All you need to know about ensemble weather forecasts

What are ensembles and why do we need them? At the Met office we are always looking for new and better ways to describe our weather predictions. Ensembles are going to be used more and more but what are they? And how do we use them?

[@Coolyoghurt22]

Very colourful and interesting video. Thanks Alex

[@jimrobin]

Very interesting! Thank you. 👍

[@echosonicmusic]

Love this "Even Deeper Dive" - thank you!

[@alayneperrott9693]

Brilliantly explained and much needed, Alex! There was an excellent example this morning where US forecasters were showing the cone of probability and a spaghetti plot (from the NGC) for Tropical Storm Helene, currently developing into a hurricane in the Gulf of Mexico. They were clearly trying to combat complacency about the likelihood of severe impacts such as high winds and flooding outside the 67% probability cone representing its forecast track. Given the relative reliability of different forecasting models on different time scales, it would be helpful for fans if you would kindly label the source of ensemble predictions that feature on Deep Dive: such as UKMO, ECMWF, GFS or more.

[@tomasmatulaitis9284]

Cool stuff Alex, loved it. Very well explained, always a joy listening to you. Keep it up!

[@Fred-wy8zw]

Excellent - love the detail

[@JamesBrock80]

An excellent explanation. Thanks!

[@RobertKillington]

Thank you. I found this helpful for understanding the information so often provided in the Deep Dive videos. As someone else has suggested, perhaps this series could be called An Even Deeper Dive?

[@chrisharrison4744]

No mention of the wet or dry seaweed hanging in the porch like in olden days. Thanks for the interesting insight into forecasting from the Met Office.

[@shaunyboy6539]

Fascinating. Thankyou

[@carbon1740]

Top drawer Alex, I really enjoyed the even more in depth info, thanks 👌

[@pauldavidson2443]

Fascinating and informative - thank you

[@PhilipMurphy8]

Great job, thank you

[@jacksonbritton4436]

We definitely need more videos like this

[@Wdf-76]

Thank you for this insight and giving me an understanding. Would you consider making a video to explain sounding charts please?

[@ianhodgson9779]

An excellent explainer. Very clear and concise. It would be great if the message gets through to people. But as a Brit, I do wonder what we would have to talk about if we can't complain about the weather and weather forecasts 😂. I do have a related query on the hour by hour forecast on the Met Office website. When I look at the forecast first thing in the morning to plan when to take the dog for a 30 minute walk and it says for instance 50% chance of rain next to 1pm symbol, how should I interpret this? Does it mean that if I stick my head out of the door at exactly 1pm I stand a 50% chance of finding it raining. Or does it mean 50% chance of some rain falling in the 60 minute interval 12.30 to 1.30 (or 1.00 to 2.00)? It seems to me that I have a better chance of completing my walk without getting wet if it's the latter (In my mind option 2 means I have a 50% chance of MAYBE getting wet, whereas option 1 means I have a 50% chance of DEFINITELY getting wet). Or am I overthinking this?

[@ianmcshane9728]

Very interesting. Thank-you. How will the forecasts change so we can access the probabilistic model to give us (for example) the risk of rain in Derby on a given future day?

[@andrewbeevers4686]

The MetOffice app already uses ensembles behind the scenes.

[@mickeyfilmer5551]

Brilliant explanation. How will AI help with future forecastig though?

[@user-vr4xt7nf5n]

Really interesting. Thank you.

[@andrewbeevers4686]

Any plans to incorporate ECMWF ENS output into the MO app to extend to say 10 days?

[@thewonkyeyedwoman]

I tell what I would like you to try is, please can you outline the UK and Island a little better. Sometimes it’s really hard to see it with all the other colours on there, many Thanks x

[@LaurieDriver-y7j]

With two thirds of the planet covered by ocean, and presuming you have far less information gained from the atmosphere over the ocean, is it reasonable to suggest that straight away you’re missing ~2/3 of the information you’d like?

[@metoffice]

Bouys and ships send observations from over the ocean. Plus satellite imagery captures from above the atmosphere right around the globe.

[@IsHimself]

Order from chaos. Top job, Met Ensemble Office

[@metoffice]

Thanks

[@billiondollarman3847]

Just look Out the window ... ⛈️☔☁️🌧️🌞🌡️🤔👌

[@wildlifegardener-tracey6206]

That was really interesting and informative. Thanks Alex.

[@poppyholly1759]

Very interesting. It did cross my mind that this is in essence a presentation of a mathematics problem. Ever thought of joining forces with Numberfile?

[@Michael-B26]

Another great explanation, Alex! For another idea in this series, please could you go into more detail about the set of regimes you often show (I think it’s the 30 most common weather regimes seen because the title of the chart is something like Regime 27 of 30). Would be fascinating to see them, along with commentary about why some are common, through to not common. You and other presenters often bring these up in deep dives and 10 day trends and we get a little insight, but I’d love a dedicated video going through them in a bit more detail.