BrickFielder

Looks complicated enough for forecasts to be very difficult, but it looks like quite a few people expecting storms may be disappointed. Forecast SkewT's suggest cloud height may be limited and I guess we would need to see the midday soundings before we really get an idea. The forecast SkewT for southampton suggest storm development would be difficult, however I suspect the forecast SkewTs are likely to be slightly wrong. The first factor coming into play today is low level moisture advection with the lightning wizard charts suggest two distinct bands crossing the UK. The first of these two bands I think is likely to trigger convection particularly just inland from the south coast and might well benefit from insolation ahead of it. As to whether clouds will reach thunderstorm level then I am not sure. The second factor then may come into play which is areas of wind divergence aloft which will lift air potentially above the convective top. The south coast from midday to mid afternoon seem likely areas for this to occur along with perhaps an area in the north midlands. The third factor is low level wind convergence areas which again given insolation should create convection, although this may be complicated by another factor - orographic lifting especially across wales and the south west. Notice how winds converge over the south west, parts of wales and the north midlands. The forth Factor is the potential development of a surface low late on over the north midlands which shows up on the 850 wind charts. The fifth factor is downstream cloud cover from orographic and convergence zone lifting. Any predictions for today should come with a large caveat as a result. Key areas for me would be along the south coast early afternoon and potentially the north midlands later, South Wales and the south west. It is entirely possible that there will be no storms at all today, but with so many factors coming into play my hunch is we will. Cloud top temperature charts by lightning wizard suggest some areas may still see storms.

Good forecast my the MetOffice yesterday they pretty much got it spot on. Today convergence zones and moisture convergence in the lowest levels are likely to be the trigger for any storms today. Key area is likely to be south of London from the forecast charts. Forecast SkewT's show temperatures and low level moisture is key. Possible spoilers are residual cloud from decaying frontal system sweeping down the north sea and the low pressure system out to the south west not behaving as expected. Main risk will be isolated heavy downpours mainly in the south. Other areas to possibly watch would be just north of exeter, lincolnshire and perhaps through oxfordshire.

My first thought about today even without looking at the charts was that dewpoints were probably over done and surface temperatures under done. Now having looked at the forecast skewT's I don't think it makes much difference. Forecast SkewT's are a forecast only though and you need to cross reference them with actual soundings and here we see some temperature inversions at 800hpa and 650hpa. This means that initially cloud will build at a low level until a certain temperatur is reached when it will build to 650hpa. A further rise in temperature will be required to get cloud building to the highest levels. I also notice the instability on the actual reading (which I think will only be modified slightly during today) is more temperature dependant and instability is considerably weaker. What you should also notice is that lapse rates are rather week, which means air parcels will be slow to rise and hence storm clouds slow building. Watching the clouds yesterday in the west I saw how time ran out before the clouds could really start to build. Storms tend to need a trigger and today I think the key is divergence at mid levels. 700hpa vertical velocity charts and mixed layer cape charts tend to confirm this. This I think ties in with satelite cloud pictures where a band of cloud slowly moving east will destabilise during the day. Spoilers for today would be slow cloud build and poor cloud top temperatures. Slight instability just inland of eastern coasts where convergence zones set up at the surface could trigger an isolated weak tornado if the instability is realised. Lapse rates steepen a little during the day and temperatures are likely to stay higher in the south east so perhaps around the London area will be key and the convergence zone north east of London late afternoon could play a part. Over all I think the storm risk is limited today but expect a few heavy showers trundling north west from London and Birmingham lat afternoon.

I think Estofex largely have it right today when they say. S-UK was not added to the level 1 due to ongoing concerns of limited CAPE, as clusters of showers/embedded thunderstorms may decrease insolation/diabatic heating. A few marginal hail events are possible. If stronger diabatic heating occurs, the risk of an isolated tornado increases during the evening hours as LL shear intensifies. Cape is not that impressive and there is a risk of clouding over in the south east corner of the UK. Forecast SkewT's do show some turning of the winds through the mid layers which would make a slight risk of super cell development if instability was higher. Low level winds are just a little too brisk for tornado risk and I would see heavy showers being rather isolated. Some thing to watch might be a slight tongue of vorticity moving up from central France through central southern areas(suggested on the EUMET Satellite obversations), although this is likely to shift. Biggest risk would be localised heavy rain and hail. I am not quite sure what to make of overnight condiitions either. Surpisingly we may see some instability through the mid levels. Fax charts show a mixture of frontal and trough conditions and since this is coming in over night we should not expect much in the way of surface based instability (Forecast SkewT's confirm this). Still there may be some surface based convergence which could play a part. Based on that skewT you would suggest just very wet weather with some instability around the 500mb level but no real instability. The reason why I was looking at this was to see whether was a tornado potential. On the whole the whole thing looks more frontal than convective and it is unlikely to have the necessary updraft potential. Worth keeping an eye on though, as it is hard to predict. Key risk though would be for very strong wind gusts,and localised flooding. With trees heavy with leaf forecasters will be keeping a close watch on this.

Marked convergence zone moving slowly south is likely to be the focus of activity today. GFS and NMM suggest it is likely to be quite marked but the RASP model might suggest it slightly more broken. Convergenc zones tend to raise the risk of very spout like formed tornados, providing there is enough lifting at the convergence zone. Instability according to the models looks rather weak, suggesting lifting might not be that impressive. Considering that convergence zones can of themselves create some lifting and models have a tendency to under estimate surface temperatures while in some circumstances (this tends to be with winds from the direction of Spain) over estimate dew points it is difficult to determine the instability available. Cloud tops look a bit limited or slightly better further west, while a bit of a dry slot through mid to upper levels does not quite overlap the convergence zone. Mid level vorticity looks better over the south west but appears to be receding and lapse rates begin to decline later in the day to the east. Forecast SkewT's show the cloud top limit at 500hpa which is barely enough for a thunderstorm, with marked wind shear limited to above this region. Over all its not that impressive at first glance, but if I had to pick some areas then I would look at an area around exeter and possibly north london. The first due to slightly better instabillity and cloud height and the second because of the wind field and possible heat island effect of London. Main risk I think will be heavy showers and hail, with perhaps a very outside risk of a weak short lived funnel.

Rather messy situation today, but one thing to remember is that without instability you are unlikely to get severe storms. This is typically measured using CAPE and model view on this today are a bit mixed. Dewpoints I think might be key and a touch low in some parts of the south if forecasts are correct. Wind fields tell a mixture of stories.Low level convergence along the frontal zones, might perhaps be condusive to spout formation although it looks as if moisture profiles where moisture is present all the way up may not be that favourable for strong convection. Key area might be South west wales where there might be a little dryness aloft,and a little instability. The south east corner of the UK is closer to the jet and as such winds aloft are stronger. For super cell formation you might want to see some turning in the winds aloft or at least a marked change in wind speed aloft such that winds on one side of a storm are stronger than the other. I would certainly be looking at the channel islands in this respect, but am not sure instability and favourbale winds overlap across the south. Models could be wrong though and there are specific oragraphic features to the UK to make prediction difficult. Stronger surface winds over the sea in southern costal areas may play a part as well. NMM vorticity charts suggest a lobe of vorticity moving across the country from around devon through to the wash and I think I would look closely at the northern and southern boudaries of those lobes of vorticity for increased activity (Its the change in vorticity that is the key in my view). Forecast SkewT's suggest more instability through the midlands into east anglia, but more favourable wind fields for strong storms to the south. Cloud tops will not be that particularly high but the freezing level might suggest hail is likely. My overall view would be that there is a risk of hail and sharp down pours across the midlands and east anglia. Lightning and thunder risk due to cloud tops not being that high might be low although cloud top temepratures are low. Slight risk of spout based short lived tornadoes from around Hull to Liverpool and perhaps more particularly south west wales. There might be a very slight risk of tornados just inland of southern coastal areas where vorticity changes and surface winds get slowed by land surface. You would need to see instability materialise a bit more than models suggest for even this slight risk to materialise. Highest risk is hail and sharp downpours,but I have a suspicion that models will be slightly off the mark today.

It is not a bad description of the tornado genesis mechanisms that you would tend to find in the US plains. There are variations on the themes of horizontal vorticity being uplifted which tend to occur more regularly outside the US plains and its why Florida/California/UK might have more tornadoes per land area than Oklahoma, but of a much weaker variety. For a tornado to exist for any length of time you probably do need a super cell (turning cloud) and conditions for these are best where very warm air meets very cold air like in the US plains. There are other mechanisms by which than can be created, like storm splitting which can occur. Short lived tornadoes can also be created from existing vertical vorticity, like wind eddies around cliffs, thermal eddies due to orographic conditions etc. Another good place to start is ESTOFEX's (European Storm Forecasting Center) research and education link. http://www.estofex.org/

Increased cloud due to cosmic ray variations as mentioned above is one method that the solar activity can affect the weather. I some how doubt that it is the major solar factor afecting the stratosphere. I have seen some discussions on whether UV levels affect absorbtion of energy through the straosphere and also can affect levels of ozone in the stratosphere. Remeber ozone transports have a big impact on stratospheric conditions. Here is a link to a paper discussing some of these issues. ftp://ftp.lpl.arizona.edu/pub/lpl/lon/stratosphere/hood04agu.pdf One area which has not really been well explored yet is the affects of solar activity on levels above the stratosphere and whether those changes can affect the propagation of gravity waves into planetary waves. What I think I am suggesting here is that solar activity induced waves in the very top most layers of the atmosphere can have an impact on whether stratospheric warmings either occur or are weakened. Here is a link to a paper which sort of covers this subject, but I have lost the link to the NASA modelling system for levels above the stratosphere which perhaps came to more robust conclusions. http://hal.archives-ouvertes.fr/docs/00/31/63/46/PDF/angeo-16-69-1998.pdf Another solar affect is through the strength of the QBO which again has impacts on the stratosphere and weather gravity waves are likely to cause upward planetary waves are to propogate. In simple terms this is whether the triggers for stratospheric warmings actually cause a warming. ftp://ftp.lpl.arizona.edu/pub/lpl/lon/stratosphere/mccormack07jgr.pdf

Hi GP. I was definately in the camp that thought significant mountain torques due to the MJO were the main source of warmings and I am not quite so confident about that now. Rather I think it might be one source, with lesser mountain torques playing a significant part depending on their latitude. By significant mountain torques I am thinking about across Asia/Himalayas , US/Rockies and South America. By lesser mountain torques I am thinking about Greenland and Norway in which case the state of the AO may play a part and the MJO in a different way. I would be interested to here your thoughts on this ?

I expect forecast to be a bit tricky in the 8 to 10 day range as the displacement of the stratospheric vortex might or might not end. Perhaps I can show in charts what I mean about the end of the displacement. Notice how in this chart the blue low area is centered towards the UK. Now a couple of days later the forecast chart looks like this. The blue low area is shifting back towards the pole, or perhaps splitting. Not quite sure whether this evolution is right or whether we have a different kind of warming. The following chart suggest perhaps a split at the lowest level. Notice how the warmer air at the lowest level of the straophere on this chart is making its way round towards the UK from the US. That to me suggests a higher risk of high pressure in the atlantic and towards the UK. The following stratosphere vorticity chart out at tend days suggests a negative AO. So interpretting this and putting any sort of confidence on things is difficult. Because of the potential transition I would give a low confidence on my thougths which are : Perhaps ironically the end of the stratospheric warming is giving us a chance of colder weather. Because the colder weather is not really stratospheric warming induced the chance of sustained blocking is limited. My best guess is that we will get a chance at some northerly weather followed by an easterly period. At this point without further changes to the stratosphere I cannot see the cold spell lasting more than a week. So do we get another warming or not and here I am trending towards saying Yes based on the fact that we should have had some wave breaking over Greenland recently. Charts perhaps give hints but its too early to tell. Still some variation on Windy and mostly wet will be nice however long it lasts (probably going to regret saying that, I usually do). The old Maxim that whatever the east coast of the US gets, we get soon after might actually hold true for once in the 8 -16 day range, so perhaps worth watching their weather for once. Beyond that I would be guessing, but I think another cold spell in February is likely.

Nick Interesting report but I have only scanned it quickly. Some things I took from the report were : If we accept the given threshold of the horizontal divergence as indicator of mountain waves, Greenland, northern Scandinavia, Iceland, and Novaya Zemlya can be identified as the most active locations for stratospheric mountain waves during the 2009–2010 winter. and It was shown that the magnitude of the divergence is directly proportional to the temperature anomaly in a limited area surrounding the resolved mountain waves. This suggests to me that strong mountain waves associated with low pressure systems crossing mountains might confirm the idea that stratospheric warmings have their origins in tropospheric anomalous weather conditions, with the north atlantic being a key area. As for a total disintegration of the vortex in the short term, then this is possible and certainly I would expect wave breaking across some of the regions mentioned in the article Nick highlighted. For evidence I think I would be looking for a split vortex at the very highest level in the stratosphere which is not really there in the forecasts yet. Even then I think it might take a week or so to work down to lower levels and affect our weather. Some interesting possibilities though.

The potential cross polar air flow coming up might be interesting from a cold air displacement point of view. My guess would be that this could spill cold air into some new areas, super charging the jetstream in places. The US comes to mind.

Well it is really not the kind of stratospheric warming you would really want. Warmings tend to take a number of courses depending on the orriginal source of the disturbance that caused the upward propagating wave that disturbs the vortex. These are either a displaced vortex, a split vortex or break down of the vortex. Here we appear to have a displaced vortex and at the upper most level it is displaced towards the UK and Scandinavia. When we look at the vorticity charts for the lowest level modelled in the stratosphere we can see why it is not that good for snow lovers, since typically low pressure at ground level tends to congregate around the polar vortex at upper levels. At 8 days out the suggestion here would be high pressure towards southern england and low pressure systems skimming Scotland. That is actually a much more settled period really than we have now. So how does that compare to the ECM Deterministic forecasts. Well its not far off. A couple of days further out and things change a little and we get more of a ridge in the Atlantic and perhaps the hint of a northerly. The trouble is having seen these types of model forecasts before low atmosphere dynamics will act against the upper level forcing to mute the signal. Thats why I think the ECM deterministic forecast probably has the picture right. In terms of weather this is probably a return to more unsetlled weather. Looking further out you have to take into account that this displacement of the vortex has caused a fairly strong weather pattern with quite stormy weather towards the UK. This in itself is a disturbance which might cause an upward propagating wave which will disturb the vortex again in a little over a months time. My guess is that providing the wave does propagate (here conditions are not that ideal) then this type of disturbance (north atlantic based) would cause probably a split in the vortex. Again a guess would suggest that part of the vortex would be towards the UK intially, but would slowly move. If this comes of and its a big if then you might expect alternate cold and wet/stormy weeks through February. As ever its just guess work beyond about 5 days out.

There are a number of areas to consider today, although generally instability looks pretty poor. Perhaps a prime interest area today would be parts of eastern scotland, where there is likely to be a little instability with light but turning winds in the lowest level. This could be good conditions for a weak short lived tornado to develop. Another area to watch will be Kent and east anglia where we might get some destabilisation during the afternoon. Turning winds through the mid levels although weak are interesting although low level wind shear is generally not enough for tornado devlopment and updrafts will nto be that impressive a storm developing at an outflow boundary could in theory produce a tornado. Overall it seems unlikely to me. Next up is eastern parts of Wales perhaps stretching up to Manchester and the south west. Since there is some mid to upper level wind divergence strecth through from Ireland across this area late on and the troposphere boundary will be quite high there is a chance of some isolated storms. Vorticity charts suggest development in a line downstream of upland areas of Cornwall and Southern Wales. Conversely instability looks pretty non existant although some vertical velocity is suggested. Isolated and late afternoon could see some heavy showers. Overall its not that impressive, although I rather fancy someone in eastern scotland spotting a weak short lived funnel (maybe not touching down). Eastern England maybe a bit too messy for strong storm development and instability over the west may be too weak. I think I prefer the prospects on Saturday. In other words watch the radar and see how things develop is the best option now.

Mixed bag of opportunities for storms today. Over riding driver will be steep mid level lapse rates spreading eastwards. Upper level divergence occurs comming in from the east but is coming in later. Instability is fairly low until mid afternoon and then picks up into the early evening. Low level convergence Zones are likely to play a focus for storms. Potential areas for me would be South Wales mid afternoon to early evening. An area through the Midlands moving southwards during the late afternoon. Scottish borders, Ireland during the afternoon. East Anglia, Lincolnshire and possibly just north of London early evening. Since winds are generally weak going up through the atmospher the chance of a sustained tornado is poor, but convergence zones especially around north norfolk and Lincolnshire could support a weak short lived tornado (Caveat being updrafts may not be strong enough). Although I think cloud cover will hinder developments across the midlands at times since things are likely to be messy due to plenty of moisture aloft, late afternoon in the western part of the west midlands could prove interesting.There is also a chance of embedded thunderstorms in the rain band moving across the south west. Forecast SkewT's show a mixed bag with best instability probably across the midlands moving eastwards. Notice how the winds turn in the lowest level around Kings Lynn, but instability is fairly poor. Low freezing level means hail will be a risk again. Cloud cover will be key again, which may hinder some development. So plenty of opportunities some of which may come off. Best of watching the radar and satellite pictuires from here on in.

Not really that hopeful for most of the UK today. The exception being Ireland. Mid level lapse rates are pretty poor. Some suggestions about the north east getting some storms around, but looking at the forecast SkewT's I am not that impressed. Obviously this area does come under an area of synoptic lift, so it is possible to get an isolated storm, and these forecast SkewT's can be wrong , but on this basis I would not be that keen. Instability appears to be pretty limited. If I was to pick soemwhere I think I would look at somewhere like north wales. Instability is weak, but you could just about get a low topped storm from that SkewT. Looking at the Satellite pictures there are a couple of bright cells to the west and south west of Wales which make me think that there could be some fast moving heavy showers sweeping in from the south west. These types of cells might be worth watching for Wales and just maybe western parts of England. Low risk storm day, but if I had to pick somewhere then it might be Cardiff and on towards the Worcester area and again from north wales on toward Liverpool post frontal.

Some positive and some negative signs for storms tomorrow. As usual it is still al little early to put much meat on the bones. First lets talk about some of the negative factors and first up is mid lavel lapse rates. If you generally consider 26 degress diffrence between 850hpa and 500hpa to be the minimum lapse rate for storms to develop then most of the UK will not see storms. Next up is a forecast SkewT for Wrexham which shows cloud bases will not be that low and cloud tops will be lower than you would generally expect for a thunder storm. Looking at the very upper winds (300hpa) we don't really see much in the way of divergence aloft. Despite all indications that we will at best see some heavy showers rather than thunderstorms there are some factors which interest me. First up in the deep layer wind shear, which is relatively high in places. That sort of shows there is the possibility of rotating cells. While this would suggest tornadoes are possible the poor low level shear, weak instability and high cloud base puts a severe limit on the potential (read very low probability). The mid and upper level humidity charts kind of interest me as well because there is a very stark contrast here. Most interesting of all are the following charts. The first gives hints about general lift and subsidence of air and suggests lifting over parts of northern England. The second shows a mid level jet streak approaching from the south. Of course all this can change before tomorrow so we will need to wait and see, with the indicators for storms being rather weak at the moment.

Today could well be a bust as far as storms are concerned especially considering the cloud cover and the fact that we have a fairly cold air feed.For me there are three areas of interest. Firstly the occlusion currently crossing the midlands may pep up as it crosses Lincolnshire from around mid day. The forecast skewT shows it is possible but the air is moist all the way up. The next area to consider is the north east coast and here I am not convinced, the forecast skewT is not that promising. Both mixed layer and suface based cape are better but I do wonder how deep that instability is. The third area is from an area from oxford through to the east midlands from mid afternoon onwards. By this time the mid level lapse rates are begining to reduce. However there is a chance of the cloud brekaing up a little with some daytime heating helping. I also like the fact that it is under the left exit of a jet streak with some divergence aloft. Forecast SkewT's suggest there is a window of opportunity, which disappears late afternoon. Will any of these storms come off? I am not sure. The relatively cold air feed means instability will not be that great. Models don't appear to agree on moisture levels and there is not much in the way of clear skies on the satelitte pictures. Prime risk would be hail, low level shear is enough for tornados but updraft strenghts probably will not be strong enough to aid formation. An isolated one cannot be ruled out of course. Supercells seem unlikely to me due to the lack of wind shear through the mid levels. Some final vorticity charts which back up my thinking (note the 500hpa vorticity charts are somewhat different) (higher Absolute vorticity can suggest potential for air to lift). If you still non the wiser on whether we will get storms or not, then you are not alone.

Thursday looks interesting at the moment. To early to predict as the timing is most likely to be off, due to the developing system out in the Atlantic. Fax charts show troughs which is encouraging, but 06 model output is likely to downgrade things again. If the potential starts to pick up a little from the Wednesday midday model then I think it might be possible to get an isolated storm. Worth keeping an eye on anyway.

Slight chance of a thunderstorm although conditions are not that good for most of the country stormwise. Prime area I think would be across the midlands moving eastwards during the afternoon. The trouble is that there is not much of a trigger despite the moister pool of air across this area. I think we might be looking for orographic lift triggering across cornwall and wales. There is not much in the way of wind shear although I do notice clouds are moving at a moderate pace today. The zero degree isotherm is still quite low so the risk of hail is high. A couple more charts. Over all there is a chance of an isolated thunderstorm, probably down wind of the moors in the south west and the mountains of wales. Key area might be somewhere like Worcester to Wrexham in the afternoon or perhaps Reading late afternoon. Mostly I think it will just be heavy showers and many will see heavy showers passing either side of them. Biggest risk I think is from hail.

Saturdays forecast did not work out as expected ,what with the milky cloud cover at high levels in places blocking out surface heating. Thats the trouble with storm forecasting there is always that little dynamic that you miss that changes the outcome. Still on to todays potential and in a way I am a little more hopefull today, with some caveats again. First up an upper level jet streak places anywhere in a line from roughly southampton through to east anglia northwards under the left exit of a jet streak. Now I would like to compare three forecast SkewT's.London, Birmingham and Manchester during the afternoon. Firstly we have London where lapse rates are not steep enough, the air is less moist and we have no instability (no storms). Next up is Birmingham where lapse rates are steeper, the air moister all the way up and we have instability, but notice that cloud tops will top out at around 400hpa. Next up is Manchester where things are more unstable, the air is moister still and cloud tops are even higher. From a storm point of view, I slightly prefer Birmingham to Manchester as the moisture all the way up in Manchester could make things slightly messy. So on to a real measured skewT from Larkhill. Ok so some of you will be looking at the wind field at around the surface level and thinking tornado potential, but this would have been early morning and may not really be representative of conditions during the day. Apart from that it looks like with some daytime heating it could produce a storm. What we ideally need for storms is some sort of trigger.A surface trough or mid to upper level trough will do. Well there is a hint of something at 700hpa for Wales and some noticeable vorticity at 500hpa although I am not sure it over lays instability. So what about instability today. Ok neither of those is brilliant and where we have some instability it does not coincide with high cloud tops. So what about super cells and tornadoes as lightning wizard charts might be possible. Here I am going to point out that wind direction is unidirectional through the atmosphere. Unlike Saturday though I rather like the conditions for a rotating cell today. Here the differential in wind speeds might be enough to think about left moving super cells and storm splitting. As always it is important to look out the window and see what the actual weather is telling you. What I am seeing is a brisk breeze at the surface which tends not to be good for tornado formations. The clouds are moving along at a fair pace which suggest some wind shear. Cloud bases are mixed with some quite low which would be good for tornado formation. The sky is quite messy and temperatures at the moment are not that high. On the satellite I am watching the pulse storm which crossed cornwall and how the anvil streaks out ahead, probably somewhat blocking the heating out ahead of it.The track of the anvil is not quite the same as the storm track which is why I say somewhat and this might be indicative of some shear at upper levels. On balance I am not sure. If it was July I would be tempted to say we will get some storms. The limited cloud top in places, lack of instability push me towards fast moving heavy showers. The pulse storm which developed towards cornwall says otherwise and the fact that it looked circular was interesting. Key places for me might be Ireland, Wales and a hunch says a track from the south west through the midlands to lincolnshire and east anglia, but then I would considering where I live. As ever you know I will have missed a dynamic and the one chart which concerns me is the following one with limited cloud tops. Isolated risk of storms and low risk of an isolated tornado. Maybe the thing to watch today is the potential for hail with the zero degree isotherm quite low.Back to satellite and radar watching from here.

OK first of all lets have a look at the models, which I think are doing a better job than yesterday, although there is one caveat. I am not sure they have the cloud cover quite right. I am expecting some clearer skys across parts of the south later on, particularly the south west and possibly the south east coast.This I think puts the models slightly off during the afternoon for some southern areas. Looking at upper wind levels we have a small jet streak approaching from the south west during the day, with divergence at the left exit and to some extent along the right flank. Humidity through mid to upper levels moves north during the day, but notice the drier air at 500hpa coming in over east anglia and through the south west at 700hpa. This suggests there might be some good isolation coming up from the south west late on and the possibility of better storm organisation for east anglia. Vorticity charts would suggest a band of rain moving up through the midlands and another moving up through the south west through wales. Looking at lightning wizards charts for today you might be a bit worried about tornados and super cells. Quite correctly this model is picking up a truning of the winds up through the atmosphere, but rather than being concentrated through the mid levels the turning of the wind is mostly at the upper level. Rather than a rotating cloud you might get a anvil streaking out from the storm, rather like the storms over spain yesterday. That does not mean there will be no super cells in fact the forcast skewT for York looks promising.Notice the turning of the wind in the top right of the chart. Ok lets look at another skewT this time for the east anglian coast. What I could draw your attention to is the low level winds, where you have some turning and more importantly a significant difference in the wind speed at the surface and the cloud base. With the right conditions, namely a good updraft then this wind field could produce a short lived tornado. Short lived because without the turning cloud (super cell) it would not be sustained. So we should be asking ourselves what is the potential for a good strong updraft, apart from instability (Cape) and here lightning wizard charts help. Notice how the cloud base is likely to be higher the further east you are, which is not so good for tornado genesis, but there is some lift suggested across the midlands and east anglia. Ok one more chart and this one represents low level moisture and I want you to look at the low level moisture coming in from the south west. That should push up dew points late afternoon which I think could spark off some isolated storms. Ok lets have a look at a satellite picture to verify how the models are doing. Not too bad I think although there is that caveat about cloud cover. The MCS travelling up across into the midlands and moving northwards will I think most likely just produce rain until late afternoon in the north when it might start to break up a bit and re-invigorate. So some potential for northern England. The other MCS is perhaps a little more active in that it is driven more by divergence aloft, again I think this will re-invgorate later, but notice the isolated storm tagging along behind. These I think show some potential for the south west and parts of Wales. Notice also the potential for some line convection over France which might come into play if it moves our way. We should also note that line convection and tail storms have a way of creating their own little environments especially with respect to outflow boundaries and storm splitting which can change the wind field. This could pose an isolated severe storm threat. I feel fairly confident about the scenario for Wales and northern England but less so for southern England where much depends on cloud cover and how things develop during the day. Key places to watch would be southern Wales and northern england (Manchester/ Leeds corridor) with anything else a bit of wild card. There again I could be wrong as there are usually some dynamics I fail to pick up which alters things. I hope it was an interesting insight anyway.

Satellite shows a feature having crossed the normandy coast and approaching the south west. The positioning and timing of this make current model forecasts a little bit off. I am also watching the stuff over Spain as the residuals of these storms could potentially affect the outcome tomorrow. Looking at the satellite I would be concerned about some flash flooding heading towards the Somerset area, but it does depend on whether those storms fade and become elevated. Next up would be parts of Wales and onwards toward Manchester. A further band of slightly weaker activity should cross the Midlands by the look of it, although there does look to be some line convection around the jersey area at the moment which is interesting. Plenty of radar watching to do over the next few hours. As for tomorrow, then the mid level lapse rates are not that impressive and upper levels are fairly saturated, which could make things rather messy. At the moment I am taking the models with a pinch of salt with storm risk areas being generically further north. More tomorrow.

I am not really seeing a strong forcing mechanism either today or tomorrow. Tomorrow there is perhaps a chance of some low level wind convergence from east anglia across Merseyside and around the London area, but that may not coincide with the best low level moisture pooling. Orographic lifting could play a part especially across Wales or even heat island affects over big cities. Not really convinced yet.

Chance of a few storms tommorrow in the south west.