Saturday, 24 September 2011

High pressure to bring a spell of more settled weather to many parts of the UK

High pressure to bring a spell of more settled weather to many parts of the UK

24th September 2011
It is not difficult to see the area of high pressure that is set to bring a pleasant spell of weather across many parts of the UK over the coming week and possibly into early October. Although the best of the weather is likely to be further south throughout this period, this will certainly be a welcomed spell of settled weather for many parts, after the summer that never arrived, and the severely cold and snowy winter that we are about to experience.

Winter 2011-12 Update

As in my last update on the 2nd September 2011. "I expect the most frequent and heavy snowfalls to occur across many parts of the UK during NOVEMBER, DECEMBER, and JANUARY" at present. I initially expect frequent and significant snowfalls across many northern regions and Scotland throughout this winter. Any earlier snowfall is likely to be more confined to northern and western parts of the UK, although large scale low pressure systems also offer the potential for significant snowfalls to many parts of the UK.

I also expect NOVEMBER, DECEMBER, JANUARY, and FEBRUARY to feature largely below-average temperatures across many parts of the UK, it is likely that temperature and snowfall records will be broken within this defined time frame. I initially expect temperatures to really struggle across many northern regions, including Scotland (Western Scotland in particular), Ireland (Northern Ireland in particular), North West England, and parts of Wales.

Future updates will follow accordingly and become more location specific as we head into and progress through winter.

Our initial summer and winter 2011 forecast for this year was originally published on Exacta Weather in January of this year, before any other forecaster worldwide. It is also available to view with an official YouTube date stamp from the 4th February 2011 below.

James Madden (UK Long Range Forecaster)

Published: 24th
 September 2011 (19:24) BST
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Saturday, 10 September 2011

Hurricane Katia - Weather Warning

Hurricane Katia – Weather Warning

Hurricane Katia started out as a category one hurricane, which will dissipate to a large scale low pressure system as it approaches the UK and Ireland, due to the lack of heat in the North Atlantic in comparison to its origin. Many parts of the UK are therefore likely to experience strong to damaging gale force winds that could exceed 90mph in some places, with stormy features throughout Sunday and Monday at present, and as originally forecast in the autumn update last week. The regions at risk of the most disruption at present include many parts of Scotland, Northern Ireland, and Northern England, although most if not all of the UK is at the risk of severe gales. There is also a high probability for very heavy rainfall across many parts, with the potential for flooding in Scotland, Northern Ireland, and many coastal regions. If an update is required due to any major changes then one will be posted, in the meantime it would also be advisable to keep up to date with local and national weather warnings.

A very interesting article I also came across on Katia in the link below, features John Cangialosi from the US National Hurricane Center, who said it would change from a tropical storm to a "classic wintertime storm" by the time it reached Scotland.

Now a “classic wintertime storm” to me generally consists of SNOW or ICE in American and English terminology. Any UK snow in September would certainly raise a few eyebrows, whilst also exceeding my expectations of early snowfall in October and November.

Based on the meteorological credentials of John Cangialosi and his terminology of “classic wintertime storm”, I decided to give his comments some further thought, and snow is not actually an impossibility, if that is what he means, although he may just be referring to the characteristics incorrectly?

However, extratropical cyclones from cooler atmospheric conditions and cyclone tilting, allow cool air to be drawn into the circulation, and the low pressure system transitions from warm to cold.

So could we see snow in Scotland and other parts of the UK from this severe bout of weather? and is this what John Cangialosi means? Only time will tell as to how things will develop, but his statement does make scientific sense if the scenario unfolds as I explained, and the conditions are right.

James Madden (UK Long Range Forecaster)

Published: 10
th September 2011 (07:21) BST
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Saturday, 3 September 2011

Coldest UK summer (2011) in nearly two decades?

Coldest UK summer in nearly two decades?

2nd September 2011

UK Autumn & Winter Weather Forecast 2011-2012

Many parts of the UK and Ireland are coming to terms with what the media has been recently reporting as the coldest summer in nearly two decades, and as we originally forecast back in January and early last month in the link below.

The media have been reporting that this was coldest UK summer in 18 years on the basis of provisional Met Office data. I still need to review the HADCET data for previous summers, but since these reports was published the Central England Temperature (CET) has been adjusted from a mean of +0.1 to a final figure of -0.4 for August. The Met Office did correctly state in the link below that the media had taken this from figures based on August CET that was not yet complete.

The Met Office also stated that the CET only represents a small part of the UK? Yet they fail to mention how valuable the CET dataset is to meteorologists and climatologists as the oldest recorded dataset in the world (over 350 years), and in terms of Northern Hemisphere temperatures. It will be interesting to see how their summer review that has not yet been updated for August in the link below reflects upon this, if at all.

June Mean CET = -0.4 below average

July Mean CET = -0.8 below average

August Mean CET = -0.4 below average

The summer also turned out to be wetter than average across the UK with dominant grey skies, and torrential downpours/flooding that became a frequent feature across many areas and all as we originally forecast. Parts of Scotland experienced their wettest 24 hours ever recorded, with severe flash flooding to the South of the UK since the last update.

Autumn 2011

The UK can expect a similar theme to continue as we head into autumn, with a notable increase in usual wind strengths for this time of year across many parts of the UK, that will result in frequent and potentially damaging gale force winds and strong stormy features throughout autumn and winter. Although some places further South may see some spells of settled weather at times, the general theme for autumn as a whole looks largely wet and very windy with dominant grey skies. It will be generally unsettled and turn progressively colder with an early start to winter, especially more so in the regions of Scotland, Northern England, and Northern Ireland.

Winter 2011-12 Update

As we head towards winter, I expect to see the first signs of some moderate to heavy snowfalls as early as October or November in certain parts of the UK. In terms of the meteorological winter, I expect December, January, and February to experience below average temperatures, with the heaviest snowfalls occurring within the time frame of November to January across many parts of the UK.

The most important factor within our weather forecasting calculations is solar activity and other major natural factors that it influences. Radiant energy from the sun is the primary influence on both the earth's ocean and atmosphere.

Low solar activity and ocean behaviour alter atmospheric circulation and block jet stream patterns that create enhanced moisture in terms of snowfall. The UK and Ireland is hit by prolonged periods of extreme cold and snow from the Arctic regions, as cold easterlies or north-easterlies develop. Huge swirly low pressure systems also offer the potential for widespread disruption from heavy snowfall across many parts of the UK including the South, as they clash with the predominant cold air over the UK.

Coupled with other in depth factors such as recent volcanic activity and changes to the Gulf Stream/North Atlantic drift that we consider, this does not bode well for the severity of the UK and Northern European winter of 2011-12. Frequent and prolonged cold spells with heavy dumps of snow from blizzard like conditions is likely across many parts of the UK. The areas we expect to be worse hit throughout include the vast majority of Scotland and the Scottish Highlands, Northern England, and Northern Ireland. We have particular concerns as to the huge implications that this may pose to the infrastructure of the UK and Ireland transportation systems/economy.

James Madden (UK Long Range Forecaster)
Published: 2nd September 2011 (15:57) BSTContent copyright © 2010-2011. Exacta Weather. All rights reserved.