Storm Angus

The first named winter storm came with strong warnings, of high winds and heavy rain overnight on Saturday into Sunday. Although it was breezy we did not see particularly high winds here, but the system was notable for its very low pressure (a new record for this location) and for a great deal of rain (a new record for 24 hour rain in this location).

The wind peaked around 2am Sunday morning with gusts of 34.8 knots and an average of 13 knots (which is Beaufort force 4 or a “moderate breeze”: enough to lift small pieces of paper or leaves)

wind speed graph

 

There was a clear change in wind direction, from SE to W and then SW just a little after the strongest winds, as the depression moved through. The wind fell briefly to calm as this happened. This, with the pressure trace, suggests that the centre of the depression passed straight over us.

change in wind direction

The major feature of this system was rain. We had 43.8mm in the day (9am – 9am) which is 1.73 inches and a new record for this weather station. The peak rain rate was only 21mm/hr with just over 8mm in the heaviest hour. We had heavy, rather than torrential, rain for many hours, as the graph shows.

rainfall graph

 

There was a new record low pressure here of 969.62hPa — 28.63 in — and a sharp fall and then rise in pressure as the deep depression passed through quickly.

Pressure graph

 

The system was a classic “bomb” depression. It formed and deepened quickly, then passed quickly along the English Channel and across the SE of England. This was driven by an active jet stream. Such systems are fairly common at this time of year.

September Weather

Monthly Climatological Summary for Sep 2016

Elevation: 60 m Lat: N 51 10 32 Lon: W 000 09 41

Temperature (°C), Rain (mm), Wind Speed (kts)

 Day Mean Temp High Temp  Time  Low Temp  Time Heat Deg Days Cool Deg Days Rain Ave wind speed High Wind  Time Dom Dir
01 16.9 24.4 16:23 10.7 06:18 2.6 1.2 0.0 1.2 13.9 17:51 SSW
02 16.2 19.7 13:07 13.3 04:25 2.2 0.2 2.4 1.4 19.1 17:47  S
03 16.1 20.5 15:19 10.4 07:00 2.4 0.2 4.4 4.1 24.3 16:14  S
04 17.5 19.7 14:59 14.8 06:29 1.0 0.2 1.2 1.2 20.9 01:14  SW
05 17.9 22.8 18:20 13.9 07:26 1.6 1.2 6.0 0.1 7.0 05:04  S
06 20.9 23.7 14:46 17.9 22:48 0.0 2.6 0.0 0.6 8.7 11:07 SSW
07 21.3 28.2 15:47 15.6 23:56 0.2 3.2 0.0 1.1 19.1 14:27 SSE
08 17.7 23.7 14:48 12.6 06:43 2.0 1.4 0.0 2.9 24.3 08:56 WSW
09 18.5 22.1 14:10 14.9 02:24 0.8 1.0 0.0 3.9 29.5 12:29  S
10 18.1 20.6 11:15 14.3 23:59 0.5 0.3 4.0 2.0 20.9 11:46  S
11 14.5 21.7 14:51 7.7 07:02 4.4 0.7 0.0 0.9 15.6 14:02  S
12 17.5 25.4 14:25 8.8 05:30 3.1 2.3 0.0 1.0 17.4 12:19  S
13 22.3 30.8 14:44 14.7 05:22 0.8 4.8 0.0 0.8 15.6 12:28 SSE
14 20.6 27.1 15:56 15.2 23:57 0.5 2.8 0.0 1.3 17.4 10:34  S
15 19.8 28.1 13:18 13.3 03:25 1.3 2.8 0.0 1.6 17.4 13:43  S
16 16.1 18.3 00:00 13.0 23:57 2.2 0.0 13.4 3.6 34.8 14:41  N
17 13.8 15.4 16:44 12.2 04:03 4.5 0.0 0.2 4.6 22.6 11:08  N
18 16.4 19.3 13:19 14.0 05:19 2.0 0.1 0.2 0.8 12.2 11:15  N
19 16.0 19.7 11:35 13.3 07:02 2.5 0.2 2.4 0.4 10.4 16:44  N
20 15.3 18.3 15:17 12.6 23:58 3.0 0.0 0.0 0.4 8.7 15:44 NNW
21 16.3 21.9 15:33 12.1 06:59 2.8 0.8 0.0 0.3 19.1 14:05  S
22 15.7 19.8 16:16 11.6 05:18 2.8 0.2 0.0 1.1 13.9 16:53  S
23 13.5 19.7 15:25 6.9 07:01 5.0 0.2 0.0 1.0 15.6 13:34  S
24 16.1 21.8 12:26 8.6 02:28 3.1 1.0 0.0 3.1 31.3 12:51  S
25 16.0 19.7 13:24 10.2 23:59 2.4 0.1 2.4 1.2 20.9 05:42 SSW
26 12.9 18.5 16:00 8.4 03:43 5.4 0.0 0.0 1.5 19.1 13:32  S
27 14.2 18.8 16:12 7.8 02:06 5.9 0.0 0.4 0.6 24.3 10:33  S
28 17.8 21.7 13:03 15.7 10:00 1.2 0.6 0.8 3.7 24.3 07:05  S
29 14.1 19.7 15:12 10.2 07:46 4.3 0.1 0.8 1.2 17.4 15:26  W
30 16.9 18.3 14:48 14.6 19:13 0.6 0.0 0.0 3.5 19.1 13:33  S
Mean Temp High Temp Day  Low Temp  Day Heat Deg Days Cool Deg Days Rain Ave wind speed High Wind  Day Dom Dir
Sept 16.9 30.8 13 6.9 23 71.1 28.2 38.6 1.4 34.8 16 S

Perseids Update

The night of 12-13 August was also busy, with the camera capturing 81 meteors or about half as many as the peak of the Perseids. There was about half an hour (between 2 and 3 am) affected by cloud but otherwise the night was clear.

Hour (UT) Perseids Total Meteors
21 10 10
22 10 13
23 14 14
00 10 13
01 9 17
02 6 7
03 6 6

It looks as if the number of Perseids is diminishing rapidly so that other meteors become more significant in the numbers. this is exactly what would be expected, even though we will see a few Perseids in the nights ahead as the shower fades.

Perseid Meteor Shower 2016

The image shows two perseid meteors captured simultaneously along with a high flying aircraft (short trail), some stars of the Pegasus and Andromeda constellations and some hot pixels due to the camera’s increasing age. The camera is a standard close-circuit, standard definition video camera, feeding sonotaCo software.

Many experts were predicting an increase in the number of meteors in this year’s Perseid shower. We were fortunate to have a clear night and my meteor camera certainly saw lots of Perseid meteors. On a typical clear night through most of the year, the camera will capture between 4 and 12 meteors. From darkness on 11 to first light on 12 August 2016 it caught more than 150! There were so many that there were several captures of two simultaneous meteors and even one with three!

This is the third Perseid shower that the camera has observed and by far the busiest here.

Hour (UT) Perseids Total Meteors
21 6 8
22 17 18
23 28 31
00 22 23
01 30 36
02 37 46
03 12 16

The first and last hours were affected by daylight

The camera will generally capture any meteors in its field of view with a magnitude brighter than 1.7 or so. It has an approximately 60 degree wide field facing just south of east, (towards the Netherlands, Belgium and Northern France)

To see many more perseid (and other) meteors captured by video cameras visit the UK Meteor Network (of which the Horley camera is a proud member)

What are the Perseids?

From time to time the earth collides with dust, grit and pebbles. Even tiny objects move in orbits round the sun at very high speeds, so as they encounter our atmosphere, they become very hot from friction with the air and almost all of them vaporise completely. From the ground we see a “shooting star” or meteor: a fast moving spot of light that sometimes leaves a trail. Very rarely, an object of greater size (depending on what it is made of) can survive the heating and fall all the way through the atmosphere. This is a meteorite.

As a comet or asteroid orbits the sun, it can leave debris behind in the form of dust, grit and pebbles. They can escape the comet or asteroid because it has weak gravity due to its relatively small size. When the earth passes through the orbit, there will be more meteors, even if the comet or asteroid itself is far away. As the orbits of many comets and asteroids are stable, we can predict when an increase of meteors will occur, with many known showers occurring at the same time each year. As the objects are all moving in parallel, the will appear to radiate from a point on the sky (which we call the radiant) just like parallel train tracks appear to meet at a point in the distance. An annual increase in meteors of this kind is called a meteor shower and these are usually named after the constellation or a nearby star from which the meteors will appear to originate (though meteors can appear anywhere across the sky).

The Perseids occur in late July and early August each year and appear to radiate from the constellation Perseus. This meteor shower usually produces more meteors than any other each year. It is known to be caused when the earth crosses the orbit of comet Swift-Tuttle.

Predictions of how active the perseids will be are based on the position of the comet within its orbit (when the comet has recently passed, the orbit will be more dusty), and by mapping the density of particles in the orbit using previous observations.

Storm Katie

As predicted, Storm Katie produced high winds here, with a peak gust at 06:02BST of 62.6kts or around 70mph. Highest sustained winds were Beaufort 7 (Near Gale)  at 28.2kts or 32.5mph.

Wind speeds during Storm Katie

 

 

 

 

 

 

 

 

 

 

 

 

 

Storm Katie was a classic Atlantic storm, with “bomb” or “explosive cyclogenesis” where the central pressure drops very quickly indeed, intensifying the winds around the low pressure area. At times, pressure was falling or rising by over 3hPa/hr, unusually rapid and strong.

Pressure during passage of Storm Katie

 

 

 

 

 

 

 

 

 

 

 

 

 

There is some discussion around this storm having a strong “sting jet” – well described here: http://www.metoffice.gov.uk/media/pdf/2/p/Sting_Jet_Flyer.PDF

We have not suffered any damage, except for some small branches and twigs down in the garden, and some surface water covering part of the lawn and some borders this morning. Bins and rubbish are scattered up the road and I found someone else’s bin (thankfully empty) in my front garden (It was marked, so easy to return it). There are reports of lots of fallen trees but so far, nothing major and no reports of injury (at least yet. Let’s hope it stays that way)

This storm was fairly strong, but well within normal range for Atlantic depressions.

Long Lasting Meteor

At 20:05 on 14 February 2016 my video meteor observatory saw and captured this meteor for a total of just over 5 seconds. This is an usually long time for a a meteor, especially as it looks as if the meteor leaves the frame while it is still visible. The software analyses it as an Epsilon Columbid: a member of a minor shower occurring around this time of year. it seems to have been about magnitude 0—bright but certainly not a fireball. There is no “parent body” known for this shower. Most meteor showers are caused by a trail of debris (dust and small grains) left behind in its orbit by a comet or asteroid. These tiny particles burn up when the earth crosses the orbit later and they fall into the upper atmosphere.

The software was able to estimate the first part of its path over the ground:

longmeteor

when it went out of frame it was probably quite close to the coast, near the Suffolk/Norfolk border. An accurate ground map and orbit will only be possible if it was caught by at least one other video observatory, which we will not know for a while. All my data goes to the UK Meteor Network, and is then deposited in EDMOND: a huge and growing database of meteors observed by video, which has contributors mainly in Europe and Brazil and in other countries, most of whom are amateurs. Researchers use this data to study the orbits and nature of meteors.

There is probably not anything particularly significant about this meteor, just another tiny piece of debris, left behind by a comet or small asteroid but it’s long and quite slow track across the sky (To give an idea of scale, the two bright stars it passes early in its trail are Regulus and Al gieba – alpha and gamma – in the constellation of Leo)

Snow!

I saw some light snow, almost frozen drizzle, falling last night, but we woke to about 2cm on the ground, on branches and hedges. This was enough to make the world white, but the centre of the road was clear and where people walked, their footprints went right through to the pavement underneath.

As so often, this was from slightly warmer air pushing in from the Atlantic, into the very cold arctic air which was been feeding in from the North. It will slowly become less cold as the Atlantic air takes over, so more snow is unlikely unless the colder air returns.

Weather 2015

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In a nutshell, 2015 temperatures were 1.1C above the long term average with December 6.4C above. The Met Office say that it was the warmest and wettest December on record. September was significantly cool.

Rainfall was 5.6mm above the long term average. January and August were wet, while March, April and October were dry.

November Weather 2015

This November has been remarkably mild in Horley, apart from a brief, but significant cold snap.

Through almost all of the month, the jet stream flowed west-east driving a sequence of depressions off the Atlantic, bringing mild temperatures with regular rain and some windy times as fronts came through. there were a couple of genuinely windy spells with a force 7 (near gale) on 21, the strongest sustained wind recorded here in the last two years. This was a northerly, combined with low temperatures, so it felt particularly bitter. There were a nine days with gusts over 30knots.

Total rainfall was 82.8mm, with some rain falling on 24 days, and significant rain on 12. There were no days with more than 20mm rain. The total rainfall was 7.5mm less than the long-term average.

The mean temperature for the month was 10.5C, no less than 3.3C above the long-term average. The maximum for the month was 16.7C on 6th, but the daily maximum was above 15C from 2nd–17th inclusive. Despite a predominantly mild picture, there was an outbreak of air from the arctic from 21st to 23rd, which saw frost each night, mean temperatures below 3C and a minimum of -4.4C on 22nd.

                                      Heat  Cool   Avg
    Mean                              Deg   Deg         Wind      
Day Temp  High   Time   Low    Time   Days  Days  Rain  Speed High
------------------------------------------------------------------
 1   8.6  11.7   14:12   5.6   02:37   9.7   0.0   0.4   0.0   3.4
 2  10.6  16.1   14:37   8.6   06:38   7.7   0.0   0.2   0.2   8.6
 3  11.1  13.7   15:29   9.2   21:50   7.2   0.0   0.2   0.0   7.0
 4  12.2  13.9   14:00   9.2   00:03   6.1   0.0   5.0   0.1  10.4
 5  14.2  15.2   11:15  13.4   00:00   4.1   0.0  15.2   3.1  29.6
 6  14.9  16.7   13:38  13.3   05:50   3.4   0.0   5.0   3.2  26.0
 7  14.6  16.5   10:17   9.3   23:57   3.7   0.0   9.6   4.6  36.6
 8  12.4  15.9   18:17   7.1   03:51   5.9   0.0   0.2   3.2  26.0
 9  12.8  15.0   12:42   8.8   06:08   5.5   0.0   0.0   4.2  33.0
10  14.2  15.3   11:39  13.3   22:16   4.1   0.0   0.0   3.9  22.6
11  13.7  15.4   12:33  12.4   23:50   4.6   0.0   0.0   2.3  19.2
12  13.5  15.5   12:37  11.6   07:02   4.8   0.0   0.2   3.4  38.2
13   9.7  13.9   00:06   6.6   18:58   8.6   0.0   1.4   3.1  27.8
14  10.3  14.3   23:32   7.3   01:03   8.0   0.0  10.0   3.4  29.6
15  14.2  15.6   13:28  13.1   23:24   4.1   0.0   0.0   5.6  24.4
16  12.9  14.0   12:07  11.7   19:18   5.4   0.0   5.6   3.6  36.6
17  13.9  15.3   15:14  12.6   00:00   4.4   0.0   5.8   6.4  36.6
18  12.8  14.9   12:25  10.3   06:31   5.5   0.0   2.6   5.7  31.4
19  11.1  12.8   00:00   9.2   22:23   7.2   0.0   1.4   2.1  26.0
20   7.5   9.3   00:00   4.2   20:02  10.8   0.0   0.0   1.0  26.0
21   2.9   5.9   12:57  -2.2   23:45  15.4   0.0   2.8  12.0  45.2
22   1.0   6.4   13:31  -4.4   06:57  17.3   0.0   0.0   0.9  14.0
23   3.2   7.5   13:47  -2.2   07:04  15.1   0.0   0.6   0.1   8.6
24   8.0  10.3   08:39   5.8   20:46  10.3   0.0   8.8   2.2  19.2
25   7.6  10.3   13:14   4.4   23:55  10.7   0.0   0.2   1.7  24.4
26   8.1  10.2   13:19   4.1   01:27  10.2   0.0   1.6   0.1  12.2
27  10.2  12.2   11:10   5.4   23:58   8.1   0.0   2.6   3.9  33.0
28   6.5  10.4   21:23   1.6   07:51  11.8   0.0   0.2   3.0  27.8
29  11.4  13.2   15:37   9.5   00:13   6.9   0.0   1.0   6.1  34.8
30  11.6  13.3   21:22   9.1   04:45   6.7   0.0   2.2   4.3  26.0
------------------------------------------------------------------
    10.5  16.7     6    -4.4    22   233.3   0.0  82.8   3.5  45.2

Max >=  27.0:  0
Max <=   0.0:  0
Min <=   0.0:  3
Min <= -18.0: 0 Max Rain: 15.2 on day 5 
Days of Rain: 24 >= 0.2 mm  12 (>= 2.0 mm)  0 (>= 20.0 mm)
Heat Base: 18.3  Cool Base: 18.3  Method: Integration

Ex-Hurricane Kate

Early this week attention focused on the first storm named by the Met Office and Met Eirann. “Abigail” was a typical winter Atlantic storm, one of many which would be expected to impact on the British Isles each year. The reason for naming storms is explained:

As the UK and Ireland’s National Met Services, the Met Office and Met Éireann operate to maintain public safety through severe weather warnings and forecasts. Working together, it is hoped that naming storms will help raise awareness of severe weather and ensure greater safety of the public. The Met Office and Met Éireann will continue to issue weather warnings in the normal way using the Met Office National Severe Weather Warning Service and Met Éireann Weather Warnings. A storm will then be named when it is deemed to have the potential to cause substantial impacts in the UK and/or Ireland. To avoid any confusion over naming, if a storm is the remnants of a tropical storm or hurricane that has moved across the Atlantic, the already established method of referring to it as, e.g. ‘Ex-hurricane X’ will continue.

Abigail brought strong winds and some disruption to Scotland and parts of Ireland, along with heavy rain. Here, in southern England, it was nothing unusual for November: breezy and wet.

ex-Hurricane KateRight now, Weather across the British Isles is coming from a large, complex system of low pressure, another Atlantic storm, but this one has the remains of a Hurricane mixed up in it. Kate formed at the beginning of the month off the Bahamas and reached Hurricane strength just before it became part of an Atlantic storm system that had already left the north American continent heading westwards. This happens several times a year and the main effect is to add a great deal of energy and moisture to the storm as the hurricane adds enormous amounts of tropical air to what is already a clash between air from the polar region and air from the tropics.

This system has brought huge amounts of rain to the north and West of the country, especially Wales. This rain has been heaviest where the air has been forced up by terrain (“orographic” rainfall) and has been heavy enough to cause significant flooding. Again, here in the south of England, things have not been too unusual. We had light but very persistent rain for many hours yesterday, giving a total of about 10mm. It is also rather mild for the time of year as we experience a warm, wet tropical airmass. Today it is breezy, but nothing extreme.

As the system rolls through into Europe, it looks as if cooler polar air will be pulled down across the British Isles behind it, with temperatures likely to fall to seasonal norms, for the first time this autumn. November so far has been about 5C above the long term average for this location.