Bomb Cyclone

  • Storm Dennis has developed into a formidable “bomb cyclone”.

    After Storm Ciara, less than a week ago, Bomb Cyclone Storm Dennis will lead to another dose of power cuts and major travel disruptions in the UK and northern Europe.

    Dennis is now the fourth named windstorm of the season in Europe.

    Dennis is also a Bomb Cyclone after its central pressure dropped 1.38 inches of mercury (46 mb) in 24 hours – from 29.4 to 28.1 inches of mercury (996 mb to 950 mb).

    This incredible drop in pressure is almost two times greater than what is needed to be considered a ‘bombogenesis.’

    And the explosive cyclogenesis seems to continue as the air pressure at the center of the storm is now around 935 mbar. That’s equivalent to a strong Category 3 Hurricane!

    Further strengthening may put Dennis in the running for being one of the most intense North Atlantic storms on record. The top-five most intense storms all recorded a pressure of 27 inches of mercury (925.5 mb) or lower.

    And again such air pressures could wreak havoc air traffic!

    Violent windstorm in Iceland and giant waves

    Tomorrow Iceland is doomed. The North Atlantic cyclone Dennis is about to sweep the island with life-threatening wind gusts of 180-220 km/h (112-137 mph)!

    Giant waves as high as 12-15 meters (40-50 feet) are possible west of the British Isles and south of Ireland as Dennis moves through the region this weekend.

    Such waves will cause coastal flooding and erosion ahead of and through the duration of the storm in western parts of Ireland, Northern Ireland, Scotland and western France, causing amazing sea foam invasion.

    First Ireland and the United Kingdom

    The storm will first hit Ireland and the UK and their major metropolitan areas like London, Manchester, Birmingham and Dublin on Saturday morning.

    The south-southwesterly winds of 80-96 km/h (50-60 mph; strongest over 100 km/h (62 mph)) will sweep cross most of Ireland and the United Kingdom as early as Saturday afternoon and shuld continue through Sunday.

    Consequently, the UK Met Office issued wind yellow warnings for much of the country through the weekend and into Monday for Northern Ireland and Scotland.

    Powercuts, travel chaos…

    After Storm Ciara, less than a week ago, Storm Dennis will lead to another dose of power cuts and major travel disruptions.

    Diverted or cancelled flights into and out of the United Kingdom area are possible due to the strong winds.

    Additional tree damage and subsequent power cuts are likely, even with less potent wind gusts.

    And Northern Europe: Wind and rainfall

    Increasing winds will be noticeable from northern France through Belgium, the Netherlands and Germany to southern Scandinavia late Saturday, but the strongest winds in these areas will likely hold off until Sunday.

    The windward-facing coasts will experience the strongest wind gusts, on the order of 96-112 km/h (60-70 mph).

    In addition to the wind, there will be lots of rain with widespread rainfall amounts of 12-25 mm (0.5-1 inch) forecast from the British Isles and northern France to southern Finland.

    Windy conditions will persist after Storm Dennis. Colder air should also follow the extravagant bomb cyclone, bringing large amount of snow at higher elevations. Get prepared and be ready for this second bombogenesis in a row across Europe….

  • What’s been especially noteworthy about the winter’s weather is the frequency and intensity of the storms spawned in the North Atlantic. Yes, it’s the third extraordinarily intense North Atlantic bomb cyclone in 10 days. And that’s unprecedented!

    This is the peak time of year for bomb cyclones in the North Atlantic due to the insane power of the jet stream and intense air mass differences that tend to move over moisture-rich waters.

    But, what’s been especially noteworthy about the winter’s weather is the frequency and intensity of the storms spawned in the North Atlantic.

    Normally, just a few of extratropical cyclones see their minimum air pressure drop to 930 millibars or lower.

    Yet assuming Storm Dennis does so, this will have happened three times in the past 10 days, just after the low-pressure area that helped propel Storm Ciara into Europe last weekendalso bombed out.

    Energized by an unusually powerful jet stream — a highway of air at about 30,000 feet that is powered by the thermal contrasts between air masses — these weather systems are developing rapidly and reaching extraordinary intensities in a region already known for strong winter storms.

    Winds in the core of the jet stream are forecast to be as strong as 240 mph late Friday, which could lead to another record for the fastest transatlantic flight, first broken Sunday.

    The Arctic Oscillation

    The Arctic Oscillation (AO) is a climate pattern characterized by winds circulating counterclockwise around the Arctic at around 55°N latitude.

    When the AO is ‘positive’, a ring of strong winds circulating around the North Pole acts to confine colder air across polar regions.

    In its negative phase, the AO is weaker and more distorted, allowing southward penetration of colder, arctic airmasses and increased storminess into the mid-latitudes.

    We are currently in a positive state, with a very strong jet stream, low pressure predominating near Greenland and a ridge of high pressure to its south in the northeastern Atlantic.

    That ‘positive’ Arctic Oscillation is one of the main reasons winter has been absent in much of the eastern United States and parts of Europe, and it’s helping to turn the North Atlantic into a virtual bomb cyclone express lane.

    In addition to the deaths and damage from Ciara, the winter’s North Atlantic storms have also affected North America.

    Last month, for example, Newfoundland and Labrador were buried by one of their worst blizzards on record, when a storm underwent rapid intensification and piled snow up to the second and third stories of buildings in downtown St. John’s.

    The next explosive cyclogenesis

    The next bombogenesis has been named Storm Dennis, and computer models as well as meteorologists forecast its air pressure to plummet to between 916 millibars and 924 millibars. This range would qualify it among the top five strongest North Atlantic storms ever observed.

    The strongest North Atlantic cyclone on record was the Braer Storm in 1993, which had a minimum central pressure of 913 millibars. That storm was named after an oil tanker that broke apart during the storms in the Shetland Islands, resulting in a large and damaging oil spill.

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