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26-11-2011, 10:37   #1
Discodog
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Which Model for rainfall - A laymans guide ?

I monitor rainfall forecast daily as I spend a lot of time outdoors. Recently I have noticed big variations between different forecast sites - especially yr.no & XC. I know that XC uses the latest GFS.

I use the Weatheronline expert charts but it seems that the only rainfall prediction is via the GFS model. I also use the EHMI site where their rainfall prediction is based on HIRLAM.

So who do you think is the best at predicting where & when rain will fall ? Is there one model that is accepted as being more accurate ?
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26-11-2011, 10:52   #2
 
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Weatheronline also has the NAE, which is the hi-res son of the UKMO, as well as all the others. Compare this with the GFS and HiRLAM and you should get a good overview of what should happen.

It should be noted, however, that no model is absolutely perfect when it comes to precip forecasts, but the LAMs will give the best output.
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26-11-2011, 10:55   #3
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I like the NAE (available on weatheronline). It has a higher resolution that the global models like the GFS.
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26-11-2011, 11:08   #4
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Thanks. I can see what you mean when I compare the GFS & NAE. Is a HIRLAM rainfall prediction available on Weatheronline - is it called something else ? I find that the EHMI HIRLAM rainfall animation to be pretty accurate - it's a pity that the map is a bit small.

For me it's the timing of the rain that is more important than amounts. I am forever looking at the radar & trying to extrapolate as to when or whether a lump of rain will hit my location.
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26-11-2011, 11:11   #5
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Quote:
Originally Posted by Discodog View Post
Thanks. I can see what you mean when I compare the GFS & NAE. Is a HIRLAM rainfall prediction available on Weatheronline - is it called something else ? I find that the EHMI HIRLAM rainfall animation to be pretty accurate - it's a pity that the map is a bit small.

For me it's the timing of the rain that is more important than amounts. I am forever looking at the radar & trying to extrapolate as to when or whether a lump of rain will hit my location.
HIRLAM :

http://www.meteociel.fr/modeles/hirl...mode=2&carte=0
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26-11-2011, 11:18   #6
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Thanks but I find that the EHMI map is much clearer & easy to use. Other web sites would do well to copy this:

http://www.emhi.ee/index.php?ide=19,394,416,418

EDIT: HIRLAM may not be so good ! The EHMI shows Ireland as dry & we have torrential rain here !

I have also just realised that NAE only covers 48 hours ahead.

According to yr.no. I might as well give up on next week whereas XC is far more optimistic.

Last edited by Discodog; 26-11-2011 at 11:24.
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26-11-2011, 11:43   #7
 
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Originally Posted by Discodog View Post
Thanks. I can see what you mean when I compare the GFS & NAE. Is a HIRLAM rainfall prediction available on Weatheronline - is it called something else ? I find that the EHMI HIRLAM rainfall animation to be pretty accurate - it's a pity that the map is a bit small.
The NAE's right there on the same page as the GFS!!

http://www.weatheronline.co.uk/cgi-b...0&PERIOD=&WMO=
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26-11-2011, 11:46   #8
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The NAE's right there on the same page as the GFS!!

http://www.weatheronline.co.uk/cgi-b...0&PERIOD=&WMO=
I know - I referred to looking at it in a previous post

It was HIRLAM that I was trying to find..
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26-11-2011, 11:47   #9
 
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I know - I referred to looking at it in a previous post

It was HIRLAM that I was trying to find..
Oh duh.....I'm still half asleep!!!
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26-11-2011, 11:51   #10
 
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By the way, yr.no is the HiRLAM for Europe, and ECMWF for the rest of the world.

http://www.yr.no/place/Norway/Sogn_o...anced_map.html
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26-11-2011, 11:53   #11
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Oh duh.....I'm still half asleep!!!
I was walking the dogs along the Galway coast - that wakes you up

I guess that part of my frustration is trying to extrapolate the radar. Last night I was sure that a shower would miss me so I walked the dogs .....& came home drenched

Last Monday a huge lump of rain moved up towards Galway & I was about to give up & go home - but at the very last minute it changed direction !
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26-11-2011, 11:53   #12
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I don't get what your saying Disco,

NAE shows exactly what was forecast.
NOON



MET RADAR

Attached Images
File Type: jpg NAE PRECIP.JPG (327.7 KB, 220 views)
File Type: jpg met rad.JPG (39.8 KB, 220 views)
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26-11-2011, 11:57   #13
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By the way, yr.no is the HiRLAM for Europe, and ECMWF for the rest of the world.

http://www.yr.no/place/Norway/Sogn_o...anced_map.html
I used to rely on yr.no. but their longer range forecasts seem way off recently. There have been a series of forecasts where they, at the week end, predict a dire week ahead but then it's not so bad.

It may sound daft but XC seem to be the optimists & yr.no. the pessimists.
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26-11-2011, 12:04   #14
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I don't get what your saying Disco,
NAE shows exactly what was forecast.
Yes but I have only discovered NAE today

But, as I have already pointed out, NAE only covers 48 hours. On Sunday evening I will be trying to plan the week. I will be trying to guess which days will be best for which task. So I have to use sites that give longer range predictions.

In any given week I might have say three days where I need some dry weather. So it's case of trying to balance the forecasts & the timing of rain can be critical.
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26-11-2011, 12:07   #15
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Oh ok.

As far as Im aware no higher resolution model goes past 48 hours.

Maybe Met Eireann have something but the time gets too far ahead after 48 hours to be called hi res in my book
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