TRENDS for the week of 4 to 10 Jan 2021
-- Temperatures will average 2 to 4 deg below normal values, somewhat milder near the end of the interval.
-- Precipitation will be slight, confined to bands of sea-effect wintry showers in a few areas, with results of about 10 to 25 per cent of normal values.
-- Sunshine will be above normal in western regions to near normal or a bit below average in the east.
FORECASTS
TODAY will continue cold with bands of mixed wintry showers moving inland in central Leinster, with cold rain or sleet the most likely forms, but some snow or hail mixed in also. This morning's icy conditions in some central and western counties will continue for several hours this morning, with some poor driving conditions especially on untreated secondary roads. Mainly sunny skies will prevail further west and in parts of both the north and south, but frequent cloudy intervals will be the rule in most of Leinster. Winds east-northeast 30-50 km/hr will add a chill to highs reaching only 2 to 5 C (colder values likely inland west to north).
TONIGHT will see some continuation of the cloud and wintry showers over parts of the east, and patches of clear sky further west, with bitterly cold lows in some places, reaching -5 C. Closer to -1 or 0 C near the east coast.
TUESDAY will present more or less of a repeat of today's weather with scattered wintry showers in the east, more sunny intervals further west, highs near 4 C at best, and winds east to northeast 30-50 km/hr.
WEDNESDAY the wind direction turns more northerly which may change the distribution of the sea effect wintry showers, making them more likely to appear in Ulster and north Connacht, but there could still be some in Leinster with a slight easterly component to the northerly breeze. It will remain quite cold, with a weak milder sector perhaps bringing temperatures up briefly in Ulster towards evening, morning lows for most areas will be -5 to -2 C, and afternoon highs 3 to 6 C.
THURSDAY and FRIDAY will continue quite cold in a northerly wind flow, sometimes backing to the northwest, bringing in more wintry showers across many parts of the country, but amounts will be slight. Winds north-northwest around 30-50 km/hr. Lows near -3 C and highs near 5 C.
NEXT WEEKEND most guidance currently shows this cold spell relaxing gradually, with the result that temperatures will edge upward each day, to around 7 C on Saturday and 9 C on Sunday. Some guidance suggests that cold air is not going to be pushed very far east by this weak Atlantic resurgence, and there could be a "battleground" scenario developing by middle of next week (around the 13th-14th) where cold air clashes with the milder Atlantic air along a frontal boundary through some parts of Ireland (most likely west Ulster to north Leinster on current indications). This may lead to some snow or sleet developing in Ulster, but longer term the weak milder regime is shown holding on for a while. Many following developments in the stratosphere seem to think that a second cold spell is quite likely later in the month, so this may not be the end of cold weather if it does turn milder next week.
-- Peter O'Donnell for IWO