Advanced Alert : Stormy Conditions possible early next week.

Thursday, 20 September, 2012

ADVANCE ALERT for possible heavy rain and strong winds by Monday covering large parts of the country. Details are still somewhat sketchy but model consensus is increasing, and a looping track will bring these effects to most regions at various times. This storm is not "Nadine" which now seems more likely to stall over the Azores and then back away to the south or southwest, but the storm expected in Ireland breaks away from Nadine's cloud mass later today or Friday morning, and in any case will become about as strong as Nadine might be on a similar track. Watch for updates as we get closer to this event on Monday. The system has slowed down somewhat from yesterday's early forecast and this will leave more of the weekend dry although first effects of the system will be felt later Sunday. ... Each global model has a slight variation on the theme of this storm system looping around and the UKMO does not bring it as far north which would leave Ireland in northeast winds throughout, whereas the ECM makes a wider loop that would be reflected in stronger winds from a southwest direction at some point. The other models are somewhat intermediate. This situation will be interesting to follow but the chances of a severe storm event are rising to the 50-50 range now, at least for some coastal regions. 

Forecasts for Ireland

TODAY ... Rain gradually ending across the north-west, and tapering off to drizzle by afternoon in central, east and northeast (including much of Leinster), although amounts across the south especially southwest, slight, as most of this system will continue to be north of a line from Galway to Dublin (possibly more like Athlone to Wicklow by mid-day through afternoon). Rainfalls of about 7-15 mm possible in Ulster, trending to trace amounts in southwest. Afternoon highs 13-16 C for most, 16-18 C south.

TONIGHT ... Rain will be slowly fragmenting to light showers and drizzle and the southeast will be under the last remnants with 2-4 mm amounts, trace amounts elsewhere, and some clearing late in Ulster, leading to patchy ground frost. Lows 3-7 C north to 7-10 C south.

FRIDAY ... Any remnant rain or drizzle in southeast clearing, otherwise partly cloudy skies developing from north to south, a chilly start with isolated frost in north-central counties, some sunny breaks mid-day and afternoon with highs only 12-15 C in all areas. Winds rather light but a trend towards northerly breezes then calm at night.

SATURDAY ... Partly cloudy with some good sunny intervals possible before becoming more overcast, showers possible near west coast by evening ... morning lows about 2-6 C with scattered ground frost, and afternoon highs about 15-17 C.

SUNDAY ... The morning may be dry for most of the north and west, with drizzle moving into the southeast. Cold to start with frosts in Ulster and Connacht inland, lows -1 to +4 C, but 5-8 C southeast. Increasing cloud with showers or periods of rain by evening, 5-10 mms possible, and highs 13-16 C. Winds generally light at first then increasing to E-NE 20-40 mph.

MONDAY ... Periods of rain and moderate or even strong winds developing as low pressure loops around from Britain and across western counties by Monday night. Rainfalls 20-40 mms possible, lows near 8 C and highs 12-15 C, with cyclonic winds tending to increase more dramatically at a distance from the low centre where winds could be quite slack. As the track is not that certain, the best idea at present is to alert all districts to some potential for strong winds, but more likely NE winds in the north and SW winds in the south around this low. Some model depictions suggest potential for wind gusts above 50 mph.

TUESDAY ... Variable cloud, showers or periods of light rain, NE to N winds of about 20-30 mph, chilly with lows near 7 C and highs 10-13 C.

OUTLOOK ... Slow improvements but rather unsettled and cool for several more days, eventually the possibility of frosts returning.