The severe storm this weekend and why it’s not a hurricane

26 10 2013

There is much coverage of the storm heading our way later this weekend with mentions of it being a ‘hurricane’. This is not strictly correct as we don’t get hurricanes in the UK and this is why.

Hurricanes are warm latitude storms; they draw their energy from warm seas and can only begin to form where the ocean is warmer than 26 degrees Celsius or so, and can really only become a major storm when the sea is warmer than 28 degrees Celsius. That’s like a warm bath, so you won’t find one around the UK anytime soon!

Other limitations, like wind patterns in the upper atmosphere and the forces caused by the Earth’s rotation, mean hurricanes are normally found in an area between 8 and 20 degrees north of the equator.

You can find a full explanation of what hurricanes are and how they form on our What are hurricanes? video

The storm which is due to develop tomorrow night and affect the UK during Monday is a mid latitude storm, the sort which affect us through the autumn and winter. These are formed in a very different way – by the meeting of different air masses on what is known as the polar front, leading to low pressure (storms) forming, often around the latitude of the UK.

The storm which is due tomorrow is expected to bring very strong winds and heavy rain, and we are warning of winds gusting 60-80 mph quite widely and locally over 80 mph, especially on exposed coasts, both in the southwesterly winds ahead of the low centre and west to northwesterly winds behind it.

Winds of that strength are classified on the Beaufort scale as ‘hurricane force 12’ but that is not the same as being a hurricane. Winds of this strength could bring down trees or cause structural damage, potentially causing transport disruption or power cuts and we are working closely with the resilience community to ensure they are prepared for the expected conditions.

You can find practical advice about what to do in winter weather on our Get Ready for Winter website.


Actions

Information

9 responses

26 10 2013
Andy Jones

Just wanted to say that this blog’s a pleasure to read. Clear-headed and informative. Good work!

26 10 2013
Anthony Cohen

Whether you call it a hurricane or not is academic- The effects of 80mph+ winds on the public are exactly the same whatever you call it. The information provided in the “Get ready for Winter” website and your infographic on Severe Wind are extremely lacking in providing practical guidance for the public. I am quite sure that safety for people and property could be improved considerably with better information. I look forward to your reply and hope that even within the next 12 hours or so, you take my comments seriously and improve the information to the public through the media and on the relevant websites.

This is an extract from the North American guidance notes from the Weather Underground Website:

Hurricane and Typhoon Preparedness Checklist

Build an emergency kit and make a family communications plan
Know your surroundings
Learn the elevation level of your property and whether the land is flood-prone, which will help you know how your property will be affected when storm surge or tidal flooding are forecasted
Identify levees and dams in your area and determine whether they pose a hazard to you
Learn community hurricane evacuation routes and how to find higher ground
Determine where you would go and how you would get there if you needed to evacuate
Make plans to secure your property:
Cover all of your home’s windows with permanent storm shutters or 5/8 inch marine plywood, cut to fit and ready to install (tape does not prevent windows from breaking!)
Install straps or additional clips to securely fasten your roof to the frame structure
Be sure trees and shrubs around your home are well trimmed so they are more wind resistant
Clear loose and clogged rain gutters and downspouts
Reinforce your garage doors; if wind enters a garage it can cause dangerous and expensive structural damage
Plan to bring in all outdoor furniture, decorations, garbage cans and anything else that is not tied down
Determine how and where to secure your boat
Install a generator for power outages
If in a high-rise building, be prepared to take shelter on or below the 10th floor
Consider building a safe room
During a Hurricane or Typhoon

Listen to the radio or TV for information, and keep your weather radio handy
Secure your home, close storm shutters and secure outdoor objects or bring them indoors
Turn off utilities if instructed to do so. Otherwise, turn the refrigerator thermostat to its coldest setting and keep its doors closed
Turn off propane tanks
Avoid using the phone, except for serious emergencies.
Moor your boat if time permits.
Ensure a supply of water for sanitary purpose such as cleaning and flushing toilets: fill the bathtub and other larger containers with water
Find out how to keep food safe during and after and emergency
You should evacuate under the following conditions:

If you are directed by local authorities to do so, and be sure to follow their instructions
If you live in a mobile home or temporary structure—such shelter are particularly hazardous during hurricane no matter how well fastened to the ground
If you live in a high-rise building—hurricane winds are stronger at higher elevations
If you live on the coast, on a floodplain, near a river, or on an island waterway
Read more about evacuating yourself and your family. If you are unable to evacuate, go to your wind-safe room. If you do not have one, follow these guidelines:

Stay indoors during the hurricane and away from windows and glass doors
Close all interior doors, secure and brace external door.
Keep curtains and blinds closed. Do not be fooled if there is a lull; it could be the eye of the storm, and winds will pick up again
Take refuge in a small interior room, closet or hallway on the lowest level
Lie on the floor under a table or another sturdy object
Avoid elevators.

27 10 2013
Dave Britton

Tony
You make some valid points about being prepared and taking precautions to protect ourselves, family and property, which we should all do in this case. Fortunately we do not experience storms of the strength of the hurricanes and tornadoes which affect the USA.
It is important to remember, however, that the winds in hurricanes and tornadoes are much stronger than those we are forecasting for southern Britain overnight and tomorrow morning. For example a hurricane is classified as category one when the sustained, constant wind speed is 74-95mph – tonight we are expecting short gusts of 60-80mph.
Helen

28 10 2013
John Benton

Anthony it sounds as if you don’t live in the UK. While there are some comments in your long post which are simply common sense precautions that anyone would take, you are coming over as a tad alarmist and overenthusiastic given the weather conditions experienced in the UK.

26 10 2013
bloggulator

Finally some balance, with some scientifically based sense to counter the much over-sensationalised hype and fear-mongering by the corporate media. Well said, UKMO.

26 10 2013
Michaela Williams

Agreed :)

27 10 2013
Jane Campbell Powell

Semantics! Semantics! I wanted to see satellite pictures of the approching weather, not too worried if i it’s a storm, St Jude or a hurricane as I am in a caravan with the awning up. Dad tightened the guy ropes and checked the tent pegs over the w/e. . There are various heavy objects holding the groundsheet down (for example a sewing machine circa 1970 and six ‘underbed storage boxes’, 3 of which have lids that ‘somehow’ ‘click-to’ which increases their security in windy weather) so it is more the practicalities I was interested in . . . like should I take the awning down (shame because it has been such nice weather lately (i was sun-bathing only a week ago! – in the awning – ) as you were saying :) or leave it up and rely on the heavy objects? there’a nice book-case (one of two) made from the wood of the old houses of parliament – the rare bits that didnt burn
or option 3 get the hell out of here?

27 10 2013
Dave Britton

Hello Jane
It’s not for me to suggest what you should be doing, however I would recommend following the advice of the authorities in the area you are staying.
Helen

27 10 2013
Clive Dumper

Please stop using degrees Celcius. They are the international (except USA : -) unit of temperature and there should be no degrees involved.

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s




Follow

Get every new post delivered to your Inbox.

Join 5,823 other followers

%d bloggers like this: