Gusts belie the truth about Friederike

The worst is just about past now from low Friederike as she shoots off towards Germany to wreak more havoc no doubt. Yesterday mornings yellow warning of strong winds for gusts of 50-60 and a “small chance” of 70 mph issued by the Met Office didn’t last too long, because it was updated at around 03 UTC with a more cautiously worded one that upped the maximum gusts to 75 mph* (fig 1).

Figure 1 – Courtesy of the Met Office*

I don’t know what prompted the update at 03 UTC, but I don’t think it was the gust of 93 mph at Capel Curig, which happened at 2350 UTC and even before the warning had come into force (I did question why the start time had been 0005 UTC and not much earlier at 21 UTC). I think it was more likely that the Chief had just seen the T+3 forecast wind for eastern England from the 00 UTC mesoscale model, because let’s face it these days, and for many years past if truth be told, computers do all of the forecasting.

As always the media, and the Met Office to a large extent, seem to be completely fixated with gusts, and totally forget that storm force 10 – the basic definition of what constitutes a storm – is defined in the Beaufort scale as a 10 minute mean wind speed of 48 knots or higher. At Wittering this morning a true storm did occur, not many people noticed it, but I did, as did a lot of people in that part of Cambridgeshire as it rattled their windows. The winds were meaning at gale force 8 for around three hours between 03-06 UTC, with a maximum gust of 64 knots (~74 mph) at 05 UTC. The Met Office never mention the highest mean wind speed in any of their warnings, either for coasts, hills or inland, it would be just another thing that would require verification, and more often or not they would get it wrong anyway. Here’s a plotted grid of the last 24 hours observations from Wittering (fig 2).

Figure 2

Overall the updated warning just about covered it as far as maximum gusts were concerned (fig 3), that’s if you ignore the gusts at Capel Curig (93 mph), Aberdaron (78 mph) and Lake Vyrnwy (76 mph).

The last couple of days have been totally confusing since Met Éireann decided to call a tightening of the W’NW flow storm Fionn on Wednesday, especially when a potential and much better candidate for being named a storm arrived the very next day. I know that storm force winds can and do occur when the centre of the low is more than 800 miles away as it was on Wednesday on the west coast of Ireland. My idea for what it’s worth is that a truly memorable storm, and one that should be named, is a storm that’s associated with an intense vortex like the Braer Storm of January 1993 or the Burns’ day storm of 1990 were.

Figure 3

The final chart is the number of hourly observations when the mean speed was 34 knots or more – a gale to you and me (fig 4).

Figure 4

*I know I’m being even more picky than usual but if we have a ‘widely 50-60′ and a ’65-75 in some places’ what about gusts of 61-64?

Author: xmetman

An ex-metman passionate about all things to do with weather, climate and clouds

6 thoughts on “Gusts belie the truth about Friederike”

  1. Tim
    I agree with most of your points. The last couple of days was all bit of a farce really. Please subscribe if you’ve not already done so.
    Bruce.

  2. You are probably correct, but I personally believe that a 10 minute mean of 48 knots is just as effective at blowing down a tree as is a gust of 60 knots that lasts 30 seconds or less. If you can dig up any links you have to any papers concerning gusts and mean speeds and what does the most damage I would be grateful.

  3. It’s getting farcical. I know there’s a lot of rivalry between Meteo France and the Met Office, and that’s probably a big reason why the French named it! In this day of social media people are accessing data from many weather services, and the multiple naming of storms needs to be coordinated across the board to avoid confusion.

  4. London City Airport (my closest station) had a gust of 73mph at 4:50 and with 996mb pressure; this is much windier than the 50-55mph gust forecasted
    in fact i think between 3 and 6 AM it was REALLY windy – with gusts often around 65mph
    Models behaved poorly with this development – in fact early runs turned out to be more close than later runs (i noticed this happens a lot on the GFS)
    Met Office also were not great on dealing with this – they issued yellow warning of wind for London yesterday – cancelled it in the afternoon (probably based on recent models run that downplayed the wind) only to add it again at 1am this morning (like who’s gone take notice) – i think this was more worthy of a named storm than Fionn (which mostly affected Ireland)
    I mean does MO have to pay someone when they name storms – hence why they’re so adamant

    Meanwhile winds have calmed down here but Amsterdam is recording mean winds of 57mph with gusts of 75mph in the past hour

  5. To defend the use of gusts, from an impacts (ie damage) perspective they correlate best with observed damage.

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