Whither the weather?

What are forecasters – professional and amateur – predicting for Ireland’s weather in the months to come?

The weather for the coming year will see a return to mild winters and hot summers, or perhaps colder winters and wetter summers. Take your pick, because when it comes to long-range forecasting, the results – much like the weather – are varied and changeable.

Day-to-day weather forecasting has become a lot more accurate in recent years, but many meteorological offices refuse to give forecasts beyond a few weeks because of concerns about accuracy.

Met Éireann, for example, gives forecasts of up to a maximum of 10 days, while the UK Met Office had to reverse a policy of longer-range forecasts last year because of incorrect predictions.

That vacuum has been filled by a number of websites that offer their predictions through such sites as irishweather online.com and predict weather.com.

Here we ask forecasters for their predictions for Ireland this year – and how they arrived at them.

Gerald Fleming, Chief forecaster, Met Éireann

The basic method of forecasting we use is the scientific approach. We start with the weather as it is now and make observations based on reports from a network of stations. We feed this into models of the atmosphere, and there is a large fleet of computer programs that do this. We run our own models, but for forecasting beyond two days we tap into the European Centre for Medium-Range Forecasting. In general the most we can do is 10 days ahead. This centre has done monthly and seasonal forecasting, but it is still in the research phase.

Seasonal forecasting in this part of the world is much less certain. For the year ahead I can say very little. We had a period of very rapid warming through the 1990s as part of climate change. That seemed to come to a halt.

There are other processes at work, which have two, three and four timetables. The year-to-year variability is considerable. I think when we complete analysis of 2010 it will be seen to have been a relatively cool year. As we go towards the second week of January we should see milder weather. The typical pattern we have had in many of the past 10 winters was for very mild weather. It looks like we’re getting back to that.

Ken Ring, Author of 'Predict Weather Almanac for Ireland 2011'

Our method looks at trends and moon orbits. My 2010 book predicted the last weeks of October and November would bring early frost and snow, and December would bring daily precipitation and colder temperatures.

After a dry first half, January will see precipitation from the 14th and thereafter every few days. Another colder spell should arrive from January 19th to 30th. February may be cold between the 3rd and the 13th, and the 26th and the 27th, with possible snow in the first week, but relatively dry between the 10th and the 24th. It will be cloudy and milder from February 11th to 28th. March is mostly dry, with two or three significant rain days around the 7th and 8th, and cold from the 10th to the 16th.

April’s first week brings frost and snow to the northeast and possibly the last of the overnight subzero temperatures, with nice weather from the 21st to the 27th. Apart from temperature dips in mid May, most of Ireland should be out of the frost range by the end of April. The summer should be mild. It won’t be too warm but will have good dry, sunny spells in the second and third weeks of May, during the first half of July and between August 26th and Sept 17th.

Mark Dunphy,

Irish Weather OnlineFor the long range, which is anything past 10 days, more reliable forecasts are available from the research index values than from the global models, which tend to lose accuracy to a large extent past about day seven, and certainly on the monthly to seasonal time scale.

Irish Weather Online forecasters rely primarily on an intuitive blending of research products with state-of-the-art conventional products that are more generally available and probably consulted by almost all practising long-range forecasters.

Some variability is setting in, and we are expecting a brief but possibly quite dramatic warming mid-month before colder weather returns. With regards to the summer, as we look that far into the future, reliability falls off, but I would be surprised if it were as wet as the trend of the past four years, or as hot and dry as, say, 2006 or 2003 was. Pattern-matching would suggest a fairly normal summer, with a selection of different types of weather patterns alternating warm and dry with cool and wet, but perhaps nothing too extreme.