Storm Brings Near Record Low Pressure to the U.K.

By: Christopher C. Burt , 8:58 PM GMT on December 26, 2013

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Storm Brings Near Record Low Pressure to the U.K.

An intense extra-tropical North Atlantic storm passed over northern Scotland on December 24th causing the pressure to fall to 936.8 mb (27.66”) at Stronoway around 1 p.m. local time Christmas Eve Day. This was the 3rd lowest pressure ever observed at a land site in the British Isles (next to a 927 mb/27.37” reading at Belfast, Ireland on December 8, 1886 and 925.6 mb/27.33" at Ochtertyre, near Crieff in central Scotland on 26 January 1884).



Barometric readings plotted for Stornoway during the recent storm event. Graphic courtesy of Stephen Burt.



Enormous wind-blown surf pounds the Cornish village of Mousehole on December 24th. Photo by Stan Miles.

The intense storm brought a long period of high winds and heavy rain to all of England and Scotland causing significant flooding and damage to many regions. At least two fatalities have so far been attributed to the storm. Over 1000 homes were flooded in southeastern England where the heaviest rain fell, up to 70 mm (2.75”) in South London on December 23rd. Surprisingly, given the strength of the low pressure system, wind gusts were not all that impressive:

Peak wind gusts at low elevation sites observed (as so far reported to the U.K. Met Office):

92 mph at Needles Old Battery, Isle of Wight

84 mph at Berry Head, Devon

76 mph at Langdon Bay, Kent

75 mph at Gorleston, Norfolk

75 mph at Manston, Kent

75 mph at Mumbles Head, West Glamorgan

75 mph at South Uist Range, Western Isles

Wind gusts of this magnitude are not uncommon for strong winter storms in the U.K., nor have the rainfall totals been that exceptional. However, the heavy and widespread rainfall followed what have been a wet past two weeks, hence the flooding.



A flooded neighborhood in South London Christmas Day. Photographer not identified, image from BBC.

What HAS been exceptional is the low-pressure readings. At its strongest, the storm bottomed out at 927 mb at noon GMT on December 24th just northeast of Scotland according to the U.K. Met Office.



Synoptic analysis for 12 UTC on December 24th. Map courtesy of the U.K. Met office and Crown Copyrighted.



A satellite/radar composite image for 6:15 UTC, December 24th. One can see the heavy rain bands over southeastern England that caused the flooding in that region. Image courtesy of the U.K. Met office and Crown Copyrighted.

The 936.8 mb observation would make this the 3rd lowest pressure reading ever observed on land in the British Isles and the 5th lowest observed in the North Atlantic according to climatologist and weather historian Stephen Burt (see references at end of blog). The lowest pressure ever measured in the U.K. was (as I mentioned in the opening paragraph) 925.6 mb/27.33" at Ochtertyre, near Crieff in central Scotland on 26 January 1884). The North Atlantic lowest was 912-915 mb (26.93”-27.02”) during a storm southeast of Iceland on January 10, 1993 (for details about extreme low pressure events in the North Atlantic see the article on this subject written by Stephen Burt referenced below).

It is interesting to note the influence of the recent storm event in the U.S. (designated Gemini by The Weather Channel) on the U.K. storm. One can see how the exceptional moisture plume that resulted in the phenomenal rainfalls in the eastern and midwestern U.S. last weekend were entrained into the North Atlantic low-pressure system and resulted in the heavy rainfall over southeast England.



A rainbow satellite image of the moisture from winter storm Gemini (just exiting the U.S.) flowing across the Atlantic and entraining into the storm over the North Atlantic. NOAA

Meanwhile, it would appear another series of powerful storms will lash the British Isles today (December 26th) and through the weekend.

KUDOS: Stephen Burt (no relation of mine) for keeping me posted on the storm’s progress and for forwarding some of the above graphics. Stephen has also written a very informative article concerning extreme cyclones to have affected the British Isles in the past, which can be found in the journal Weather Vol. 62 No. 1 January, 2007 pp. 4-14: 'The Lowest of the Lows’. Also note these other aricles on the subject by Stephen:

Burt SD. 1983. New UK 20th century low pressure extreme. Weather, 38: pp 208–213

Burt SD. 1987. A new North Atlantic low pressure record. Weather, 42: 53–56.

Burt SD. 1993. Another new North Atlantic low pressure record. Weather, 48: 98–103.


Christopher C. Burt
Weather Historian

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4. WunderAlertBot (Admin)
8:32 PM GMT on December 30, 2013
weatherhistorian has created a new entry.
3. blairtrewin
10:11 AM GMT on December 27, 2013
One of the things which struck me about this system was that its pressure gradient (on its southern side, anyway) was very even, so there was no particular zone with extremely tight gradients (and hence extremely high winds).
Member Since: October 25, 2010 Posts: 0 Comments: 27
2. Engxladso
11:51 PM GMT on December 26, 2013
Thanks Christopher.

I saw a BBC meteorologist explain that the depth of the low pressure was proportional to the very fast speeds of the jet stream over the Atlantic at the time because the jet stream was 'sucking' air away from the surface quicker than it could be replaced. He further explained that these speeds were caused by the large temperature contrasts between the cold Canadian air and warm air over the Eastern seaboard when NY was at 21C and Quebec at -7C last Sunday.

As a layman, this was the most easily understandable explanation I have ever heard as to why low pressure areas form along frontal boundaries.
Member Since: November 18, 2012 Posts: 0 Comments: 6
1. barbamz
9:05 PM GMT on December 26, 2013
Thanks a lot, Christopher. Earlier, I've saved the record jet stream values which might have influenced this system (?):




Source.
Member Since: October 25, 2008 Posts: 43 Comments: 5020

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About weatherhistorian

Christopher C. Burt is the author of 'Extreme Weather; A Guide and Record Book'. He studied meteorology at the Univ. of Wisconsin-Madison.