Storm Dennis to bring Heavy Rain, Risk of Flooding - Dundalk Chamber of Commerce

Storm Dennis to bring Heavy Rain, Risk of Flooding


NDFEM Crisis Management Team met this morning following briefings from Met Éireann and OPW on weather conditions for the coming weekend.

Storm Dennis will give rise to very disturbed weather over the weekend. The storm centre will be well to the northwest on Saturday and Saturday night (close to the south of Iceland) coming closest to Ireland later on Sunday as it tracks towards the north of Scotland.

Saturday 15 February

The centre of storm Dennis will be just to the south of Iceland during Saturday but will bring heavy rainfall (30mm – 45mm) countrywide with some potential for high intensity rainfall over short periods. High winds are forecast countrywide. Further spells of heavy rain or showers over Saturday night, with winds easing for a time inland but gales will continue in coastal counties.

The following alerts are issued for Saturday:

Yellow rainfall alert for Ireland: spells of heavy, locally thundery rain, on Saturday will lead to some flooding; valid from 06:00 – 21:00 Saturday 15 February.

Yellow wind alert for Ireland: Very squally southerly winds veering southwesterly with mean speeds 50 to 65 km/hr gusts to around 100 km/hr, strongest on exposed coasts and hills. Winds moderating from the northwest later; valid from 03:00 – 20:00 Saturday 15 February.

Sunday 16 February

Storm Dennis will track closer to Ireland as it heads towards the north of Scotland. Extremely windy and very showery on Sunday with stormy conditions in Atlantic coastal counties, especially northwestern counties. Widespread heavy rain ( 30mm – 40mm) and hail showers with thundery downpours at times, but drier and brighter in parts of the east and south. Cold with afternoon temperatures of 4 to 8 degrees Celsius with a very significant wind chill factor. Showers and extremely windy conditions for a time on Sunday night.

Costal Conditions

OPW have issued a High Tide Advisory for the weekend.

A period of very high storm surge is associated with Storm Dennis which may result in sea levels approaching or exceeding Highest Astronomical Tide (HAT) in the coastal areas shown below from tomorrow afternoon, Saturday 15 until Monday morning 17 February 2020.

Whilst storm surge levels are currently relatively low in all coastal areas, they are predicted to increase significantly as follows, from tomorrow morning until Monday morning, in the coastal areas shown below:

  • 1.00m at Lough Swilly
  • 0.80m at Donegal Bay
  • 0.70m at Sligo
  • 0.65m at Killala
  • 0.70m at Clew Bay
  • 0.55m at Roundstone
  • 0.80m at Galway Bay
  • 0.55m at Shannon Estuary
  • 0.70m at Arklow
  • 0.75m at Wicklow
  • 0.80m at Dublin Bay
  • 0.80m at Drogheda
  • 0.80m at Dundalk Bay

As these forecasts of storm surge may change, OPW advise all local authorities to monitor surge and sea level forecasts closely throughout this notice period (from Saturday 15 to Monday 17 February).

River Levels

River levels are high throughout the country but most gauges indicate that levels are receding. Given the cumulative rainfall from Storm Ciara and Storm Dennis, the risk of river flooding is high. Local authorities are requested to monitor levels in all catchments. Latest EFAS model runs do not indicate significant flooding but the EFAS model is not calibrated to smaller fast flowing rivers.

NDFEM request that all local authority Severe Weather Assessment Teams monitor weather conditions throughout the weekend and consider activating crisis management and Local Co-ordination arrangements, if required.

NDFEM will continue to monitor weather conditions throughout the weekend with Met Éireann and OPW. We would request that you would contact us should any significant flooding incidents occur in your area over the weekend.