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Heavy Rain Risk Sunday Night/Monday

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Comments

  • Closed Accounts Posts: 2,693 ✭✭✭Redsunset


    Had mad rain all day.the front really did come to life again in the east,
    Just to add that rainfall totals by the models were not so crazy after all.


  • Closed Accounts Posts: 5,234 ✭✭✭thetonynator


    Had very heavy rainfall from approx 9p.m. Sunday until 5p.m. Monday, stopped for an hour or so n the morning. Dont have any way of measuring it, but it wasn't light rain or mist at any point, it was heavy rain all the time!!!


    River Nore has gone from its lowest level in years to a full flood.


  • Closed Accounts Posts: 5,150 ✭✭✭Deep Easterly


    redsunset wrote: »
    Just to add that rainfall totals by the models were not so crazy after all.

    Yep, I guess they were onto something alright. The NAE model, which I don't normally have much time for as it tends to overdo rainfall intensity, did surprisingly well I think - not only in terms of actual accumulations, but where the highest accumulations would occur.

    A further 16.0mm here since midnight and still raining, albeit much lighter. A very morose and doleful morning.


    Met rainfall radar sequence for the period 1.00am 6th Sept to 12.00am the 7th Sept, which proved to be one of the wettest days over much of Ireland for quite a while:



    What I find interesting is how the slackening 500hpa gradient affects the speed of the actual showers that developed in the SW relative to the speed of the frontal zone as the upper low moved in over the west during the afternoon!


  • Registered Users, Registered Users 2 Posts: 15,945 ✭✭✭✭Discodog


    yr.no have got today so wrong !. Its hammering down here with thundery showers that appear to be travelling in circles so no escape !.


  • Registered Users Posts: 595 ✭✭✭Chicken Run


    so
    rain gauges
    can I make one at home ??
    I'm bored and can't work cos it's raining...
    Normally gauge the amount of rain by what's in the horse's empty feed bucket but it tipped over in the wind.


  • Closed Accounts Posts: 4,279 ✭✭✭Su Campu


    Sligo airport has just had heavy rain. They issued 3 METARs in 4 minutes, with visibility (in metres) and cloud base lowering rapidly each time.

    http://www.dawn-it.com/met/

    2010-09-07 10:00:00 METAR EISG 071000Z AUTO 20004KT 150V240 7000 -RA FEW004 BKN012 OVC026 13/12 Q0991 RERA=
    2010-09-07 09:42:00 SPECI EISG 070942Z AUTO VRB03KT 3900 +RA FEW005 BKN010 OVC017 13/12 Q0991=
    2010-09-07 09:39:00 SPECI EISG 070939Z AUTO VRB03KT 4000 +RA FEW005 BKN015 OVC020 13/12 Q0991=
    2010-09-07 09:38:00 SPECI EISG 070938Z AUTO VRB03KT 4200 +RA SCT010 OVC017 13/12 Q0991=
    2010-09-07 09:30:00 METAR EISG 070930Z AUTO 17005KT 150V210 5000 RA BKN014 OVC020 13/12 Q0992


  • Closed Accounts Posts: 5,550 ✭✭✭Min


    Danno wrote: »
    Min, I was looking at the radar returns on NetWeather premium... this one at 3.45am caught my eye...

    http://live.laoisweather.com/images/sep2010/0345.png

    I think places like Castlecomer got more than here. There is a station in Coan village, SE of Castlecomer that would make interesting reading.

    Yeah that was heavy rain on Sunday night as the radar confirms, not to mention the rest that fell, it was exceptional.

    I live a few miles from Coon as the crow flies, I only saw the rain records for there twice - one last year on Met Eireann's summer report and another on the major thunderstorm event of 1985.
    It would be interesting indeed if there was access to that information.


  • Registered Users, Registered Users 2 Posts: 8,913 ✭✭✭Danno


    Min wrote: »
    It would be interesting indeed if there was access to that information.

    I have a feeling that information will surface fairly shortly... ;)


  • Moderators, Science, Health & Environment Moderators Posts: 4,471 Mod ✭✭✭✭mickger844posts


    Discodog wrote: »
    yr.no have got today so wrong !. Its hammering down here with thundery showers that appear to be travelling in circles so no escape !.

    I have lost all faith in Yr.no as their forecasts over the last number of weeks especially with regards to rain and totals have been way out. I can't rely on them anymore.


  • Registered Users Posts: 95 ✭✭sliabh beagh


    my 24 hr total maxed out at 54.9mm from 8pm sunday til 8pm monday(6/9/10)


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  • Registered Users, Registered Users 2 Posts: 8,913 ✭✭✭Danno


    The story [so far]...

    Rain begins at 9pm Sunday night...
    by 3.26am a rate of 57.8mm/hr is recorded
    by 10am a total of 83.3mm has been recorded.
    by 4pm Monday another 32.1mm is added
    by 7pm Monday the rain mostly light but another 3.5mm is added
    by 9pm Monday a few showers add a further 2.2mm to bring the 24 hour total to 121.1mm
    At 9am Tuesday another reading is made. Only 1.1mm fell overnight bringing the 36 hour total to 122.2mm
    Tonight, 9pm Tuesday the 48hr total is 122.7mm as 0.5mm was recorded from showers during the day.

    Looking at the radar, a big clump of thundery showers are pushing in from the west.


  • Registered Users, Registered Users 2 Posts: 14,654 ✭✭✭✭M.T. Cranium


    Danno, that was fortunate that your area missed out on heavier showers today. What's the local situation on flooding?

    The activity over western Galway and Mayo looks intense and as SC noted there are signs of convective development, it's almost like a meso-scale convective complex although it's a bit cool for that. I could imagine there being 20-30 mm per hour rainfalls in that, not over any reporting stations at this time, wondering if Nacho Libre is near or in that area? Anyone else on hand to give us a reading on conditions? It seems to have kept a bit of distance from Galway and where I imagine DE lives, but could be seeing lightning from it perhaps. Those Connemara lakes are going to overflow at this rate.


  • Registered Users, Registered Users 2 Posts: 5,991 ✭✭✭Storm 10


    Nothing to report in Galway City yet but that rain looks like it will hit at some stage will keep you posted.


  • Registered Users, Registered Users 2 Posts: 10,243 ✭✭✭✭Oscar Bravo


    Very heavy rain in Castlebar at the moment.no thunder or lightening to report though.


  • Closed Accounts Posts: 6,466 ✭✭✭Lumi


    It seems to have kept a bit of distance from Galway and where I imagine DE lives, but could be seeing lightning from it perhaps. Those Connemara lakes are going to overflow at this rate.
    Dry and breezy in Galway and likely to stay that way judging by the latest radar. I suspect that it's the same story in Tuam. Pity - I was looking forward to a reprieve of Sunday nights extravaganza. Looks like Nacho's having all the fun tonight!


  • Closed Accounts Posts: 4,279 ✭✭✭Su Campu


    There are some stations on the IWN in that area MT. Ballycroy is up to 71mm for today, and Westport 40mm


  • Registered Users, Registered Users 2 Posts: 2,292 ✭✭✭MayoForSam


    Just after driving back from Castlebar to Tuam, some of the most intense rain I've ever driven in, my wipers could not keep up.


  • Registered Users, Registered Users 2 Posts: 8,913 ✭✭✭Danno


    Danno, that was fortunate that your area missed out on heavier showers today. What's the local situation on flooding?

    No major flooding around here. The River Nore, Irelands fastest flowing river is less than one mile away from here so it takes the load away smartly. I have photos on this thread here... http://www.irelandsweather.com/forum/general-weather-discussion/heavy-rain-sunday-and-monday/60/

    ...if you go to page 9 on that thread you will see more photos from Omagh, County Tyrone, Northern Ireland. RTE TV News tonight showed footage from flooding in Athlone in Westmeath County and Mountmellick in Laois County. See here... http://www.rte.ie/news/2010/0907/6news_av.html?2815124,null,230


  • Registered Users Posts: 6,328 ✭✭✭sunbabe08


    there was a nice storm that passed over galway and mayo. lucky them:)


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  • Registered Users Posts: 101 ✭✭fishmahboi


    sunbabe08 wrote: »
    there was a nice storm that passed over galway and mayo. lucky them:)

    Judging from the radar and from forecasts outside of met eireann it looks like the southwest will get heavy thundery showers that gradually weaken as they approach the east


  • Closed Accounts Posts: 2,667 ✭✭✭WolfeIRE


    The HIRLAM suggest that Connaught and Donegal, along with the upper Midlands will see the most rain tonight and tomorrow. A lot of places will escape with the odd shower or two. Thursday looks to be the best day of the week before Friday brings another band of rain across the country from the west.


  • Registered Users, Registered Users 2 Posts: 7,242 ✭✭✭pauldry


    so
    rain gauges
    can I make one at home ??
    I'm bored and can't work cos it's raining...
    Normally gauge the amount of rain by what's in the horse's empty feed bucket but it tipped over in the wind.

    Best way to make a rain gauge thats simple,

    Get a 2 litre water bottle from supermarket flat bottom (ooh)better
    Cut off top quarter as even as possible
    put this back into bottle upside down
    paper clip both sides for added support
    put bottle into a pot of stones or something to hold it steady and level
    put in a cool place that gets little sun to avoid evaporation
    measure mm with ruler after a days rain;)


  • Closed Accounts Posts: 4,279 ✭✭✭Su Campu


    pauldry wrote: »
    Best way to make a rain gauge thats simple,

    Get a 2 litre water bottle from supermarket flat bottom (ooh)better
    Cut off top quarter as even as possible
    put this back into bottle upside down
    paper clip both sides for added support
    put bottle into a pot of stones or something to hold it steady and level
    put in a cool place that gets little sun to avoid evaporation
    measure mm with ruler after a days rain;)

    Measuring the depth of water that way does not convert into mms rainfall as quoted officially. 1mm rainfall means a depth of 1.0mm over an area of 1.0m², ie. 1 litre. So a bottle with a small "funnel" will catch only a fraction of that litre, therefore you will need to take the area of the funnel into account. Measure this area, and divide it into the number of mms of water you measure in the bottle.

    Eg. your bottle has a diameter of 15cms, so a radius r of 7.5cms (0.075m). It's area will be pi*r², (3.142 x 0.075²) = 0.0177m²

    If you measure say 2.5mm in the bottle after a day, then your actual rainfall will be

    2.5 / 0.0177 = 141.2mm (a lot!). To measure a small rainfall amount (say 5mm, you would only have a depth of 0.09mm in your bottle - impossible to measure accurately. That's why it's good to have as large an area as possible feeding into a narrow bottle, like a graduated cylinder.


  • Registered Users, Registered Users 2 Posts: 8,913 ✭✭✭Danno


    From a standard 5" gague 10mm rain weighs 127g.


  • Registered Users, Registered Users 2 Posts: 7,242 ✭✭✭pauldry


    Crikey?

    So better take out that applied Maths book then:)


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  • Registered Users, Registered Users 2 Posts: 1,787 ✭✭✭Joe Public


    Su Campu wrote: »
    Measuring the depth of water that way does not convert into mms rainfall as quoted officially. 1mm rainfall means a depth of 1.0mm over an area of 1.0m², ie. 1 litre. So a bottle with a small "funnel" will catch only a fraction of that litre, therefore you will need to take the area of the funnel into account. Measure this area, and divide it into the number of mms of water you measure in the bottle.

    Eg. your bottle has a diameter of 15cms, so a radius r of 7.5cms (0.075m). It's area will be pi*r², (3.142 x 0.075²) = 0.0177m²

    If you measure say 2.5mm in the bottle after a day, then your actual rainfall will be

    2.5 / 0.0177 = 141.2mm (a lot!). To measure a small rainfall amount (say 5mm, you would only have a depth of 0.09mm in your bottle - impossible to measure accurately. That's why it's good to have as large an area as possible feeding into a narrow bottle, like a graduated cylinder.


    I don't think pauldry's simple method would be too far out as to be useful enough as a rough guide. The tolerance may be ~ +/- 10%. If he put 16 such bottles side by side in a large square formation they would all roughly fill by the same height over a period of a few hours rain.
    Even if he had a bottle with a base surface area of 1.0m² and a bottle with a base surface area of .25m² they would both fill to more or less the same height. It may not be official but it will give Chicken Run something to peck at.


  • Registered Users, Registered Users 2 Posts: 9,235 ✭✭✭lucernarian


    Su Campu wrote: »
    Measuring the depth of water that way does not convert into mms rainfall as quoted officially. 1mm rainfall means a depth of 1.0mm over an area of 1.0m², ie. 1 litre. So a bottle with a small "funnel" will catch only a fraction of that litre, therefore you will need to take the area of the funnel into account. Measure this area, and divide it into the number of mms of water you measure in the bottle.

    Eg. your bottle has a diameter of 15cms, so a radius r of 7.5cms (0.075m). It's area will be pi*r², (3.142 x 0.075²) = 0.0177m²

    If you measure say 2.5mm in the bottle after a day, then your actual rainfall will be

    2.5 / 0.0177 = 141.2mm (a lot!). To measure a small rainfall amount (say 5mm, you would only have a depth of 0.09mm in your bottle - impossible to measure accurately. That's why it's good to have as large an area as possible feeding into a narrow bottle, like a graduated cylinder.
    I'm think I'm not following this. It could be that I'm thinking about this arseways. But surely the depth only has to be adjusted if there's a funnel being used? I.e. If rain is being collected from a large area and concentrated into a smaller glass jar or beaker (like a 5" gauge) then the actual rain depth would have to be adjusted accordingly. If a funnel with 20cm^2 area collects rain into a cylinder with 10cm^2 cross sectional area, then the depth in the cylinder would have to be simply halved to get the appropriate depth.

    With something of uniform diameter, like a flat bottomed cylinder or a box, then only the depth need be recorded even if it's ability to accurately collect rain is suboptimal.

    Also, where are the units in that calculation?! 2.5mm/17,700mm^2 = 0.00014mm^-1 which is not a valid unit of volume.:)


  • Closed Accounts Posts: 4,279 ✭✭✭Su Campu


    I'm think I'm not following this. It could be that I'm thinking about this arseways. But surely the depth only has to be adjusted if there's a funnel being used? I.e. If rain is being collected from a large area and concentrated into a smaller glass jar or beaker (like a 5" gauge) then the actual rain depth would have to be adjusted accordingly. If a funnel with 20cm^2 area collects rain into a cylinder with 10cm^2 cross sectional area, then the depth in the cylinder would have to be simply halved to get the appropriate depth.

    With something of uniform diameter, like a flat bottomed cylinder or a box, then only the depth need be recorded even if it's ability to accurately collect rain is suboptimal.

    Also, where are the units in that calculation?! 2.5mm/17,700mm^2 = 0.00014mm^-1 which is not a valid unit of volume.:)

    No wait, you're both right - I'm the one who got it arseways! There should be no calculation required as long as the two diameters are the same. D'oh! :rolleyes:

    And on my planet, mm^-1 is a valid unit of volume!! :pac::pac:

    No more late night posts by me!


  • Registered Users, Registered Users 2 Posts: 9,235 ✭✭✭lucernarian


    Su Campu wrote: »
    And on my planet, mm^-1 is a valid unit of volume!! :pac::pac:

    No more late night posts by me!
    Well if it makes you happy:D

    I'm glad I didn't haul out the auld physics book, it's got more calculus and vector planes than you can shake a stick at...


  • Registered Users, Registered Users 2 Posts: 2,267 ✭✭✭kc66


    This thread made for interesting reading, seeing as I was stuck out in that weather for most of Sunday night / Monday morning with only a t-shirt on me. Never saw anything like it. Electric picnic was great.


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  • Registered Users Posts: 101 ✭✭fishmahboi


    Anybody got info about the rain on thursday night?


  • Closed Accounts Posts: 5,150 ✭✭✭Deep Easterly


    fishmahboi wrote: »
    Anybody got info about the rain on thursday night?

    Yes, we have no information yet, but when THEY let us know, thou'st will be the first to know...;)

    Ya wide?


  • Closed Accounts Posts: 5,700 ✭✭✭irishh_bob


    several reports on rte last night and today suggested that today would start off wet but would become increasingly dry by afternoon and evening , in the north east , we got the exact opposite , heavy rain for about an hour and a half straight from 5 pm - 6.30

    you would need a different forecast for every parish in this country


  • Closed Accounts Posts: 228 ✭✭wild handlin


    fishmahboi wrote: »
    Anybody got info about the rain on thursday night?

    Due to sweep in from the SW around mid-day and quickly spread to the rest of Ireland by nightfall, with heavy and thundery bursts expected according to RTE weather this evening.


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