As a storm chaser with good weather forecasting skills I have been trying to work out when UK (and European) airspace will return to some kind of normality so that I (and everyone else) can start to get home. I have Just done another weather forecast computer model run this morning and discussed the situation with some of my meteorologist colleges. The consensus is that the existing wind regime over the Volcano will continue to bring any ash that is produced directly over the UK until late Friday night. Saturday in to Sunday the winds will shift to Southerly and the ash plume will be taken north, well away from the UK. It will take some time for all existing ash over the UK to disperse but by Saturday evening most of the UK should be clear and flights can be expected to resume departing the US Saturday, arriving UK Sunday. Then late Monday night and in to Tuesday Northerly winds are forecast to start returning, so if the bloody thing is still erupting further ash may return to the UK Tuesday into Wednesday.
Forecast accuracy confidence for the weekend is high, for early next week not so high. The forecast is based on computer model data which gets less accurate the further ahead you look. 2-3 day accuracy is very good, 4-5, reasonable, 6-7 more variable and 7-10 less reliable. Beyond 10 days you may as well use a crystal ball.
Volcanic activity appears to be decreasing (lets hope so) but we have seen that the volcano goes through cycles of activity. At the moment the adjacent Katla volcano is shown no signs of activity.
UPDATE HDW : Interesting but last night (Tuesday 22nd April 2010) the aviation authorities along with other government bodies decided the ash above the UK is not such a problem to aeroplanes after all, let’s wish Alister a speedy and safe return from the USA and hope the so called experts have not compromised passenger safety for economics !