Bilz

Any chance of the cloud shifting down this way sometime soon? It's done a good job at keeping those temps down at -2C all day, but it'll need to clear for tonight's predicted severe frost.

Seems to me the BBC grossly misjudged the temperatures today. I believe 2 or 3C was predicted, but across the South Midlands temperatures are widely between -2 and -3C at the moment. Light snow falling again here in Oxford, everything is white with ice, frost and snow and the temperature is stuck at -2C. Perfect winter's day ^_^

Still between -1 and -2C here in Oxford with very light snow falling, which has given everything a very fine white coating on top of the frost. Another ice day perhaps?

Ahrens is a good book. It was our required reading in the first year of meteorology at Reading Uni. Very qualitative with detailed descriptions, so it's not too heavy going if you don't have a mathematical background. Atmospheric Science by Wallace and Hobbs is another one I'd recommened. Similar to Ahrens, but more mathsy. You just have to overlook the typos ^_^

NWS now saying that a collision between the cold front and outflow boundary could lead to rapid storm development south of Oklahoma City. Should hopefully be seeing some storms pop in the next hour down in Norman then.

I'm in Norman, Oklahoma, and have to say this looks like the best opportunity for severe storms I've seen here since arriving last August...baseball hail, 75 mph gusts, tornadoes and flooding are possible, apparently. If the moderate risk box stays as it is, I think some chasing might be in order.

So, like, where's this 10cm of snow we've been expecting today here in Oxford. Met Office has a warning out for our county for additional accumulations, yet it's light sleet currently falling here. Is the mass of precipitation over Wales going to progress any further east, or is it looking unlikely for us now?

Steady snow continuing at Reading university. Accumulations are over 6cm.

Woah, big juicy flakes once again falling here in Reading after temporarily easing off, adding to the 2" or so already lying.

A thick mantle of snow lying now here in Reading, probably 4cm or more, but beginning to ease a little. BBC Weather showed snow until 9am over us, so is there any more to come?

Already several centimeters of lying snow here in Reading, and there's still a few more hours of this to come I understand.

What sort of depths can we expect here in Reading?

Temperature hit -8.0C at 0600 this morning in nearby Besnon. Now up to -6C. Coldest morning of the winter for many areas.

Seriously foggy here in Oxford, and it's been getting steadily thicker since sunrise. Visibility must be down to around 100m. Temperature struggling as a result, and currently just 1.7C

I'm off to the Austrian Tyrol for 5 days over the Xmas week, departing on the 22nd and returning on the 28th. I think we're staying somehwhere the Kitsbuhl Alps, probably near Salzburg or Zell Am See. Does anyone know the current conditions for the region, if any snow is due soon and the likely weather for the Tyrol over Xmas?

I think their warning page is stupid. For this weekend, for example, they have a warning of severe gales for every area of the UK, and underneath is found a description of the warning for each area. But instead of giving a specific warning with precise details for each region, they just reprint the exact same warning 14 times. What's the point? Just one warning and the risk map will suffice.

My anemometer is mounted on a thick plastic tube 2 to 3 feet above the roof top, which is very easily obtained. You'll also need to fit a special roof tile to push the pole through from below.

Anyone remember the storms of 3rd - 5th January 1998? It was a ferociously stormy period which probably saw some of the highest wind gusts ever recorded over southern England and Wales. Despite this and the fact there was a programme devoted to it a number of years back, I never see it get much of a mention in storm discussions. Here are the synopic charts for that period: The strongest winds occurred when an intense secondary depression crossed England rapidly during the morning of the 4th Jan (you can see it brewing to the west of France on the second chart). It produced storm force winds of between 55 and 70mph, with a peak gust of 115mph recorded at Swansea. We had an enormous gust of wind in Oxford during the morning, which was probably responsible for most of the fallen trees across our region. It went eireely quiet in the afternoon, probably as the low pressure centre passed over us, before the violent gusts picked up again in the evening. Top wind speeds in our region were around 70mph. The storm made the front pages of all the newspapers, and I would upload the map from the Telegraph depicting wind speeds around the UK if my scanner was working...

5 months? I thought winter began in December?

Well last winter looked full of promise after the Met Office issued their 'below average' forecast during the autumn of 05, but I don't seem to recall a more bitterly disappointing and uneventful winter during my lifetime. Although it was below average in the south, there weren't really any notable cold snaps, snowfalls or gobsmackingly-cold temperatures. Instead it was week after week of rather cold weather by day and a slight frost by night, and these conditions just dragged on into late-March. So I don't want a repeat of that thankyou - too boring. Give me mild and wet if it means we get a decent storm this winter.

Interesting charts, well done Looks like ex-hurricane Flossie was a particularly severe event for the north. I bet the Norwegians have some vivid memories of that one. I seem to have some recolection of Lili a decade ago...or at least I think that's the storm I can remember.

The SALR is a little bit more complicated, because unlike dry air parcels, you have to take into consideration the amount of heat absorbed or released by the moist air parcel when moisture evaporates/condenses into it. It is given by the following formula: dT/dz = -g/cp - (L/cp)*(dr/dz) where L = latent heat of vaporisation = 2,500,000 J/Kg and dr/dz is the change in the mixing ratio of the air parcel with height - ie the amount of water vapour per unit mass that evaporates from or condenses in the air parcel. Hence the SALR is not constant, but depends on the change in moisture content of the air parcel. Consider an ascending DRY air parcel. As it ascends, it cools at the DALR and its relative humidity approaches 100%, causing it to become saturated. Further ascent causes condensation and the release of latent heat which offests the rate of cooling. Its temperature now falls at a lesser rate called the SALR. In this situation, moisture is lost, hence the term dr is negative in the equation, making the whole of the second term positive and resulting in a smaller dT/dz. As you go higher, the air parcel becomes colder and is less able to 'hold' moisture. Consequently, dr/dz becomes very small and the SALR approximates to the DALR. Now consider a descending moist air parcel. As it warms, moisture evaporates (dr is positive) and this evaporation cools the air parcel, offsetting its rate of warming.

The dry adiabatic lapse rate is given mathematically by: dT/dz = - g/cp where dT/dz is the rate of change of temperature with height, g = acceleration due to gravity = 9.8m/s/s cp = specific heat at constant pressure. This is the amount of energy required to create a unit temperature change of an air parcel when it is kept at constant pressure = 1004 J/kg/K = 0.0098 K/m or 9.8K/km

Apologies if anyone has already posted something along these lines, but with the recent unseasonaby windy weather, I thought it would be interesting to discuss memorable summer depressions. I thought I'd give 2004 a mention. Unusally, there were two notable areas of low pressure that brought gales to the south and west during that washout summer, and occurred within two weeks of eachother. The first of these was on 23rd June: and the next struck on 7th July: (GFS shows low pressure system the next day) I remember 7th July was particularly nasty in Oxford. With that low centre positioned over Kent, a fierce notheasterly gale began during the morning, stripping leaves from trees and even uprooting a few. Very unusual, especially as we are so far inland. Parks were forced to close in the afternoon as gusts touched 40 or 50mph over the region. Maximum gusts for the event were around 60mph I believe. Anyone remember any other notable summer storms?

I've always preffered to term forces 7 to 11 as follows: 7. Moderate gale 8. Gale 9. Severe Gale 10. Storm 11. Violent Storm I mean what's the 'fresh' and 'whole' about in describing the strength of a gale? Sounds kinda stupid don't it. I know both ways are acceptable tho Remember the scale continues up to 17 to incorporate the five categories of hurricane as described by the Saffir Simpson Scale.