simonjk
Well-known member
Hi all,
Sorry it's been a while since I posted to the forum, been doing lots of luvvie type TV things!
Back now though, so here are my thoughts for the weekend.
As always there is more at http://www.weatherweb.net
Cheers,
Simon
Simon Keeling
Weather musings….watch out for a weekend freeze…
Issued: 1400 Monday 31st January 2005
The mild weather we’ve all been experiencing during the weekend could lull us into a falso sense of security. High pressure to the west has been allowing mild winds to flow across the UK and Ireland. As I write this feature, temperature in southeast Scotland are at 13C, with much of the UK and Ireland into double figures. See http://www.weatheronline.co.uk/cgi-bin/a...RT=2&INT=24 for a list of current temperatures.
However, continuing the topsy turvey January theme, conditions do look set to change as we head into the coming weekend. All computer models seem to agree that low pressure will pass north of Scotland, with high pressure remaining west of Ireland. The combined effect of the movement of these two pressure systems will be to introduce cold northerly winds across the whole of the UK and Ireland.
Another feature which is of interest to me just now, is the kink in the isobars across Scotland. I wouldn’t expect this aspect of the forecast ot be correct in terms of timing, but it is interesting to note that the compter model is hinting at disturbances in the northerly flow. These could well turn out to be polar lows, which would bring more persistent outbreaks of snow.
To understand whats going on, take a look at http://expert.weatheronline.co.uk/cgi-bi...013112_3106.gif
And then compare this with http://expert.weatheronline.co.uk/cgi-bi...020612_3106.gif
Load 'em both up on your screen. Okay, take a look at the first one. Both are the 500mb flows and temperatures, the first is for midday today, and the second is for midday on Sunday.
500mb is about 18000ft and the wind flows along the contours. Where these are closer together, the strong the upper wind. Now, in the first chart, notice how there is a high west of Ireland (this is where the 500mb surface is highest) with temperatures around -20C. It's acting as a block and sending all the associated systems around it. This is getting pounded from the north, and eventually it gives in a moves away southwards. By the weekend we've a trough through the UK and ireland with upper temperatures around -35C. This will serve to reduce surface temperatures and also bring more unstable conditions with an increasing risk of wintry conditions.
To see how the cold air breaks through it's interesting to see http://expert.weatheronline.co.uk/cgi-bi...TERMIN=31012005
This is a loop of the forecast charts through the next week, allowing you to see how the cold air attempts to break through, and then makes it this weekend.
Also, watch how the high builds back to the west of Ireland by Sunday and the flow returns to the north.
Seems straight forward doesn't it, what could possibly go wrong? /forums/images/graemlins/smile.gif Well, for starters, the high may collapse sooner than we think. If this happened the flow would be more westerly, and the depth of cold would be reduced. The ridge may not build behind the cold air on Sunday, and again, this would result in the flow being from the northwest and less cold.
It will be interesting to watch the computer models over the next few days to see how things change. Also, look out for any kinks in the isoabrs from Saturday onwards over the UK and Ireland. These could indicate polar lows, which would mean short spells of snow. But that's a different story.
Hope that's been of use/interest…
Bye for now,
Simon
Simon Keeling
Weather School and Weatherweb.net
Sorry it's been a while since I posted to the forum, been doing lots of luvvie type TV things!
Back now though, so here are my thoughts for the weekend.
As always there is more at http://www.weatherweb.net
Cheers,
Simon
Simon Keeling
Weather musings….watch out for a weekend freeze…
Issued: 1400 Monday 31st January 2005
The mild weather we’ve all been experiencing during the weekend could lull us into a falso sense of security. High pressure to the west has been allowing mild winds to flow across the UK and Ireland. As I write this feature, temperature in southeast Scotland are at 13C, with much of the UK and Ireland into double figures. See http://www.weatheronline.co.uk/cgi-bin/a...RT=2&INT=24 for a list of current temperatures.
However, continuing the topsy turvey January theme, conditions do look set to change as we head into the coming weekend. All computer models seem to agree that low pressure will pass north of Scotland, with high pressure remaining west of Ireland. The combined effect of the movement of these two pressure systems will be to introduce cold northerly winds across the whole of the UK and Ireland.
Another feature which is of interest to me just now, is the kink in the isobars across Scotland. I wouldn’t expect this aspect of the forecast ot be correct in terms of timing, but it is interesting to note that the compter model is hinting at disturbances in the northerly flow. These could well turn out to be polar lows, which would bring more persistent outbreaks of snow.
To understand whats going on, take a look at http://expert.weatheronline.co.uk/cgi-bi...013112_3106.gif
And then compare this with http://expert.weatheronline.co.uk/cgi-bi...020612_3106.gif
Load 'em both up on your screen. Okay, take a look at the first one. Both are the 500mb flows and temperatures, the first is for midday today, and the second is for midday on Sunday.
500mb is about 18000ft and the wind flows along the contours. Where these are closer together, the strong the upper wind. Now, in the first chart, notice how there is a high west of Ireland (this is where the 500mb surface is highest) with temperatures around -20C. It's acting as a block and sending all the associated systems around it. This is getting pounded from the north, and eventually it gives in a moves away southwards. By the weekend we've a trough through the UK and ireland with upper temperatures around -35C. This will serve to reduce surface temperatures and also bring more unstable conditions with an increasing risk of wintry conditions.
To see how the cold air breaks through it's interesting to see http://expert.weatheronline.co.uk/cgi-bi...TERMIN=31012005
This is a loop of the forecast charts through the next week, allowing you to see how the cold air attempts to break through, and then makes it this weekend.
Also, watch how the high builds back to the west of Ireland by Sunday and the flow returns to the north.
Seems straight forward doesn't it, what could possibly go wrong? /forums/images/graemlins/smile.gif Well, for starters, the high may collapse sooner than we think. If this happened the flow would be more westerly, and the depth of cold would be reduced. The ridge may not build behind the cold air on Sunday, and again, this would result in the flow being from the northwest and less cold.
It will be interesting to watch the computer models over the next few days to see how things change. Also, look out for any kinks in the isoabrs from Saturday onwards over the UK and Ireland. These could indicate polar lows, which would mean short spells of snow. But that's a different story.
Hope that's been of use/interest…
Bye for now,
Simon
Simon Keeling
Weather School and Weatherweb.net