Storm Dennis, Thunderstorms, Tidal Surge & Gortmore Severe Squall - Feb 16th 2020

It wasn't long after the effects of storm Ciara had passed when the Atlantic conveyor belt developed a secondary storm which was soon christened storm Dennis. This storm generated considerable hype on social media and terrible and deliberate missinformation by certain facebook pages who were more interested in likes rather than facts, wind speeds of 200km/hour were wildly promoted causing much concern to those who didn't know better. In truth storm Dennis in itself was an unexceptional storm, with inland gusts of 40-50mph with perhaps 60mph at the coasts expected this was a normal run of the mill Winter low pressure system. However it did have several interesting components which held my interest, models were showing low to moderate CAPE during Sunday moving inland then spreading north later in the day, this combined with very cold air aloft and 40-50 knots of deep layer shear would generate intense convective showers and squalls. Several convective outlooks were issued, a slight risk from Convective Weather and ESTOFEX even placed us inside a higher lightning risk box. This combined with such potent shear meant showers would form lines or even squall lines at times with multicellular models, in fact slight supercellular traits couldn't be ruled out either. I decided I would be chasing on Sunday and Roisin wanted to come with me too as she was overdue a lively day out in nature.

On Sunday morning I was studying charts at 08.00 UT, it seemed there had been a shift with instability overnight, it now looked like the best CAPE would be to the NW and peaking between 1500 and 1600 UT perfectly timed for daylight hours. Radar already showed scattered showers forming over the ocean to the west and moving inland on the strong Wly flow, I reckoned with an over lap of peak solar heating with best CAPE we had a slight chance of seeing something. Truth be told my expectations were very low so I wasn't expecting much, we just wanted a nature fix and this set-up provided us with the excuse we needed to hit the road. We left Cookstown at 09.30 and arrived at the coast early, the sky was blue and sunny and there where no hints of storm clouds anywhere, however what got our attention was the ocean itself, I hadn't expected an exciting sea today however it was putting on a show and this quickly became the focus of our day. We watched the breakers surging towards shore from a cliff top above Downhill Beach with cross winds shearing their tops, it was an impressive sight however we wanted to get closer to the action so we targeted Benone Strand.

It was one of those glorious fresh days that made you thankful you made the decision to go out, nature was showing off, lifeguard hut in the dunes with towering breakers barging towards shore.

I had the 100-400mm on the 600d crop sensor for extra reach, you can feel the wind whipping those tops from this still image, a surfer on these would have been perfect, some day I will score in that regard.

The cool thing about Benone is you are literally at sea level, there's nothing between you and the sea, it seemed others had storm spotting in mind too, the place was thriving with walkers and cars where parked on the sand off the concrete close to the sea, with high tide over an hour away with low pressure dominating the forecast I wasn't ruling out several storm surges, I actually informed several people about this risk who where not from the area and they moved their cars, but I couldn't tell everyone.

I normally try to avoid 'clutter' in my images as much as possible however with so much human activity I decided to use the foreground interest for a sense of scale and to get that human-nature intimacy, I was down low on the sand, gusts of wind shaking the long lens, the cars made for great scale here as large breakers thundered in. In the background is oil tanker Stenberg anchored off shore at the outer Tuns marker waiting to go into Lough Foyle direct to Foyle Port at Lisahally. She was due to go in before high tide this day however the wind and sea state was too dangerous so she remained at the outer anchorage for another 24 hours.

I was a fair distance back here zooming in 300-400mm to bring in the waves closer to the cars, however the depth of field was very shallow so the focus location is in one area only, the distance was too much to stop down hand holding in this wind, but I didn't care about the technicalities of photography today, I was simply documenting the action and enjoying myself in the process.

There were several people bathing in the sea, some people are dead against this sort of thing while others consider it fine, this guy was with an experienced swimmer in a wet suit outside of frame, they seemed to know what they were doing.

He's certainly enjoying himself, he smiles much the same as I do when I hear thunder. I got some nice footage of two girls bathing while large breakers towered behind them, the video is below. Roisin and I had a coffee in the Sea Shed cafe and met the two girls there, turned out they had been living in New Zealand and had recently moved back to N. Ireland, both are experienced swimmers, I really need to contact them and send them the footage as I promised I would.

Those waves were getting taller and the sea was getting closer

Then a car got trapped in the sand, the beach was too wet from the tide and the car sank under its own weight and spun out. However there's a great community spirit at Benone, this family came along and helped the owners of the car. The husband let air out of the tires and put mats under the wheels and after a bit of work they got the car free, lovely people here to help one another out, I was laying back in the grass among the dunes here taking telephoto shots, this one was focused on the waves.

This was focused on the people. This nice family contacted me later on facebook and didn't mind me sharing the images, neither did the owner of the car too, they were just glad to be free from the sand. The Husband is a fisherman and understands the tides well and how unpredictable the ocean can be, he's also handy in these situations.

Roisin and I went to the Point Bar for dinner at Magilligan Point, we were amazed by the state of the lough, I have never seen it like that in my life, it was like a raging ocean with crazy waves which were fast moving with short troughs between peaks, it was actually frightening looking, and the lough was massive, no wonder shipping was cancelled this day. The waiter in the Point Bar said he had seen it far worse than that, the lough was washing his windows for one time, I would love to have got footage of that.

After a lovely dinner (I had the Atlantic Salmon) we went back to Benone. The sky was turing very dark, radar showed a thunderstorm over Donegal with recent c-g strikes on the W side and that cell was approaching here and the light was dropping fast.

Getting darker and very moody, the atmosphere felt like something was going to happen, I was outside the van crouched low beside the wheel to get shelter from the gusts filming with the 400mm when I saw a bright flash in the viewfinder, it was lightning!!, Roisin yelled ''lightning'' from inside the van, she said the sky lit up pink from an in-cloud bolt, we listened for thunder and sure enough we could hear the heavens rumbling above the sound of the ocean.

We were swallowed by the storm and bombarded by strong gusts and hail stones. Suddenly out of nowhere a storm surge - the biggest of the day - made its way up the beach at alarming speed catching many cars off guard. I seen it coming but knew it was too late to move, I just switched on the Go Pro and made sure Roisin was also filming with her phone, she was getting quite worried. Everyone panicked, cars reversed or turned as fast as they could to escape the ocean coming in, a family with children were caught off guard on the right. I could have reversed but I decided not too, there was too much going on, in such a mad rush it would have been all too easy to accidentally reverse into a person or child, or even hit another car in the chaos, I said to Roisin just sit tight, let it overtake us, which it did, then wait for it to retreat again, that was the only plan. Roisin had never experienced this before and was rather shocked and excitable and even scared, however I had been in far worse storm surges than this before and knew we were fine, it looks dramatic but the water was rather shallow, but it made for good footage, the above is a frame grab from the window mounted Go Pro.

As the tide withdrew back to the sea more thunder rumbled for a long time to our half left, nature was sure showing off, thunder and lightning and a storm surge all at the same time. We where in a bit of bother, the front wheels sank deeper in the wet sand and we were stuck, the wheels had no traction and with every press of the accelerator the wheels went deeper so I stopped trying. Luckily for us a lovely family came to our rescue, I put my floor mats under the front drive wheels and the family and their sons all pushed, on the third attempt the van was out and we were back on firm ground and free. Yet again the nice people of Benone saved the day and asked for nothing in return, I thanked them for their help, another man even had offered to tow me out, great to see such local support.

Once I knew the van was save we were back to chase mode, that thunderstorm was now passing over and a clearance appeared behind it, look how low the base is on this storm, moving rapidly from left to right and feeding on all that ocean moisture, we got nice moody light for this moment, I can't believe we got thunderstorms already, that's the second day of lightning I've experienced inside a week and this was the loudest thunder so far and its only February, 2020 is really starting to talk.

Flanking region of ocean thunderstorm with lower portion of anvil visible to the left, this 4x4 pick up truck made for some cool foreground interest

Roisin and I then re-located to Gortmore Viewing Point above Lough Foyle, we had got our wave action now we wanted storm clouds and a different perspective. We had just arrived when a massive cell came into view, it appeared over Donegal and began crossing the lough heading our way. The sky was deep charcoal black with nasty low level dense clouds, a huge wall of hailstones could be seen falling from the base extending the entire length of the Foyle and passing Benone, it looked brutal, it was already raining and gusting hard, I ran outside to the look out point for a few images, the camera and I were getting battered and soaked, the wind was absolutely raw and unrelenting, check out that sky.

That's one massive dense hail core, I ran back to the van and got attacked by hailstones, the core was close, they actually hurt my face, I took a wind reading of 46mph however this was in the sheltered part as the van was shielding us from the worst, I was just sticking my hand out the window for a rough reading, my hand was pure red with the cold. Then suddenly it hit, the full onslaught of this cell's downdraught and outflow winds impacted the area hard, Roisin and I couldn't believe how powerful it was. For the second time this day Roisin was getting unnerved, the van was shaking so violently we half jokingly worried the van might tip over, I ended up changing the angle of the van with respect to the wind so a lesser surface area presented itself, I held down the break and pulled on the handbrake, the van seemed to shake like mad as if a mob a hundred strong where pushing the van. Outside it looked like the road was being power hosed with horizontal hail and rain bands, it was truly severe, my guesstimate was 70mph easily, perhaps stronger, this was a proper severe squall event, this elemental punishment was sustained for 15 minutes before suddenly easing.

It was a thrilling experience and our first severe convective encounter of the year. We filmed the event with phones, DSLR and Go Pro however none of these devices even came close to showing the severity of the event at all, the reason was there were no trees or other objects to interact with the wind, it was a barren mountain top and road so really nothing to visually show the intensity of the wind, had this been snow this would have been insane, but we experienced it and that's all that mattered, what a fitting end to an exciting day of action.

Various DSLR footage of the waves at Benone with 100-400mm lens including the stuck car and Go Pro footage of the storm surge which got us too, the waves are fun to watch.

Our footage of the severe squall event on Gortmore which doesn't do it justice but it's here for the memory. Roisin and I were battered, soaked and chilled to the core and headed home just before sunset. The cell had passed over, the wind dropped, and blue skies returned, all we could see were flat clouds to the west, it seemed that cell had used up the last available CAPE in spectacular fashion. Back at home we warmed up and relaxed for the rest of the evening, a hot whiskey was the only thing which warmed me up again, a good chase, thanks very much for reading.


Martin McKenna

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