HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY TUESDAY JANUARY 27TH 2015.
NEXT UPDATE WEDNESDAY JANUARY 28TH 2015 08:00
THE CURRENT GENERAL SITUATION A strengthening SW flow ahead of active cold fronts crossing SE over the UK tonight and tomorrow will be followed by an increasingly cold and windy westerly flow tomorrow.
MODELS-2 WEEK HEADLINE Becoming colder with snow showers or snow at times before becoming less cold and changeable again later next week.
THE JET STREAM ENSEMBLE FORECAST The Jet Stream Forecast shows a week long spell with a deep trough over Europe keeping the flow well South of the UK in NW winds. In week 2 the pattern flattens markedly over the Atlantic and Europe with the flow returning North across the UK between High pressure re-established to the South of the UK and Low to the North.
GFS OPERATIONAL The GFS operational today continues to illustrate the colder theme of weather now for the rest of this week, the weekend and the start to next week with cold West, NW then North winds with wintry and snow showers affecting all areas at some point across the UK with the exposed areas facing NW and North. A marked wind-chill will accompany the cold period. Then as we move through next week milder air will try to dislodge the cold from the Atlantic and a messy mix of rain and snow will accompany that before a slow return to milder SW winds and occasional rain arrives later in the run.
THE GFS CONTROL The GFS control run is not fully available at time of publish but as far as it goes show a lessening of the cold spell as we move into next week from the West.
THE GFS CLUSTERS The GFS Clusters also are only available up to 132hrs today and show a cold and wintry NNW flow across the UK in total domination at that point.
UKMO UKMO this morning continues to show the UK in a very cold Northerly flow to start next week with plenty of snow showers flooding South across the UK with only Central inland areas of Southern Britain least at risk.
THE FAX CHARTS The Fax Charts show plenty of troughs feeding South and SE in the cold flow from tomorrow giving rise to plenty of instability sufficient to give many areas the risk of either wintry or snow showers, the latter especially at the weekend as the flow turns more Northerly.
GEM GEM today continues to show the dissolve of the cold weather early next week in the wake of less cold but very unstable westerly winds with heavy rain and gales likely at times with wintry showers at times too, these especially in the North.
NAVGEM NAVGEM today keeps the cold going over the UK into next week with a ridge eventually cutting off the cold North flow by Tuesday but with the likelihood of it remaining cold with the possibly of a battleground snow event towards the West by midweek
ECM ECM this morning looks very messy as the cold northerly flow dissolves away early next week. Temperatures are shown to steadily rise by day at least as a broad ridge crosses the UK from the West. Frosts are still likely at night though and it would likely stay largely dry.
ECM 10 DAY MEAN The 10 Day Mean this morning looks like broadly setting the UK back on it's default position later next week as Low pressure lies well to the NW and High pressure to the South with broadly westerly winds likely across the UK and a much less marked trough over Europe.
NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend remains for much colder and windy weather later next week and through next weekend. The longevity of the spell has firmed up somewhat on milder conditions returning from the West as we move deeper into next week.
MY THOUGHTS The cold period is almost upon us now and remarkably the models have held firm on it's evolution of this spell from the weekend. However, the models have found it less easy to agree on the end of the spell which is looking likely towards the middle of next week. In the meantime there is concrete support for a cold and windy West, NW then North wind over the coming 5-6 days starting tomorrow with snow and sleet opportunities for many on all days though as always the hills of the North and West will probably fair best. I know we shouldn't be looking for the end of the spell before it arrives but I wouldn't be giving my report much credibility by not and it does look like there is very good support for less cold conditions to move across from the West by the middle of next week give a day or two. The way that happens is shown by most models to be a real cocktail of options at the moment but the likely scenario is for Westerly winds to regain a foothold across the UK by next weekend with rain at times. GEM shows a more extreme version of this with gales and heavy rain on a strong Westerly flow and the ECM 10 day Mean chart is ugly if it's continued cold your looking for. However, the operationals over the last few runs have shown much volatility in their range of options so I feel the ensembles tell a truer picture and that suggests milder weather as we progress through next week. Nevertheless we have a period of 5-6 days when there is some good opportunity for snow even in the South and though inevitably some will see little or none there will be some who see a lot with disruption and news coverage likely but overall by this time next week I think we will be seeing a moderation in the cold and a gradual return to a more default position we have been in for much of this Winter.
Martin G
Kilmersdon Radstock Bath Somerset