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Found 20 results

  1. The early hours of September 1st, 2017 brought unexpected but very severe thunderstorms to the south-east of England. Not only was it the intensity that makes them memorable to me but also the fact that (as far as I remember) they were largely unforecast and occured in a cool pattern. Proof you don't need heat to get big storms. After a brief warm spell, the closing days of August 2017 were cool/very cool with a slack NW flow. As high pressure built in from the mid Atlantic, a shallow trough became embedded in the mix and brought instabillity into the 1st. You can see the trough develop and pass into the low countries on the synoptic charts. I remember vividly being at home during the evening listening to music with my headphones in minding my own business when a flash from behind distracted me, only to my surprise there be a vivid lightning show. I checked the radar and a rash of severe thunderstorms were clung onto the south-east. Over the course of a couple hours the storms remained slow moving with torrential rain practically staying in place as storms back-built, dumping copious amounts of rainfall and causing localised flooding (coming after a locally exceptionally wet summer too). Most notably however was that despite it being night I could make out that there seemed to be a tornadic element with the clouds rotating and I did see what looked like a funnel cloud/tornado develop in the sky out my bedroom window, but didn't end up coming to much. It remains one of the most intense thunderstorms I've witnessed along with June 25th, 2016 (unbeaten to this day) and October 23rd (or 24th), 2022. Do you have any memories of these storms? Were they as intense in your area or was it a New Ash Green special?
  2. Hello everyone, I've just introduced this new topic about Greece. As you may know Greece doesn't mean just sun, fair weather and beaches. Furthermore, the very complicated orography can affect the weather from a place to another even if the distance is just a few Kilometers. So, I will use this topic to prove what I said . Of course, if anyone has any comments, queries or even matterial from Greece, he/she can upload.
  3. Long term viewer of this site and thanks for the great content. This is meant as a fun and hopefully informative thread to see to apprepciate some storms that may not be that well known. Perhaps even historical. I'll start with one from 1994. For those that haven't seen this, it's a fantastic delve into the past for what I believe was the mesocyclone on June 24th 1994. I remember this storm rolling into North London at around 7pm. A lightshow to remember! and part two being this...Notice how dark it becomes
  4. The Spanish met service have named the low pressure system for the end of this week Miguel Miguel will bring heavy rain to the UK through Friday and Saturday
  5. Storm & Convective Forecast Issued 2018-08-06 21:33:50 Valid: 07/08/2018 00z to 08/08/2018 00z THUNDERSTORM OUTLOOK - TUESDAY 7TH AUGUST 2018 Synopsis North Atlantic upper trough will begin to amplify S and SE across the far west of Britain during Tuesday, with a strengthening upper flow across the UK – as SWly jet stream shifts S and E across the UK. Ahead of the jet streak, a weak surface cold front will progress slowly east, to lie North York Moors - West Sussex by 00z Weds. A very hot, humid and increasingly unstable airmass ahead of the cold front across SE England and East Anglia is forecast to destabilise and produce thunderstorms in the evening here before the front clears through and introduces cooler and more stable air. … SE ENGLAND and E ANGLIA … Surface-based CAPE will build up through the day due to surface heating of humid plume in conjunction with lapse rates steepening in association with advection north of EML (elevated mixed layer) aloft. However, this surface instability is likely to remain capped. However, a shortwave in the strengthening flow aloft will move NE from Bay of Biscay area in the morning crossing NW France in the afternoon. The increased lift by the shortwave along NW edge of hot and humid plume over France and SE UK combined with increasing mid-level instability as dry air intrusion punches NE overlapping plume, is forecast by many models to break out thunderstorms across Brittany and Normandy by early evening, before spreading / expanding NE across SE England then East Anglia through the evening. Thunderstorms are likely to be elevated, though 40-50 knots of 0-6km shear forecast will allow storm organisation into clusters, perhaps even an MCS passing over parts of Kent and eastern E Anglia, so there is potential for strong storms that may bring locally intense downpours leading to flash-flooding, isolated hail, strong wind gusts and frequent cloud-to-ground lightning. These storms should clear away NE into the North Sea after midnight. Issued by: Nick Finnis
  6. Here are the current Papers & Articles under the research topic Thunderstorms. Click on the title of a paper you are interested in to go straight to the full paper. A climatology of convective available potential energy in Great Britain A lightning climatology for Europe and the UK, 1990–99 Mesoscale convective systems over the UK, 1981-97 Types of Thunderstorms The Met Office Arrival Time Difference (ATD) system for thunderstorm detection and lightning location. The Synoptic Setting of a Thundery low and Associated Prefrontal Squall Line in Western Europe
  7. Greetings ^^ This is my first post ever here on this site Hope we get along well ^^ Here is some collections of videos showing a very loud thunderstorms in Kuwait Hope you enjoy it One of the videos has my lightning detector in action ^^ The third video has the lightning detector & also a lightning strike X) Reminding : At the beginning of every video is the beginning of each storm, so the thunder will get louder the more you proceed with the video Note : For better experience please wear your headphones - thanks!
  8. A new thread for all things convective around the UK going into the summer of 2018. Old thread here: Convective weather relating to Europe should go into here: A chance of a few thunderstorms this week with central and southern parts of England and Wales looking most at risk. Although Monday is now moving into the reliable timeframe it is still too early to discuss specifics for the week as a whole. It is likely though that this week will provide some thundery showers or storms for a few of us. An easterly flow will probably favour more western areas for home grown storms, but elevated storms from the continent could also affect southern and south-eastern areas at times.
  9. I've just been looking through the lightning archive and I have been absolutely amazed at how much lightning has been recorded throughout this month so far. Every day so far, except for the 21st has recorded lightning somewhere in the UK, mainly in Scotland and Northern England. It really makes me think... has the UK just had one of it's most thundery Decembers on record? The dates that really caught my eye were the 7th, 10th, 11th and 19th (all pictured below).
  10. Please carry on here folks. Such boring weather we are having at the moment Lol. Let's hope tomorrow delivers something. Looking good for some if I must say.
  11. Yes I know it's only mid-April, but I think it's a good time to start asking "what do you want for summer" as late April and May can often be quite summery. You can select more than one option in the poll, just in case you want a few weather types. For example, I chosen heatwaves and thunderstorms - 'cause let's face it, it's what a summer should be!
  12. Wow!! look at the potential for this weekend and next week I really hope this comes off for us all. Please please let there be no downgrades lol. Anyway, please carry on here as you were.
  13. Here is a selection of wild weather photos that I have collected from the web. The thread gallery here contains almost 70 incredible photos. Apart from an amazing gallery of photos the question is are these severe weather events around the world becoming more extreme, not only this but are they becoming more frequent? (Have placed each image onto a same size background to enable easy viewing without size changing) Gallery: === === === === === ------
  14. A new thread here for the rest of Autumn. Autumn has been very good for storms this year! although sadly not everybody has had one yet. One rumble of thunder and one flash of lightning so far this year for me which I'm most grateful for . I am certainly not giving up any hope just yet as we all know storms can happen anytime of the year. Anyway good luck again all and don't forget to post up any pics and videos you have.
  15. New thread here. Some have been lucky and some haven't. Not one rumble of thunder for me so far this year!! but there's still time. Thanks for all your reports, pics and videos. Please carry on here.....
  16. The weather system is developing and starting to move into SW UK as i type with heavy rainfall setting in now, this system developing into a small but potentially potent low pressure is going to move quickly across Southern England through the early hours of Sunday and throughout Sunday. NAE and GFS bring a large area of heavy rainfall across Southern areas, some of this rainfall causing flooding, the air is cold at the surface and upper temperatures are reasonable for wet hill snow, and even a risk sleet at lower levels in places, although that risk is low. Another element of this system is the winds, there is likely to be strong gusts as the low moves across, with the south coast and some areas just inland from here through Sussex and Kent we could see gusts 50-70mph, the strongest along Southeast coasts i expect, and 35-50mph gusts across inland SE England and possibly other parts of the S/SW. Recent radar: Recent radar shows heavy rain moving into the SW now The NAE accumulated precipitation up to midnight tonight indicates 15-20mm quite widely and as much as 20-45mm across parts of Central Southern and SE England: GFS accumulated precipitation up to midnight shows 15-17mm widely: The surface pressure at 0900am on NAE shows the small-scale in size but potent low: There are two low pressures systems on the above chart of interest, the one we are focusing on at this stage is shown over Southeast England here at 9am or where NAE expects it to be placed at that time. NAE ppn at 0300hrs-0900hrs this morning, some very heavy downpours can be expected through Sunday and with these a higher chance of the rain turning to wet snow over the hills, or sleet at lower levels, but i must say that it's a low risk of anything at low level. (keep watch on Dew points/Surface temps) A move south of the low and we could see a higher sleet/snow risk and a move north i would expect the stronger winds on the South coast to be further inland. We could also see hail, the GFS 500hpa shows very cold temperatures at that level, chart is for 1200hrs: There is a risk of thunderstorms please see the convective thread for the information. Last of all below is a warning map i have created to show where i expect the most severe weather to be from the data i have looked at, a few of those charts are posted above. ESS
  17. Red sprites, blue jets and elves are upper atmospheric optical phenomena associated with thunderstorms ....... Sprites are electric discharges shaped in the form of a carrot or vertical column that form in the mesosphere (at a height of between 50 and 85 km). They often appear with a luminous "halo". Elves are rings that expand and propagate themselves horizontally at the speed of light across the base of the ionosphere (85-700 km). There is also a third group, jets, which are bluish lightning bolts that can electrically connect the top of the clouds with the base of the ionosphere. What is a sprite? A sprite is a very brief, luminous glow that occurs in the middle atmosphere. Sprites often start around 45 miles high (in the mesosphere) and extend upwards to the edge of the ionosphere (around 55-60 miles) and sometimes downwards into the stratosphere below (to as low as 15-20 miles). They are primarily red in color, except for some bluish tinge in the downward extending tendrils. When were sprites discovered? Human beings have probably noticed red sprites out of the corner of their eye since they first began roaming the Earth. Since 1886, scientists have periodically reported in scientific journals that they thought they had seen something they did not understand high above thunderstorms. Yet the “discovery†can be traced to 6 July 1989 when University of Minnesota Physics Professor John R. Winckler was testing a low-light video camera for an upcoming research rocket flight. On playing back the tape, he and his graduate students, Robert Franz and Robert Nemzek, were astounded to find two fields of video showing two giant columns of light towering high above distant thunderstorms in northern Minnesota. They were quick to realize this “accident†might actually explain over a century of unexplained visual reports of strange lights above thunderstorms. How long does a sprite last? Sprites are very brief. The portion of the event that might be visible to the naked eye often lasts less than one hundredth of a second. When using a “night vision†camera, they are visible for longer periods, but rarely more than one tenth of a second. GO TO TOP How big is a sprite? Huge! Aside from stretching vertically for as much as 45 miles, the sprite can often be tens of miles across. Often sprite events comprise a series of individual sprites that occur in clusters stretching 50 miles or more across the sky. The entire volume of atmosphere enveloped by a sprite can cover thousands of cubic miles. What causes sprites? Lightning. Sprites are the result of extremely powerful lightning discharges sometimes occurring within thunderstorms. They are almost always triggered by a powerful positive cloud-to-ground (CG) flash which lowers massive amounts of electrical charge to the Earth. This momentarily increases the electric field in the middle atmosphere beyond the point of “dielectric breakdown.†In other words, a giant spark occurs, usually starting around 45 miles above the ground. Electrical streamers then race both downwards and upwards from that point. Though sprites may look rather “solid†in many images, when viewed through telescopes, many sprites are actually composed of networks of thin channels of electrical streamers. Only a very small percentage (<10%) of positive CGs actually produce sprites, and then, only in certain storms. Do sprites connect with the clouds below? Good question. At least from the low-light camera images obtained to date, it does not appear that the downward extending tendrils actually reach the tops of thunderstorms below. But the brilliant glow from the parent lightning discharge in the cloud makes it difficult to tell for sure. It is important to note that sprites do NOT shoot up from the cloud. The luminous structure actually starts many miles above the storm which contains the parent lightning discharge, and extends both upwards and downwards. It is possible that some tendrils may extend all the way back down to the cloud, but scientists are still working to prove this. What gives sprites their color? Current thinking is that sprites result when free electrons in the thin atmosphere are accelerated by the sudden change in electric field strength caused by the parent lightning discharge far below. When the electrons slam into molecules of nitrogen, they cause the nitrogen to glow. Certain energies result in primarily red optical emissions, but in the lower part of the sprite, blue colors can also be seen. The process is not all that dissimilar from the aurora, where the energetic particles are supplied by the solar wind. Oxygen also is activated in the aurora, accounting in part for the green and white colors that also occur in that phenomenon. Some humans see sprites as white or green in color, but that is a result of the inability of the human eye to distinguish colors at such low intensities. How did the sprite get its name? When people first began reporting sprites, initially from naked eye observations, and then in 1989 on video tape, no one really knew what to call them. Rocket lightning, “flachenblitzâ€, upward lightning, cloud-to-stratosphere, and even cloud-to-space lightning were just a few of the names used. This started getting very confusing very fast, especially as no one knew if the phenomenon was actually lightning (as opposed to be being a result of lightning), whether it was connected to the clouds, which way it went, and whether it reached into “space.†Thus, early on, scientists realized that a name was needed that was descriptive of the phenomenon, but did not imply that we understood the physics before we did. "Sprites†are mythical, fleeting, and playful creatures that appear in mythology and Shakespearean plays. The name was first suggested by Prof. David Sentman of the University of Alaska-Fairbanks in 1994, and it stuck. As new transient luminous events (TLEs) above thunderstorms were discovered, they were given names in the same vein: elves, trolls, gnomes, pixies and blue jets (which just named themselves because they looked just like...blue jets.) What shapes do sprites take? Like snowflakes, no two sprites are alike. Early on, scientists were rather bewildered by the amazing variety of shapes they were seeing in their TV monitors. Soon they started attempting to classify them by shape, and terms like carrot sprites, angel sprites, broccoli sprites and A-bombs emerged. Tall, skinny sprites, now usually called columniform sprites (or c-sprites) were initially called diet sprites (who said scientists don’t have a sense of humor!) Can you see a red sprite with the naked eye? The majority of sprites are probably just a bit too fast and too dim to be easily seen by the naked eye. But given the right conditions, one can visually observe the brighter sprites. (See our section on how to watch for sprites.) It is difficult, though not impossible, to capture a sprite on a consumer camcorder. If you can add a “night scope†attachment, your chances of capturing one on tape go way up. How do scientists detect sprites? Sprites and related phenomena can be detected in a variety of ways. Aside from the naked eye, low-light cameras and sensitive optical sensors are the main instruments used to detect sprites. One can also detect sprites, or more properly the radio emissions from their parent lightning, by using extremely low frequency (ELF) and very low frequency (VLF) radio receivers. Do sprites make thunder? There is growing evidence that sprites - or their parent lightning - may produce sound waves at extremely low frequencies (around 1 Hertz). Below the range of human hearing, these infrasound waves can be picked up by special receivers at ranges of hundreds if not thousands of miles away. While not thunder in the usual sense of the word, these infrasound emissions are the acoustic signature of the processes which produce sprites. Where have sprites been observed? Sprites have now been observed over much of the world, with the exception of the Arctic and Antarctic regions where thunderstorms are almost non-existent. The High Plains of the United States probably have some of the highest sprite rates due to frequent, large nocturnal thunderstorms during spring and summer. But sprites are likely to be common above storms in northwestern Mexico, Argentina and southern Brazil and central Africa. Sprites have been photographed over Europe, Japan, Peru, China and Australia, to name a few. What is the connection between the Space Shuttle Columbia and sprites? Shortly after Prof. John Winckler observed sprites from the ground in 1989, NASA officials realized that they had been using similar low-light cameras on the Space Shuttle to take pictures of lightning and other events. A review of the payload bay video cameras flown from 1989 to 1991, found at least 18 examples of what appear to be sprites. Then in 2003, the first Israeli astronaut, Ilan Ramon, flew on the STS-107 mission with optical equipment designed to make detailed, calibrated images of sprites. Within several days of launch, successful images of sprites (and elves) were sent back to Earth for further analysis. Did sprites pay a role in the loss of the Space Shuttle Columbia? Shortly after the tragic loss of the Shuttle Columbia on 1 February 2003, wild rumors began to fly that the Shuttle was brought down by a sprite. This was fueled by reports of a picture taken by an amateur astronomer in San Francisco purporting to show some sort of “lightning-like bolt†striking or emanating from the orbiter as it flew over the California coastline. As of this writing, NASA has not released the image for external scientific review. But neither the description of the image nor the weather conditions at the time suggested that a classic sprite could have been involved. If the image does not turn out to be simply an optical illusion, then the possibility of some as yet unknown electrical phenomenon at the base of the ionosphere will have to be investigated. What are the major “layers†of the atmosphere? Earth’s atmosphere is proportionately thinner than the skin on an onion. And like the onion, it comes in several layers. The lowest layer is called the troposphere. Rarely more than 10 miles deep, it contains almost all of Earth’s weather systems. The next layer is the stratosphere, where temperatures slowly increase with height, producing stable conditions. It is also home to much of the planet’s shield of ozone. This gas absorbs most of the harmful ultraviolet radiation streaming in from the sun. At about 30 miles the stratosphere gives way to the mesosphere. This layer is where many incoming meteors burn up, leaving fiery trails across the night sky. Higher yet is the hot thermosphere, where most aurora are found. The outermost layer is called the exosphere which gradually merges into “space,†which as we have come to learn, isn’t quite as empty as once thought. The ionosphere, a region of electrically charged particles, is considered more a part of the thermosphere, and it, too, surrounds the planet like a shell. What is an elve? The elve was first theoretically predicted by scientists at Stanford University in the early 1990s and then observationally confirmed by imagers on the Space Shuttle and the ground (by Tohoku University scientists) several years thereafter. The elve results from an especially powerful electromagnetic radiation pulse (EMP) that emanates from certain lightning discharges. As the energy passes upwards through the base of the ionosphere it causes the gases to briefly glow. Though as bright as a sprite, the elve only lasts for less than a thousandth of a second. This makes elves virtually impossible to see with the naked eye. They are most likely red in color, and if you could see them, they would look like giant expanding doughnuts. They occur at a height of around 60-65 miles, and can expand outward to several hundred miles in diameter. What is a blue jet? The blue jet was caught, again quite by accident, on low-light cameras from the University of Alaska-Fairbanks onboard a NASA research jet in 1994. The jets appear to spurt upwards from cloud tops at speeds of 50-100 miles per second, reaching heights of up to 25 miles before fading. They last generally less than a quarter of a second, but it is possible to perceive their upward motion with the unaided eye. While generated by storms with high lightning rates, unlike red sprites, blue jets do not appear to be related to specific cloud-to-ground lightning discharges. They also appear more likely to occur near the highest portion of intense thunderstorm cells, such as those which produce tornadoes and severe weather. Can you see blue jets with the naked eye? Yes. At least the brighter ones. They emerge from the tops of intense thunderstorm clouds that are highly electrically active. They are a pale blue in color, and often appear as grainy, upward shooting blobs or cones of light leaving a trail behind. It is best to be within 100 or so miles of the storm as blue light does not transmit well through the atmosphere. A moonless night in a rural area away from city lights, and a dark adapted eye will help in spotting the elusive blue jet. What is an upward superbolt? We are beginning to think that true “upward lightning†may well exist. Regular lightning flashes can sometimes jump outside the parent cloud, and rarely extend a short distance (less than a mile) above storm tops. But a growing number of reports describe brilliant white channels extending upwards many tens of thousands of feet above storm tops. They resemble ordinary lightning channels, but also appear to last much longer, up to one or two seconds, and do not flicker. They also seem to grow upward out of the cloud, and upon reaching their maximum height, the entire channel dims away. They may well occur above the tops of explosively growing clouds. They often occur every few minutes, and episodes can last for a half hour or more. Thus, they may not be too hard to photograph.e http://www.sky-fire....ejetselves.html
  18. Starting a topic early as there is a risk of some active weather as early as wednesday eve/night along the cold front, with an unstable air mass following on behind, creating the potential for thunderstorms, these arriving overnight potentially into the SouthWest and moving inland into thursday morning, with this convective activity becoming more widespread lasting into the night time and through friday. I have included some charts to show the unstable air, the cold front could be quite active with some very heavy downpours, not to sure about thundery at this stage though!
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