uk.sci.weather (UK Weather) (uk.sci.weather) For the discussion of daily weather events, chiefly affecting the UK and adjacent parts of Europe, both past and predicted. The discussion is open to all, but contributions on a practical scientific level are encouraged.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
Old November 1st 09, 05:54 PM posted to uk.sci.weather
external usenet poster
 
First recorded activity by Weather-Banter: Nov 2004
Posts: 7,921
Default Rainfall forecasting exercise


"Will Hand" wrote in message news:...
Thought I'd use the NAE output shown at
http://www.weatheronline.co.uk/cgi-b...&ARCHIV=0&WMO=
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).
--


  #2   Report Post  
Old November 2nd 09, 11:54 AM posted to uk.sci.weather
external usenet poster
 
First recorded activity by Weather-Banter: Oct 2009
Posts: 1,730
Default Rainfall forecasting exercise

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


Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Contrail spotting exercise ... Martin Rowley uk.sci.weather (UK Weather) 0 February 12th 11 11:57 AM
Global Rainfall is mostly a Zero-Sum-Parameter; and thistle seed solution to Global Warming solves Rainfall also a_plutonium sci.geo.meteorology (Meteorology) 2 July 28th 07 11:22 AM
Forecasting 'officially' begins in Exeter Jon O Rourke uk.sci.weather (UK Weather) 7 September 17th 03 04:49 PM
Forecasting Minima Dave Wheeler uk.sci.weather (UK Weather) 0 September 3rd 03 10:37 PM
A Manner of Forecasting the Weather M C C uk.sci.weather (UK Weather) 0 July 27th 03 04:26 PM


All times are GMT. The time now is 08:05 PM.

Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Copyright ©2004-2025 Weather Banter.
The comments are property of their posters.
 

About Us

"It's about Weather"

 

Copyright © 2017