Dr Joanne Williams
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jowilliams.bsky.social
Dr Joanne Williams
@jowilliams.bsky.social
4.1K followers 890 following 7.9K posts
Sea-level and tidal scientist. Liverpool, UK.
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jowilliams.bsky.social
The headline: "Northern Lights set to dazzle UK once again tonight"
The forecast: 🌧️🌧️😭
Screenshot of BBC weather map for 2100 tonight (12th Nov 2025). A massive rain band splats across the north, which lingers all evening.
November 12, 2025 at 10:50 AM
jowilliams.bsky.social
Also FUCK AI CRAPPY GENERATED IMAGES IN SEARCHES THIS IS WRONG PLEASE CAN WE TAKE THE INTERNET BACK 15 YEARS ARRGGGHHHH.
Ahem. Sorry 'bout that
Crap Ai gen picture of a not-pigeon with mangles not-labels that came up when I was trying find out what the beak bulge is called.
November 9, 2025 at 4:28 PM
jowilliams.bsky.social
Relatable.
Comment in a paper from the 1960s describing the tides of the Thames as difficult to model because "it is a very critical and resolant [sic] estuary"
November 5, 2025 at 4:12 PM
jowilliams.bsky.social
Is this because the upstream lock has been deliberately and usually completely closed for some maintenance reason? (Last week wasn't unusually low tides at Sheerness, further downriver than London.)
Tide data at Sheerness, downstream of London, for October 4th - November 3rd. The lowest tides in this period were the spring tides 6th-10th.
November 3, 2025 at 9:27 AM
jowilliams.bsky.social
I have just discovered "self-threading" needles and if you struggle to thread a needle give them a go! Fine needle threaded in poor light, almost by feel, first time. Came undone twice while sewing, but easy to redo.
Self threading sewing needle. It has a double eye that then forks with a tiny gap. You thread it by forcing the cotton through down the fork, like flossing.
October 29, 2025 at 7:51 PM
jowilliams.bsky.social
Last time I was in this bookshop they only had one by @tkingfisher.com ... Pleased to see they've got the message!
Store shelf with several kingfisher books, including one in prime facing position and a hand written recommendation note.
October 25, 2025 at 5:32 PM
jowilliams.bsky.social
Pigeonholes
Frontage of an elaborate building, boarded up, with a row of ~ 30 stones supporting an overhang. There is exactly one pigeon in each gap.
October 23, 2025 at 11:56 AM
jowilliams.bsky.social
Given the pain in the ass that is transpennine, northern and Avanti sharing lines, all charging a slightly different amount (roll a dice) and refusing each others tickets so you have to know in advance exactly which colour late train you will catch, I am not convinced that monopoly of trains is bad.
Rail timetable screenshot of 3 consecutive trains between Preston and Lancaster. They take 15, 17 and 14 minutes, all direct with no stops between. They are run by Transpennine, Avanti and Northern. You can't tell from the timetable which is which (you have to click through and I've already forgotten), One is £8.30, one is £4.90, one is £8.50. If you accidentally get on the wrong one your ticket may not be valid and you can get a massive fine. This is Competition and Market Forces or something.
October 22, 2025 at 8:15 AM
jowilliams.bsky.social
Ah, that makes sense. I think it's because the background is respecting the user's colour palette default choices but the text that belongs to the figure isn't. I've just tested by changing to a hideous custom palette (screenshot). Bsky must assume you want a black default background.
Version of the screenshot which has some of the text in dark pink and the background in hot pink. The text which had previously disappeared is in black.
October 20, 2025 at 10:05 AM
jowilliams.bsky.social
Yes sorry, for some weird technical reason the scale and some other bits aren't attached to the image when I copied it. Here's a screenshot instead:
Still from an animation of the tide around the UK & Ireland at 10:45BST on 20th October 2025. There is High Water (red, the tide is "in") at Liverpool, north east Scotland and near Dover. There is Low Water (blue, the tide is "out") in Cornwall and Brittany, southern Ireland and Hull. Heights measured are in metres from a model zero which is roughly (it's complicated!) local mean sea level. Text at the bottom: "This 2½-day forecast animation shows the total water level of tide plus storm surge progressing around the coast of the UK. The highest water level is coloured red, while the lowest level is coloured dark blue. If a high tide occurs during a large positive surge then coastal flooding is likely."
October 20, 2025 at 9:40 AM
jowilliams.bsky.social
A good way to think about tides is a really wide (100s of km) wave, a few metres tall, sloshing continuously round the ocean. The high bit of the wave gets to each place along the coast twice a day. Because the coast and seabed is a complicated shape, the tide gets funneled, delayed and echoed.
Still from an animation of the tide around the UK & Ireland at 10:45BST on 20th October 2025. There is High Water (red, the tide is "in") at Liverpool, north east Scotland and near Dover. There is Low Water (blue, the tide is "out") in Cornwall and Brittany, southern Ireland and Hull. Heights measured are in metres from a model zero which is roughly (it's complicated!) local mean sea level. Still from the same animation 3.5 hours later. ie, the tide around the UK & Ireland at 13:15BST on 20th October 2025. High Water (red, the tide is "in") has moved around the country and is now near the Lake District, Edinburgh and still near Dover (but smaller than before). There is Low Water (blue, the tide is "out") in Normandy, South Wales, the Hebrides and Lincolnshire. Heights measured are in metres from a model zero.
October 20, 2025 at 8:01 AM
jowilliams.bsky.social
Clicking randomly through @noc.ac.uk report on the Arctic and you need this beauty. From noc.ac.uk/science/arct...
Utterly absurd and delightful sea floor ... creature? Colony of tiny creatures? It branches with about 4-5 levels from a bowl shaped centre. The end of each branch has a tightly coiled tip. Coloured a coral pink. Filename suggests it's a Basket Colony and photo by Dan Jones.
October 13, 2025 at 4:39 PM
jowilliams.bsky.social
For a while I thought the 3rd was Wadham's cloister, but I think our chapel windows are taller. Anyway you can't really take a picture of the back of Wadham's chapel without getting distracted by the deeply weird Bowra statue. Hope he's still there to freak out the current generation of students.
Sculpture of a bald bloke merged with a chair. The top half is a bust and arms in a relaxed pose, the bottom is a chair, as if his legs and lower torso have been gouged out. It's labelled Maurice Bowra. Courtesy of a travel blogger called Caroline.
October 9, 2025 at 1:41 PM
jowilliams.bsky.social
The rules vary between schools. But this is the ranking for children in a Catholic primary picked at random from the first page of search results from the Liverpool area. It is typical. It's improved. 10 years ago, *children in care* ranked below faith admission.
"7. Any other children".
Oversubscription Criteria Where there are more applications for places than the number of places available, places will be offered according to the following order of priority. 1. Looked after children and previously looked after children. [ie children in care of the state] 2. Baptised Catholic children resident in the parish 3. Other Catholic children. 4. Members of an Eastern Christian Church not in full communion with Rome 5. Children of other Christian Ecclesial Communities whose membership is evidenced by a minister of religion. 6. Children of other faiths whose membership is evidenced by a religious leader. 7. Any other children
October 8, 2025 at 8:47 PM
jowilliams.bsky.social
At Lowestoft, #Amy brought the surge a little later, on the 4th and 5th of October. Still a skew surge of just over 1 metre. But there's less difference between neap and spring tides, so the levels were much higher than the usual range expected before weather effects.

bsky.app/profile/jowi...
Tide gauge data at Lowestoft, showing a predicted (without weather) tide ranging from 1-2m to 0.5 - 2.5m. But observations rose to about 3.5m twice, on the 4th and 5th of October.
October 6, 2025 at 5:53 PM
jowilliams.bsky.social
At Liverpool, #Amy raised the high tide, with a skew surge of around 1 metre on 3rd October 2025. But Liverpool in October has a huge range between neap and spring, so despite the calm weather today the tides were even higher! So the total won't be unusual there.
bsky.app/profile/jowi...
A week of predicted (without weather) and observed tide gauge data at Liverpool, with a tidal range of 4-7m on the 1st October and about 2-10m on the 6th October 2025.
October 6, 2025 at 5:53 PM
jowilliams.bsky.social
And this is the effect at Millport (nearest coastal gauge to Glasgow).
Tide gauge at Millport showing more than 1 metre skew surge at high tide on the evening of October 3rd 2025
October 3, 2025 at 10:34 PM
jowilliams.bsky.social
But Lowestoft the highest recorded level in 2024 was from a storm (Dorothea) in December. It was a less widespread skew surge, but also because it fell near smaller tides it was not a high total at most sites.
Summary figure for storm surge due to Dorothea around Dec 17th 2025 (and another storm the following week). Bars indicate height of observed tide over the predicted tide. Predicted tide levels are not shown, but the waning quarter moon was Dec 19th and tides were heading to neaps.
October 3, 2025 at 8:49 AM
jowilliams.bsky.social
So the severity of a storm surge can vary massively from place to place. In 2024 storms Kathleen & Pierrick (April) had the highest recorded water levels at most places in the UK, because they happened to fall near really big astronomical tides.
Summary figure for storm surge due to Kathleen, around April 7th 2025. Bars indicate height of observed tide over the predicted tide. Predicted tide levels are not shown, but the new moon was Apr 8th and spring tides just after.
October 3, 2025 at 8:49 AM
jowilliams.bsky.social
At Lowestoft though, there's less than a metre difference between neap and spring tides. So it makes less difference which day a storm arrives. There's a bit of protection from it falling on neap tides, but not nearly as much as at Liverpool.
Astronomical tide predictions (the part before weather is accounted for) for the next week at Lowestoft, showing high waters starting at about 2.3m today the 3rd Oct 2025 (neap tide) rising to around 2.8m on the 9th October. Times in UTC (not BST).
October 3, 2025 at 8:30 AM
jowilliams.bsky.social
Why does it matter what the tidal range is? Well, at Liverpool say, the normal high tide tomorrow is ~9m. A skew surge of 1m would still be less than the 10.04m expected on the 10th Oct *anyway*. There's risk from waves, but at least the average level should be ok for the usual sea defences.
Astronomical tide predictions (the part before weather is accounted for) for the next week at Liverpool, showing high waters starting at 7m today the 3rd Oct 2025 (neap tide) rising to over 10m near midnight the 8th-9th October. Times in UTC (not BST).
October 3, 2025 at 8:30 AM
jowilliams.bsky.social
Storm #Amy is expected to bring storm surges to the south east on the night of Oct 4th-5th, raising the high tide by around 1 metre. Fortunately it is not spring tides yet, but in areas with a smaller tidal range we can expect high total levels.
ntslf.org/files/ntslf_...
Ensemble of surge forecasts for Oct 2nd - 8th 2025. Storm surge starting north west England and Scotland on the 4th, then going down the east coast. This is surge residual so the peak (nearly 2m) will not coincide with the highest tide. Small triangles indicate the time of high tide at each site. Spring tides are a couple of days after full moon, which is not till the 7th.
October 3, 2025 at 8:16 AM
jowilliams.bsky.social
An update on the ensemble surge forecast.
Latest here:
ntslf.org/files/ntslf_...
Ensemble storm surge forecast at UK coastal sites for the storm (ex-Humberto) arriving UK around 3rd-5th October 2025. Surge likely on 4th-5th, mostly south east, but there is still a spread of over a metre on the forecast. Full moon is not till 7th October so this storm should be before spring tides.
October 1, 2025 at 9:21 AM
jowilliams.bsky.social
Ensemble surge forecast for the UK, Sep 29-Oct 5th. All quiet till the 3rd when it diverges massively. By the 5th the spread is over a metre at Sheerness. Oct 2nd is neap tide just after the half moon, and spring tides will be around the 9th/10th.
Ensemble surge forecast for the UK, Sep 29-Oct 5th. All quiet till the 3rd when it diverges massively. By the 5th the spread is over a metre at Sheerness. Oct 2nd is neap tide, spring tides will be around the 9th/10th.
September 29, 2025 at 3:49 PM
jowilliams.bsky.social
Synchronicity @oddthisday.bsky.social
Two consecutive posts both threatening sentiment bot
September 18, 2025 at 5:19 PM