Penellype's Weather Channel

[Penellype]

Very hot today in the south, with the highest temperature of the year so far likely to be recorded somewhere today. All change from tomorrow as cooler and fresher air moves in from the Atlantic behind cold fronts which may spark off intense thunderstorms in places - this process is already starting in Scotland and northern England.

While many places may get away with a mainly dry weekend, this looks likely to be the trigger which leads to a much more unsettled spell of weather with low pressure becoming stuck over the country. At present there is no signal for a return to the hot and dry weather we have been seeing recently, out to the end of the first week in July.

Things can change fast at this time of year. The hurricane season is starting in America, and often our weather gets a nudge from a dying hurricane system which can completely change the forecast practically over night.

Useful links for tracking storms:
radar - Weather Radar - Live UK Rainfall Radar - 5 Minute Updates - Netweather.tv
lightning Real-Time Lightning Map :: LightningMaps.org

[vixylix]

I hate storms, so if one of these arrives over York I will probably be hiding under the table

Weather warnings - Met Office

Me too P - I'm gutted these potential storms have fallen on the one day a week that I'm in the office rather than at home - and I'm on the train home. Could be interesting - doesnt feel remotely humid enough to storm though!

[Penellype]

We had a batch of storms across northern England and Scotland this morning (further north than Leeds and York), and there is another one moving into western Scotland at the moment. There's a band of showers currently across the country through Liverpool and Manchester, slightly to the south of Leeds, but these currently don't have any lightning with them. I think things could pep up a bit this evening, but these things are incredibly difficult to forecast accurately.

[Penellype]

A chilly night in places tonight as the wind falls light and skies clear. Tomorrow should be a fairly decent day, but rain already approaching Ireland is waiting to pounce and the rest of the week will be intermittently and fairly thoroughly wet as low pressure centres itself over the country. It will also be windy at times.

By Wednesday we have this:



This large and complex area of low pressure is rotating over the top of us, and moving very slowly east. Although it is hard to see where they are from the above chart, there are several fronts associated with this low and their estimated positions at this time are shown on the Met Office fax chart:



It is hard to pin down the detail as far as the timing and position of the rain goes, but Wednesday looks a very wet day.

The low sticks around until Friday, but by Saturday the models are forecasting a ridge of high pressure, which will probably only last a day before more fronts bring rain on Sunday. There is a lot of uncertainty, but things currently look fairly changeable into the first week of July. There is no sign of a return of last week's heatwave.

The ensemble chart for York shows the increase in rainfall well:



The white average forecast temperature is pretty close to average for the time of year, but this hides the up and down fluctuations of the individual ensemble members which are typical of low pressure systems. If you pick out the thick green line you can see the up and down fluctuations rather better.

[Jay22]

Just been in the garden and it's absolutely freezing, the wind was biting although as you say Penellype, it seems to be dying down a little. There is no happy medium in this country is there?!

[Penellype]

This is one of the occasions when the general forecast has proved pretty much spot on for the whole week. The low that brought this week's wet weather is now moving away to be replaced by a slight ridge, and better weather, at least for the southern half of the country tomorrow. Low pressure will continue to plague the north and west particularly, but most places should see some brighter weather and an improvement in temperatures over the weekend especially where the sun comes out. Rain is never very far away though, and there may well be showers in places.

The ensemble chart for York shows the continuing unsettled weather well, with plenty of rainfall spikes (although nothing as big as this week's have been) and the charactaristic up and down temperature profile of low pressure systems (follow the thick green line to see it in the 2nd half of the chart).



The message really is make use of any dry weather because it may not last long!

[Potstubsdustbins]

Well today was a surprise, woke up this morning, looked out the widow, dull and overcast as per our local predictions.

As SWMBO and I set off for the club at 1-00pm we put on our fleece's and got in the cab, half way there the sun broke through. We spend the next two hours with the fleece off, bathed in warm sunshine with our friends.

[Penellype]

Some serious uncertainties in the weather for later this week with the models disagreeing at times, and big differences between the runs.

The midnight GFS ensemble run for York looked like this:



But by noon it was looking like this:



That's a crazy difference in forecast temperature and rainfall for 7th July (supposedly in the "reliable" timeframe)!

Take any mentions of heatwaves for this week with a pinch of salt and be prepared for anything from relatively cool and calm weather to hot and thundery.

[Jay22]

We are spending Friday and Saturday with friends in the big smoke...hopefully the weather will be good by then!

Thanks again Penellype for keeping us up to date.

[Penellype]

Models are firming up on this warm spell towards the end of this week, when it could get quite hot in the south. This is not the same sort of warmth that we had in the middle of June, when we had several days of warm and dry weather. This time the air is quite unstable and showers are likely with thunderstorms probable in the south and it will be cooler and fresher by the weekend. It will always be cooler and rather more unsettled in the north.

[Jay22]

Och, I'm emigrating!!

[Penellype]

Och, I'm emigrating!!

Sorry, don't shoot the messenger!

The reason why its so much more settled in the south is that we have high pressure to the south and low to the north. Although things wobble about a bit from day to day, Sunday's chart sums this up perfectly:



and here is the rainfall chart for the same time:

[Potstubsdustbins]

The forecast said possible thunder and lighting between 7 & 9 this evening, its just arrived.........20 minutes late will they...................never get it right

[Penellype]

Ours arrived right on cue, although the 33mm of rain in 1 hour that we had forecast missed us by about 20 miles and fell on Malton instead. We got a much more sensible total of about 5mm, but we did have the thunder and lightning.

[Greenleaves]

Not even a cloud in North Hampshire