Penellype's Weather Channel

[Penellype]

Here is the actual situation at 6pm today:



Some small pink areas of snow showing up in the London area along with a large area of sleet. It is likely that more of it will turn to snow as the evening progresses.

[KevinM67]

From that pic Penellype - I take it the top 1/3 of Scotland doesn't get any weather ?

[Jungle Jane]

We just had a little snow,it's settled on the grass about 1cm but melted into the wet roads & paths,I think it's raining now.

[Penellype]

From that pic Penellype - I take it the top 1/3 of Scotland doesn't get any weather ?

It does, but I wanted the map to be big enough to see the pink areas around London, and my screen wouldn't show any more of it. The next size down:



Is that better?

[KevinM67]

Ignore me Pen - I was just being an @rse.

[Thelma Sanders]

We have about 3cm here and it is still falling heavily and blowing a hoolie with it

More worrying is the storm surge and high tide coming down the East coast, some coastal towns are being evacuated now.

Wonder if they'll need to shut the Thames barrier, if it comes up the estuary.

[Penellype]

We have about 3cm here and it is still falling heavily and blowing a hoolie with it

More worrying is the storm surge and high tide coming down the East coast, some coastal towns are being evacuated now.

Wonder if they'll need to shut the Thames barrier, if it comes up the estuary.

Yes the storm surge is a serious concern. I don't know whether the Thames barrier will be shut - I presume they have criteria to work from which will trigger shutting it.

Radar currently showing the heavy snow in Kent:

[Potstubsdustbins]

What amaze's me is the different weather we have for a small country, 40 miles away in Buxton snow,
70 miles away East coast flooding, here in Notts nothing, no snow, no wind and very little rain............

[Penellype]

So we had the windy day that was forecast on Wednesday, and the colder weather behind it. We had the snow in the south followed by this morning's band of snow and cold northerly wind and we had the coastal flooding from the storm surge. Does this mean that the weather models have finally got this all worked out?

Well...

The next phase is the build of high pressure over the weekend which is supposed to bring a brief milder spell before it gets colder again next week. The winds will be coming around the top of the high instead of from the north pole, so it should in theory be warmer. In these situations, if there is snow on the ground the warmer air tends to ride up over the cold surface air and produce damp, murky or foggy conditions, which are a lot less warm at the surface than might be expected. Until today the idea was that the east might not see much of a warm up at all, and the south would quickly become cold again as the winds turned into the east, leading to a possibly prolonged cold spell.

Today's model runs suddenly have the high further south and west. This means that the cold air that was heading our way next week now heads for Spain and Portugal instead, and we remain under a relatively mild high pressure. Bear in mind it is January - this is not going to be warm and there could still be frost at night if skies clear, but it is not the big freeze that looked likely a day or 2 ago.

There is plenty of time for the models to change their minds again, so I wouldn't be taking any bets on this at the moment!

Tomorrow - cold start, particularly where there is lying snow. Gradually warming up especially in the west, where temperatures may nudge double figures by Sunday. Colder in the east.

Sunday - rain moving in from the north west as the weather warms up.

Monday - cloudy, damp and chilly, still mild in the west.

That's as far as I am prepared to go at the moment as I really haven't a clue what the models are doing. The difference between the midnight and midday runs of the GFS is clear from the ensemble charts for York:

Midnight



Midday



The position of the white average line compared to the red 30 year average line is significantly different between the 2.

[Penellype]

What amaze's me is the different weather we have for a small country, 40 miles away in Buxton snow,
70 miles away East coast flooding, here in Notts nothing, no snow, no wind and very little rain............

We are in a geographical position which lends itself well to sharp changes in weather. To the west is a large expanse of ocean which holds heat well and provides an ample supply of water. To the east there is a huge continent which loses heat rapidly in the winter and is relatively dry. This leads to big temperature contrasts over small distances resulting in weather which is changeable and often difficult to predict. There is also a long coastline relative to land which lends itself to showery weather or fog under some conditions and there are some fairly big mountains which create microclimates and barriers to rainfall (the west is generally wetter than the east because the east is sheltered from the prevailing westerly wind by the pennines for example). The UK is also long from north to south, leading to big temperature contrasts between north and south.

We are actually in a position where we can be affected by any of 6 distinct air masses, all of which have different weather types. There is a good explanation of these and their charactaristics here:
Weather Facts: Air masses and their sources | weatheronline.co.uk

[Penellype]

I should probably have added to #129 that there is a risk that the rain on Sunday may start off as snow as it moves into the south east, although it will then turn to rain as the air warms up.

[Penellype]

A yellow warning for snow in the east has been issued by the met office for tomorrow Severe weather warnings - Met Office. This is on the front edge of the rain which is moving in from the north west which may turn to snow as it hits the cold air.

There are also currently snow showers over parts of Scotland and rain and sleet which may turn to snow in places over Wales and parts of southern England.

[Penellype]

Another dull and probably damp day for many parts tomorrow, starting mild in the west but chilly in the east, and becoming colder from the east during the day. High pressure is building over the country and while the current flow is coming mainly from the south west, as the high collapses over scandinavia the wind is drawn more into an easterly direction. This is not a strong easterly flow but it does dilute the warmer air somewhat.

High pressure sticks around for much of the week, with the usual (at this time of year) associated mist and murk. Forecasters will say it will be mainly dry, some places may actually find it persistently damp while others may be treated to some sunshine - this seems more likely as the winds move round to the south later in the week. Winds from the south will not be as warm as they sound, as the air over France is currently very cold. Expect temperatures to be around mid single figures, falling to around freezing at night if skies clear, warmer at first in the north and west.

Detail for the end of the week is unclear, with significant differences between the models appearing. It seems likely that some time either over or just beyond the weekend there will be a change to a more westerly pattern with milder, wetter and windier weather at least for a time.

This is the ensemble forecast for York:



The change to wetter weather longer term can clearly be seen.

There is also an interesting development in the stratosphere, with a significant warming which consistently appears towards the end of January. This is outside the reliable forecast range, but if it were to happen it would be likely to lead to a increase in high pressure to the north about a couple of weeks later - this pattern can become locked in and persist for some time. The precise positioning of the high is crucial, and can lead to very cold conditions for the UK if it sits over Greenland. There is no way of telling where it might go, but the possibility is there for an extended cold period mid February onwards. However, if the high were to position itself over America, we might get an early taste of spring...

[Jungle Jane]

It's definitely cold here in Essex,yesterday I took my daughter & her friend to the cinema at 9pm & the windscreen & all windows were frozen,had to scrape them,it was 1 degree celsius. I hope we see a good reduction in slugs this year

[Penellype]

The cold does have advantages, although having said that I noticed that the aphids on my mizuna appear to be surviving the frost