Wednesday, 10 December 2014

10th December 2014 - On Bombs and Bombogenisis

Thought for the day: "Some native Americans never got lost - apparently they used a Sat Navajo"

Today the weather is a subject of interest again. I know we are British and if in doubt we have to talk of the weather, but in this case there are heavy seas in the North, 50ft waves by all accounts, and 80 mph winds..
And this is all due to what has been termed a WEATHER BOMB.

Weather Bomb !!  Where do they come up with these expressions? I am now 60 years old and have never heard such an expression before. Okay it is a big Storm - I thought we called big storms hurricanes and tornadoes!  Bomb ???

A Met Office "be aware" warning is running for parts of Scotland, England and Northern Ireland.
Parts of western Scotland are braced for strong winds and "unusually high" waves, while there have already been a string of road accidents amid snow and ice.
But with newspapers predicting a UK weather 'bomb' for the second year running, what does the term actually mean?

Best go to Wikopedia for an answer..

"Explosive Cyclogenesis (also referred to as a weather bomb, meteorological bomb, explosive development, or bombogenesis) refers in a strict sense to a rapidly deepening extratropical cyclonic low-pressure area. To enter this category, the central pressure of a depression at 60˚ latitude is typically taken to decrease by 24 mb (hPa) or more in 24 hours. This is a predominantly maritime, cold-season (winter) event, but also occurs in continental settings. They are the extra-tropical equivalent of the tropical rapid deepening."

So... that is better !!!  No ??  okay
So this is a new term that the press have just picked up??

Apparently no !!
In the 1940s and 50s meteorologists at the Bergen School of Meteorology began informally calling some storms "bombs" because they developed with a ferocity rarely, if ever, seen over land. By the 1970s the terms "explosive cyclogenesis" and even "meteorological bombs" were being used ...

Oh !! Okay !

But then all becomes clear. We can blame a usual suspect for this - and in this case it is not the USA..
"The term “weather bomb” is popularly used in New Zealand to describe dramatic and/or destructive weather events. Only very rarely are these events actually instances of explosive cyclogenesis, as the rapid deepening of low pressure areas is a rare event around New Zealand. The “bomb” name may lead to confusion with the more strictly defined meteorological term. "

But apparently, our friends in the USA are not as innocent as they may appear.

The independent tells me ..
"The term ‘weather bomb’ was imported from the US and New Zealand. UK forecasters usually opt for the marginally less terrifying term: “explosive cyclogenesis”."

What’s the difference between a normal storm and a ‘weather bomb’?
When storms quickly intensify and pressure rapidly drops in the centre - by 24millibars in a 24-hour period - this is classed as a weather bomb.  - Okay that is clear!!
So, when dry air from the stratosphere flows into an area of low pressure, air within the depression rises very quickly and increases its rotation - creating vigorous storms.  So we are in for some bad weather.

So, back to the Independant...
A cyclogenesis system is moving far north of the UK and is expected to pass over Ireland as it moves slowly towards Iceland.
Despite the distance, the UK could be hit with a batch of windy, wet ‘bombs’ on Thursday, with snow possible in Scotland, according to ITV News. Potentially damaging strong winds and ferocious waves are expected in northern Scotland tonight into tomorrow.
In the open ocean, some waves could reach up to 18m, but will lose energy towards the shore, according to BBC News.

But - luckily - all is not panic.. 

However, a Met Office spokesperson told The Independent that the forecast will likely change as the weather systems are highly unpredictable.

As I see it ...
If it is not Sunny, then we will possibly have rain or snow, wind or cloud, sleet, frost, cold spells or unseasonal warmth, fog, mist, and the wrong leaves on the line .....

Basically - no change then!!

Glass of 41 ?? Don't mind if I do !

Looked out of the window... turned out nice again in Llanelli .. 

 Picture of the day 
never know when it may come in useful

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