@ Just Wondering : First of all thanks for taking the time to give a detailed description of your thoughts. I read both what you wrote to me and Captain Smithy and I think I can see a good part of your view of things, now.
Please correct me, where I'm wrong in my following hypothesis :
From the whole of what you write I conclude, that you thought of the bad weather area as a more or less homogenuous entity that would move in with lengthy periods of rain, poor visibility and low ceilings in connection with strong winds. Maybe like a warmfront or a weather active warmsector after a warmfront.
With your statements and after having watched the
RADAR pictures from the 23rd of the whole of the British Isles ten times or more I get a totally different "greater picture", as you put it.
What you are calling "the storm" was a multitude of smaller and larger rainbands with frequent embedded shower-CBs within a very clear airmass, that all would travel on a northeasterly path from the Irish West Coast over Northern Ireland and then deep into Scotland. They gained and lost intensity in very rapid cycles as dictated by a) available radiation and b) the superimposed complex pattern of secondary troughs (fluctuations in upper winds rapidly changing lifting and instability patterns.)
I disagree with your opinion that most of the bad weather "steamed up the Scottish West Coast" as I couldn't see that on the composite RADAR pictures at all. The rain bands spawned many CBs with strong showers over Ireland, which infallibly lost some power over the stretch of water enroute to Scotland, which might be the reason, why the forecasters wrote
rain in the TAFs and not rain showers.
Nevertheless it was a convective weather pattern and the lateral structure of the precipitation area was as complex as the blossom of a rose and as predictable as the trajectory of a falling feather, while I suppose you thought of the "weather area" as a rigid structure like a brick, with a similarly predictable trajectory. While it is easy to forecast the flight path of a brick after its launch - e.g. you can catch it - what you are demanding is like a forecast of the shape of the rose blossom, while we are still looking at its bud.
To illuminate what I just said I will show some METARs from Belfast, as you gave me a very valuable hint by mentioning RVRs.
Belfast had basically the same weather as Glasgow that day.
But, inland the shower-CBs could pick up a lot more energy from surface warming than their wrecks which stranded every now and then in Glasgow.
Just one of the CBs made a direct hit in Belfast and you can see the result here:
SA 23/08/2009 17:20-> METAR EGAA 231720Z 18010KT 150V220 9999 FEW018 SCT039 17/15 Q1002=
SA 23/08/2009 16:50-> METAR EGAA 231650Z 19011KT 9999 FEW013 SCT016 18/16 Q1002=
SA 23/08/2009 16:20-> METAR EGAA 231620Z 18009KT 140V220 8000 SCT015 17/16 Q1001=
SA 23/08/2009 15:50-> METAR EGAA 231550Z 17012KT 8000 SHRA SCT019CB 17/16 Q1001=
SA 23/08/2009 15:20-> METAR EGAA 231520Z 21006KT 170V230 6000 VCSH SCT016CB 16/16 Q1002=
SA 23/08/2009 14:50-> METAR EGAA 231450Z 20009KT 8000 VCSH FEW007 SCT015CB 15/15 Q1002=
SA 23/08/2009 14:20-> METAR EGAA 231420Z 23018KT 1500 R25/0600 R07/P1500 +SHRA BKN010CB 16/15 Q1002=
SA 23/08/2009 13:50-> METAR EGAA 231350Z 17015G27KT 140V200 9000 -RA BKN019 18/15 Q1002=
SA 23/08/2009 13:20-> METAR EGAA 231320Z 16016KT 130V190 9999 BKN026 18/15 Q1002=
SA 23/08/2009 12:50-> METAR EGAA 231250Z 16015G27KT 9999 -SHRA SCT017 18/15 Q1002=
SA 23/08/2009 12:20-> METAR EGAA 231220Z 18012KT 140V210 9999 FEW014 BKN017 18/16 Q1002=
It ws just one strong shower out of many others that missed the airfield by a small margin. What the forecaster
is scared of, is that you might be caught in weather like that of 14:20z when strong showers are underway. That is why during days with shower activity some harsh minima are included in the TEMPO groups, although the weather may be perfectly flyable for 95 % of the day.
Still it is not state of the art to predict the trajectory and intensity of single convective cells such as those of showers and thunderstorms over an extended period of time, say more of 30 minutes, with reasonable accuracy.
I already wrote a lot, if you are still with me, one more word to TAF interpretation with regard to the wind, that you stressed so highly. TAF compilation is regulated by ICAO Annex 3, as already mentioned in this thread. Annex 3 allows the inclusion of gusts in TAFs only above 25 knots. So, if I think the wind will be 16016G24KT I only write 16016KT, while only 2 measly knots are separating my expectation from the 16016G26KT you are taking offense at. At least during the afternoon I'd be surprised, if gusts hadn't come in the 20 to 23 knots range in Glasgow.
Thanks again for sharing your detailed opinion - it was very insightful for me to see your practical view point and what you expect from a TAF.
I'm sure, in just a few years there will be a lot of competition in European Aviation Meteorology services. So maybe soon you might be able to choose where you get your information from. Additionally modern self briefing providers are giving professional pilots more and more opportunities to browse weather data according to their own demands and skills.
So, if you don't like the MET-office, I see some hope for you.