TRENDS for the week of 2 to 8 May, 2021
-- Temperatures will average 3 to 5 deg below normal values.
-- Rainfall will average 25 to 50 per cent above normal values.
-- Sunshine will average 50 to 75 per cent of normal, and winds will
become much stronger than they have been in the past two weeks (very
strong at times Monday into Tuesday).
FORECASTS
TONIGHT will become windy with intervals of rain and some fog especially
over higher parts of the north where it could produce very poor
visibility at times. Winds will continue to increase from the southeast,
veering to southwest in parts of Munster towards morning. Temperatures
will be steady 4 to 7 C. Rainfalls of about 10 mm expected.
MONDAY will continue wet and windy with the winds veering gradually
around to a westerly direction, becoming very strong especially from
Galway Bay south to Kerry, and later along the south coast. Speeds of 70
to 110 km/hr are possible. Temperatures will peak at only around 13 C
in the south, 9 or 10 C north, and will be falling slowly by late
afternoon with passing squally showers with hail and thunder possible.
There could be some brighter spells in the strong winds too. A further
10 or 15 mm of rain is likely.
TUESDAY the storm will be slowly moderating but the morning could remain
very windy especially in coastal areas of the west, and wherever a
northwest wind is channelled by the terrain (at least 60 to 90 km/hr in
exposed areas). It will remain unseasonably cool with passing squally
showers, and the risk of wintry showers on northern hills. Lows around 3
C and highs 7 to 12 C (coldest in Ulster).
WEDNESDAY and THURSDAY will continue unseasonably cool with passing
showers, some of which could turn wintry at times in Ulster, Connacht
and parts of north Leinster, as well as higher terrain further south.
Winds will not be as strong, northwest to north 40 to 70 km/hr, but they
will add a chill to this outbreak. Highs both days only 7 to 12 C with
morning lows around -1 C possible. There is some chance of a sleety cold
rain with snow on hilltops pushing into parts of the south around
Wednesday night into Thursday, and this will turn winds there more to an
easterly direction, but the partly cloudy, showery regime is likely to
be unbroken further north.
By FRIDAY into SATURDAY, a second Atlantic storm may directly affect the
weather in Ireland, although some guidance takes this low just far
enough south to be more of a problem for northwest France and southern
England. There's a risk of a persistent cold rain in northeast winds,
again with some potential for wet snow to mix in or fall on hills.
Temperatures will be very cool for this time of year, possibly only
around 6 or 7 C in some places; the further north one goes, it may
actually become a bit milder just because of the sun getting through the
overcast more often away from this southern storm track.
By SUNDAY next weekend this particular disturbance should be moving away
but leaving a cold northerly flow with showers and temperatures still
quite cold (8-10 C).
The following week looks a bit warmer in stages, as the colder air mass
will moderate over Ireland and Britain but there will still be passing
frontal systems bringing some rain and temperatures will only come back
up a few degrees into the 13-15 C range.
Peter for IWO