Which weather app is the most accurate for ireland?

Supertramp said:
Thanks. I like sense of what's going on overall (low and high pressure systems), how close the isobars look (wind) and after that I agree it's a bit of a lottery about the exact direction and force.

I sometimes find being in a sheltered marina (or Strangford) leaves me more nervous of setting off whereas stopping at anchor in a less than sheltered spot encourages setting off and taking things as they come. Psychology over weather.
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Regularly sailling, I agree. But I had to "negotiate" with the boatyard to get lifted in, needed to organise someone for a bridge to lift and so on. A lot of things have to be planned, and literally everything but northerlies would be okay. Just when I started the thread, the prognosis were flipped 180° from one to another. But yeah, seems like they're all just inaccurate and unreliable until a few days ahead of the actual date.
 
Personally if I was the OP I would escape Waterford when a weather window might open and moor up in Dunmore East or even Kilmore Quay and see how it goes from there - disasters often can be avoided by not being rigid. Lots of nice harbours between Waterford and Ardglass as the OP knows but it will take a few days and spring is not here yet

The east irish coast is in the lee of prevailing westerlies and the outer banks give shelter from easterlies much of the way but a northerly would indeed be a right pain. A westerly or south westerly however would be great
 
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Although, some NWP models run to beyond 10 days, and there is some skill, I only start looking 10 days ahead and then, as I tried to make clear at #15, as a starting point looking for consistency with subsequent predictions. Sometimes the atmosphere is more predictable than at other times. Looking at forecasts on consecutive days gives a handle on that.
There are spells when predictions are clearly unreliable. We had a spell last year, late June/early July when forecasts for the next few days differed greatly from one day to the next. Later, they became more consistent and we could plan our return to the UK from France with some confidence.
Forecasts of wind are often remarkably good - within the +/- one force at least. However, bear in mind that the atmosphere is really finely balanced. An example I have quoted in the past is of a W F4 up the English Channel. If pressure at Southampton is 1004 hPa, then it will be about 1004 at St Malo. A fall in pressure of 1hPa at Southampton, 0.1% will result I’m F5. A fall of 2 hPa would give a F6. Just worth bearing in mind.

I sometimes see statements about forecasts or weather ALWAYS being so-and-so. Some may remember David Houghton who used to advise the RYA on major events worldwide. He would visit an area and gal to locals. If someone said that something always happens, it usually meant about 30% of the time. I treat categorical statements on these forums in the same way.
 
DangerousPirate said:
Regularly sailling, I agree. But I had to "negotiate" with the boatyard to get lifted in, needed to organise someone for a bridge to lift and so on. A lot of things have to be planned, and literally everything but northerlies would be okay. Just when I started the thread, the prognosis were flipped 180° from one to another. But yeah, seems like they're all just inaccurate and unreliable until a few days ahead of the actual date.
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Glad you managed your trip and got decent weather.

However, not sure you can (ie you definitely shouldn’t) try to make assertions about forecast accuracy based on one week in one location! Clearly 7 days out is less accurate than 1 day out. But they can still be very useful provided you understand that:
(a) Some more extreme weather systems are fairly predictable a week ahead - a settled high pressure system, or a seriously bad low heading your way, are probably to be taken as fairly likely (though a big low passing close by, the wind directions will change based on precise path)
(b) Other weather systems are more complex and less predictable - this is where variety in the models warns to not rely on things till closer to the time.
Using the week look ahead forecast as a routine process has resulted in some really brilliant sailing in locations I didn’t plan to go to - and equally allowed time to get the heck out of locations about to get a pasting.
 
dunedin said:
Glad you managed your trip and got decent weather.

However, not sure you can (ie you definitely shouldn’t) try to make assertions about forecast accuracy based on one week in one location! Clearly 7 days out is less accurate than 1 day out. But they can still be very useful provided you understand that:
(a) Some more extreme weather systems are fairly predictable a week ahead - a settled high pressure system, or a seriously bad low heading your way, are probably to be taken as fairly likely (though a big low passing close by, the wind directions will change based on precise path)
(b) Other weather systems are more complex and less predictable - this is where variety in the models warns to not rely on things till closer to the time.
Using the week look ahead forecast as a routine process has resulted in some really brilliant sailing in locations I didn’t plan to go to - and equally allowed time to get the heck out of locations about to get a pasting.
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Good advice, much as my #15. I would only add that similarity between models is not a reliable guide. Models use the same equations and the same data. Variation between models arises because of small differences in model formulation and small differences in how the massively complex data are analysed to get the T=0 to start the forecast. Effectively, they are a small sample from a big ensemble. They might all be clustered around the same correct or incorrect forecast. That is why my starting point is to look at one model with inputs at 24 hour intervals. Is the model coming up with similar or different results with different data inputs? If they are similar, I then look at other models.
Major differences for the next couple of days is rare. If they do differ, believe in none. Never forget the smoothing within models nor the inherent variability in the atmosphere on scales that are, basically, unpredictable.
 
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