winter model output Winter Model Output Discussion -12Z 07/02/13 onwards

[PolarWarsaw]

With all the rain before snow this weekend, I'd imagine accumulations thicker than 'sludge' are very unlikely away from the northern hill tops. Whilst the snow may be falling, it's most likely to struggle to stick to what will be very wet ground levels that haven't been under sustained cold to cool the ground beforehand. I'd imagine ice will be the key issue through Monday/Tuesday - not snow.

[Sussex Jules]

Don't worry, any rain will turn to snow

I'm not worried it's the weather afterall, it's just posts like this make it all very confusing.

[MR EXTREMES]

ukmo is very clean route nice ridge and nobody has commented strange.

[Barry12]

First post on the MOD thread. As a newbie/lurker for a while, I have to say that for new followers, they have got a cat in hell's chance of learning if its "a downgrade for Sun/Mon"...followed by post saying "an upgrade for Sun/Mon".

For learners like me please can posts be backed up with charts or explanations to these type of comments or posts in general.

Sorry if off topic!

For me the signs of an upgrade was obvious as it has been a trend to slow the Low pressure down, which gives for time for the cold uppers to move in, so when the low pressure did arrive the uppers would be upgraded therefore making rain turn quickly to snow. This low pressure is slower too so expect more prolonged snowfall, it could still be snowing in the SE come midday-Monday.

[Bolton67]

Very marginal Sunday and Monday on this run for the SE. The dew points in Kent never go negative those two days, eg:

Many other areas north M4 should be ok, DP wise.

your geography is very poor. Not just the south east would it be marginal. all of the East Midlands and parts of the West Midlands too .

[MR EXTREMES]

your geography is very poor. Not just the south east would it be marginal. all of the East Midlands and parts of the West Midlands too .

details will change dramatically by sunday could possibly not get any at all.

[Cecil Hogmanay Melchett]

Atlantic coming back by thursday on gfs?

[lawrenk]

First post on the MOD thread. As a newbie/lurker for a while, I have to say that for new followers, they have got a cat in hell's chance of learning if its "a downgrade for Sun/Mon"...followed by post saying "an upgrade for Sun/Mon".

For learners like me please can posts be backed up with charts or explanations to these type of comments or posts in general.

Sorry if off topic!

Couldn't agree more. I'm also trying to learn and within a minute we go from "looking like an upgrade for the south so far" to "looks very wet across the south".

I appreciate it's a Model Discussion but surely there can't be that much room for interpretation?

[A.J]

First post on the MOD thread. As a newbie/lurker for a while, I have to say that for new followers, they have got a cat in hell's chance of learning if its "a downgrade for Sun/Mon"...followed by post saying "an upgrade for Sun/Mon".

For learners like me please can posts be backed up with charts or explanations to these type of comments or posts in general.

Sorry if off topic!

Don't be sorry, welcome to the Model Output Discussion ....In answer to your to points, it's a bug bear we all have to live with here in this thread and it usually comes from following circumstances.......1) some members automatically going to the GFS ppn type charts and either seeing too much or too little pink from an 'in their own back yard' perspective and either ramping accordingly or alternatively having a hissy fit and throwing a teddy or two out of the cot, without looking at the bigger picture and leading on from that ...2) some members not having a clue what they're talking about.....

There are other circumstances as to why the inconsistencies in posting happen, but it's generally one of the above!

Hope this helps, please don't be put off from posting,...back to the 12z output.......

[Panayiotis]

With all the rain before snow this weekend, I'd imagine accumulations thicker than 'sludge' are very unlikely away from the northern hill tops. Whilst the snow may be falling, it's most likely to struggle to stick to what will be very wet ground levels that haven't been under sustained cold to cool the ground beforehand. I'd imagine ice will be the key issue through Monday/Tuesday - not snow.

Sorry but youre wrong here in Cardiff the last snowfall event started off with heavy rain for 2 hours before turning to snow, this gave me 6 inches of snow.

[Cheshire Freeze]

Those getting hung up on the frontal event perhaps shouldn't. A strong easterly flow, low thicknesses and uppers following across England and Wales especially. Looks ripe for trough formation post frontal rain/snow. This could potentially provide more snow to many others.

[Roger J Smith]

Will that pesky GFS ever stop its cold ramping?

/irony

Combined model runs so far suggest rapid development of Channel low scenario and a rain-snow line that advances through Saturday and early Sunday to about a Worcester-Luton-Ipswich line then that retreats to about 30 miles inland from the Channel by Monday. Heavy snow therefore likely across much of Wales and central England into northeast England, possible mix in Ireland.

However, this situation is clearly so volatile that a slight adjustment to track and intensity could pull in the colder air over some southern regions earlier than models currently suggest, the change in GFS in particular over 24-36h is remarkable. In the longer term, if the models could have been slightly out over four days, then imagine how far out they could be in eight or twelve. There are hints of a very cold and very snowy outcome several times down the road. At the very least you would have to imagine that the month would end up 2-3 C below normal, but in these cases, snow cover can become a feedback mechanism and without much change in uppers you can end up more like the record-breaking range of 5-6 C below normal. Remember, the three coldest Febs only averaged between -1.5 C and -2.0 C (CET) which is no colder than the two-week period last year.

[Mucka]

Good agreement between UKMO and GFS for 120 with the UKMO being slightly better in that it has less energy moving out of the Atlantic and makes a little less of the shortwave activity.

[PolarWarsaw]

Sorry but youre wrong here in Cardiff the last snowfall event started off with heavy rain for 2 hours before turning to snow, this gave me 6 inches of snow.

Indeed so but what was the intensity of the snow? How cold/marginal was it between snow and rain. It was perhaps a little more IMBY, because if it rains it simply wont stick in this neck of the woods. I do think that the rain beforehand will vastly affect accumulations.

[Cecil Hogmanay Melchett]

nope its not going to be long lasting if gfs 12z is believed!!

[Cheshire Freeze]

Atlantic coming back by thursday on gfs?

Are you purposefully looking for doom and gloom every run? You've ignored every bit of potential before then.

[Isolated Frost]

Equivalent temp plot for Sunday eve-- put a line between say, Norwich and Liverpool and it's all snow for that line northwards. Basically, much of the E Midlands, parts of the W Midlands/E Anglia and NW England, as well as all of NE England and southern Scotland, though the strongest precip should be across the midlands. Expect significant accumulations across the peak district and parts of the pennines.

Similar point of view with the wet bulb temps- looking at a very snowy image across NW England (esp high ground) and much of Yorks/Pennines.. sleet, rain and snow for the Midlands and East Anglia.

Rolling that forward to Monday morning- heavy snow for much of East Anglia, the Midlands and SE England, with heavy rain, sleet and snow in the SW (heavy snow on high ground in the midlands and south/south-west). A strong easterly develops- the advection of cold air on top the low is marked and substantial as we move through Monday-

A day of first heavy snow for southern areas, turning into one with heavy snow showers moving in from the E and NE.

Looks like a very eventful couple of days, with some strong winds and heavy precip moving through, before colder air is introduced from the east.

[MR EXTREMES]

Atlantic coming back by thursday on gfs?

no alantic just middle ground.

[Panayiotis]

Indeed so but what was the intensity of the snow? How cold/marginal was it between snow and rain. It was perhaps a little more IMBY, because if it rains it simply wont stick in this neck of the woods. I do think that the rain beforehand will vastly affect accumulations.

It was exactly the same setup as the one we are seeing for Sunday/Monday.

[Isolated Frost]

nope its not going to be long lasting if gfs 12z is believed!!

Without meaning to sound to offend, are you actually reading the charts pre 120? Or even reading all of them, instead of those that suit you? Plenty of cold on the GFS again

[shaky]

Steve any comments on the ukmo charts thus far??

[Coast]

As a newbie/lurker for a while, I have to say that for new followers, they have got a cat in hell's chance of learning if its "a downgrade for Sun/Mon"...followed by post saying "an upgrade for Sun/Mon".

For learners like me please can posts be backed up with charts or explanations to these type of comments or posts in general.

Yes, can I reiterate that one liners calling 'upgrade', 'downgrade' or some other from of wording that has no analysis or is not backed up by charts/data, means that a majority of members following this thread haven't a clue what to make of an actual interpretation of the models.

Edited February 7, 2013 by Coast

[Average Joe]

Couldn't agree more. I'm also trying to learn and within a minute we go from "looking like an upgrade for the south so far" to "looks very wet across the south".

I appreciate it's a Model Discussion but surely there can't be that much room for interpretation?

Someone took the words right out of my mouth. To be honest, being a new reader to these posts i've noticed that as the winter's gone on those who are more desperate for snow will snatch at any little sight of cold weather to jump on that bandwagon, and those who who don't will do the exact opposite. What started off as being very interesting and informative comments have got incredibly confusing during this current cold period.

Speaking selfishly, for someone who's livelihood goes up the swanny when snow causes the disruption it does, it's previously been great in order to get some kind of informed advanced warnings of what to expect and when. Not the kind of "snow"/"rain" snipes currently being made.

[SE Blizzards]

nope its not going to be long lasting if gfs 12z is believed!!

And after it's shambolic performance over the last few days is it to be believed??????

[Cheshire Freeze]

At 168 the Atlantic, for the first time this winter, looks like it's running out of purpose. Wonder where FI will take us. I wouldn't rule out Greenland height rises.

Can't post charts as on phone, laptop charger is bust!