Spring Model Discussion 17/3/13 6PM onwards....

[Cheshire Freeze]

Well the ECM OP was an outlier to its mean particularly after 192hrs

Yes but remember the ECM DET is higher resolution I think and therefore should handle energy distribution better than the ENS. The ENS will probably show a solution closer to the GFS at this time.

[Cloud 10]

The ECM pressure anomaly chart for today shows nicely the magnitude of the Northern

blocking/almost record breaking negative AO across the Northern hemisphere at the

moment,with copious amounts of arctic air being forced down to mid latitudes.

[Harsh Climate]

Here's where I think where the heaviest snow will fall on friday/saturday (Red box.) In the yellow zone, a few shifts in the output over the next 24 hours and those places could be highest risk.

I expect generally 8-10 inches in worst affected areas with considerably more on high ground. I dont expect more than 20cm to low ground because I think accumulations will be stumped a little due to the marginality of the event.

[Backtrack]

The Midlands as well as North West England look to be the sweet spot as things stand currently. Could be some serious totals over the Pennines and around Pennine areas especially. 0C isotherm sat nicely at 400-500m widely, as well as good timing from the front.

Rare event for March, enjoy!

[Snowy Liverpool1]

Ian how's it looking for Liverpool? it's definitely north enough unless anything changes and it looks to be in a good area in terms of precipitation amounts, but the coast always puts this area at a disadvantage in snow events.

Edited March 20, 2013 by Snowy Liverpool1

[Backtrack]

Good consensus there from GM and UKPP: Approx 15-30cm of snow Dumfries & Galloway. Call it 20...!

Any chance you can start an 'Ask Ian' thread? Would be the best thread, ever!

[Cloud 10]

Well the ECM OP was an outlier to its mean particularly after 192hrs (outlier perhaps wrong word, to the cold end of the ensembles)

You would still "deal" if offered these ensembles though.

[winterof79]

What is it looking like for Western Pennine area's Ian, east of Manchester.

The clue is in his post really guys

fergieweather, on 20 March 2013 - 20:28 , said:

UKMO actively considering amber upgrades tomorrow am: firstly for snow (GM has 30+mm rain equivalent much of Central Midlands into NE: severe drifting & power line accretion a real hazard) and also for heavy rain in areas under the higher Theta-W air. Snowfall accumulations to t+84 look untroubling effectively south of Brum (a lIttle on UKV about as far south as Cotswolds etc) but potentially awful further north if this verifies.

[A.J]

C'mon guys & gals please!...This is not the ''will it snow in xxxxxx' thread, this is Model Output Discussion thread, the clue being in the name, so let's keep it on topic

[Harsh Climate]

Again the esembles have the precipitation reaching northern england easily

I don't buy this 'it won't get any further north than the midlands' talk

[iand61]

The Midlands as well as North West England look to be the sweet spot as things stand currently. Could be some serious totals over the Pennines and around Pennine areas especially. 0C isotherm sat nicely at 400-500m widely, as well as good timing from the front.

Rare event for March, enjoy!

Hope your right BT.

I'm ready for sunshine, long evening walks and cold beer sat outside pubs but would love to see what could turn out to be a once in a generation spring snow event and for once we are looking to be right in the thick of it.

[Man With Beard]

Good consensus there from GM and UKPP: Approx 15-30cm of snow Dumfries & Galloway. Call it 20...!

Thanks for taking the time to give these snippets of info and I'm sure most of us realise you can't give a forecast for every town!

I'm sure Ian would agree that these totals still need to be treated cautiously; as we've seen, the models are still acting a little erratically regarding where the snow lines are drawn. Right to flag up the risk, wrong to assume the details just yet.

Edited March 20, 2013 by rjbw

[Matty M]

Again the esembles have the precipitation reaching northern england easily

I don't buy this 'it won't get any further north than the midlands' talk

It really depends what happens in reality, important in times like this to actually take a step back from the models and look at satellite/ radar/ the latest plotted OBS, maybe even draw up your own isobars!

Alterations of around 50 miles in the synoptic could occur with not much model notice, forecasters are using past knowledge which tells that in this situation fronts tend to struggle to get as far north as modelled.

[stodge]

Evening all

I'm still considering the potential rainfall numbers for the SW and central southern England over the next 48-72 hours and IF North Wales is in line for a major snowfall that has the potential for major flooding in the future.

http://www.wetterzentrale.de/pics/Rtavn9618.png

In excess of 100mm over Cornwall and parts of west Wales sand presumably with the equinox at hand spring tides might be an issue as well so there could be some real problems in areas far removed from snowfall.

[fergieweather]

The Midlands as well as North West England look to be the sweet spot as things stand currently. Could be some serious totals over the Pennines and around Pennine areas especially. 0C isotherm sat nicely at 400-500m widely, as well as good timing from the front.

Rare event for March, enjoy!

Yes re broad distribution but emphasis actually further east is current headache for UKMO given latest areal probs and amounts.

Edited March 20, 2013 by fergieweather

[fergieweather]

Thanks for taking the time to give these snippets of info and I'm sure most of us realise you can't give a forecast for every town!

I'm sure Ian would agree that these totals still need to be treated cautiously; as we've seen, the models are still acting a little erratically regarding where the snow lines are drawn. Right to flag up the risk, wrong to assume the details just yet.

Yes: UKPP total considered overdone by x2.... hope so, as some look scary. So figures I gave you are UKMO modified.

[A.J]

Yes re broad distribution but emphasis actually further east is current

Just for the sake of humouring me & suspension of my disbelief, just please post that MOGREPS & EC in conjuction with UKV (and any other models the met uses) have just released flash updates progging 50+mm of snowfall ppn as opposed to 50+mm of RAINfall for the SW/M4 Corridor....me, and many others in the SW regional would be eternally gratefull..and I promise to my team collegues that I'd never moan about off-topic posts in the MOD thread ever again!

[Matty M]

The latest 18z NAE has resorted back similar to the 0z Run, it has got rid of all the northerly progress seen in the 6z and 12z.

'Forecaster's nightmare'

[Severe Siberian icy blast]

The latest 18z NAE has resorted back similar to the 0z Run, it has got rid of all the northerly progress seen in the 6z and 12z.

'Forecaster's nightmare'

Well I'm viewing it on weather online but it seems the ppn type hasn't updated yet although the ppn totals have and look a bit further southwest

[Matty M]

Accumulated precip at 48hrs NAE.

Flooding risk for Southeast Ireland. Potential for serious snow for northern parts of Ireland?

I will leave the UK analysis to others

[Summer Sun]

The latest 18z NAE has resorted back similar to the 0z Run, it has got rid of all the northerly progress seen in the 6z and 12z.

'Forecaster's nightmare'

Hence the reason UKMO will be glad to see it gone

Northern England still looks a good spot to be

[Cheshire Freeze]

Hence the reason UKMO will be glad to see it gone

Northern England still looks a good spot to be

That's still the 12z...... 'Wed 12+48'

[Snowy Liverpool1]

The latest 18z NAE has resorted back similar to the 0z Run, it has got rid of all the northerly progress seen in the 6z and 12z.

'Forecaster's nightmare'

Eh?

Reaches Scotland easily.

Edit: realised it's still 12z

Edited March 20, 2013 by Snowy Liverpool1

[A.J]

Hence the reason UKMO will be glad to see it gone

Northern England still looks a good spot to be

bare in mind that, that is the 12z NAE ppn type charts Gav

[Harsh Climate]

The latest 18z NAE has resorted back similar to the 0z Run, it has got rid of all the northerly progress seen in the 6z and 12z.

'Forecaster's nightmare'

No it hasn't

Looks the same

EDIT: Lmao, about 15 people beat me to it, that's some backlash for posting a wrong chart

Edited March 20, 2013 by Harsh Climate