Met Eireann Radar

Redsunset · 29-11-2009 8:29am #1

I want this highlighted so here goes.

no%20way.JPG

Im sorry but im very unhappy with our rainfall rate colours on the radar.

There is no way 0.1 falling on me for most of the night.

met eireann poster can you please have someone look at this.

the metoffice radar shows more realistic rain fall rate

Now i know there's the faithfuls to our homegrown who say its right,but its just simply not.

i want to be able to view met eireanns radar with confidence and not have to be checking others.

yes i am having a rant but i feel its needed,because its being happening alot and i have been letting it go but can no longer.:mad:
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Redsunset · 29-11-2009 8:34am

poster Snaps

"ive found the same as well the met eire rainfall radar is very un accurate. The UK met offices seems the best but the detail on ireland is to low scaled!"

Redsunset · 29-11-2009 8:37am

I agree with the low scale on metoffice but its doing the simple task of getting rainfall intensity correct.

i want that on our own because its fairly good other than that

holly1 · 29-11-2009 8:37am

I have to agree,its pelting down:eek: and they are showing mostly blue.Never had much confidence in it:(

Redsunset · 29-11-2009 8:44am

holly1 wrote: »

I have to agree,its pelting down:eek: and they are showing mostly blue.Never had much confidence in it:(

Yes Holly1 it sure is pelting it out there and there has been no better situation than now to highlight this error and that be easily rectified hopefully.

octo · 29-11-2009 9:14am

redsunset wrote: »

There is no way 0.1 falling on me for most of the night.

But, doesn't light blue imply 0.1-0.5 mm/hr, and doesn't yellow signify 0.5-3.0 mm/hr? Where do you live and what hourly rainfall did you nearest station report? (Btw, I'm not official ME spokesperson) UKMO gets the same radar data.

DOCARCH · 29-11-2009 9:25am

I saw Dublin AP reporting 5.0mm from 6am to 7am. BTW, I have recorded 21.9mm in 12 hours (since 8.30pm yesterday evening).

octo · 29-11-2009 9:35am

DOCARCH wrote: »

I saw Dublin AP reporting 5.0mm from 6am to 7am. BTW, I have recorded 21.9mm in 12 hours (since 8.30pm yesterday evening).

What colour should that be under the UKMO scheme of things? The UKMO uses the same irish radar data as ME, but I'm guessing they overwrite their own rainfall intensity colour scheme. 22mm in 12 hours is less than 0.5mm per hour - which is BLUE in the ME radar colour scheme.

Redsunset · 29-11-2009 9:40am

0.1 / 0.5mm per hr is still not good enough

i take it your not experiencing this rain personally

it should be yellow at least for 0.5/ 3mm per hr.

its constant and my closest station is oak park that recorded 1.5mm as of 8am.

something is not adding up ,simple as

M.T. Cranium · 29-11-2009 9:50am

I'm with Redsunset on this, I look at radars pretty much every day for forecasting and I always check against two other sources (UK metoffice and meteociel) which sometimes reveal intensity that you would not deduce from the Irish radar. It seems to be more likely to fall short in these northeast flow situations and I have to wonder if it's an issue with the local hills blocking out part of the beam from Dublin airport. The Shannon radar seems more reliable on the whole.

This case with the rainfall last night is particularly obvious by comparison of the different radars. Since the UK display picks up the Dublin radar I am not sure why it would be better, perhaps they noticed some regularized problems and changed their display algorithms.

Radar displays are calibrated to minimize ground clutter and anomalous propagation, but it would seem that some attention may need to be paid to how this particular radar displays steady precip from that direction. It may not have been an issue for the forecasters since they may have come to these same conclusions and become used to the adjustments required.

DOCARCH · 29-11-2009 10:10am

octo wrote: »

What colour should that be under the UKMO scheme of things? The UKMO uses the same irish radar data as ME, but I'm guessing they overwrite their own rainfall intensity colour scheme. 22mm in 12 hours is less than 0.5mm per hour - which is BLUE in the ME radar colour scheme.

22mm in 12 hours is more than 1.8mm per hour?

I think one of the issues is that Met E just uses the two Irish radar sites while UKMO uses it's own + the two Irish sites. Would it not be worthwhile Met E incorporating UKMO radar as well? This would give a more accuarate picture (for the east and north at least).

On the other side of the coin, UKMO radar very often overplays the rainfall. i would use neither as an accurate guide for rainfall amounts - just an indicator of where precip is occuring.

Redsunset · 29-11-2009 10:23am

What im noticing M.T as i was playing the animation for Met Eireann radar is that as the rain gets closer to shannon the intensity peps up somewhat to yellow.

so maybe there is something blocking the beam over eastern ireland

Deep Easterly · 29-11-2009 12:54pm

Not sure if this is any use but I ripped this from Wikipedia regarding rain rates:

When classified according to the rate of precipitation, rain can be divided into:

Very light rain — when the precipitation rate is < 0.25 mm/hour
Light rain — when the precipitation rate is between 0.25 mm/hour - 1.0 mm/hour
Moderate rain — when the precipitation rate is between 1.0 mm/hour - 4.0 mm/hour
Heavy rain — when the precipitation rate is between 4.0 mm/hour - 16.0 mm/hour
Very heavy rain — when the precipitation rate is between 16.0 mm/hour - 50 mm/hour
Extreme rain — when the precipitation rate is > 50.0 mm/hour

http://en.wikipedia.org/wiki/Rain

GSF · 29-11-2009 12:56pm

I've wondered why met eireann dont get a feed of the Northern Ireland radar output? They seem to rely of Shannon & Dublin only. If the UK met take the Irish radar data, why no reciprocal arrangement?

octo · 29-11-2009 1:03pm

Deep Easterly wrote: »

Not sure if this is any use but I ripped this from Wikipedia regarding rain rates:

When classified according to the rate of precipitation, rain can be divided into:
Very light rain — when the precipitation rate is < 0.25 mm/hour

Light rain — when the precipitation rate is between 0.25 mm/hour - 1.0 mm/hour

Moderate rain — when the precipitation rate is between 1.0 mm/hour - 4.0 mm/hour

Heavy rain — when the precipitation rate is between 4.0 mm/hour - 16.0 mm/hour

Very heavy rain — when the precipitation rate is between 16.0 mm/hour - 50 mm/hour

Extreme rain — when the precipitation rate is > 50.0 mm/hour

http://en.wikipedia.org/wiki/Rain

I think that's in the states. Here, its:

Light, 0-2.0 mm/hr
Intermediate, 2-6 mm/hr
Heavy, 6+

But that's for regular precipitation. Shower precipitation and snow have a different scale which I don't have to hand at present.

Deep Easterly · 29-11-2009 1:12pm

Thanks Octo. I think it is a bit tricky to judge rainfall rates to be honest. I think, subjectively, low intensity rates driven by a cold, strong wind can seem more intense than they actually are due to the general nastiness of the day! That is just my personal opinion though.

lucernarian · 29-11-2009 2:02pm

M.T. Cranium wrote: »

I'm with Redsunset on this, I look at radars pretty much every day for forecasting and I always check against two other sources (UK metoffice and meteociel) which sometimes reveal intensity that you would not deduce from the Irish radar. It seems to be more likely to fall short in these northeast flow situations and I have to wonder if it's an issue with the local hills blocking out part of the beam from Dublin airport. The Shannon radar seems more reliable on the whole.

This case with the rainfall last night is particularly obvious by comparison of the different radars. Since the UK display picks up the Dublin radar I am not sure why it would be better, perhaps they noticed some regularized problems and changed their display algorithms.

Radar displays are calibrated to minimize ground clutter and anomalous propagation, but it would seem that some attention may need to be paid to how this particular radar displays steady precip from that direction. It may not have been an issue for the forecasters since they may have come to these same conclusions and become used to the adjustments required.

Ah now, Shannon having the more reliable radar? The UKMO radar seems to think the radar there works part time! It is so intermittent and unreliable, and it's woeful for frequently having clearly faulty and excessive sensitivity in some directions and not in others. To use a weird analogy, it's like as if a multicoloured circular pane of glass was hit in the centre, and the cracks spread outwards. And I'm not just talking about the Wifi interference towards Waterford lol.

Also, these hills NE of the airport? What hills? A small cluster kinda NNE and N is all that exists, from The Naul eastwards. I think the Wicklow mountains would have a far more severe impact on a 100m asl radar station like Dublin Airport.

Mothman · 29-11-2009 6:38pm

Agree that Met E display often under respresents the rate, but I also think that the Met Office is as often over stating the intensity and so I think somewhere in between.

M.T. Cranium · 29-11-2009 7:13pm

To be more clear, I meant that hills to the southwest of Dublin might be interfering with radar coverage in some inland parts of Ireland. I was talking about precip bands moving in from the northeast. Sorry about the confusion there. As to Shannon radar, I will have to watch for those effects you describe. I haven't been finding it user-unfriendly in the last six months but that's the extent of my frequent use of it. Perhaps because the whole country has been covered with rain almost non-stop in that time, I have grown oblivious to any finer details.

lucernarian · 30-11-2009 3:06am

Have a look at the radar sequence that the UKMO provided on this webpage:

http://www.metoffice.gov.uk/corporate/pressoffice/2009/ht20091123.html

Let's just say that Shannon's brief appearance in it is a rather dodgy one too!

snaps · 30-11-2009 6:20pm

shannon radar not recording now on either met irl or met uk. So when shannon is not recording data we do not know whats coming, like tonight, heavy rain coming in off the atlantic

Sponge Bob · 30-11-2009 6:47pm

I don't understand why there is no western sector weather radar at the Radar / VOR beacons in Belmullet ( Dooncarton ) and in Mizen ( Mt Gabriel) which are marked L and R on the map here , page 9

Shannon is down in a bloody hole and the radar to the north is obscured by the burren and often shows drizzle in Galway when it is fairly chucking down .

Those two would give another 80 miles of coverage to the horizon .

octo · 01-12-2009 7:28am

Sponge Bob wrote: »

I don't understand why there is no western sector weather radar at the Radar / VOR beacons in Belmullet. Shannon is down in a bloody hole and the radar to the north is obscured by the burren and often shows drizzle in Galway when it is fairly chucking down . Those two would give another 80 miles of coverage to the horizon .

Of course they's love it, particularly for the North West like you say, but my understanding is they cost a bomb, both to install and to run. Hard to justify in these times. Shannon and Dublin have air traffic safety payoffs which make them worthwhile.

Discodog · 01-12-2009 12:43pm

I am a rainfall radar obsessive. I work outdoors & the ME radar on my mobi even decides my coffee breaks !. It is also a critical component in night time dog walks. During unsettled weather I would typically check the radar 5 times per day !.

As I am in the West I am relying on the Shannon radar. The 15 minute refresh was a big improvement however the real refresh rate, ie delay between reading & when it is published, can be anything between 5 mins & 45 mins. I am puzzled as to why this should vary at all - surely it is automated.

In the main I would say that it is pretty accurate but there are quite a few times when it disappears altogether. I also wish that it had more range. I suspect that the accuracy here comes from the fact that it is looking out over flat sea.

In case anyone from ME is reading, how about introducing a predictive element as well, also please make a permanent visible outline of Ireland that shows up through the rain image.

Sponge Bob · 01-12-2009 12:55pm

octo wrote: »

Of course they's love it, particularly for the North West like you say, but my understanding is they cost a bomb, both to install and to run. Hard to justify in these times. Shannon and Dublin have air traffic safety payoffs which make them worthwhile.

I did not think they were _that_ expensive but I could be wrong. This one is USD16k with 240nm range for example

http://www.avionix.com/store/bendix.html

Weather forecasts in Ireland are useless , either it is raining or not and timely radar data is vital. As well as that the shannon and dublin radars often go down and we need some redundancy .

Mt Gabriel also provides advance ATC for Heathrow approaches and if not Dooncarton why not Knock Airport or Malin for Derry Airport .

Popoutman · 01-12-2009 6:10pm

Some of the reason for not giving the quick updates is that it is part of a pay-for service as far as I know. If you want the free data, it's delayed.

Could be very wrong though.

Discodog · 01-12-2009 6:25pm

The strange thing is the delay varies. It's almost like you can image a fella who has other jobs to do & suddenly looks at the clock !.

Deep Easterly · 01-12-2009 6:30pm

Discodog wrote: »

I am a rainfall radar obsessive. I work outdoors & the ME radar on my mobi even decides my coffee breaks !. It is also a critical component in night time dog walks.

That must be one hell of a serious dog walk if you have to check the radar before you venture out!

I love walking my dog when the weather is wild, wet and windy, but I suppose that is one of my own personal kinks. :pac:

Discodog · 01-12-2009 6:37pm

I am out in all weathers so for a change I like to dog walk in the dry, if possible, plus the dogs hate the rain !. Before the radar it was down to trying to view the clouds. Like check the wind direction & notice when the stars disappear. Where I walk there is absolutely no cover & if the rain doesn't get you, the salt spray will.

It is amazing how many people do not know about radar. I have had so much fun telling neighbours that it would rain in 20 mins & that the rain would last for 10 mins. One old boy says that I have the "gift" !

octo · 02-12-2009 7:06am

Popoutman wrote: »

Some of the reason for not giving the quick updates is that it is part of a pay-for service as far as I know. If you want the free data, it's delayed.

Could be very wrong though.

I know for certain this is not the case. In fact the image you get on met.ie is exactly the same as the one the forecasters work with, although there might be a slight delay in sending it to the met.ie webservers. A proper radar image takes 10-15 minutes to generate and another few minutes to process. Also, there is a 1km resolution on the met images compared with a 5 (I think)km resolution on the UK met office image. In their case, the image on the web is an inferior product.

Popoutman · 02-12-2009 10:57am

octo, thank you for that clarification!

That clears up a misconception that I had. I know of the image generation delay, but I wasn't aware that the image was as live as MetEireann get it.

Met Eireann Radar

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