Ophelia, strongest eastern Atlantic hurricane on record, roars toward Ireland

NOAA satellite picture

From Washington Post by Jason

On Saturday, Hurricane Ophelia accomplished the unthinkable, attaining Category 3 strength farther east than any storm in recorded history.
Racing north into colder waters, the storm has since weakened to Category 1, but it is set to hammer Ireland and the northern United Kingdom with damaging winds and torrential rain on Monday as a former hurricane.

 Wind wave height (until 13-14 meters forecasting) on Ventusky
see also CEFAS WaveNet interactive map
or Irish weather buoy network (IMOS) for live observations

The Irish Times reported that the storm could be the strongest to hit Ireland in 50 years.
The Daily Mail reported that the UK Met Office had compared the storm to Hurricane Katia, the tail end of which struck the region in 2011.

(National Hurricane Center)

The storm, about 700 miles south-southwest of Ireland’s southern tip and packing 90 mph winds, is jetting to the northeast at 38 mph.
As it heads north, it is forecast to weaken further and morph into what’s known as a post-tropical storm by Sunday night.

It is passing over progressively colder water, which is stripping the storm of its tropical characteristics.
However, even as these cold waters cause the eye of the hurricane and its inner core to collapse, its field of damaging winds will expand and cover more territory — even if it doesn’t pack quite the same punch near its center.

Percent likelihood of at least tropical storm-force winds over Ireland and the United Kingdom. (National Hurricane Center)

Maximum sustained winds of at least 70 mph are projected by the time Ophelia reaches Ireland, and the National Hurricane Center forecast shows almost the entirety of Ireland guaranteed to witness tropical-storm force winds of over 39 mph.
Hurricane force gusts of up to 80 mph are possible.

“This will be a significant weather event for Ireland with potentially high impacts — structural damage and flooding (particularly coastal) — and people are advised to take extreme care,” the Irish Meteorological Service said.
It issued a “red warning,” its highest-level storm alert for the southern and coastal areas.

GFS model projects wind gusts near 80 mph over southwest Ireland early Monday. (WeatherBell.com)

The UK Met Office issued an “amber wind warning” for northern Ireland, the second-highest alert, where it is predicting wind gusts up to 70-80 mph, and released the following statement:

A spell of very windy weather is expected on Monday in association with ex-Ophelia. Longer journey times and cancellations are likely, as road, rail, air and ferry services may be affected as well as some bridge closures.
There is a good chance that power cuts may occur, with the potential to affect other services, such as mobile phone coverage.
Flying debris is likely, such as tiles blown from roofs, as well as large waves around coastal districts with beach material being thrown onto coastal roads, sea fronts and properties.
This leads to the potential for injuries and danger to life.

Parts of southern and central Scotland and northern England also may face a hazardous combination of tropical storm-force winds and heavy rain.
Because the storm is moving so fast, its powerful blow will be brief, the worst lasting six to 12 hours in most locations.
It will leave the British Isles by Tuesday morning.

On Sunday, ahead of the storm, strong southerly winds were drawing abnormally warm conditions into the British Isles, with high temperatures up to 77 degrees (25 Celsius) forecast.
The Daily Mail reported that “swarms of deadly jellyfish” (actually, Portuguese man o’ war) had washed ashore on southern beaches.

Ophelia’s place in history

Ophelia near peak intensity Saturday. (NOAA)

When Ophelia became a major — Category 3 (or higher) — hurricane Saturday, it marked the sixth such storm to form in the Atlantic this year, tied with 1933, 1961, 1964 and 2004 for the most through Oct. 14, according to Phil Klotzbach, tropical weather researcher at Colorado State University.

 A singular trajectory

The storm is most remarkable, however, for where it reached such strength — becoming the first storm to reach Category 3 strength so far east.

This figure really says it all. #Ophelia is a huge outlier from the typical envelope of major hurricane tracks in the Atlantic

— Sam Lillo (@splillo) October 14, 2017

Much-above-normal water temperatures and light upper-level winds helped the storm reach such unusual intensity so far north and east in the Atlantic Ocean.

 Sea surface temperature difference from normal over Atlantic waters which Ophelia traversed. (NOAA)

While having a major hurricane so far east in the Atlantic Ocean is rare, it is not particularly unusual for former tropical weather systems to slam into Ireland and the United Kingdom.
As we wrote Friday, this happens about once every several years, on average, conservatively.

Links :

• WashingtonPost : Ophelia may slam Ireland, Britain as an ex-hurricane, but this isn’t as rare as you might think
• NYTimes : Ireland and Britain Brace for Unusual European Hurricane  / 10 Hurricanes in 10 Weeks: With Ophelia, a 124-Year-Old Record is Matched
• CNN : Hurricane Ophelia heading to Ireland, then Scotland
• Mashable : 'Red' alert in Ireland as ex-hurricane Ophelia roars ashore with destructive winds 
• Weather Underground : Ophelia Hits Category 3; Destructive Winds On Tap for Ireland
• Irish Times : Why is Hurricane Ophelia so powerful and why is it heading for Ireland? 

Norway NHS layer update in the GeoGarage platform

136 nautical raster charts updated

see GeoGarage news

Des lois et des hommes : A turning tide in the life of man

On the Irish island of Inishboffin, we are fishermen from father to son.

So, when a new European Union regulation deprives John O' Brien of his ancestral way of life, he takes the lead in a crusade to assert the simple right of indigenous people to live off their traditional resources.

www.desloisetdeshommes.com

Joining together NGOs, fishermen from all over Europe and ordinary citizens, John braved industrial lobbies for 8 years and proved, from the Donegal coast to the corridors of Brussels, that another Europe is possible.  

Links :

• Vimeo : Extract  I / II / III / IV
  

Yvan Bourgnon : from Alaska to Greenland on a beach catamaran

1st North-West passage solo sailing on a beach catamaran

Hidden ice canyons in the making

ESA’s CryoSat and the Copernicus Sentinel-1 missions have been used to measure subtle changes in the elevation and flow of ice shelves that, in turn, reveals how huge canyons are forming underneath. Warm bottom ocean water is entering the cavity under Antarctica’s Dotson ice shelf and is stirred by Earth’s rotation.

This is causing one side of the ice shelf to melt.

The canyon, which has formed over 25 years, is now 200 m deep in places and the ice just above it is heavily crevassed, affecting the shelf’s future ability to buttress the ice on land. 

From ESA 

We are all aware that Antarctica’s ice shelves are thinning, but recently scientists have also discovered huge canyons cutting through the underbelly of these shelves, potentially making them even more fragile. Thanks to the CryoSat and Sentinel-1 missions, new light is being shed on this hidden world.

Antarctica is surrounded by ice shelves, which are thick bands of ice that extend from the ice sheet and float on the coastal waters.
They play an important role in buttressing the ice sheet on land, effectively slowing the sheet’s flow as it creeps seaward.

 Some fast-thinning glaciers drain into the Amundsen Sea

(Pine island, Twaites, Haynes & Pope, Smith, Kohler and Dotson Ice shelf in the Admunden Sea)

with the GeoGarage platform (NGA chart)

The ice sheet that covers Antarctica is, by its very nature, dynamic and constantly on the move. Recently, however, there has been a worrying number of reports about its floating shelves thinning and even collapsing, allowing the grounded ice inland to flow faster to the ocean and add to sea-level rise.

While scientists continue to study the changing face of Antarctica, monitor cracks in the surface of the ice that might signal the demise of a shelf and learn how these changes are affecting the biology of coastal waters, they are also aware of dramatic changes taking place below the surface, hidden from view.

Ice shelf appears flat

There are huge inverted canyons in the underside of ice shelves, but little is known about how they form and how they affect the stability of the ice sheet.

One type is thought to be caused by subglacial water that drains from beneath the ice sheet and runs into the ocean.
In this region, the ocean water is stratified, with the warmer water at the bottom.
However, as the colder meltwater pours down into the ocean it then rises because it is less dense than the seawater – but as it rises it drags up the warm bottom water which causes the underbelly of the floating ice shelf to melt.

Another type is thought to be caused by the way ocean water circulates under the shelf.
Scientists have been using ESA’s CryoSat to study changes in the surface of the ice shelf and the Copernicus Sentinel-1 mission to study how shelves flow to learn more about what’s going on hidden from view.
Their focus has been on the Dotson ice shelf in West Antarctica.

 Dotson ice shelf from Sentinel-1

Noel Gourmelen from the University of Edinburgh said “We have found subtle changes in both surface elevation data from CryoSat and ice velocity from Sentinel-1 which shows that melting is not uniform, but has centred on a 5 km-wide channel that runs 60 km along the underside of the shelf.

“Unlike most recent observations, we think that the channel under Dotson is eroded by warm water, about 1°C, as it circulates under the shelf, stirred clockwise and upward by Earth’s rotation.
“Revisiting older satellite data, we think that this melt pattern has been taking place for at least the entire 25 years that Earth observation satellites have been recording changes in Antarctica.
“Over time, the melt has calved in a broad channel-like feature up to 200 m deep and 15 km across that runs the entire length of the underside of Dotson ice shelf.
“We can see that this canyon is deepening by about 7 m a year and that the ice above is heavily crevassed.

A figure showing Dotson Ice Shelf and the Amundsen Sea Sector of West Antarctica.

Colors show ice flow of grounded ice across the grounding line (white line) feeding floating ice shelves (DIS and Crosson Ice Shelf (CIS)), as well as ocean regions of high annual primary productivity (APP) (Arrigo et al., 2015).

(Image credit: Noel Gourmelen)

“Melt from Dotson ice shelf results in 40 billion tonnes of freshwater being poured into the Southern Ocean every year, and this canyon alone is responsible for the release of four billion tonnes – a significant proportion.
”The strength of an ice shelf depends on how thick it is. Since shelves are already suffering from thinning, these deepening canyons mean that fractures are likely to develop and the grounded ice upstream will flow faster than would be the case otherwise.
“It is the first time that we’ve been able to see this process in the making and we will now expand our area of interest to the shelves all around Antarctica to see how they are responding. We couldn’t do this without CryoSat and the European Commission’s Copernicus Sentinel missions,” added Dr Gourmelen.

Links :

• Washington Post : Worrying new research finds that the ocean is cutting through a key Antarctic ice shelf
• BBC : Satellites spy Antarctic 'upside-down ice canyon'