..Considerable Uncertainty

December 7, 2012

Weather Forecasts


I’ll start with the forecast for Monday & Tuesday.

Colder air coming in from the East will lead to largely dry and cold conditions across the United Kingdom, a North-East airflow across Eastern areas could bring some snow showers across Eastern parts and down into South-East England, this is something that’ll need monitoring closer to the time when we’ll be able to forecast these potential snow showers more accurately.

The uncertainty comes from Wednesday onwards. Models today have thrown a spanner in the works and develop a short-wave near Norway, this prevents high pressure from developing to our North and instead allows the Atlantic to make inroads across the UK bringing increasingly milder conditions. The 12z GFS & UKMO model show this happening.

GFS Model at T144

GFS Model at T144

UKMO Model at T144

UKMO Model at T144

The GFS Ensembles however paint a different picture and show just how uncertain things become from Wednesday/Thursday onwards.

GFS Ensembles

GFS Ensembles

The above chart shows how the ensembles begin to become increasingly scattered from around the 13th onwards with some bringing in milder air far more quickly than others. This suggests a great deal of uncertainty in the final outcome. There is however growing support for a breakdown to more Atlantic conditions late next week, how this plays out however remains uncertain though there are two different options.

  • Atlantic low pressure systems push in bringing milder conditions fairly quickly, a very short spell of snow followed by rain
  • Atlantic low pressure systems attempt to push in but become slow moving, bringing a more significant spell of snow

The ECM shows how a slow breakdown will bring potentially widespread snowfall across many parts, the usual high uncertainties still apply, of course.

ECM Model at T144

ECM Model at T144

Things are finely balanced between the two solutions and it’s something that I’ll be keeping a close eye on in the coming days. Before that though, surprise snow events on Monday/Tuesday cannot be ruled out so keep checking back for updates on that.

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6 Comments on “..Considerable Uncertainty”

  1. guyfawkes Says:

    if you were to give % to either atlantic air option, what would it be?

    -Atlantic low pressure systems push in bringing milder conditions fairly quickly, a very short spell of snow followed by rain %

    Atlantic low pressure systems attempt to push in but become slow moving, bringing a more significant spell of snow %

    Reply

  2. skribbledotcopy Says:

    When you say “potentially widespread across many parts”, where.in the UK are you referring to?

    Reply

  3. matt Says:

    I’m just hoping the money spent on the new coding at the met office is going to be useful because they predicting the high pressure to take charge and give use some widespread snow when it interacts by slowing this pressure down and i know there is only 20% chance of this happening but lets just hope that snow comes sooner than later 😦

    Reply

  4. Callum Says:

    I see the ‘beast from the east’ was so close to us but yet so far. Would of been mayhem in the uk. Shame it never arrived 

    Reply

  5. Sib Says:

    Yeah looks like the atlantic will win the battle. Will stay cold frosty but as soon as the low pressure system moves in it will push the beast away with it and we will see rain instead of snow. At least that’s what the models predicting so far.
    Would like Damien to shed some more light on it though.

    Reply

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