Southwest & Central Southern England Regional Discussion

[gottolovethisweather]

That more southerly blob that is heading for the South-East coast is going to be a doozy, I reckon!

What the .... is a doozy?

[AWD]

What the .... is a doozy?

http://m.urbandictionary.com/#define?term=doozy

Could be something around first thing tomorrow morning for similar areas too;

Edited December 16, 2012 by AWD

[katemart]

Still thundering here, akthough the weird cells have now gone and we just have general grey cloud cover. Interesting that ESTOFEX predicted this but all the local forecast were for dry and sunny all day.

Ooh, they did predict possible tornadic activity!!!!! http://www.southamptonweather.co.uk/stormforecast.php

[katemart]

http://m.urbandictio...fine?term=doozy

It's a girl with a great rack, obv, gtltw!

[gottolovethisweather]

http://m.urbandictio...fine?term=doozy

Could be something around first thing tomorrow morning for similar areas too;

Thanks AWD, personally, I liked the third version

Not really any the wiser but of course, this forty year old chap would struggle with those hip types from Southampton. Extraordinary indeed, but alas no Thunder for me.

Dare I sit here and see what the GFS 12z conjures up. Hmmmmm., decisions decisions.

It's a girl with a great rack, obv, gtltw!

Spotted that one, thanks. That image and your storm will be imprinted in my mind for the most of the day now.

[TropicThunder]

All calmed down for a bit, but it's gone very dark now with ominous looking clouds to the west. Hopefully more to come.

[gottolovethisweather]

Thunder and lightning! It sounds a bit high up like.

Yes it looked quite active in your part of the region, how many Thunder claps did you receive?

[*Stormforce~beka*]

Didn't really take off here. Must have been on t'edge of the southampton one.

[*Stormforce~beka*]

Claps - 0. Just distant rumbles. I must be in that break on the radar lol.

[gottolovethisweather]

Didn't really take off here. Must have been on t'edge of the southampton one.

Just to show you how darn close you were, Sb and for information purposes. Meanwhile, my storm drought continues but well done to you lucky lot of so and sos.

Claps - 0. Just distant rumbles. I must be in that break on the radar lol.

Turn down that bloody Eastenders garbage on the TV.

Edited December 16, 2012 by gottolovethisweather

[katemart]

Temp fell by almost 2 degrees in the past hour: http://southamptonweather.co.uk/wxflashchart-day.php

Back to drying my knicks in front of the fire again, then *sigh*

[gottolovethisweather]

Blue skies now and the Temperature only dropped 0.5c so rather disappointing, but at least nature delivered entertainment to some of us for free.

Temp fell by almost 2 degrees in the past hour: http://southamptonwe...shchart-day.php

Back to drying my knicks in front of the fire again, then *sigh*

Temp fell by almost 2 degrees in the past hour: http://southamptonwe...shchart-day.php

Back to drying my knicks in front of the fire again, then *sigh*

Have I stumbled onto the wrong forum again.

I best watch the GFS 12z to see if it can pull off a stonker!

Edited December 16, 2012 by gottolovethisweather

[TropicThunder]

Blue skies now and the Temperature only dropped 0.5c so rather disappointing, but at least nature delivered entertainment to some of us for free.

Looks like we got lucky today, but tbh this year has been rubbish for storms down here. Nice surprise though, and a brief distraction in the never ending hunt for snow!

[katemart]

Not as exciting as it sounds, gottolove - and there's a few manky y-fronts in there,too! Right, fings to do. Hopefully there will be some interesting reports from the south-east region when I pop back in later on :-)

Absolutely chucking down again - and the blue skies on the horizon have completely gone

Edited December 16, 2012 by katemart

[*Stormforce~beka*]

Gah! Yea im in North Winchester.

[gottolovethisweather]

Hello, I'm going to present a quick and brief analysis of what weather is forthcoming, according to the GFS 12z. My main area of interest, along with a few other folk is whether we are in for anything colder than the current scenario. Of course, seven days is a long time in Meteorology and I suspect the subsequent ensembles will indicate that FI is at best, t+120 from now. As a consequence, only the general trend is of interest in my summary.

It is best to look at things from a global perspective so I will copy below, how the GFS 12z views the current situation, by looking at the NH Jetstream profile at t+0, i.e. 12pm today.

Let's move on 48 hours to midday on Tuesday 18th December, courtesy of the NH Jetstream profile and subsequent T850s.

From the above, you can see the Uppers (T850s) aren't particularly noteworthy, i.e. near average, but the Jestream has moved back over us. Of note, however, note a buckling of the Jet out in Mid-Atlantic, this is something to follow as we progress through to the next set of charts.

By t+96, i.e. midday on Thursday 20th December (FI ? ) we have the Jetstream diving Southwards once again and a better, almost a potential break-off (split-flow?) in Mid Atlantic. Meanwhile the T850s are still near average for the time of year. Having said that, there are are some much colder uppers just over the North Sea and between t+48 and t+96, they have moved a whole lot closer.

Finally, the furthest I will allow myself to search is at the seven day range, i.e. t+168. Come next Sunday (23rd December), there is a tease going on, as can be witnessed by the the NH Jetstream and T850s at that timescale. Will it be cold enough for snowfall by then and/or is there any potential, time will tell.

On the face of it, the last two charts shown above don't look too inspiring for anything wintry but the block is holding strong out East and a depression is potentially stalling out West. I WILL SAY NO MORE AT THIS STAGE!

*as an aside, I have gone against my morals and jumped on one individual run but if and should you continue to follow this saga, you will find things, synoptically speaking are far from boring.

**all charts come courtesy of a netweather Extra full subscription, so I surely won't be repeating these summaries every day.

Edited December 16, 2012 by gottolovethisweather

[AWD]

Wednesday & Thursday look rather concerning for our region, with copious rainfall projected over a short space of time.

The GFS has a lot of rainfall projected, in two main bands. One in the morning then another overnight with lighter rain inbetween not really helping;

The UKMO also showing heavy & persistent rain moving in from the SW on Wednesday;

With gusty winds associated too;

Be interesting to see what the ECM and tomorrow, the NAE make of it. Definetly one too watch though, could turn into quite a concerning event down here.

[gottolovethisweather]

Wednesday & Thursday look rather concerning for our region, with copious rainfall projected over a short space of time.

The GFS has a lot of rainfall projected, in two main bands. One in the morning then another overnight with lighter rain inbetween not really helping;

The UKMO also showing heavy & persistent rain moving in from the SW on Wednesday;

With gusty winds associated too;

Be interesting to see what the ECM and tomorrow, the NAE make of it. Definetly one too watch though, could turn into quite a concerning event down here.

And after all that, we best hope that the battleground event as show at t+168 in my post above DOES NOT come about as shown. Your forecasted period IS as good as within the reliable timeframe too.

[Nights King]

Looking forward to some more rain the ground is parched here.

[cerneman]

Few sharp showers today.Not liking prospect of too much rain next week,

[slb97]

Evening all,

No thunder here today much to my disappointment but torrential rain and hail for a time which caused the main road and pavements to flood this afternoon.

[Dorsetbred]

A good afternoon for chasing downpours, as I drove from Poole to Southampton. On the way back the wife commented how dark it was over Bournemouth,

When we were almost in Bournemouth, the heavens opened.

Some really good precip including hail on the leading edge.

This week is looking up & down, Weds is looking wet and rainfall amounts see variable, as is the wind.

Looking mild, through the festive, and my money goes to a green one down here.

Edited December 16, 2012 by Dorsetbred

[AWD]

I think there is going to be some rather frigid rollercoaster rides of emotions regarding those chasing cold weather. The models have such a tantilising pattern to which we are currently rather unlucky to be missing out on such a potent cold pool to our NE. I can't see anything changing broadly until the upstream pattern changes, to which there is currently no strong, reliable forecast of this happening for the foreseeable, especially one that would deliver for our part of the world. Therefore don't expect cold/snowy weather for the remainder of the month down here. If we do somehow get something, then that's a bonus, just don't expect nothing.

However, the Stratosphere continues to support much brighter potential in January. It's just a question of will the blocking set up in a favourable position for us, and how long will the warming(s) take to filter down to the troposphere and deliver for us.

Remember this;

http://en.m.wikipedia.org/wiki/Winter_of_1946–1947_in_the_United_Kingdom

A winter that didn't start truly until late January and lasted throughout February and into March.

We are now very reliant in the Stratosphere delivering and reorganising or destroying the PV, which would totally alter any upstream pattern. Some are wary about this and I can understand why, it's a risky area in which we are all still learning about.

The fact is every Northern Hemispheric winter see's the PV strengthen as the thermal gradient tightens. So we have the natural westerly flow strengthened also which is a prime recipe for the many depressions that form mostly off Newfoundland, and travel across the Atlantic to us. If the conditions are right, these depressions will bulldozer any cold weather or blocking situations out of the way pretty quickly. Something which we are currently seeing, but mainland Europe aren't as much.

What is essential if we want to see any prolonged, sustained and potentially snowy weather is to reverse the zonal Westerly flow.

In the past most of the notable cold/snowy periods have been associated with some kind of stratospheric warming event. This then has gone on to cause either a vortex displacement or vortex split.

Obviously the dynamics of any SSW or any major stratospheric warming are complex to say the least.

It was no coincedence that in the 1962/3 & 1946/7 winter certain things that were occurring at the time would set up a major warming that would last around 6 weeks or more.

Taking a look at the 1962/3 winter in particular:

In late December the PV was very cold and nearly circumpolar and was also surrounded by a chain of anticyclonic cells located from about 25N - 45N. When the PV is strong and cold it becomes very unstable and one of the more active anticyclonic cells retrogressed from the Mid Atlantic to the central US. This was a sign of things to come later on in January.

The anticyclone over the US caused temperature increases in the stratosphere, but collapsed in late December because it was a wave breaking 1 event, which is insufficient enough to break down the PV on its own

Around January 14th there was a rapidly building anticyclone in the Atlantic and a more slack anticyclonic system stretching across Asia from the Western Pacific Ocean. The two anticyclones began to squeeze the PV and made it elongate into a nearly symmetrical bipolar, or a wave breaking 2 pattern. Eventually these two anticyclones destroyed the PV completely and replaced it with high latitude blocking & easterly winds. In a nutshell, thats how the stratosphere influenced the great winter of 1962/3.

As for the dynamics of a major stratospheric warming, as I said its complex and I dont think anyone fully understands it yet.

The onset of a warming is defined by the first appearance of the -35c Isotherm at 10mb. The warming ends when temperatures warmer than -35.C are no longer observed.

Prior to the warming the PV tightens and winds increase, the vortex becomes very unstable at this time.

Planetary waves and stationary waves, known as waves 1 & waves 2, are responsible for the stratospheric/tropospheric coupling. Amplification of these waves is essential if we are going to get a major stratospheric warming.

Major warmings have two distinct phases in the lower to middle stratosphere. A split vortex event or a vortex distruction event.

Before any warming, you get a "pre warming". A well developed, cold, PV is present. An increase in kinetic energy between 30mb and 10mb, the temperature gradient from 50N to 80N reverses, and increases with altitude. As the temperature of wave 1 amplifies and peaks the resulting increase at 10mb is greater than at 30mb.

Temperature increases cause the height field of wave 1 to amplifiy, at the same time wave 2 declines to a minimum. After this, wave 1 rapidly starts to decay, like the Canadian Anticyclone in Dec 1962 did, and wave 2 quickly developes splitting the PV.

The main difference between major and minor warming's is not the amount of actual warming that occurs, but the difference in amplitudes of the diiferent waves. A ratio of 10:1 occurs between the amplitudes of wave 1 and wave 2 during the "pre warming" phase of a major warming. For minor warming's the ratio is much smaller, being only 2:1. This implies that major warming's are much more likely to occur when there is a dramatic increase in amplitude of wave 1.

In a major warming there is also a "critical layer". The critical layer is a level at which the mean flow switches from westerly to easterly. The mean flow below is westerly and the mean flow above is easterly, but at the critical level between the two the mean flow is neutral. This is based on the fact that geostophic planetary scale disturbances can only propagate upward when the mean flow is light and westerly. When the wind is easterly, or strongly westerly, propagation ceases.

A planatary wave encountering a critical layer is damped. As the wave is damped its energy is absorbed by the critical layer and its amplitude decreases rapidly. A large temperature gradient, either vertical or horizontal develops around the critical level. As the planetary waves continue propagating up into the stratosphere, they are absorbed by the critical layer, further deceleration of the vortex occurs and the critical layer descends even further through the stratosphere and eventually propogates down to the troposphere.

By going by the above, you can actually see similarities between this winter and some of the great winters such as 1947 & 1963. Both of which started late, both of which had similar stratospheric warming's as what's currently forecast and both of which had similar conditions to that we've had and look like having this December. By no way am I saying we are going to have another winter like 1947 or 1963, but it shows how quickly things can change, especially when placed with stratospheric warming's.

Most of the above is stuff from stratosphere reports, or stuff I have learnt or taken from experts on the stratosphere such as Chionamanic & GP. I hope it's not to far of the point, feel free to correct any mistakes I may have made as i am still learning and no way near knowledgeable on this subject.

The main point of this post is to highlight the importance of stratospheric warming's, the influence they can have on both tropospheric conditions and ground conditions. Whilst, for our part of the works, December looks like going our on a whim, this does not mean winter also is going out on a whim. There are a lot of knowledgable members on here going for a colder second half of winter, and I for one am with them.

There is a long long way to go yet, and a lot to forecast over the next couple of weeks that will impact on where we go in January. In terms of snowfall, there is an age to go. Winter is more than capable of biting still.

Edited December 16, 2012 by AWD

[AWD]

Am I the only one left standing in here? lol.

The NAE is starting to show Wednesdays rain event now so it will be interesting to see how this handles the depression. T48 shows a heavy, organised band of rain, approaching from the west, getting into Cornwall by dawn:

This is associated with a large depression in the Atlantic. Tight isobars also suggest gusty winds at times;

For anyone pondering about the Stratosphere. There has been a mention of downgrades in the Strat thread this morning. This is in terms of the temperature of any warming, which has been downgraded to more realistic levels. The warming itself is still there however at day 10. Here you can see two charts for the 10hpa level;

This is it currently;

This is it at day 10;

The 30hpa level now;

And at day 10;

You can see from those charts that there is still a significant warming forecast to take place, along with promising signs of a decent wave break 2.

Where this leads to & how it will affect the PV is currently uncertain, and this is the point I will transfer you over to the experts in the Stratosphere thread as I'm not confident on any outcome of any warming currently.

For the short term then, its all -

RAIN. RAIN. RAIN. MILD. MILD. MILD.

Edited December 17, 2012 by AWD

[AWD]

Looks like some shower activity tonight over Devon, Dorset & Channel coasts in particular;

I wonder, like yesterday, if there might be a rumble of thunder and a flash of lightning associated with these;

Possibly?