Generalelectrix

Hi @all Beginning to look very interesting surprisingly early in the event already, wow.. Harry posted a question a bit earlier on: quote:"Does anyone have any thoughts on the potential for an MCS Saturday night also?" This model is pretty much more often correct than not IMO http://www.modellzentrale.de/WRF/animate2b.htm?../12Z/?25?h/maxDBZ_eu.png?3?0 Edit: Excuse moi, I thought this link would send you straight to the Piccie, but it doesnt, so you have to download all images and then forward click to Sat 19 Jul 06z Shows some whopper storm with max dBz of 60+ (!!) predicted radar reflectivity spanning right from London to Dover. Havent seen this predicted for quite a while. That could be our Saturday morning MCS, and what a violent one.. Might be useful to keep an eye on the next runs. Here the link: http://www.modellzentrale.de/WRF/index_all_en.php (click on sim. reflectivity/shear) We wait and see, huh? Ralph

Morning@all @ Greenday: No, the dryline will be further south today, I expect it to extend from about Basle in Switzerland to Salzburg, Austria. This line will separate moist, unstable airmasses in the north from dry "foehn" air immidiately north of the alpine ridge. Strong foehn winds coming from the south are expected as of this afternoon as the low pressure area moves in from the west to southern Germany, creating a pressure gradient over the alpine region. I expect violent developments along this dryline over northern parts of Switzerland, southern Germany right into Austria with large hail and strong wind gusts due to the effect of evaporative cooling in the dry airmasses! As I am currently working there I will take off a bit earlier than usual this afternoon and position myself somewhere in the southern part of the Black forest, it will either be a corepunch for me or maybe some spectacular photos of isolated cells immidiately to my north, strobing away in the evening light. We shall see.... Will report back Ralph

@ Flashbang: Thats where I would have headed too, we would probably have met had I made it to the UK yesterday Ralph

Well, I would say your chances of catching a cropper on the speedway are easily thousandfold compared to being struck by lightning, so dont worry.. Ralph

@ Speedway Slider: The setup last night wasnt your everyday thunderstorm. Storms which fire up in the region of a high pressure area normally tend to to be more intense lightning wise because the updrafts can go to a great height and have higher windspeeds. Yesterday was typical, the cap was broken sometime during the evening, a few cells fired, grew stronger and started organizing themseves. A very localized small low pressure area is created by the cells and thats what keeps them going. Possibly heat rising from London and Reading helped with the initial triggering. Judging by the number of strikes over the Reading area it surprises me that "only" 10 house fires were caused. Also, with these setups the electrical power of the strikes is higher than with ordinary storms, the strike is hotter and can set off a fire more easy. Lastly it always surprises me how few lightning conductors I spot on houses when I am in the UK... @Flashbang: Hogs Back has quite a lot of trees which hinder the view, did you position yourself more to the east end facing Farnham? Glad you guys and girls in the storm starved region got a good lightshow last night, Im actually quite sad I missed out, was supposed to have been back in the UK yesterday afternoon,but too much work in germany, better luck next time Ralph

@ Speedway: Umm, sort of see what you are getting at, in the case of the bolt passing overhead at 4miles up and striking ground 4 miles away the rule would apply, otherwise, if the bolt passes overhead closer and strikes 4 miles away the rule wont apply, you get to hear thunder first from that section of lightning closest to you, regardless of where it finally hits ground. Thats why these strikes have such a long, reverberating thunder. Ralph

Quote Speedway Slider: Now, does that mean that anyone under the length of that bolt, ie from where it left the anvil/cloud to the point if strike, lets say 7 miles away would here the thunder instantly as it would be directly over people for 7 miles, everyone underneath the bolt would not count past 1 second before they heard the thunder produced from the section of bolt above them, if so, that would be the thunderclap from hell, yes? No, remember the bolt is quite a couple of thousand feet above their heads, so ther is a certain time delay. Those bolts do sound rather ominous though, reverberating thunder with deep bass. The thunder at the point where the bolt then strikes the ground is instant and incredibly loud, more like an explosion at the ammo dump Never heard something like that before or since On the video Norfolk Sheep posted the stepped leaders are clearly visible btw Ralph Edit: explosion is putting it mildly, massive detonation is the better word, remember that a pos strike carries a multiple of amperage as compared to a neg CG, the diameter of the ionised channel is thus larger and more air is displaced at once!

@Speedway Slider: well, yes, youre basically summing it up, its normally towards the end of the Thundercells life cycle that the positive charge in the anvil takes over. There has been much speculation as to how and why but basically it is so that normally the base of a thundercloud is negatively charged and thus the ground directly beneath it automatically takes on the opposite, positive charge as well as the upper part of the Cb, also positive. The strength of the positive charge of the ground decreases the further away the storm is, basically like isobars around a low pressure centre for example. When the storm is mature the ground underneath it and the surrounding areas in close proximity are strongly positive charged, so a pos bolt out of the upper cloud would have an immense distance to travel to a less charged area away from the storm and the difference in potential normally doesnt allow for a breakdown. (Very rarely it does, EXTREMELY DANGEROUS, experienced it only once about 30 years ago.) Now when the storm is weakening, the negative charge on the base of the storm decreases and with it the positive charge of the ground underneath decreases in proportion, i.e. the neutrally or even negatively charged areas of ground surrounding the storm shift closer to it. (remember the isobars) Now the distance (or voltage) required for a strike to take place is much reduced, hence the occurrence of positive CGs then. Im not good at explaining, hope this helps a bit. To what happened 30 years ago: I had just moved to South Africa on a few year work stint and had bought myself a seconhand stereo receiver, a Sansui unit, the last one with valves I think (Budget was tight then) To gain access to uncensored news you had to tune into an AM station located in the then independant Transkei, it was called Capital Radio 604 and was funded by Capital in UK. To improve reception I climbed 2 trees in front of the apartment and crossed them with a length of scooby wire with the end leading through the window to the stereo. I did notice a thunderhead in the distance (30 miles maybe) flashing away in the dusk, went back inside, connected up the aerial, pushed the ON button, uncorked a beer while the valves warm up, stood by the window looking outside and then WHAM!! A bolt of lightning exited the anvil, travelling a large distance horizontally to eventually hit a tree close by, which in turn literally exploded, spewing bark everywhere. Incredible sharp crack of thunder, neighbours ran outside to look. My "aerial trees" had not gotten hit but out of the corner of my eye inside the room I saw a flash from inside the stereo and it went silent. The thin scooby wire had vaporized at the aerial connector of the stereo and when I opened it up three capacitors in the tuner were popped. After replacement the unit worked fine for many years, and I think if it had been a more modern transistorized stereo it would have been destroyed beyond repair. The scary thing about this is how much potential must have been in the air at the point where this bolt out of the blue hit to where the makeshift aerial was, the distance being at least 300 yards. Never seen something like that in Europe..... Ralph

Hi@all Nice to hear that so many left the NSC in the last couple of days, thanks for uploading photos and vids, keep it going Re: the electrical nature of strikes, just wanted to add that the most dangerous pos CGs are the ones coming out of the clear sky underneath the anvil. They can strike many miles away from the actual centre of the storm lightning activity, the "bolt out of the blue" as its called. Anyone of the chasers ever noted that when a storm has just passed, the last strike is normally a loud booming pos CG after which the storm moves on. That one usually is the final strike out of the anvil and is the sign to pack your cameras and equipment and get going.. In Europe, Stuttgart is getting pasted for the second time in 24 hrs see here http://www.metradar.ch/2009/pc/index.php The right mover with the hail in its baggage is moving in the direction of the airport there.. Ralph

Hi, 7cm hail just been reported south of Stuttgart, Funny how just in time for the 70 anniversary of the D-Day landings many major German cities get a pasting from above once more To whom it may interest: here is a link to a Swiss website providing hi res Radar coverage with lightning overlay of Switzerland, SW Germany, E-France, Austria west and northern Italy. It is free of charge and very accurate: http://www.metradar.ch/2009/pc/index.php You can watch Stuttgart being thumped in technicolor, Blue means slight, green medium, yellow high and pink extreme precip with hail. Orange dots are cc strikes, red dots are CGs Please excuse the quality of the english version grammar wise, I am busy preparing a revised one :-) Ralph

Morning@all Sadly the death toll in Germany has risen to 6, mostly people who were buried under fallen trees. Although I did voice my concerns twice in this forum about the impending dangerous setup it came alot worse and more violent and further south/ east than expected. That is what makes forecasting such a tricky art. Railway and bus transport are still disrupted up north, cleanup is in progress. There will surely be some more news during the course of the day. Right now I am checking out the charts for my region, todays the day.... Ralph Cheers @ Brickfielder for your insight, very conclusive. UK and continent weather may have some more surprises in store for today

@ Flashbangetc and Harry: Not all places on the continent are Stormdorados: I am right now sat on the Swiss border in Constance and this is also a place which is notoriously avoided by storms. Tonight there were thunderheads flashing like burnt out cfls around me but nothing to grasp really. Not one decent storm this year. But I know one or a couple will come this year, and you will get you fair share too, just wait a little... Night Ralph

Jawoll, vee take zat, but only 0.5 points for our UK players, to make 1 point you need bigger hail, ja? Ok, enough off topic, there is something I wanted to point out a while ago already: for those living on the south and east shores there might be a possibility of spotting sprites or blue jets in the troposphere above these cells over the continent. Night vision binocs would be excellent aid. Here more: http://www.sky-fire.tv/index.cgi/lookforsprites.html Ralph

Now start looking for the "cold ring" signature on the IR satpics, should appear soon. This is a rare event even here on the continent. Here more info on this https://www.google.de/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0CFMQFjAC&url=http%3A%2F%2Fwww.eumetsat.int%2Fwebsite%2Fwcm%2Fidc%2Fidcplg%3FIdcService%3DGET_FILE%26dDocName%3DPDF_CONF_P61_S7_04_IRSICZIB_P%26RevisionSelectionMethod%3DLatestReleased%26Rendition%3DWeb&ei=eRmWU7itOeuq7QaH0ID4Bw&usg=AFQjCNEhRaSYn29JItrJdqGtco3OOiY9IQ @ Knoxgar (off topic) Bin gespannt was du sagst wenns dich morgen so trifft nothing important back to topic Ralph

@ Tara: fastforward the SAT24 loop, makes it easier to determine the direction @ Noah: Nowcast is the name of the game, you can see its getting unstable NW of the french supercell Ralph Bremen: http://www.bremen-tourismus.de/webcams

Hi@all Just fired up the computer, and a quick peek at the charts gave me wide eyes! In my post yesterday I mentioned a volatile situation developing over France, BeNeLux and nortern Germany. I would like to change that to highly explosive. The so called "loaded gun" is about to be fired by the current passage of a very pronounced short wave trough over the BeNeLux which in turn initiates the formation of a surface low that can quickly erode the CAP. The rapid formation of supercells and clustering into a massive MCS will be the result, with us maybe witnessing a rare phenomenon here in Europe, the "cold ring shape", visible on IR Satpic as a round area of very cold cloudtop surrounding the warmer dome shaped and pulsating updraft area. Massive hail expected, making the current action there harmless in comparison. Destabilisation further westwards is very probable, the SE UK can definitely expect some action later on. (see Estofex &co) Widespread conclusiveness.. What still gives me thought is that due to the public holiday in these places many peeps will be travelling or out in the open and get caught unawares Ralph

Thanks @ Brickfielder for evaluation @ Panayotis: Cool vids, watch the clouds bang their heads on the CAP.. Ralph

Agreed @ The PIT. lets have a peek at the Hers... sounding when it arrives, we will at least see a tendency then. Münster (Monster? ) storm not bad, Vee Haf red alert: http://www.unwetterzentrale.de/uwz/index.html Ralph

@ The PIT: I fully agree with you, but it is undoubtedly the most reliable instrument for nowcasting and short term forecast, these arent computer generated data sets but actual evaluation of the conditions prevailing in the upper atmosphere. Had the Herstmonceux ascent taken place at12z yesterday we could have called it a day in the SE right away and gone swimming instead :-) Todays ascent (shold it succeed,grin) should give us a good hint of things to come tonight and into the early hours of tomorrow morning. @ Harps and Mapantz: Its gonna be a tight one for anything to hit land IMO, would be nice but unfortunately with the current charts the pressure setups arent going to change much till tomorrow night, both the high and low pressure areas stay put. Just a quick peek at the Theta E and LI charts show a pronounced stabilization westwards across the channel from the continent to the British isles with some instability scraping the far SE in the hours tonight. The influx of increasingly unstable airmasses to France, BeNeLux, northern Germany as time proceeds into Monday night (LI of -5), increasing windspeeds aloft and good shear make me ponder somewhat as to the setup on the continent: It seems to boil down to a very volatile situation there, with good chances for violent Supercell formation, major hail and thepossibility of tornadoes. Unfortunately this coincides with the end of the long weekend (Pentecost), lots of people will be travelling back home in densely populated areas, hmm, something to keep an eye on maybe... Would love to post some charts to illustrate, but just cant seem to get it working Ralph

Morning@all The balloon crew at Herstmonceux have managed to launch the "midnight express" The Skew-T diagram 00z today basically sums it all up (courtesy UNI Wyoming) http://weather.uwyo.edu/cgi-bin/sounding?region=europe&TYPE=GIF%3ASKEWT&YEAR=2014&MONTH=06&FROM=0800&TO=0800&STNM=03882 Cap, divergence, dry air intrusion etc, all convection killers for the SE UK I would say: BBQ and swimming time today there Ralph

Goodness, on SAT24 vis Brussels looks like its been nuked, wow. That cell looks almost like a "hot tower" judging from the impressive shadow its throwing. Wonder how high the cloud tops are. Goes to show what happens when the cap is finally broken by a mechanism like UHI or similar. Those isolated cells just suck up the energy laden air under the lid surrounding the storm like a gigantic Hoover and spew it upwards into the troposphere. Quite amazing.... Talking about being capped: Was wondering what kept convection from getting-a-going in SE UK,the reason why I was chasing the 12z Herstmonceaux sounding. Looking at the GFS 18z charts for wind at 300 Hpa gives an idea: High winds aloft create divergence at the right exit (SE UK) Left exit is where the action is now over the UK. The position of the Jet will stay the same till past monday if the outcome coincides... Something to bear in mind when forecasting the next two days methinks Hope some more have a little lightshow tonight, I sure wont Ralph

@ gael force: maybe the baloon popped Nottingham sounding not hot at all, Mr. Sun seems to have a fair bit of work to do still... Camborne sounding is a little better, CAPE starting to pick up there. Ralph

Thanks Dancerwithwings, I have now scoured the net for releases sooner than those here http://hoot.metr.ou.edu/upperair/sound/current/international ,no luck :-( I fear that the state funded Infos are clammed for a certain timespan before being made public free of charge. This gives the mets which have access to paysites a head start on people like us in the forum... nevermind.. Ralph

Quick question: which website is updated the quickest in regards to the Herstmonceux soundings? The 12z from today would interest me a great deal.. Thanks Ralph