A review of winter 2015/2016 in Ireland

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  • The daily NAO index for the past 120 days. Each daily value has been standardized by the standard deviation of the monthly NAO index from 1950 to 2000 interpolated to the day in question. CREDIT: NOAA/ National Weather Service.

    A strong El Niño may have contributed to the synoptic that led to the exceptionally wet and mild winter in Ireland. Ocean conditions in 2015 bear some similarities to the powerful 1997 El Niño. This NASA visualization shows side-by-side comparisons of Pacific Ocean sea surface height anomalies measured by satellites in 1997 and 2015. CREDIT:NASA

  • A review of winter 2015/2016 in Ireland
    05.03.2016 15:06

    ‘Mild, wet and windy’ is an expression all Irish people are familiar with from TV and radio weather broadcasts. However, winter 2015/2016 really took this term to the limit.

     Weather data just released has indicated the winter was the wettest on record in over half of the meteorological stations in the Republic of Ireland. Mean surface air temperatures were around 1C above the long term average (LTA) whilst six named Atlantic storms brought frequent episodes of gale force winds.

    Temperature

    Frequent incursions of tropical maritime air led to surface temperatures being warmer than average in all synoptic stations. Eastern areas of the country had the mildest temperatures, with the winter temperature at Phoenix Park, Co Dublin exceeding its LTA by 1.5C, its warmest winter since 1998. Temperature deviations in western fringes were somewhat less pronounced with Markree in Co. Sligo only recording a +0.1C deviation from the long term mean. The winter lacked any significant cold spell with the coldest temperature of the season just minus 5.9C in Mullingar, Co. Westmeath.

    Wind

    The introduction of the naming of Atlantic storms by UK and Irish weather institutions coincided with a particularly stormy winter. Six named storms impacted Ireland during the 3 month winter period. Desmond (Dec 4th and 5th), Eva (Dec 23rd), Frank (Dec 29th and 30th), Gertrude (Jan 29th), Henry (Feb 1st) and Imogen (Feb 7th and 8th). However, there was no extremely notable wind gust reported, with the season’s highest gust of 73 knots at Belmullet on December 23rd not exceptional for an exposed coastal station in the west of Ireland.

    Rain

    The most noteworthy statistic from the released data is the record breaking rainfall totals that were recorded. With the polar front frequently lying across Ireland there were spells of incessant rainfall, particularly in the south and west. Over half of the synoptic stations in the Republic of Ireland reported their wettest winter on record.  Malin Head on the north coast of Co. Donegal recorded its wettest winter since 1885 with a seasonal accumulation of 567mm, 173% of its LTA rainfall. The greatest deviation from the LTA occurred at Roches Point in Co. Cork where the rainfall total was 248% of the LTA.

    A strongly positive North Atlantic Oscillation (NAO) led to a mild, windy and exceptionally wet winter in Ireland. The closest comparison in recent history would be the winter of 1998 which was also dominated by a strong zonal flow across the north Atlantic. No region escaped the incessant rainfall with all stations recording rainfall totals significantly greater than their long term average.

    By: Matthew Martin