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First storm chase of 2010. I had this day in mind for a week in advance as GFS was very keen on producing an unstable atmosphere over Ireland during midday and into the early afternoon on Monday. With each model update the instability remained which was a very encouraging sign, however there where slight shifts on exactly where the best regions would be so it was an up and down emotional battle. One day moderate CAPE would be over the Republic, the next over the midlands, then N. Ireland, this was typical of future convective set-ups and was to be expected. At the time I knew it was ridiculous to think this would be reality at +100 hours away from the day in question, however after what seemed like months of cold dry weather and high pressure I was getting excited at the very thought of seeing any vertical clouds in the sky and was pumped up to get out there with the camera. Things were looking very good indeed with, at one stage, 800 CAPE and LI's of -3 which is darn good for March, a period just knocking on the door of the convective season. Sea surface temps (SST's) were colder than usual at this time of year which could inhibit any decent convective potential, however the Sun was now high enough to produce moderate solar heating so inland convection was most definitely on the cards.
On Sunday night, just hours away from the target day, the latest GFS update completely downgraded the entire thing to the extent that it would be a marginal day, on the positive side there was still potential for thunderstorms since there was strong wind shear and that's a very important ingredient. People get obsessed with CAPE however large instability means nothing unless you have certain other parameters in check, and if these are present, then marginal events can often produce surprises which can surpass the more active days. CAPE had been reduced to 400 at best with LI's between 0 and -1, N. Ireland had just over 300 so it was far from over. The wind shear was something I had noted with interest because in the past these low CAPE - high shear environments have produced severe weather, including tornadoes, so as far as I was concerned it was game on. ESTOFEX followed with a convective outlook for thunderstorms with a chance of a narrow convective line forming with severe wind gusts possible along with an isolated tornado.
Late in the night my computer had caught a virus, not one, but 24, all of them trojan horses. The anti-virus software I was using was inadequate and panic set in as warnings popped up on the screen in an unending cycle. Getting desperate, I downloaded an updated version of the same package and did a scan. The software found the threats and stored them, however they were still on the computer. On the plus side those annoying pop-ups had gone and I could use the net again, I decided that the worst was over and I would look at it again another time because all I could think about was getting out on my first chase of the year. After few phone calls earlier in the evening with Conor McDonald a plan was made, we would be chasing together in the morning and that promised something exciting.
I wake up early in the morning and look out the window to see a sunny blue sky with trains of fair weather cumulus drifting in from the W within a strong flow, they didn't look like the friendly kind, the motion and gradual improvement with substance and height with distance towards the W hinted that something bigger would be coming in later. With spirits high I switched on the computer ready and eager to see the latest forecasts and model updates. Disaster, my monitor had a black screen with white text instructions warning me that there had been a fault with Windows XP, I clicked on several of the options to fix the problem but none of them would work at all, the screen was frozen so I couldn't even see my desktop or get online, I was frustrated and furious, I tried to remain calm and had another go but it was hopeless, the computer was messed up, I tried turning it off at the tower and it didn't even do that, so with an angry fist whacking the keyboard (what did it ever do?) I turned the computer off at the mains. I couldn't believe this problem had happened on this morning of all mornings when I really needed to get online, I felt completely blind with no sat images and radar. My day had got off to a great start!
09.00 UT. I just remembered that my Sister had an Ipod so I borrowed it and got online which brought some relief. The thing was incredibly slow to use and navigate so I was getting agitated again, some of the sites I needed came up as 'page cannot be displayed' so you could imagine my mind set at that time. I only got on one site as I drank my morning tea, it was TORRO, and they had a convective discussion issued...
A TORRO CONVECTIVE DISCUSSION has been issued at 10:15GMT on Monday 22nd March 2010
Valid from/until: 1015 – 2000GMT on Monday 22nd March 2010 for the following regions of the United Kingdom & Eire: S Scotland, W Scotland, NW Eire, N Ireland
THREATS
Wind gusts of 45-55mph; hail; isolated weak tornadoes; isolated CG lightning
SYNOPSIS
Marked cold pool will cross the area today. Around and ahead of it, deep lift will serve to cool the mid-upper troposphere enough for showers and isolated thunderstorms to form. Deep layer shear is sufficient for storms to organise into lines, enhancing wind gusts. In addition, reasonably steep low-level lapse rates and 15-20 knots of 0-1km shear gives a slight chance of tornadoes. Forecaster: Paul Knightly.
That forecast lifted my spirits somewhat and validated my suspicion that this day had some potential after all. With that terrible internet speed I decided to close the Ipod down in search of faster information. I rang Conor who was also up monitoring the situation, he checked the radar and confirmed a convective line forming over the W coast of Ireland showing yellow radar echoes of large size indicating moderate rainfall, and being so early in the day this was a good sign that the post-frontal trough was moving inland invigorating convection. The sferics charts showed two c-g lightning strikes over inland coasts so this line was already producing, we planed on intercepting it once it moved E further inland. The radar updates showed the forward motion of this line to be very slow and it was then that we realised we were up too early and that we may have to wait until late afternoon before it hit us so we decided to take it easy for a while and catch up later.
I had some time on my hands and feeling the need to get online and check things out, including my emails, which there are usually tons of each day, I decided to drive down to the local Maghera library. With luck there where several computers free and I got busy with my fingers. There was a guy sitting beside me to the L who kept glancing over at me to see what I was looking at, he thought he was being very sly and subtle about it which made me laugh inside because I had seen him doing it every time with my peripheral vision. I flicked up the TORRO risk map and opened the animated sat images, radar, and latest GFS CAPE updates for each hour, this was second nature to me and I thought nothing of it, however this guy thought it was brilliant, he must have been really fascinated by what he saw because he lost all interest in his own computer. I forgot about him once I seen the latest radar update - yikes - that line, which had earlier been slow, was now moving E at phenomenal speed, the kind of speed which got my adrenaline pumping, it was clearly a squall line now and had moved from the coast to near central Ulster within a very short period of time, I went into combat mode, it was now time to make a move or we would miss it, I exited the building swiftly and I'm pretty certain my computer chair was still spinning when I was gone lol.
I jumped in the car, getting impatient when I got held up by traffic in Maghera, then head up Station Road, this thing must have been almost on us by now and would soon hit Maghera so I needed to get Conor. The buildings blocked the view of the sky however once I reached high ground I glanced over to the W and got a shock. The blue sky I had seen earlier had been replaced by a huge chunky mess of convective clouds clearly visible over the Sperrin Mountains making a bee-line for Maghera, it looked like a large nasty outflow boundary and below it the sky was almost black over the Glenshane Pass area where, no doubt, heavy precip was falling. I arrived at Conor's door and filled him in on the situation using as little words as possible to save time, he knew the score and what I was at, having experienced similar pre-storm sensations before, and within sec's he had grabbed his camera and we where on our way.
Driving through the town on our first storm chase of the year gave us a major buzz, it felt great to be on the road so the atmosphere in the car was a positive one. I love that moment in time when we head out full of hopes and dreams, not knowing exactly what was going to happen or what we would see. Would we be coming back later in a foul mood after seeing nothing and slagging off the forecasters?, or would we be punching through the air with joy and satisfaction after catching a great event on camera?. It's this unpredictable aspect of storms and severe weather which attracts us in the first place.
We where driving down the road outside town, it was dark and gloomy with spits of precip hitting the window, I was about to take the turn at the fly-over when we intercepted the squall line, or to be more truthful about it the squall line intercepted us!. The calm conditions turned blustery as outflow winds hit us along with heavier precip then suddenly a very powerful gust of wind roared down the fly-over in a straight line from R to L lifting large numbers of leaves off the ground and blasting them across the road at high speed as the more powerful convective elements within the line went to work, that was quite a strong squall indeed, not quite severe but certainly not too far from it. Those leaves racing across the road at that speed was quite a sight indeed and difficult to do justice to. One of us commented ''outflow'', to which we both sniggered, we were enjoying ourselves already. I drove on up the road to the Glenshane Pass and the conditions were pretty bad, strong gusts of wind, VERY heavy rain and hail stones clashing off the windscreen, and I could feel the car shaking with the convective gusts. It seemed like day turned to night so I had to use full headlight beams.
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This is the visual sat image from SAT24.com showing the scene during that exact moment we where getting battered by rain and hail on Glenshane Pass. The blue 'X' marks our approximate location directly under the W to E moving (L to R) squall line. Lough Neagh is just visible ahead of the leading edge as a dark gap where the storm was yet to hit. As you can see, the squall line is almost the entire length of Ireland itself, and along it can be seen a vertical row of updraught towers and numerous cbs with fluffy anvil tops streaming away back to the W, several of those towers may in fact have been overshooting tops. Behind the squall line to the W can be seen several large showers and possible thunderstorms over the Republic and midlands. Further to the E, over Britain, is the occluded front which had been over us the previous night.
Back on the ground we drove for what seemed like an eternity through that barrage of rain and hail. Part of me was annoyed that we didn't get out earlier to see the line approaching from the distance because it probably had cost us a good image of a gust front/shelf cloud, but perhaps it didn't have a good one. The good news was that we where there and got on our target which was the main forecast event of the day, if anything was going to drop from it then we where already on the scene and would catch it so there was nothing at all to complain about it. We made it to the top of Glenshane then pulled into a side road along the mountain and stopped where we had a good view facing E, and waited. We sat there under heavy rain but we knew there would be a clearance from behind soon considering the rapid forward speed of this thing. Looking back again to the above sat image you can clearly see that clearance behind the line, we wanted to see this for several reasons. The most obvious being that the rain would stop meaning we could take images outside, the other that we could get a nice treat at the rear of the system in the form of a mammatus display or even a funnel or tornado, after all they were forecast.
We waited and waited, the rain seemed to ease then it eventually stopped. Behind us, to the W, the clearance yawned open with blue sky visible once again with hazy sunshine filtering down through the retreating cloud canopy. We went outside and stood on the narrow road watching the squall line moving E away from us. The very well defined rear of the line was visible and it looked quite impressive. Curving steeply up from the line was a huge anvil which rose from the embedded cbs at a high inclination from the E, completely across the zenith, and back into a portion of the W, we noted with interest that despite its mushy form it was a back-sheared anvil which suggested there where indeed strong updraughts within the squall line. Countless small mammatus pouches could be seen covering the entire anvil, some of which where arranged in curving lines towards Slieve Gallion in the S.
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We really wanted to shoot the rear of the line however our images were spoiled by large posts, powerlines, and transformers which took up a large distracting section of our frames. We ended up jumping over the wire fence at the side of the road and running across the wet undulating marsh ground until we where positioned on the other side of the wires which provided us with a tremendous view of the E skyline. The image above shows Conor shooting the squall line, we were watching the back of it as it moved away. The line was so long that it stretched across most of the N to S sky, there's a clear gap visible to the far RHS which I will explain later.
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The precip cores falling from the line looked really cool, I have always been a fan of such sights so I took plenty of images. Why on Earth I didn't set the other camera on the tripod and take video is beyond me. To the N (L) of the line where bright white hail cores falling over the land lit by a brightening Sun. To the S (R) where very black hail cores which looked very threatening with dark cloud bases. We were baffled why we couldn't see any lightning or hear thunder from that area since it really looked the part. You can see some of the mammatus forming on the back of the anvil shield, which at this time was still overhead despite the line being tens of miles distant from us.
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This is looking NE at the rear of the line that's not visible in the above two images, this is the far L section of it looking over the mountains where a long white hail curtain was falling over the hills. We spotted a very interesting form emerge out from the back of the line, either among the hail curtain, or close to the rear of it. It caught our eyes at the same time as we scanned the sky and chatted. While we watched this line we discussed many things, reflected on past events, and plotted future ones, however all the while our eyes never abandoned the sky incase we missed something. We certainly didn't miss this lowering, at first I thought it was just a rather dense string of falling hail because on many occasions these can look like funnel clouds when observed from a distance, it's a very common rookie mistake and is easily done. I was just saying to Conor about easily people could be fooled by that when we both went quiet and studied it further.
Conor said, ''Marty, I think that's a funnel'', to which I replied, ''actually, I think it is too'', we both laughed in an unsure fashion then watched with fascination as the smooth tubular-shaped lowering curved gently and seemed to descend towards the ground while sporting a more finer snout, at it's lowest point it went below the level of the hills in the frame and seemed to be rotating, we were fairly sure it could have been a funnel but due to its great distance we couldn't confirm it so I guess we will never know. The 'funnel' vanished after approx 30 sec's and was never seen again. I only managed to get this one 55mm capture of it which is slightly overexposed. I have marked the location of the suspect at image centre, you will need to study it at a certain angle towards the screen from a dark room to appreciate it more.
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This is the same image which I have cropped, contrasted, and darkened slightly. It actually does look like a funnel cloud bending towards the hills. We did notice that the tops of the convection in that direction were much stronger looking over the Sperrin Mountains with numerous tall towers and several large cb anvils. We considered driving further W to watch the base of those stronger cells, which were obscured by mountains from here, but decided it wasn't going to happen because it would be a long drive to get up there and find a good view and by that time the cells would have been long gone so we stayed our ground. Conor made a good point about bringing binoculars along in the future to help confirm distant funnels. It was a point we learned the hard way that day for a glance through 7x50mm glasses would have told us in an instant what it was.
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Back to the R of the above funnel image and going wide angle towards the squall line, now much further away and showing plenty of mammatus on the back of the rear-sloping anvil. Technically that's not one anvil but several anvils from different cells within the line all acting in unison. It was cool to watch the dark line of cloud and precip sweep over the low land areas dropping hail and gusting wind across everything and everyone in it's path. A line of bright sunshine followed in its wake across the country. As the precip curtains advanced, new topography would emerge from the darkness which couldn't be seen before. It was cool to watch Slemish Mountain suddenly appear on the horizon.
Behind us more convection was building which was most impressive to the N and NW, however chasing it was not an option due to the road options. To the S there where big mushroom towers behind Slieve Gallion which were very tempting to go after. I drove slowly forward feeling indecisive about what to do then stopped on the hill looking S. We decided there was no point going any further since we were 'blind' so to speak, so we decided to drive back to Conor's house and check out the radar once again. We enjoyed a well deserved brew and studied the latest situation online. The visual sat image showed the squall line breaking in two above the centre point leaving the S half to cross over the remainder of the Republic and the N section to pass over N. Ireland. That split in the line was the reason for that clear gap I mentioned earlier visible on the 2nd image. The radar showed yellow and small pink echoes over our exact location where those dark hail curtains fell indicating moderate to briefly intense rain fall. The sferics showed that the line had produced a nice group of c-g lightning over E N. Ireland which no doubt happened while we were watching, however they where too distant to see visually. There where reports on the forums about strong wind gusts, pea to marble-sized hail, and window damage.
We decided to go back out again as there where big showers nearby to the W over the hills, and although we didn't expect any of them to turn thundery we thought we would try our luck anyway incase any photo opps presented themselves. We drove to Drumlamph woodland, a nature area owned by the National Trust, and went for a walk. There where several ponds in the area, and within them where literally hundreds of frogs mating, it was a spectacular sight, the combined noise of their croaking sounded like a distant scrambler.
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A line of heavy convective showers past over which gave us a good soaking, the sky turned overcast and blustery with a sharp temp drop. As the line cleared though we could see the back end of the shower anvils where we saw a spectacular atmospheric show of intense primary and secondary rainbows arcing through the intense hail core. We took many images of these, the above is just one. At the rear of that cell was an area of slowly rotating cloud, and falling from which was a well defined bright white hail curtain which was also rotating, that was a neat sight.
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We drove onto higher ground and stopped in the car park near the 'sweat house' and watched for more convection. A fairly impressive line of cbs moved in from the W over the Sperrins, the N (R) cell of the line looked quite stunning with a huge healthy anvil which at one time looked very firm and solid. This image is wide angle at 18mm with the nice cell to the R. I think that Sheep was staring straight at us.
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Same cell around 55mm. The white cbs looked a rewarding sight among the crisp blue sky with sunlit country below. Conor was particularly impressed with this cell so we watched it for some time as mammatus began to form. It was cold, wet, and blustery up there and we felt quite chilled so decided to head back home since it was already nearing late afternoon and solar heating was waning. During the drive down the narrow twisting country roads that same cell had drifted further E in the flow and was now visible out the passenger window above the trees, I couldn't see it from my position but Conor got a great view of the stunning mammatus bags hanging from it's anvil, he got some great shots through the window as we drove. We entered Maghera from the N side and made our way through the traffic while in front of us the entire time was that beautiful mammatus display, we couldn't get pulled over due to the busy car parks and we where still held up on the main road by traffic lights.
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The mammatus display was at its very best around that time and we couldn't get an image of it from our bad location, it really did look some sight with those white bags hanging over the buildings and Coleraine Road. Desperate to get images we drove on in a state of panic looking for a location to stop, nowhere was photogenic and there where just too many people in the town so we drove straight on up the Coleraine Road, took a R, and found a nice country location. I was that engrossed by the mammatus display that I ended up missing gears causing the car to jitter on the road as if a nutter was driving. The above image was taken from our nice new location looking W of N.
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55mm close up. In reality these looked huge, and considering their fairly high altitude under the anvil they most certainly were. If you flew past them in a plane they would look very threatening. Mammatus are associated with unstable atmospheric air so pilots are trained not to fly through them due to the risk of severe turbulence. Conor told me about the mammatus he had seen from Australia which were really huge in size and topping out at +40,000ft above the ground, now those are big.
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Final shot of the day, I ran across to the far side of the road and took this wide angle image of the anvil, mammatus, car, and Conor who was snapping away. This photogenic display was the perfect end to the chase and we both felt happy and content with the results. What began has a marginal day ended up full of fun experiences and high rewards. Considering that this was only a couple of 100 CAPE at best, and that we didn't expect to see much to begin with, we couldn't complain. We both went home feeling very satisfied. The convection died out soon after this and was replaced by a crystal clear blue sky. Later the sunset was picture perfect and planet Venus shone proudly among the deep blue glow of twilight, it was the perfect end to a perfect day.
Martin McKenna