Snow Risk Update + Uncertainty Continues

January 10, 2013

Weather Forecasts


Trying to forecast next week is continuing to prove very, very difficult with models even now struggling to agree on a particular outcome. This weekends forecast however is now starting to come into the range of High Resolution models and we can begin to forecast the weather more accurately for Saturday in particular.

Snow-Risk-MapAn area of low pressure will push to the South of the United Kingdom bringing in a period of rainfall across Southern England, however as it does so colder air from the East will begin to undercut the precipitation and we’ll see things turning increasingly wintry.

Previous forecasts suggested the snow risk would be further North however recent outputs have moved the system further South. Initially I think we’re likely to see a period of rainfall across Central Southern England and South-Eastern England but head slightly further North and things will be of a more wintry nature. As this system begins to clear Southwards through the course of Saturday we’ll start to see sleet and snow getting into the mix further South too, though I expect accumulations will be unlikely at this stage. South-West England is expected to see things remaining as rain with the colder air not pushing in here until after the precipitation has cleared.

As winds switch to more of an Easterly direction too though we’ll start to see snow showers pushing in across Eastern parts of the country, these aren’t expected to penetrate too far inland but could give accumulations of 5-10cm locally, particularly to higher levels. Another update will be posted on Friday evening to take into account the High Resolution models.

Looking ahead into next week and there’s still a considerable amount of uncertainty however we are beginning to see some slight model support I think. As the block in the Atlantic begins to build, models are starting to hint at the possibility of these failing due to a short wave pushing through, highlighted on the chart below by the curving isobars.

WAA

This has the effect of preventing the Atlantic high joining with Greenland and we see high pressure sinking South-Eastwards over the United Kingdom cutting off the cold airflow and introducing milder Westerlies. The UKMO model below also develops this shortwave

UKMO WP

Taking a look at the ECM, it does develop the shortwave but the orientation of it is much better than the above two models, as a result we see cold remaining across Eastern and Northern but with a moderation of cold across the South and West

ECM EDIT WP

Conclusion & Forecast

Through Saturday things will turn much colder with the risk of some rain, sleet and snow moving across Southern parts of England, snow showers will also begin to effect Eastern parts of the country giving localised accumulations of up to 10cm, particularly over higher ground. Further snow showers are expected through Sunday along Eastern areas, into East Anglia and perhaps the South-East which I’ll continue to monitor in the coming days. Day time temperatures through the weekend and into next week likely to be struggling to get much higher than 2 or 3c with night-time temperatures widely below zero.

Through Monday we have perhaps a more widespread and significant risk of snow as a shortwave pushes South across the country, there’s a fair amount of uncertainty over this at the moment though so we can’t be too confident about that just yet.

Towards the middle of next week, as things currently stand it looks like the cold will ease across the country with slightly milder air filtering in from the West, how mild and how abrupt this change develops remains very uncertain and there’s a chance the cold could hang on across Northern and Eastern areas for longer with the potential for battleground snowfalls,  it’s something that’ll need to be monitored through the weekend and into early next week.

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3 Comments on “Snow Risk Update + Uncertainty Continues”

  1. Luke Storey Says:

    Looking at the latest Met Office Outputs, an introduction to a growing area of High pressure over Scandinavia looks to slow the process of Atlantic Weather Systems… A UK battleground like you said may be the case of this, what does look promising is the core of the High pressure is fairly large and there looks like it may join up with Greenland as there is a sign of heightening pressure here (+144). The outputs really are contradicting themselves, there may still be hope for prolonged cold 😀

    Reply

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