http://youtu.be/iSAfzWVc6mc
(YouTube: Helen Carroll)
THIS WEEK 50 years ago, Dubliners experienced the most violent thunderstorms to hit the city during the 20th century.
On 11 June 1963, considerable flooding occurred in the area between Dundrum, Blackrock and Sandymount (as the above video shows). There were no official warnings about the severity of rainfall at the time, with forecasts predicting just “scattered outbreaks of thundery rain”.
Met Éireann marked the anniversary with an experiment to examine if its services have improved over the past five decades.
In article posted online, the agency noted, “Given that there were no computer forecast models available at the time (and no radar or satellite data), the forecast was not wildly inaccurate but it did fail to warn of exceptional rainfall.”
Nonetheless, research staff wanted to see if they would do things differently today. They re-ran the forecast for 11 June 1963 using their current system called Harmonie. It predicted a total of about 30mm of rainfall over the Dublin area but in other parts of the country, the totals exceeded 90mm.
The meteorologists explain why:
Given the random nature of thundery showers it is not too surprising that the exact details were not captured. Even higher resolution models (Harmonie currently runs on a 2.5km grid) might give a better deterministic forecast but running many forecasts – an ensemble of forecasts – from slightly differing initial states might be a better strategy to address the randomness of these events.
If this forecast had been available 50 years ago, the forecaster might have emphasised the risks of torrential downpours in thundery showers. Today, such a forecast would lead to a weather alert for the local authorities regarding the possibility of significant local flooding.
According to eye-witness accounts, the rainfall on the days of the flooding was intense. At Mount Merrion, at least 75mm of rain fell in 60 minutes.
A 24-hour total of 97.8mm was recorded at Ballsbridge but other location probably saw even more rain.
Following a public appeal for additional information, several individuals came forward with amateur observations based on the rainfall collected in garden buckets during the storm. Met Éireann said that although it is impossible to verify the accuracy of these measurements, the general consistency of the data within the area suggested that local rainfall totals probably exceeded 150mm.
So, basically, it could be worse for us today.
To embed this post, copy the code below on your site
have your say