TRENDS for the week of 27 Apr to 3 May 2021
-- Temperatures will average about 3 deg below normal values.
-- Rainfall will average near normal or possibly slightly above if it rains significantly on Monday 3rd.
-- Sunshine will average only 50 to 75 per cent of normal values.
FORECASTS
TODAY will be noticeably cooler with a few showers, more frequent across Ulster and north Connacht, north Leinster and later parts of the midlands. Winds will turn more to the north at 30-50 km/hr, highs only reaching 11 to 14 C. About 2-5 mm rainfalls can be expected in most places, but a few thunderstorm cells could develop and give heavier amounts locally.
TONIGHT will stay partly to mostly cloudy and cool with a few more showers possible, lows 2 to 5 C.
WEDNESDAY will be partly cloudy and cool with showers, moderate north to northeast winds 40-60 km/hr, highs only about 10 to 14 C.
THURSDAY will be partly cloudy with showers and chance of a local thunderstorm, lows 1 to 4 C and highs 10 to 14 C.
FRIDAY will be partly cloudy to overcast and cool with isolated showers, lows near 2 C and highs 12 to 15 C.
SATURDAY will also be rather cloudy with a few sunny breaks, lows near 3 C and highs near 13 C.
SUNDAY and MONDAY there may be some locally significant rainfalls especially in parts of the south as low pressure develops to the west of Ireland but fails to move this colder air mass, so that the interaction will lead to low cloud, rain and drizzle, possibly amounts of 10-20 mm or more. Temperatures will be quite chilly if this low develops as expected, with no sunshine to warm the air, readings of 8 to 10 C could remain in place, but if the situation is less developed then temperatures would likely get into the 12-14 C range which is perhaps more likely in the north anyway further from the frontal zone.
Then it looks like this battle of air masses will continue for a while, with no really clear indication of when it will end (which it is going to do sooner or later) so that warmer air masses can push in from the southwest. It could take a week or two of occasional frontal systems and rainfalls with depressed temperatures for a while into May.
Peter for IWO