On Nov 1, 5:54*pm, "Will Hand" wrote:
"Will Hand" wrote in message news:...
Thought I'd use the NAE output shown at
http://www.weatheronline.co.uk/cgi-b...G=en&MENU=0000...
to estimate what 1800-1800 rainfall total I would be reading at Haytor
tomorrow 1st Nov.
The gridpoint nearest to Dartmoor gives 23mm accumulation, the model will
not have the right elevation or exposure at that point and from experience
I would say that applying a factor of 1.5 is reasonable and would give 34
mm. This seems about right for a moving system running to the north of me.
Let's see how 30-35 mm pans out! *Assuming of course that the synoptics go
to plan*.
Synoptics went precisely to plan. Cold front came through at 0915 with a 3
degree temperature drop and wind veer then sunshine after heavy horizontal
rain and a strong and gusty wind up to F7 on the open moor.
Rainfall 1800-1800 measured in 5" gauge was 37.9mm, so not a bad forecast of
34mm :-))
Interesting elevated Davis AWS recorded 26.7mm (a massive 11.2 mm under-read
due to the very windy and turbulent conditions with fine & dense droplet
rainfall for some of the time). max. rate was 40mm/h at 0700 GMT.
I shall now use a factor of 1.6 for forecasting rain at Haytor in frontal
systems using that NAE gridpoint.
Will (Haytor, Devon, 1017 feet asl).
--
Will, the choice of your gridpoint from the NAE model forecast Sat.18
GMT is interesting. It gives 22 mm for the 6 hours 03-09 GMT during
the passage of the storm.
This gridpoint is nearest to me in SW Devon too, and is the one I
would take. We only had 13 mm rain here in Wembury, and 11mm at
Plymouth Mount Batten.
Haytor is about 70 km from Wembury.The forecast seemed a success for
you (with your 1.6 enhancement for ascent), but not for the masses of
people in the Plymouth area.
I would like to think the higher res of the NAE model is improving
forecast accuracy but I am not so convinced.
I am not anti-UKMO, they are doing their best to try and model these
smaller scale processes, so hats off to them. I think though some of
their claims about future success in forecasting on the very small
scale (100 km) are a bit fanciful.
Len Wood
Wembury, SW Devon. 83 m asl