Weather

[seafoid]

http://www.theguardian.com/environment/2014/feb/03/flooding-threat-severn-thames-riverside-properties#start-of-comments

•   rockyrex
03 February 2014 10:04pm
Recommend
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This whole sequence of storms since the Saint Jude's Day Storm at the end of October is very unusual. Currently they are arriving roughly every 2 to 3 days, with no sign that this will change soon.
Weather systems under-950 hPa are rare but there have been several since Mid-December. The Met Office say: " On Christmas Eve a mean-sea-level pressure of 936 hPa was recorded at Stornoway (Western Isles), the lowest such value at a UK land station for many years."
(The Met Office website says pressures below 950 hPa are rare -
Pressures below 950 hPa have been recorded at UK weather stations about 30 times in the last 200 years:
http://onlinelibrary.wiley.com/doi/10.1002/wea.20/abstract
- this reference (a paper published in 2007) was sent to me by the Met Office in reply to an e-mail I sent them asking about these very low pressures that are appearing recently)
The Met Office website also says for December 2013: "The UK overall received 154% of average rainfall. Two broad areas, one over southern and south-east England and the other extending from the Lake District to Highland Scotland, were much wetter than average with many places receiving twice the normal rainfall for the month"
Some commentators have suggested that there is no evidence of this kind of autumn/winter weather in the UK in any records, even using informal written material from the times before formal meteorology. Of course, someone will tell us that it is all normal, but some evidence for a previous period like this would be useful.
The storm arriving on Wednesday 5/2/2014 is shown on the Met Office website pressure map with a central pressure below 948 hPa. Here we go again.

[seafoid]

The Netherlands is like a mirror image of London across the North Sea. They were battered in 1953.
If nothing is done about climate change the Netherlands is basically fucked.

http://en.wikipedia.org/wiki/North_Sea_flood_of_1953


They have a system called Delta Works.

http://en.wikipedia.org/wiki/Delta_Works

"An important part of this project was fundamental research to help solve the flooding problem. Instead of analysing past floods and building protection sufficient to deal with those, the Delta Works commission pioneered a conceptual framework to use as norm for investment in flood defences.

The framework is called the 'Delta norm'; it includes the following principles:
Major areas to be protected from flooding are identified. These are called "dike ring areas" because they are protected by a ring of primary sea defences.
The cost of flooding is assessed using a statistical model involving damage to property, lost production, and a given amount per human life lost.
For the purpose of this model, a human life is valued at €2.2 million (2008 data).
The chances of a significant flood within the given area are calculated. This is done using data from a purpose-built flood simulation lab, as well as empirical statistical data regarding water wave properties and distribution. Storm behaviour and spring tide distribution are also taken into account.

The most important "dike ring area" is the South Holland coast region. It is home to four million people, most of whom live below normal sea level. The loss of human life in a catastrophic flood here can be very large because there is typically little warning time with North Sea storms. Comprehensive evacuation is not a realistic option for the Holland coastal region.

The commission initially set the acceptable risk for complete failure of every "dike ring" in the country at 1 in 125,000 years. But, it found that the cost of building to this level of protection could not be supported. It set "acceptable" risks by region as follows:
North and South Holland (excluding Wieringermeer): 1 per 10,000 years
Other areas at risk from sea flooding: 1 per 4,000 years
Transition areas between high land and low land: 1 per 2,000 years

River flooding causes less damage than salt water flooding, which causes long-term damage to agricultural lands. Areas at risk from river flooding were assigned a higher acceptable risk. River flooding also has a longer warning time, producing a lower estimated death toll per event.
South Holland at risk from river flooding: 1 per 1,250 years
Other areas at risk from river flooding: 1 per 250 years.

These acceptable risks were enshrined in the Delta Law. "

The problem is that the weather now is changing so fast that 1 per 1250 years could be one per 250 years say by 2024 . Nothing to stop it going to 1 in 50. We don't know.

And the whole flood system then would be in question.   

[muppet]

Weather systems under-950 hPa are rare but there have been several since Mid-December. The Met Office say: " On Christmas Eve a mean-sea-level pressure of 936 hPa was recorded at Stornoway (Western Isles), the lowest such value at a UK land station for many years."

http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0702.html

7-2-5. Low Barometric Pressure

When abnormally low barometric pressure conditions occur (below 28.00), flight operations by aircraft unable to set the actual altimeter setting are not recommended.

http://www.flightpedia.org/convert/28-inches-of-mercury-to-hectopascals.html

28 Inches of Mercury = 948.188283 Hectopascals

Most aircraft altimeter scales only go down to 950 hectopascals.

[seafoid]

#ukstorm This Saturday's stormy seas in the South West are forecast to be much much bigger than today - US Navy pic.twitter.com/cXmwFEkSQv

https://twitter.com/JonHillITV/status/431202848299573248/photo/1

Go bhfoire Dia orainn

[AZOffaly]

I'm supposed to be heading down to Cahirciveen for a birthday party this week. The Mountain Stage between Killorglin and Kells Bay might be interesting.

[Gabriel_Hurl]

Yesterday an hour north of the city

[muppet]

I'm supposed to be heading down to Cahirciveen for a birthday party this week. The Mountain Stage between Killorglin and Kells Bay might be interesting.

You go to interesting birthday parties!

[joemamas]

I'm supposed to be heading down to Cahirciveen for a birthday party this week. The Mountain Stage between Killorglin and Kells Bay might be interesting.

You go to interesting birthday parties!

Dodgy time of year to be hiking or hill climbing

[orangeman]

More storms on the way.


Keep the fire lit and an extra loaf of bread in the house.

[AQMP]

For anyone travelling in the West today, there's heavy snow in Enniskillen at the moment.

[Lazer]

Snowing elsewhere up north too

Newry & Armagh have snow - but not lying yet

[orangeman]

Snow is on.

[Milltown Row2]

Snow is on.

Sunny in East Antrim

[southdown]

Snowing elsewhere up north too

Newry & Armagh have snow - but not lying yet

It's that honest snow.

[armaghniac]

Sunny in East Antrim

Are you sure, I always think of East Antrim as grim.