated with the lows so anywhere is at risk of marginal conditions.

[Devon-Nelly]

Well the latest GFS is the best we've had all week, staying very cold with a continued Northerly/North westerly flow across the uk with the possibility of quite widespread sleet/snow showers and judging by the upper air temps the -5c line is way into Northern France by mid-week so it doesn't look so marginal at all, we've had far more marginal close set ups.

Ok its not showing sub zero temps and dry powdery snow everywhere but its still cold/ very cold and there is a big potential for sleet and snow maybe even to lower levels in the south and south east if troughs were to develop in the system, i would rather have this set up than a mild one anyday.

Im begining to think we could just see reloads of this sort of pattern till Early March, but who knows its just a hunch.

[MKN]

Well the latest GFS is the best we've had all week, staying very cold with a continued Northerly/North westerly flow across the uk with the possibility of quite widespread sleet/snow showers and judging by the upper air temps the -5c line is way into Northern France by mid-week so it doesn't look so marginal at all, we've had far more marginal close set ups.

Ok its not showing sub zero temps and dry powdery snow everywhere but its still cold/ very cold and there is a big potential for sleet and snow maybe even to lower levels in the south and south east if troughs were to develop in the system, i would rather have this set up than a mild one anyday.

Im begining to think we could just see reloads of this sort of pattern till Early March, but who knows its just a hunch.

One thing i would like to remind people on as you have just commented on the gfs being the best all week, is not to expect the 18z to be as good or better. If it does turn out to be worse in terms of cold and snow dont take it as gospel until weve seen the subsequent 12z tomorrow.

[Frosty.]

Well I must be looking at different models, the ecm looks cold & wintry for the north throughout the whole run from monday onwards with huge snow potential although considering most members are from southern and southeast england it's not so promising down there with cold rain more likely.

[robert]

Well I must be looking at different models, the ecm looks cold & wintry for the north throughout the whole run from monday onwards with huge snow potential although considering most members are from southern and southeast england it's not so promising down there with cold rain more likely.

I would say look for upgrades for those in the southern counties. A lot can change with this sort of setup.

[snowfish]

One thing i would like to remind people on as you have just commented on the gfs being the best all week, is not to expect the 18z to be as good or better. If it does turn out to be worse in terms of cold and snow dont take it as gospel until weve seen the subsequent 12z tomorrow.

Oh how wise - look at how things have turned out in the last few hours after DAYS of runs with agreement between ALL models of an easterly with a prolonged cold snap - well maybe the colder air temps have been there...lol! People, let's wait and see - nothing is that predictable - even for more 'seasoned' forecasters of NW! That is the beauty of weather - it changes within a very short time - this is something (as a novice) I am beginning to learn and accept - sometimes it can be a disappointing outcome, despite having 'read' the models correctly over some time....

[Devon-Nelly]

One thing i would like to remind people on as you have just commented on the gfs being the best all week, is not to expect the 18z to be as good or better. If it does turn out to be worse in terms of cold and snow dont take it as gospel until weve seen the subsequent 12z tomorrow.

Well the way this month has been i don't whether im coming or going at times lol it has literally flipped and flopped.

But im not taking it by the gospel i know there will be downgrades there always is, just trying to be optimistic as everyone seems so doom and gloom, though your right it will most likely flip and change before we get to the day itself so taking each run with a pinch of salt from the nearly empty grit bin is the best way to go lol

[January Snowstorm]

Well I must be looking at different models, the ecm looks cold & wintry for the north throughout the whole run from monday onwards with huge snow potential although considering most members are from southern and southeast england it's not so promising down there with cold rain more likely.

Uppers of -2 to -4 are not cold enough for lowland snow.

Also a low pressure moving over us is not a guarantee of snow, in fact quite the opposite with no gradient coming off a warmer sea it could be dry

[MR EXTREMES]

GFS ensembles continue to look encouraging http://www.netweathe...;type=ens;sess= If anything the 12z op was on the mild side for the important part (mon / Tue) not a single member getting above -5 850s for the foresasble. I would rather take a gamble on a marginal situation than the usual N / NE incursion that leaves 98% dry and sunny. Interesting week to come next week, think most will see deep snow, sleet and rain at some point. Only place that may miss out will be the extreme south and South west IMO.

id be reluctant to say 100% cert even for northern england apart from the hills,

one thing i will say is the south looks dry from the ecm point of view,

but better for the south on the gfs so for a country wide event the gfs is a better op.

i remember rightly lastnight someone was rather rude to me.

if i may id like to return a point of view,

dont think the south of england is a area where its unable to get the goods,

so id rather not move north just for some snow.

Ive seen some great events here back in the 80s when you see nothing weather is always a regional thing most of the time.

so its unfair to try to score brownie points because someone gets it and others dont,

remember southern and south eastern areas normally get good summer weather so it works both ways.

i love the thought of the whole country enjoying the same weather,

but this rarely happens because this is what the weather does,

like right now the ecm is not good the gfs is better for alot.

so its good to be realistic and none abusive like someone was to me yesterday regards bb.

Edited February 10, 2010 by badboy657

[Ben_Cambs]

Well I must be looking at different models, the ecm looks cold & wintry for the north throughout the whole run from monday onwards with huge snow potential although considering most members are from southern and southeast england it's not so promising down there with cold rain more likely.

The ECM 12z has 850Uppers at -4C or below for places north of the usual suspect the M4 corridor at T+168

http://www.meteociel...68&mode=0&map=0

And it is worth saying that 5th of Feb last year I recieved about 6-7 inches of snow when the Uppers were -4C, so that can be the borderline for snow. Im sure the positioning of the low will change in just about every run for the next few days or so.

Edited February 10, 2010 by Snowman0697

[Frosty.]

I would say look for upgrades for those in the southern counties. A lot can change with this sort of setup.

Agreed, the models seem to be trending eastwards but it's a slow process, hopefully the 00z will show a direct hit N'ly but it might take a few more days to sort out.

Edited February 10, 2010 by Frosty039

[yamkin]

Uppers of -2 to -4 are not cold enough for lowland snow.

Also a low pressure moving over us is not a guarantee of snow, in fact quite the opposite with no gradient coming off a warmer sea it could be dry

We had -4C uppers here on 2nd Feb 2009 and had loads of snow

[LomondSnowstorm]

Actually, the two biggest snowfalls this year came with uppers between -3 and -4 , but that was more due to the fact that in both instances there was already lying snow, temperatures began at around -8C before rising to 1C when snow was falling and there was no coastal modification whatsoever, in fact the modification from the frozen, snow covered ground was very helpful

Still, if the last point holds true which it will for most and snowfall hits at the right time (early morning) -3/-4 uppers might just be enough for snowfall provided the surface conditions start off well within the parameters for snow e.g. temperature -1.5, dewpoint -2C. Certainly for northern areas after the initial front has moved through uppers look to be around -4/-5 at most in warm sectors, which of course tend to provide the most snowfall anyway!

LS

[tinybill]

i know its f1 but if this comes should be plenty of the white stuff next week!!!

[January Snowstorm]

Of course -5 uppers in an easterly are plenty cold enough as the air is drier

I dunno what to make of this year tbh, bitterly cold yet snow days were very scarce

As someone on two said cold without snow is like beer without alcohol, pointless!!

[Magadan]

i know its f1 but if this comes should be plenty of the white stuff next week!!!

FI has zero credibility to me any more. I'm now at the point of looking at models as being worthless beyond very, very short time frames. Looking for a consensual truth in the ensembles is like a herd of sheep expecting strength in huddled, collective weakness when faced with a wolf. I'd much rather see historical-statistical modelling that takes into account solar activity, volcanic activity and other wider factors, than the current setup of fragmented data samples pumped into simplified model algorithms developed over 2 decades of mildness.

[Guest FireStorm]

i know its f1 but if this comes should be plenty of the white stuff next week!!!

remains at its low pressure and moves SE down the north sea, the tight isobars would throw all the moisture from the north sea over a very cold uk as it sinks into europe.. january would be nothing in comparrison.. but thats my imagination of the perfect storm none the less. Perfect example of FI for most !

[MAF]

I would say look for upgrades for those in the southern counties. A lot can change with this sort of setup.

evening Robert, would you include London as "southern Counties" ??

So come on guys, lets have a 3 day forecast on the latest models. from what i have seen its going to be dry/cold/frosty/showers on eastern side of UK and the odd shower moving across UK NE to SW

[robert]

evening Robert, would you include London as "southern Counties" ??

So come on guys, lets have a 3 day forecast on the latest models. from what i have seen its going to be dry/cold/frosty/showers on eastern side of UK and the odd shower moving across UK NE to SW

Evening Maf, yes I would include London and surrounding counties in with a excellent chance of a winter wonderland!

Let's see what the 18z brings, but to be honest things could come down to a 48hr out model watching with this setup.

[robert]

From the 18z it looks like some northern and southern areas will get snow Saturday.

[notananorak]

The ECM 12z has 850Uppers at -4C or below for places north of the usual suspect the M4 corridor at T+168

http://www.meteociel...68&mode=0&map=0

And it is worth saying that 5th of Feb last year I recieved about 6-7 inches of snow when the Uppers were -4C, so that can be the borderline for snow. Im sure the positioning of the low will change in just about every run for the next few days or so.

Snow can fall with a 5000ft temp of zero C. It entirely depends on the temp profile below there to the surface ( always assuming the profile above 5000ft has a lapse or is at least isothermal ). Warm frontal approach being a common example of this. Assuming a standard lapse ( in saturated air ) of around 2C per 1000ft then in unstable air -8 to -10C would be the cut-off for snow given average surface air dryness ( upper limit necessary for warm sea fetch ). The easterly mentioned above would have drier lower layers than a Pm flow ( and from memory had some WA aloft ). This an example of why the WBFL is more imprtant than the FL. Prolonged heavy snowfall can lower the snow level 3000ft (in a showery set-up this would require streaming).

[I remember Atlantic 252]

low further west at 102, dont want that

[Tim Bland]

Fax for Monday look good http://www.meteociel.com/ukmo/fax/fax120s.gif Should be all snow on the cold front at least.