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Storm & Convective Discussion 12z 21/7/14 ------>

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Here's a video I've made of this morning's thunderstorm:

 

Here are some still images from the video:

Awsome stuff mate, Love pink morning lightning, sounds like that was directly overhead :D

Edited by Stormyking

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Can I ask a question to do with convection and jet plane contrails please?

Well, here goes....

I have noticed recently that the high altitude jets seem to leave far superior contrails when the atmosphere is conducive to convection, and when not, jet contrails seem to be poor or even non existent?

Have these observations I have made true in some way, or completely coincidental and have no substance at all???

Cheers

Slider ...

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Can I ask a question to do with convection and jet plane contrails please?Well, here goes....I have noticed recently that the high altitude jets seem to leave far superior contrails when the atmosphere is conducive to convection, and when not, jet contrails seem to be poor or even non existent?Have these observations I have made true in some way, or completely coincidental and have no substance at all???CheersSlider ...

I've noticed this (well I've wondered about the link) thought it might be to do with the excitement of the molecules - ie the air is a more lively gas perhaps?Also: noticed potential for Southern counties on sat - anyone can expand on this? Edited by Flash bang flash bang etc

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I've noticed this (well I've wondered about the link) thought it might be to do with the excitement of the molecules - ie the air is a more lively gas perhaps?Also: noticed potential for Southern counties on sat - anyone can expand on this?

 

@ Speedway Slider...As contrails are mostly made up of water vapor it could be something to do with a higher level of moisture in convective situations. However, this is just a best guess.

 

Flash bang, the potential is there but at this range it is just potential and therefore won't go into too much detail as yet. It is one to keep the eye on though. Make sure to check netweather Friday/early Saturday so that you see any forecasts or thoughts people on here have on it :)

Edited by Supacell

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[email protected]

To answer Speedways question: Yes, your observation is connected to the rise of moisture level in the upper atmosphere, this is normally the case ahead of a cold front or disturbance, where large amounts of

moisture are transported to high levels by deep convection such as Cumulonimbus clouds. (Thunderstorm exhaust gasses, so to speak :rolleyes: ) This moist air is transported aloft ahead of a frontal or storm system

and when jet aeroplanes fly through this level of air the hot exhaust gases from the turbines, which contain a lot of water as a product of the cumbustion of kerosene, will condensate to form ice crystals, the so called contrails. If the weather conditions are stable upstream and air aloft is dry the ice crystals sublime (go from a solid form directly to gaseous form) and the contrail disappears soon after the plane has passed. If the level of moisture is high then sublimation cannot take place and the contrail will stay in place for a long time or even spread when enough moisture up there spawns the formation of more ice crystals. Just for interests sake: have a look at an actual (not progged) Skew-t diagram made a few hours before a cold front crosses over.

 

Ralph

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Contrails tend to form more in the warmer air occurring at high levels ahead of fronts, more often warm fronts rather than convective situations. Not totally unknown but they can occur. Somewhere in the Guides are the actual values needed for contrails to form and values for them to be persistent when looking at a T-phi or Skew-t diagram.. The level of Contrails is called the MINTRA level or Minimum Trail Level. It was first developed during the second world war to prevent bombers being 'visible' from the ground.

Edited by johnholmes
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very potent setup here! humid surface air (dew points around 21°C), a stationary convergence, PPW 40 mm, 1500 J/kg midlayer CAPE! Estofex with lvl 2 for my area!

 

Posted Image

Edited by Knoxgar

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First bangs (flash rate around 15/minute, tend to increase rapidly)

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@ John Holmes: yes, indeed so, the upper layers ahead of warm fronts have such a high layer of moisture in them that the sky tends to get hazy and full of cirrus patches that the contrails arent easy to make out anymore, especially the closer the warm front gets to your location. Those contrails also consist of ice crystals, even if the warm air aloft preceeding the WF is not as "cold" as usual, it is nevertheless still below freezing point. Interesting to learn about the MINTRA level, it surely was important during daytime raids under clear skies, if you look at old footage you can see that piston engined planes running on petrol also spewed out a great deal of water vapour, and that made those flying fortresses visible from far, hence sitting ducks...

 

Ralph

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Let the show begin!

 

Posted ImagePosted Image

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Can I ask a question to do with convection and jet plane contrails please?Well, here goes....I have noticed recently that the high altitude jets seem to leave far superior contrails when the atmosphere is conducive to convection, and when not, jet contrails seem to be poor or even non existent?Have these observations I have made true in some way, or completely coincidental and have no substance at all???CheersSlider ...

Any one who is interested in Contrails can find out plenty if you type in the science of contrails on google .you can also understand the upper atmosphere as for instance if the air is dry short tails ,wide and bumpy more moisture etc ,its a new science but handy if you want to understand upper air patterns etc . :drinks:

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Still a little far off yet but this seems enough to see at least something at the weekend in my experience as long as a trigger is present.

post-7331-0-14305100-1406673384_thumb.pn

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Met Office indicating heavy showers over Leicester this Saturday afternoon.... Is their going to be a chance they may be accompanied by thunder?

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Looks like it's going to be an unsettled day tomorrow. Just an early look on tomorrows potential. Cape showing in both surface and mixed layer as well as some reasonable DLS on the eastern side of the country could sustain things. Widespread steepening low to mid level lapse rates.

 

post-7331-0-19923600-1406716288_thumb.jp

 

Storm risk forecast widespread across the country, wind convergence showing over Scotland but not everywhere else, convection I think likely triggered from surface heating or/and trough (see below) temps highest southeast of the country and dewpoints at a fairly high temp perhaps feeling a bit humid.

 

post-7331-0-03862800-1406716339_thumb.jp

 

Precipitation charts speak for themselves and the 500mb wind direction is showing flow heading northeast.

 

post-7331-0-34792900-1406716350_thumb.jp

 

Following the wind pattern at 500mb a trough sweeps across the country through Thursday.

 

post-7331-0-58381200-1406716432_thumb.jp

post-7331-0-30347600-1406716442_thumb.jp

 

Amateur perspective ;)

Edited by Greenday
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To be fair, the Euro 4 model was pantz during the plume setups but in this case, it should be a lot better.

Wales and the Midlands the place to be for heavy showers, possibly torrential too,so the risk of some flooding is heightened in a few areas.

Devon and Cornwall could certainly see some too, due to the sw to ne trajectory.

post-15177-0-39384400-1406718574_thumb.gpost-15177-0-28591800-1406718581_thumb.ppost-15177-0-12840500-1406718590_thumb.p

The NMM 4KM model looks lively from lunchtime onwards tomorrow too. CAPE around the 300 to 400j/kg mark running from parts of the sw up to the wash and parts of the ne.

Nothing severe, but maybe a lucky few could see the odd brief storm.

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Looks like a pretty showery afternoon in store here - lightning plotted in deepest rural Aberdeenshire within last hour. Clouds looking quite lumpy. TCu I think.

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Best wake up from my hibernation and charge my batteries.. for even the slightest chance of catching another lightning bolt will thrill my heart! 

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Guest HectorTheAwesome

Only been two thunderstorms this summer here where I live in NW England. Some people have had more than 10? Well that's hard to believe. I hope we get another, in August.

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certainly interesting worst might be slight too south here.  Mapantz is those charts update from greenday's.  Reason I ask your rainfall more north just missing here wheres greenday's chart has us in its firing line.

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Do u guys think I'll get a storm? Really don't think I could cope with another one, I know they're moving northwest but seen a few people on here saying that they could go further south.

Or is it just another wait and see scenario?

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I'm here in Limousin where it's currently 27c. Some nice storms on the menu from Friday - woohoo! We've already had too humdingers, one on Monday morning in Northern France which meant we stayed in our tent for an extra two hours because it was too wet with too much lightning to come out, and another on Monday evening when we arrived at the house - fortunately after we had unloaded the car - the rain was biblical and some great CGs.

 

For now it's about enjoying the warmth, sorting the garden and some nice eats and drinks...

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It would appear that we may have a potentially interesting day tomorrow storm wise. As AJ mentioned earlier, Tony G's forecast on UKWW very revealing of possible low end supercell development through the central section of the country in a SW to NE direction. To me the possibility of thunderstorms appears quite widespread tomorrow.

 

The NMM precipitation charts show the showers aligning into bands across the country from W to E with one such band across Wales and moving through the Midlands to Lincolnshire through the earlier part of the afternoon (my interest particularly on this one from an IMBY perspective) and another that bit later in the afternoon around the M4 corridor. There are also widespread showers to the north of these bands which could contain thunder, and indeed these showers form in an airmass indicative of increasing lapse rates through the afternoon and evening.

 

CAPE is not that great on the NMM model but GFS models it higher. I will have another look in the morning but currently looks like Lincolnshire could be a sweet spot from midday to tea time tomorrow.

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Looks like the trough will pass too early tomorrow here so don't expect much for the West Midlands.

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Just popped on to check the forecast and i have to say i am impressed!

 

Out of work at 4 tomorrow which hopefully wont be too late to chase any storms that are local! 

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