 |
 |
 |
 |
 |
 |
 |
 |
Forecast: ''Slight risk general T-storms, Ireland, SW, and W UK regions 09Z-00Z Weds 2nd July 08. A rather low risk outlook with restrictions in place today. Any thundery activity today is directly associated with thermal lapse rates derived from any upper cooling. Hence, it's more than significant that some solar heating is involved. Outlook is altered for UK since overnight heavy showers over the continent advects thick mid level cloud cover across the UK. Given this recent change it is quite likely that the best chance of thunder will occur late in the period to the extreme W regions within the UK late in the day. GFS show any instability well out of line to any upper shear. Saturation at mid levels prohibits the release of potential instability for both Ireland and UK. Far W UK looks to clear this upper moisture late in the period. Current thinking for Ireland is that any sferic activity will in fact be rather limited due to this condition''.
This was the convective outlook issued by forecaster Tony Gilbert on the morning of July 2nd. Some time later TORRO issued a tornado risk discussion for Ireland and N. Ireland. Plenty of wind shear and CAPE values progged between 600 and 700 j/kg and I was getting quite excited. This was the highest CAPE value I have seen for N. Ireland this season to date. The high CAPE was forecast between 18.00 - 19.00 BST. During the day the negative lifting index was -3 which was good enough for non severe storms.
I was up early that morning and did my usual routine. I have developed a natural routine every morning, evening and night. First of all I check spaceweather.com for any astronomical news then I immediately check the convective forecasts from Tony Gilbert, ESTOFEX, TORRO, Netweather, RTE and Met Office followed by a look at the convective maps updated from the latest GFS run. All of these agreed on heavy showers. The Met Office had issued a severe weather warning for N. Ireland with the main threat being extremely heavy slow-moving thundery showers with up to 50mm locally, and hence a risk of spot flooding. When all the forecasts agree then things are looking good. I checked the latest rainfall radar which showed very heavy showers with red returns approaching my area and the sferics showed lightning crossing over the N. Ireland border and moving N. I was beginning to get a good feeling that I might see something cool today but I was worried about the overcast sky which would reduce ground heating in a big way. Now was the time to leave the computer screen and get out under the weather and observe the visible air mass and cloud forms. First I made myself a nice brew. I opened my back door and got hit by the first drops of precip from the blue radar returns, and looking skyward, I seen very promising convective clouds so I went into action mode. I was caught off guard, the heavy showers had already arrived over me sooner than I expected so I had to abandon my original plan of finding a good country location for photography. Now I had no time and it was pouring.
I decided I would remain near my home and see if there was anything worth 'shooting'. There was. I brought my tripod with me and set-up on an elevated grassy (and very wet) area in Maghera which provided me with a good view to the S, SE, E, NE, and N. My W sectors where blocked by high trees. By the way, the idea of using a tripod in daytime might sound silly but I have learned from recent experience that it's an invaluable tool. You can avoid camera shake with slow shutter speeds if the sky gets very dark and if you want to take video, which I enjoy doing, then a tripod will save you much frustration. If you want to take time lapse video/images then it's a must. I usually have one of those mini flexi tripods in my camera bag for back up incase I forget the main one.
 |
This was my first shot of the day. I should mention that there was wide spread N-S convergence zones over Ireland today. There are different types of convergence zones but today's was when two different air masses meet. The heavy rain and storms where moving up from the S to SE and the upper level clouds and wind where moving in from the N. I could see this visually at the time. Convergence zones are the place to be for storms and they also play a big role in UK funnel cloud and tornado development. I was lucky to have one of these N-S convergence zones over my home town. This is a big line of slow moving convection, S is to the R of centre where Slieve Gallion mountain can be seen and N is opposite this. It might not look like it in this wide angle shot but these were big and menacing looking cumulus congestus clouds. Heavy showers have already developed in the distance from a mess of cloud. Pity about those power lines. 12.27 BST.
 |
Zoomed in a little on the cu towers. Photography under these conditions is much more difficult than the main attraction of having good convection surrounded by a crisp blue sky. The cloud varied from grey to dark grey and the mid and upper level cloud was bright grey, almost white in colour, due to strong sunlight filtering through the filmy veil. If I exposed for the dark cloud the upper level would be burnt out and the opposite would produce a scene too dark at lower levels so I had to find a decent sweet spot between the two. So these images represent exactly the true tone and brightness/darkness of the lower, mid, and upper level clouds. Convection moving R to L here. 12.30 BST.
 |
Despite the precip and overcast sky it was actually very warm and humid. The mushy white glow of the Sun could be glimpsed from time to time through the cirrostratus veil almost overhead. These are all very low resolution images. I'm still trying to master the art of producing images of very low 'k' while maintaining good image detail/resolution. 12.31 BST.
 |
12.40 BST. Extremely heavy showers breaking out now. These were all red returns on the radar. Visually, this was quite a menacing looking scene. These were serious downpours and if you factor in the extreme slow movement of these cells then you can see why the Met Office gave a risk of flooding. That intense precip curtain is falling over the S and SE areas of Maghera. I'm sure there where drivers under that with head lights on and wipers going frantic. The bottom section of those structures was quite a sight. This is not zoomed in. I'm using wide angle here so it actually was closer to me in reality than it appears here. As you know, a wide angle can make close objects seem more distant, however you need it to take in as much of the scene as possible. My theory is, the wider the lens, and the more images I take, then the greater the chance of catching an isolated c-g bolt which could very well happen. The black dots at the top of the image are birds.
 |
13.03 BST. After an unphotogenic gust front passed through this great structure was visible. This was the convergence line in action. This was huge!!. It extended from the SE to NE sky sector and must have been miles in length. Camera is pointing SE here. It consists of a line of cu congestus and cbs, each with their own anvil tops blending in with the upper level cloud. The rear end of it was particularly nasty looking, dark, and at low elevation. Moving R to L.
 |
13.02 BST. Closer in. That's a very long precipitation curtain which runs the entire length of the base. So heavy rain falling in a dense organized line for several miles. That's St. Patrick's pitch on the foreground with Crewe Drive and Station Road above. Beyond is open countryside. I was very impressed by this structure.
 |
This is the NE section of that dark structure. Intense precip core to the R and finer fall streaks to the L.
This is a video clip I made of the earlier showers and convective structures. The gust front can be seen at the end. 1 min 41 sec's in duration.
 |
13.24 BST. Same massive structure with extremely heavy precip core. Image is looking directly E. System moving R to L. More on page two.
PAGE 2 > |
Martin McKenna