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By jjones
#1181268
i am low hours and found the very useful, thanks for posting it up.
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By Paul_Sengupta
#1189017
leiafee wrote:Before investigating this I hadn't thought of using previous METARs as a sort of doublecheck on the forecast behaviour. Will in future!


Right, yes, this is something you may have seen me mention here in the past in threads, when talking about decision making. I've spoken about looking at the "big picture"...and specifically made reference to looking at Metars over several hours to look to see what's occurring, so to speak (if you were flying near Barry...! :D ). It's also not just the nearest Metar. If a front is moving, look at everything in the area. Look at the green or otherwise dots on ukga. Look at it over a period of time. Look how fast the front is moving. Look at the cloud base underneath it as it passes airfields...see if it's lifting, dying out or getting worse.

Another thing, if there's a high pressure, today will be similar to yesterday - *but* with deteriorating visibility day by day...so if it got misty yesterday at a certain time, expect it to get worse earlier today.

The forecast you posted said the visibility was going to decrease as it got into evening and cloud was going to form and get lower and close up. The timing of these are never an exact science - in exactly the same way as the time for the fog to "burn off" is never known, or whether it even will burn off or just improve then get worse again as the sun goes over the yard arm.

You can see on the 215 that the front seems to die out, but there's an area to the south which may not officially be part of it, but still has its own "weather system".

Also, there's a bit of local knowledge there. As you've said, just as you get to the north of Bridgend, the hills rise quite steeply...and this tends to be a bit of a cloud trap. It's a bad place for it to happen as it's just on the edge of Cardiff's airspace - stopping you going over the flatlands to the south. I was in such a situation here once myself. I tried calling Cardiff to cut the corner of their airspace but they didn't hear my radio. All these people who say controlled airspace isn't really a problem as all you have to do is call them - well, I blow a raspberry at you. I was low, I was in bad weather and I was skirting high ground. Fortunately there was just about enough room between the hills, cloud and controlled airspace to squeeze through and I came out the other side into better weather to the east.

Another time I was west bound, going to Swansea to meet my parents for lunch. I passed Bridgend and the weather was getting bad. I looked at threading my way through but decided discretion, valour and all that, and decided to go back, calling into Kemble for lunch.

I did once contemplate the option of making a precautionary landing in the Bulldog. I was almost back at the airfield, but the airfield is on a ridge. I was in the flat bit between two ridges. I could have turned around and gone back, but that would have meant going back across the first ridge, and if the weather was deteriorating I didn't want to do that. So my two "outs" at that point was to go down the valley and round the edge of the ridge or to make a precautionary landing. As it was, it was good enough to get back to the airfield, but the land out was part of my thought, part of my "I'm not going to die here" armoury.

Specifically...

EGFF 291102Z 2912/3012 29010KT 9999 SCT040
TEMPO 2915/2918 8000 BKN008
BECMG 2918/2921 8000 BKN006
PROB30 TEMPO 3000/3006 4000 BR BKN004

Means by 4pm it's expected to be down to 800ft BKN, getting steadily lower until somewhere between 7pm and 10pm it goes down to 600ft and stays there, but possibly/probably getting misty with an even lower cloudbase over night.
#1189020
Cheers Paul interesting detail.

I think one of the things I did iss that the very fact it was GOING to be the sort of day that needed such careful thought on the weather.

It was there in the forecasts but just din't jump out to me at all, because 'out the window' looked so good, and so many people had sallied off in different directions...
#1189034
Normally "a picture tells a thousand words" works for me - but not when it comes to the 215. I find there is insufficient information on the weather image itself and it only ever seems to cover a brief period ahead. I don't find that very useful for flight planning purposes.

However the Airmets, despite being text only, I find to be much easier to understand and are much more local. I find they are well written and provide a good explanation of trend in the forecast.

http://secure.metoffice.com/aviation/av ... ductId=139

If you don't normally use them I would recommend them as the forecasts to fill in the detailed picture between the TAF/METAR locations.
#1189071
I know it doesn't work really for light drizzle days but many pilots don't include rainfall radar in the mix even on frontal days or Cb Ts days. In fact it is clear that neither do tv weather forecasters if Friday evening is typical. Meridian local lady about 22.40 assuring us no rain at all that night, completely dry, as I was watching a huge storm on rainfall radar and the lightning strikes page of the metoffice, running up from France over the Isle of Wight to hit east Hampshire and West Sussex about 23.15. It was already over the Isle of Wight as she spoke. I went down to the old Portsmouth walls to watch it from there, knowing approx how I could stay long as I had seen the direction and speed, but saw some magnificent lightning, then retreated as it got very close. The rain was torrential.