The Met Office - not fit for purpose?
The Analog Kid
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Originally Posted by gpn01
Problem is that the Met Office is trying to forecast a future event which, in the UK, isn't completely forecastable. We're a small island, off the coast of a large land mass, with a huge ocean with warm most air to the West and a source of very cold dry air to the North. Add to this the variability of the jetsream moving around and it all becomes very complex very quickly. If you want an accurate forecats, move to Nevada.
Yes, I know you can't use it professionally. Those of us needing accurate local forecasts for recreational purposes though, including planning flying with aircraft whose usable range of weather is very small, highly wind-direction dependent and needing little or no precipitation, generally find it remarkably accurate, up to several days in advance (once one factors in one's own understanding of the general synopsis and wider weather environment).Long and short - The Met Office should be capable of being better than their current performance.
Thanks for replying
Sigmet Nil - make no mistake this is day and daily in every respect - I just chose this occasion to voice my frustration - don't pick holes in my one example to shoot down the arguement.
My perspective is, that both forecasters wanted to say, that the basic conditions are visibility 10+ and clouds better than 1500 ft agl and it's going to rain every now and then with Visibility not below 3 km and ceiling not below 500 ft agl, but no longer than local midnight and from then on weather would be fairly quiet.
Which is more or less what happened in reality, if you discount the brief spell of morning fog the day after.
In TAF 1 the forecaster made a special point on the 20 utc rain and thought some CBs might come with that and produce strong gusts, which was maybe not too far fetched with regard to the generally lively southwesterly flow in the area. However, the pronounced gusts with the 20 utc rainshower band and the associated CBs are the only significant formal difference to TAF 2.
But after having seen the RADAR pictures I can perfectly understand why both forecasters thought, that the cloudbase might be temporarily below 1000 ft agl and visibility below 5 km. I tend to think the rain mostly came from CBs, who decayed during the overwater transit from Ireland to Scotland.
The second TAF didn't discern between the earlier showers and the 20 utc rain band and thought it would be all the same, anyway. Although that was formally correct, the 20 utc rain band indeed seems to have been the "highlight" of the day, weatherwise.
I would appreciate to learn from you (or any other pilot), why precisely you think these TAFs are of poor quality or maybe even a safety issue. (aside from the poor syntax in TAF1, where I don't know wether it stems from the original.)
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TAF EGPF 230507Z 2306/2406 09008KT 9999 -RA SCT010 BKNO15 BECMG 2306/2309 16016G26KT TEMPO 2306/2320 3000 RA BKN005 PROB 40 TEMPO 23202320 22023G35KT 4000 RA SHRA BKN006 BKN014CB BECMG 2400/2404 VRB06KT=
A short time later - two hours after getting the above !!!
TAF EGPF 231054Z 2312/2412 VRB05KT 9999 SCT010 BKN035 TEMPO 2312/2322 19015KT 4000 RA BKN007=
A short time later - two hours after getting the above !!!
TAF EGPF 231054Z 2312/2412 VRB05KT 9999 SCT010 BKN035 TEMPO 2312/2322 19015KT 4000 RA BKN007=
SA 24/08/2009 11:50-> METAR EGPF 241150Z 21009KT 9999 SCT035 17/10 Q1003=
SA 24/08/2009 11:20-> METAR EGPF 241120Z 20009KT 9999 SCT030 17/09 Q1003=
SA 24/08/2009 10:50-> METAR EGPF 241050Z 21010KT 9999 SCT025 16/09 Q1003=
SA 24/08/2009 10:20-> METAR EGPF 241020Z 19011KT 150V220 9999 SCT028 16/09 Q1003=
SA 24/08/2009 09:50-> METAR EGPF 240950Z 19012KT 9999 SCT028 16/10 Q1003=
SA 24/08/2009 09:20-> METAR EGPF 240920Z 19010KT 9999 SCT020 15/10 Q1004=
SA 24/08/2009 08:50-> METAR EGPF 240850Z 20008KT 9999 SCT016 15/11 Q1004=
SA 24/08/2009 08:20-> METAR EGPF 240820Z 19006KT 160V220 9999 FEW010 SCT016 14/11
Q1004=
SA 24/08/2009 07:50-> METAR EGPF 240750Z VRB02KT 9999 FEW012 SCT020 13/11 Q1004=
SA 24/08/2009 07:20-> METAR EGPF 240720Z VRB03KT 9999 FEW020 12/11 Q1004=
SA 24/08/2009 06:50-> METAR EGPF 240650Z 03003KT 9999 SCT020 10/10 Q1004=
SA 24/08/2009 06:20-> METAR EGPF 240620Z 03003KT 9999 SCT035 09/09 Q1004=
SA 24/08/2009 05:50-> METAR EGPF 240550Z VRB03KT 9999 FEW035 10/10 Q1004=
SA 24/08/2009 05:20-> METAR EGPF 240520Z 05003KT 5000 R05/0550 BCFG FEW045 09/08
Q1004=
SA 24/08/2009 04:50-> METAR EGPF 240450Z 00000KT 7000 R23/0600 PRFG NSC 10/09 Q1004=
SA 24/08/2009 04:20-> METAR EGPF 240420Z 26002KT CAVOK 10/10 Q1004=
SA 24/08/2009 03:50-> METAR EGPF 240350Z NIL=
SA 24/08/2009 03:20-> METAR EGPF 240320Z AUTO 27003KT 9999NDV NCD 11/10 Q1003=
SA 24/08/2009 02:50-> METAR EGPF 240250Z AUTO 22006KT 9999NDV NCD 12/11 Q1003=
SA 24/08/2009 02:20-> METAR EGPF 240220Z AUTO 23006KT 9999NDV NCD 12/11 Q1003=
SA 24/08/2009 01:50-> METAR EGPF 240150Z 21004KT CAVOK 11/10 Q1003=
SA 24/08/2009 01:20-> METAR EGPF 240120Z 24005KT 9999 FEW026 13/11 Q1003=
SA 24/08/2009 00:50-> METAR EGPF 240050Z 22005KT 9999 SCT029 13/11 Q1003=
SA 24/08/2009 00:20-> METAR EGPF 240020Z 25004KT 9999 SCT026 14/12 Q1003=
SA 23/08/2009 23:50-> METAR EGPF 232350Z 26005KT 9999 SCT024 BKN030 14/13 Q1003=
SA 23/08/2009 23:20-> METAR EGPF 232320Z 26003KT 9999 BKN025 15/13 Q1003=
SA 23/08/2009 22:50-> METAR EGPF 232250Z 28006KT 9999 -SHRA SCT009 SCT014 BKN020 15/13 Q1003=
SA 23/08/2009 22:20-> METAR EGPF 232220Z 22012KT 9999 -SHRA SCT016 BKN028 16/15 Q1003=
SA 23/08/2009 21:50-> METAR EGPF 232150Z 21008KT 9999 FEW012 SCT018 BKN030 16/15 Q1003=
SA 23/08/2009 21:20-> METAR EGPF 232120Z 21010KT 9999 SCT010 BKN016 17/15 Q1002 RERA=
SA 23/08/2009 20:50-> METAR EGPF 232050Z 21009KT 9999 -SHRA SCT010 BKN016 17/15 Q1003=
SA 23/08/2009 20:20-> METAR EGPF 232020Z 20012KT 5000 RA SCT015 BKN020 17/15 Q1003 RERA=
SA 23/08/2009 19:50-> METAR EGPF 231950Z 19012KT 4000 RA FEW015 BKN020 BKN030 17/15 Q1002=
SA 23/08/2009 19:20-> METAR EGPF 231920Z 19014KT 9999 VCSH FEW015 SCT020 BKN030 18/15 Q1003=
SA 23/08/2009 18:50-> METAR EGPF 231850Z 20015KT 9999 VCSH FEW020 SCT030 18/15 Q1003=
SA 23/08/2009 18:20-> METAR EGPF 231820Z 19014KT 9999 VCSH FEW020 SCT040 18/15 Q1002=
SA 23/08/2009 17:50-> METAR EGPF 231750Z 19014KT 9000 -SHRA FEW016 SCT024 18/16 Q1002=
SA 23/08/2009 17:20-> METAR EGPF 231720Z 19014KT 9999 SCT018TCU SCT024 BKN045 19/16 Q1003=
SA 23/08/2009 16:50-> METAR EGPF 231650Z 20017KT 9999 FEW018 SCT024 19/16 Q1003=
SA 23/08/2009 16:20-> METAR EGPF 231620Z 19018KT 9999 -RA FEW018 BKN035 19/16 Q1002=
SA 23/08/2009 15:50-> METAR EGPF 231550Z 18014KT 9999 -RA SCT020 SCT026 BKN035 18/16 Q1002 RERA=
SA 23/08/2009 15:20-> METAR EGPF 231520Z 18012KT 9000 -RA SCT020 BKN026 18/16 Q1003=
SA 23/08/2009 14:50-> METAR EGPF 231450Z 18012KT 9999 -RA FEW018 BKN024 BKN030 19/16 Q1003=
SA 23/08/2009 14:20-> METAR EGPF 231420Z 16009KT 120V220 9999 -SHRA BKN018 BKN024 19/16 Q1004=
SA 23/08/2009 13:50-> METAR EGPF 231350Z 16005KT 130V200 9999 -RA BKN020 18/16 Q1004=
SA 23/08/2009 13:20-> METAR EGPF 231320Z 14007KT 120V190 9999 -RA FEW020 BKN030 18/16 Q1005=
SA 23/08/2009 12:50-> METAR EGPF 231250Z 16007KT 9999 SCT016 BKN022 18/16 Q1005=
SA 23/08/2009 12:20-> METAR EGPF 231220Z 16011KT 9999 -SHRA BKN016 18/16 Q1005=
SA 23/08/2009 11:50-> METAR EGPF 231150Z 17011KT 9999 VCSH BKN016 18/16 Q1005=
SA 23/08/2009 11:20-> METAR EGPF 231120Z 16009KT 9999 BKN016 18/15 Q1006 REDZ=
SA 23/08/2009 10:50-> METAR EGPF 231050Z 15005KT 120V200 9999 -RA FEW015 SCT030 BKN040 17/15 Q1006=
SA 23/08/2009 10:20-> METAR EGPF 231020Z 11006KT 9999 -RA FEW015 SCT025 BKN030 16/15 Q1006=
SA 23/08/2009 09:50-> METAR EGPF 230950Z 14005KT 080V200 6000 -RA FEW010 SCT020 BKN030 16/15 Q1007=
SA 23/08/2009 09:20-> METAR EGPF 230920Z 11006KT 060V140 9999 -RA SCT012 SCT018 BKN024 16/15 Q1007 REDZ=
SA 23/08/2009 08:50-> METAR EGPF 230850Z 06005KT 9999 -RA SCT016 BKN022 16/14 Q1007 REDZ=
SA 23/08/2009 08:20-> METAR EGPF 230820Z 09005KT 9999 -RA FEW020 BKN030 15/14 Q1008=
SA 23/08/2009 07:50-> METAR EGPF 230750Z 11004KT 080V170 9999 -RA SCT020 BKN030 15/14 Q1008=
SA 23/08/2009 07:20-> METAR EGPF 230720Z 18005KT 150V240 6000 -RA FEW015 SCT025 BKN030 15/14 Q1008 REDZ=
SA 23/08/2009 06:50-> METAR EGPF 230650Z 16004KT 110V220 6000 -RA FEW010 SCT020 BKN030 15/14 Q1009=
SA 23/08/2009 06:20-> METAR EGPF 230620Z 20004KT 150V240 9999 VCSH BKN010 15/14 Q1009=
SA 23/08/2009 05:50-> METAR EGPF 230550Z 17007KT 130V210 9000 -DZ SCT010 BKN016 BKN022 15/14 Q1009=
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OK, I'll stick my head above the parapet. I'm a metman and have been for just over 20 years. I'm not in the front line operational departments anymore so can't really comment on forecast accuracy. However I can comment on and the changes I've seen and experienced in my time. When I joined as an observer in the good old days the Met Office was fully public funded and access to forecasts and products was free to all.
Then in 1996 the Met became a trading fund at the insistence of the government and as such had to show an operating profit to it's owners, the MOD. In the years since there has been constant and not insignificant pressure to reduce costs to remain competitive. It's the same in all industry of course and the Met is no different. These pressures have led to station closures, reorganisations and rationalisations across the organisation. Some of these changes were for the better but some were not (in my opinion). I believe that the loss of the local metman to the aviation or marine community has been detrimental to the office in terms of reputation. However, that being said, SOMEONE has to pay for the infrastructure and times are hard so something has to give. Unfortunately our customers are always looking at ways to reduce costs and our competitors can sometimes seem an attractive option. I think though that the Met Office is in a difficult position because as the UK's national weather service (and member of the World Met Organisation) it is obliged to maintain a comprehensive observations network of ground stations, bouys, radar, aircraft and satellites. This is obviously not cheap but provides vast amounts of good quality data to input into our very comprehensive models. Unfortunately under free data access rules this raw data must also be made available to our competitors who can simply input it into their models. Voila...forecasts, usually less accurate, but cheaper because they have less overheads.
there you have it..in a nutshell the economics of the trading fund Met Office.
Then in 1996 the Met became a trading fund at the insistence of the government and as such had to show an operating profit to it's owners, the MOD. In the years since there has been constant and not insignificant pressure to reduce costs to remain competitive. It's the same in all industry of course and the Met is no different. These pressures have led to station closures, reorganisations and rationalisations across the organisation. Some of these changes were for the better but some were not (in my opinion). I believe that the loss of the local metman to the aviation or marine community has been detrimental to the office in terms of reputation. However, that being said, SOMEONE has to pay for the infrastructure and times are hard so something has to give. Unfortunately our customers are always looking at ways to reduce costs and our competitors can sometimes seem an attractive option. I think though that the Met Office is in a difficult position because as the UK's national weather service (and member of the World Met Organisation) it is obliged to maintain a comprehensive observations network of ground stations, bouys, radar, aircraft and satellites. This is obviously not cheap but provides vast amounts of good quality data to input into our very comprehensive models. Unfortunately under free data access rules this raw data must also be made available to our competitors who can simply input it into their models. Voila...forecasts, usually less accurate, but cheaper because they have less overheads.
there you have it..in a nutshell the economics of the trading fund Met Office.
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Having worked in met for over 40 years I can see some of your points. However I have yet to see a Special from any of the civil airports which are now done by ATC etc not proffessional Observers and thus a great gap in the actual weather leaves forecasters not getting valuable information.
I can recall when we also used to get info. from Aircrew but that had dswindled away before I left the met. office
Duggymac
I can recall when we also used to get info. from Aircrew but that had dswindled away before I left the met. office
Duggymac
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Looking at the METARs provided for the forecast period (thanks SIGMET nil) the TAFs do seem fairly reasonable to me, with the exception that the strong winds didn't materialise until late afternoon/early evening on the 23rd, even then not as strong as forecast. With the light winds in the morning, when the 12-12 TAF was issued the forecast wind was revised. To me that seems perfectly reasonable. A forecast was made, the wind wasn't as strong as they thought so they revised the forecast.
Sometimes the problem is how we pilots interpret the forecast. I used to complain a bit about TAFs being wrong (there was a thread a while back on Private Flying on this subject) but then I realised the problem was how I was interpreting the TAF. I was still a student then, now I understand it a bit more. Although yes there are occasions when I read a TAF, look at the METARs and think "What the f...?".
What was a problem was the unforecast early morning Fog. Fog is a difficult thing to forecast, but here is one area where perhaps human input (with a little local knowledge) would help.
Sometimes forecasts can be spot-on, other times they can be questionable. Such is the science of forecasting I suppose.
There used to be a member here, PKPF68-77, who was very good at explaining all things Wx. However I'm not sure if he's still around; unfortunately he got involved in the willy-waving contest on the Global Warming thread on Jet Blast a while back and I've not seen him around here since.
Smithy
Sometimes the problem is how we pilots interpret the forecast. I used to complain a bit about TAFs being wrong (there was a thread a while back on Private Flying on this subject) but then I realised the problem was how I was interpreting the TAF. I was still a student then, now I understand it a bit more. Although yes there are occasions when I read a TAF, look at the METARs and think "What the f...?".
What was a problem was the unforecast early morning Fog. Fog is a difficult thing to forecast, but here is one area where perhaps human input (with a little local knowledge) would help.
Sometimes forecasts can be spot-on, other times they can be questionable. Such is the science of forecasting I suppose.
There used to be a member here, PKPF68-77, who was very good at explaining all things Wx. However I'm not sure if he's still around; unfortunately he got involved in the willy-waving contest on the Global Warming thread on Jet Blast a while back and I've not seen him around here since.
Smithy
Ever since the famous words "don't worry, there's not going to be a hurricane..." were used, general UK forecasts have largely erred towards the poor side, IMHO. I can see why in that the fuss over predicted bad weather that turns out fairly benign is far less than that over unforecast downpours, storms, snow, etc.
In the quoted example, there's also a five hour gap between the old and new forecast, in which the CBs have gone as well as the winds associated with them. Overall, the accuracy doesn't seem too bad, considering they have to forecast what the worst likely conditions are going to be (visibility, cloud ceiling, wind, SIGWX, etc.) during the period. There are also tolerances involved - I don't know what they are but they might be in ICAO Annex 3, if you want to download that for £75...
Also, in terms of commercial operations, are the two TAFs that much different? Wind is not much off the runway when stronger, min. vis. is 4Km in RA in both and cloud ceiling is 5-600' vs. 700'.
It reminds me somewhat of India: there must have been an unforecast thunderstorm in 1953 because the TAFs generally include a TEMPO TSRA for the whole period at the end, even when there is no weather at all in the rest of the forecast!
In the quoted example, there's also a five hour gap between the old and new forecast, in which the CBs have gone as well as the winds associated with them. Overall, the accuracy doesn't seem too bad, considering they have to forecast what the worst likely conditions are going to be (visibility, cloud ceiling, wind, SIGWX, etc.) during the period. There are also tolerances involved - I don't know what they are but they might be in ICAO Annex 3, if you want to download that for £75...
Also, in terms of commercial operations, are the two TAFs that much different? Wind is not much off the runway when stronger, min. vis. is 4Km in RA in both and cloud ceiling is 5-600' vs. 700'.
It reminds me somewhat of India: there must have been an unforecast thunderstorm in 1953 because the TAFs generally include a TEMPO TSRA for the whole period at the end, even when there is no weather at all in the rest of the forecast!
When we had forecasters at airports they used to have a big book (Approx A3 pages) which described local anomalies and variations in different weather systems.
It had been complied by resident forecasters over many years and covered all UK airfields and many world airfields where we used to go to. It was an excelent book and remarkably accurate which I used to take my co-pilots to be briefed on by those very nice and capable resident forecasters.
If anyone still has a copy I would love to see it.
MM
It had been complied by resident forecasters over many years and covered all UK airfields and many world airfields where we used to go to. It was an excelent book and remarkably accurate which I used to take my co-pilots to be briefed on by those very nice and capable resident forecasters.
If anyone still has a copy I would love to see it.
MM
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Sigmet wrote:
the basic conditions are visibility 10+ and clouds better than 1500 ft agl and it's going to rain every now and then with Visibility not below 3 km and ceiling not below 500 ft agl, but no longer than local midnight
Sigmet after over 30 years of flying here's my take on the above forecast:
- ALL DAY it's going to be very blustery (G26) with big crosswinds on most local runways and some extremely heavy showers (3/4000m). Spend the day making sure all the aircraft are tied down and secure or better still see if you can get a couple in the hangar because later the met man is pretty sure (PROB 40) it's going to gust 35kt in these big showers. Later sit and worry about an aircraft being damaged (we always get +10KT on the gust the met man forecasts)
In addition, with respect to the actuals and being there to see it - the visibility was excellent all day save for a shower, which gave 6k at 1050 (6k not a problem ,3k = big problem) -the 500 foot cloud base never materialised and the wind was less than 12kt all day.
I tracked the storm on radar and basically it ran north out of Ireland and did not cross the central belt of Scotland. The Belfast visibility was much lower than forecast with, I believe, RVRs being issued.
I'm not into picking detail out of actuals/tafs as I believe you need to take the big picture with weather. Saying it's "going to rain now and then with visibility not below 3 km" whilst leaving out the wind seriously distorts the picture. My take on the forecasters story was that, there is a big storm area coming and its not going to be pretty - however, it missed.
Tricky to forecast the UK weather - ok no problem, don't try........ spend your energy and resources into telling us when the hurricanes and big dumps of snow etc are coming because if it's not right, it's not fit for purpose.
the basic conditions are visibility 10+ and clouds better than 1500 ft agl and it's going to rain every now and then with Visibility not below 3 km and ceiling not below 500 ft agl, but no longer than local midnight
TAF EGPF 230507Z 2306/2406 09008KT 9999 -RA SCT010 BKNO15 BECMG 2306/2309 16016G26KT TEMPO 2306/2320 3000 RA BKN005 PROB 40 TEMPO 2320/2323 22023G35KT 4000 RA SHRA BKN006 BKN014CB BECMG 2400/2404 VRB06KT
Sigmet after over 30 years of flying here's my take on the above forecast:
- ALL DAY it's going to be very blustery (G26) with big crosswinds on most local runways and some extremely heavy showers (3/4000m). Spend the day making sure all the aircraft are tied down and secure or better still see if you can get a couple in the hangar because later the met man is pretty sure (PROB 40) it's going to gust 35kt in these big showers. Later sit and worry about an aircraft being damaged (we always get +10KT on the gust the met man forecasts)
In addition, with respect to the actuals and being there to see it - the visibility was excellent all day save for a shower, which gave 6k at 1050 (6k not a problem ,3k = big problem) -the 500 foot cloud base never materialised and the wind was less than 12kt all day.
I tracked the storm on radar and basically it ran north out of Ireland and did not cross the central belt of Scotland. The Belfast visibility was much lower than forecast with, I believe, RVRs being issued.
I'm not into picking detail out of actuals/tafs as I believe you need to take the big picture with weather. Saying it's "going to rain now and then with visibility not below 3 km" whilst leaving out the wind seriously distorts the picture. My take on the forecasters story was that, there is a big storm area coming and its not going to be pretty - however, it missed.
Tricky to forecast the UK weather - ok no problem, don't try........ spend your energy and resources into telling us when the hurricanes and big dumps of snow etc are coming because if it's not right, it's not fit for purpose.
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Channel Islands based pilots have had to put up with proffesional aftercasters for years,the early morning TAF is always going to change when Jersey met wake up and see what is actually happening, then they forecast thunderstorms even if its clearly a stable airmass, forecast fog when there is none then change their minds, but very often do not forecast fog, so it appears, then they ammend the TAF!
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Re #48 MilesMagister - We do still have a copy of the big yellow book 'Airport Weather Characteristics' if you're passing through EGNS (with thanks to Dash&Thump #8 for comments on TAFs/METARs)
Re #42 I agree with the detailed analysis SIGMETnil - as FullWing says in #47 there are parameters for introducing change groups in TAFs (and TRENDs) - but you don't have to pay £75 to download ICAO Annex 3 since all of the info is freely available in UK AIP GEN3.5 at http://www.nats-uk.ead-it.com/aip/cu...GEN_3_5_en.pdf
Re #42 I agree with the detailed analysis SIGMETnil - as FullWing says in #47 there are parameters for introducing change groups in TAFs (and TRENDs) - but you don't have to pay £75 to download ICAO Annex 3 since all of the info is freely available in UK AIP GEN3.5 at http://www.nats-uk.ead-it.com/aip/cu...GEN_3_5_en.pdf
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Not all young FO's are incompetent in weather. I know lots of pilots who are meteorologists by profession. The young FO on your right seat might be better in MET. Besides, most FO's are fresh from instructing. They might be lacking in experience, but I bet they have comparable knowledge to that guy doing your checkride.
What frustrates most is the PROB TEMPOs of TS forecasted for +9 hrs of a 24 hr TAF. Yesterdays SE UK forecast being the case in point. PROB 30 Tempos of TS absolutly nothing big around the SE yet the fact wasn't amended to reflect the fcst was wrong. Result was most of my mates came in with ++ fuel (quite rightly too based on the fcst), big cost and enviromental impact too.
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Just wondering
Your interpretation of the TAF is largely correct; very poor weather was forecast, i.e. the forecaster(s) believed that the storm was going to hit Glasgow; however what happened was that it wasn't quite as bad as they first thought, and it dissapated before reaching the West Coast.
Re: the point about the vis being not too bad in Glasgow and being worse than forecast in Belfast. Vis is notoriously difficult, if not impossible, to forecast correctly, especially when precipitation is involved; any estimate of vis in a TAF when RA or SHRA is involved is at best a stab in the dark. The vis might get very poor in a heavy shower, there again if the precip is light then the vis may stay well above 10k.
I can understand some of your points though, but the fact is that the weather didn't turn out as bad as it looked it was going to be. I don't really see the problem with that. Perhaps a tad pessimistic it could be said, but there again the forecast is always the absolute worst the Met thinks its going to be, with the data they have at the time.
Saying that the Met Office isn't fit for purpose is a little harsh though, perhaps a little too "Daily Mail". There are limitations to forecasting, we have to understand that and work with it.
Just my take on it...
Smithy
Your interpretation of the TAF is largely correct; very poor weather was forecast, i.e. the forecaster(s) believed that the storm was going to hit Glasgow; however what happened was that it wasn't quite as bad as they first thought, and it dissapated before reaching the West Coast.
Re: the point about the vis being not too bad in Glasgow and being worse than forecast in Belfast. Vis is notoriously difficult, if not impossible, to forecast correctly, especially when precipitation is involved; any estimate of vis in a TAF when RA or SHRA is involved is at best a stab in the dark. The vis might get very poor in a heavy shower, there again if the precip is light then the vis may stay well above 10k.
I can understand some of your points though, but the fact is that the weather didn't turn out as bad as it looked it was going to be. I don't really see the problem with that. Perhaps a tad pessimistic it could be said, but there again the forecast is always the absolute worst the Met thinks its going to be, with the data they have at the time.
Saying that the Met Office isn't fit for purpose is a little harsh though, perhaps a little too "Daily Mail". There are limitations to forecasting, we have to understand that and work with it.
Just my take on it...
Smithy
I think one of the main issues is this feeling that the quality of forecasting has deteriorated maybe in the last few years.
My perception is that the (old) shorter TAfs of 9 hours were more accurate than the current 24 hour TAFs.
My perception is that the (old) shorter TAfs of 9 hours were more accurate than the current 24 hour TAFs.
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Veering slightly off topic but illustrating how bad forecasts used to be: back in the late 70s I saw a news report (from the USA) in which one of the top weather forecasting companies protested that they were quite rightly proud of their forecasts as they were the best and, on average, were right 30% of the time. This meant that they were wrong more often than right. 
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Smithy
It didn't dissipate it went steaming north up the West coast
That's a statement of fact - don't need a lesson in viz. Glasgow viz was good (much greater than 10k) apart from one actual of 6k.
... no problem if you're taking a knitting class but not for aviation flight planning
A "tad" - Prob 40 - Gust 35 ?!
I watched it track up through Ireland on radar - I also looked at the actuals from Shannon, Dublin and Belfast - perhaps they could have done the same and updated the TAF.
Not fit for my purpose (such as making a safe decision to go flying) and it seems many others such as the sailing community.
Don't forget the mistake could have been the other way round - a good forecast which turns into a very bad one.... which happens often too.
Not sure the Met office agrees : http://www.metoffice.gov.uk/marine/safesee.pdf
dissapated before reaching the West Coast
Re: the point about the vis being not too bad in Glasgow and being worse than forecast in Belfast
but the fact is that the weather didn't turn out as bad as it looked it was going to be. I don't really see the problem with that.
tad pessimistic
with the data they have at the time
Saying that the Met Office isn't fit for purpose is a little harsh though
Don't forget the mistake could have been the other way round - a good forecast which turns into a very bad one.... which happens often too.
There are limitations to forecasting
Times change
In the really bad old days you could RELY on the forecast being wrong - now with the Cray beavering away, the forecasts are NOT ALWAYS wrong, but you don't know which ones. Is that an improvement? I only want to know.
The Ancient Mariner
The Ancient Mariner
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Just wondering
Fair point. Bad explanation on my part. I stand corrected.
Again fair point, but the difference in forecast vis. vs. actual seemed to be one of your main bones of contention, so I just thought I'd mention it. Didn't mean to sound like I was lecturing you or anything.
No need to be sarky chum... but plenty of us seem to make do with it okay for flight planning. Perhaps knitting TAFs would be useful however for the grannies 
Sorry, semi-humourous understatement.
Agreed, why this didn't happen I don't know.
Unfortunately for yourself the MO are the sole provider of all the UK's TAFs, there again there are plenty of us, Smithy included, who do find it fit for purpose and get on with it fine. I can't speak for the sailors however.
It can happen, and no doubt will. There was an almighty storm the year I was born which Michael Fish told us not to worry about... 
When they say "accurate" in that leaflet, no doubt they are referring to their own standards, set by themselves. They are a profit-making company so they have to blow their trumpet a bit. Again though I can't speak for marine forecasts but the aviation ones mostly seem reasonable to me, apart from the occasional "blip", which is to be expected, unless they start employing Mystic Meg, or using Tarot Cards etc. to predict the Wx, to ensure 100% accuracy
Smithy
It didn't dissipate it went steaming north up the West coast
That's a statement of fact - don't need a lesson in viz. Glasgow viz was good (much greater than 10k) apart from one actual of 6k.
... no problem if you're taking a knitting class but not for aviation flight planning
A "tad" - Prob 40 - Gust 35 ?!
I watched it track up through Ireland on radar - I also looked at the actuals from Shannon, Dublin and Belfast - perhaps they could have done the same and updated the TAF.
Not fit for my purpose (such as making a safe decision to go flying) and it seems many others such as the sailing community.
Don't forget the mistake could have been the other way round - a good forecast which turns into a very bad one.... which happens often too.
When they say "accurate" in that leaflet, no doubt they are referring to their own standards, set by themselves. They are a profit-making company so they have to blow their trumpet a bit. Again though I can't speak for marine forecasts but the aviation ones mostly seem reasonable to me, apart from the occasional "blip", which is to be expected, unless they start employing Mystic Meg, or using Tarot Cards etc. to predict the Wx, to ensure 100% accuracy
Smithy