Wettest November on record brings widespread flooding; mild and windy

MetEireann

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Atlantic depressions passing close to Ireland brought wet and windy conditions throughout almost all of November, continuing a pattern of very unsettled weather over Ireland since mid-October. Persistent and often heavy rain over this period led to unprecedented levels of flooding in parts of the west and south, as ground conditions became saturated. Rainfall totals for November were the highest on record at most stations, including the long-term stations at Malin Head and Valentia Observatory, where records extend back over 100 years.

Valentia’s total of 360mm was its highest of any month since observations began in the area in 1866, while its previous highest annual total of 1923mm in 2002 was also exceeded during the last week of this month, reflecting the persistence of wet weather throughout the year. More than twice the average November amounts were measured at almost all stations and close to three times the normal amount fell in some places. Rain or showers were recorded on almost every day, with between 22 and 27 wetdays observed (days with 1mm or more rainfall), compared with the normal range for November of between 13 and 20 wetdays. Heaviest daily falls at most stations were recorded on the 1st, in the period 16th to 19th, and on the 29th in the east; two-day falls of over 100mm were recorded in parts of the west and southwest on the 18th/19th.

Much of November was mild with little or no frost, but temperatures fell considerably towards the end of the month. Overall, mean air temperatures for the month were close to a degree higher than normal generally. Air and ground frost became widespread at the end of the month, but the total of between seven and 12 ground frosts at inland stations was below normal for November. Despite the very wet weather, sunshine totals were above normal generally, especially in the north.

1st to 26th: A series of fast-moving deep Atlantic depressions brought active frontal systems across Ireland, bringing very wet and windy conditions. Spells of rain or showers gave falls of 10mm or more on many days across Connacht and Munster, while all areas received heavy falls on the 1st, 9th, in the period 16th to 19th and on the 21st. River levels reached record high levels in many parts of the midlands, west and south, leading to significant flooding. The strong south to southwesterly winds for most of the period brought mild conditions, although slacker winds and clear skies allowed frost to form in midland and eastern areas between the 8th and 11th. A depression of central pressure 954hPa off the west coast on the 21st/22nd generated storm conditions, with very high seas.

27th to 30th: Low pressure became centred to the east of Ireland, bringing a cold northerly airstream across the country. Showers in western areas died out, but a spell of heavy rain in eastern areas brought flooding here on the 29th. Both maximum and minimum temperatures were below normal, with frost becoming widespread.

Wind and elements: Mean windspeeds for the month of between 10 and 16 knots generally (19 and 30km/h) were above normal everywhere and were the highest for November for over 20 years in the south and southwest. The month’s strongest winds were recorded between the 18th and 25th, with the highest gust of 72 knots (133km/h) measured at Belmullet on the 22nd. Isolated thunderstorms were frequent during the month, especially in western and southwestern areas; they were widespread along the Atlantic coast in the periods 6th/7th and 21st/22nd. A tornado was observed at Ballymahon, Co. Longford, on the 12th. Hail showers were recorded on many days in western and northern areas, especially on the 25th/26th. Fog was most widespread on the 28th.

The rest of this report is here

Deep Easterly

Thanks M.E. An interesting account of what was an interesting month.

Local stats recorded on Davis V2 and set against the 61-90 mean for North Galway:

Mean Max: 10.2c (0.0c) Absolute: 13.6c at 10.15pm on the 18th)
Mean Min: 4.2c (+1.3c) Absolute: (-1.6c at 7.10am on the 28th)
Overall Mean: 7.4c (+0.7c)

Total Rainfall: 292.3mm
Minus accumulation from fog + dew etc = 290.4mm
Wettest Day: (0000hrs to 0000hrs) 32.3mm on the 19th.
High hourly total: 10.4mm on the 21st.
High rain rate: 136.9mm on the 21st.
Days with > 0.2mm = 28.
Days with > 2.0mm = 21.
Days with > 20.0mm = 5.

Thunder Days: 1 (21st)
Hail days: 5
Air frost days: 5

Chart tracking daily maxima & minima for November:

Mothman

Wet in the east though here not as wet as November 2002, though shift the month a few hours earlier makes a huge difference!!
Nov 09 216.2mm 2nd wettest month in my 10 years of records
Nov 02 225.5mm
The above is 09-09z stats which is the standard met day.

The 00-00z stats are
Nov 09 251.1mm
Nov 02 222.9mm

34.9mm fell during 00-09c on 1st Nov 09. This fall was attributed to 31st Oct!

Also there was rain in the early hours of Dec 1st 2002 that was attributed to 30th Nov 02.
I keep a rolling 31day total and and this record was broken on 29th Nov with 265mm beating 249.1mm on 8th Nov 2005