Storm Brian : Orange Wind Warning Sat 21 -10-17

DOCARCH

Samaris wrote: »

Guess storm season is here!

You think this is bad/mad....wait for (lack of) snow season! :pac:

jumpjack

ryanch09 wrote: »

The possible cyclone has vanished from the NHC charts

American sites will not be of any help for Irland: NOAA stopped publishing charts for Ophelia one day before the landfall!

Annie get your Run

Just to add to the thanks for all the information on this thread, most of it I don't understand (yet!). Are we to understand that currently the forecast is predicting wet and windy weather but not a storm for Friday and Saturday? There have been a couple of queries from my parkrun colleagues about whether our events might need to be cancelled this week. We're in Dublin but other queries from Clonmel too. Any advice would be much appreciated!

flaneur

The main impact of this might be to leave us without a clear weekend to clean up after Ophelia without getting wet.

pauldry

Met Eireann say that Friday night and Saturday will be Extremely Wet and Windy so it will be stormy most likely

No Ophelia though

pjohnson

Stephen Hawkins football boots wrote: »

Hi I am due to arrive in dublin airport at about 6.30 pm on fri evening do you think this wind event will affect my flight? Sorry for the question but any info would be appreciated

I'm flying out Saturday afternoon hopefully so similarly worried

Storm 10

pauldry wrote: »

Met Eireann say that Friday night and Saturday will be Extremely Wet and Windy so it will be stormy most likely

No Ophelia though

It wont need to be Ophelia to bring down more trees and power lines etc., there must be thousands of trees out there that have been severely weakened by the Hurricane and it wont take much to knock them down. So if driving stay safe

MJohnston

Annie get your Run wrote: »

Just to add to the thanks for all the information on this thread, most of it I don't understand (yet!). Are we to understand that currently the forecast is predicting wet and windy weather but not a storm for Friday and Saturday? There have been a couple of queries from my parkrun colleagues about whether our events might need to be cancelled this week. We're in Dublin but other queries from Clonmel too. Any advice would be much appreciated!

It is a storm, but a storm is a very broad definition.

Anyway, here's a quick noobs guide to reading the model charts (and I'm writing this as a total novice myself, so I hope this doesn't come across as condescending or useless!).

Looking at Meteorite's post above, the first graphic shows the forecast for wind - specifically 'mean' winds (in the 'average' sense of the word). The blue text in the top left is in French, but you can tell that it indicates the date of each frame of the animation, and the time too. The next blue line of text tells you what the chart shows - in this case "Mean wind speeds at 10m" (10m above the surface I believe), as well as the units of measurement shown - in this case km/h.

In plain English, this means it shows what the highest constant ('sustained') wind speed will be, and the scale of the colours at the bottom are in km/h. The graphics are actually commonly colour coded so that "angrier" colours are the top end of the scales, so the angrier it looks, the worse it will be! You can also see the wind direction indicated on the lines (I'm not sure what the lines indicate exactly, they might be isobars, but it isn't really essential to understand the chart).

The second chart shows wind speed again, but in this case it's showing the strongest gusts of wind at the surface - so there's a big difference between gusts and sustained winds, gusts can be way stronger, but they can also be very brief. The scale for gusts vs sustained winds is usually different too.

The third chart shows how much rain (or more accurately precipitation, but we're not expecting snow!) will fall between now ("depuis +0h" just means "since 0 hours from now") and the date indicated in the top left, in this case Sunday 1am. There's no units shown on this chart, but as it's a European chart, I'm guessing that it's in millimetres. So parts of the Southwest might see something like 90mm of rainfall over the next few days, which is quite a lot (especially as a couple of the days will be dry).

Anyway, these are charts from a particular model called the ARPEGE. There are various different computer forecasting models created by the various forecasting services, so there's the GFS which was created by the American's national weather service, ECMWF model created by a group of European countries working together, ARPEGE is the French model, etc. There are lots of others like GEM, AROME, HARMONIE, HIRLAM and many more. You can usually identify which model created any chart because it will be labelled on the chart somewhere (in the case of the ones I explained above, it's mentioned in the black bar at the top right), or the poster will mention it.

These computer models at a very simplified level are programmed with a lot of knowledge about how weather systems are expected to work and interact, and then they run simulations starting from the current day and time and extrapolating what weather might be like in the future. Different models are run at different frequencies, but it's usually something like every 6 hours. You can usually tell the time and date that a model was run by looking at the charts created, for example the third chart above was created by an ARPEGE model run at 0Z (0 hours Zulu Time, which is essentially 00:00 GMT, which is 1am Irish time until the clocks go back) on 18th October 2017.

As you can imagine these computer models aren't perfect (because the actual weather systems are unimaginably complex), and the imperfections can add up over time. So a chart for 24 hours away is probably quite accurate, but one for 48 is less so. Beyond a point (120 hours from now) the models are so far away that the certainty that they will be accurate has dropped enough that they're unlikely to be true, you'll see many posters call charts from beyond this timeline "Fantasy Island" because they're so unlikely (but not impossible!).

This is why having multiple models to consult is important, because if they all show very different outcomes, you can say that confidence is low that any individual one of them is going to be accurate. If they are all showing very similar outcomes however, you can be very confident that they are going to be accurate - this is what happened a few days out with Ophelia, where various different models were starting to converge on a very similar outcome.

Unfortunately, even when the models seem to agree, sometimes they can vary by what on global scales seem like very tiny distances, say 40-50 miles worth of different on where the heaviest rain might happen. On an human scale though, 40-50 miles of difference can actually be quite
important, particular in such a small island as Ireland. With Ophelia, we had that kind of uncertainty about the exact path of the storm, and therefore where the worst winds might be - and that 40-50 mile variation was the difference between the West coast getting the worst of it and the East coast getting the worst of it (or somewhere in between as seemed to actually happen this time).

And to bring it back to this weekend's storm, we're talking about the models predicting the passage of an area of low pressure that is currently somewhere just off the East coast of the USA, so think of the thousands of miles it has to travel before reaching us. The various models seem to be in agreement that the system will pass close to Ireland, but the uncertainty is still at the point where the path hasn't narrowed enough to say where with any exactness (a 100 mile variation at this point is the difference between nobody feeling any effects, and it directly passing over the middle of the island).

Anyway, this got way, way longer than I intended, but hopefully it's helpful to some of our newer weather forum watchers! There are loads of other chart types available that are more complex and show stuff like air pressure, which is a whole other level of difficulty (I don't really understand these yet myself beyond the very broadest strokes like low pressure = unsettled weather, high pressure = settled weather).

spookwoman

Storm 10 wrote: »

It wont need to be Ophelia to bring down more trees and power lines etc., there must be thousands of trees out there that have been severely weakened by the Hurricane and it wont take much to knock them down. So if driving stay safe

Was just out today driving somewhere and the amount of leaning trees and debris is unreal.

jumpjack

Annie get your Run wrote: »

Just to add to the thanks for all the information on this thread, most of it I don't understand (yet!). Are we to understand that currently the forecast is predicting wet and windy weather but not a storm for Friday and Saturday? There have been a couple of queries from my parkrun colleagues about whether our events might need to be cancelled this week. We're in Dublin but other queries from Clonmel too. Any advice would be much appreciated!

It depends on what you mean with "storm".
Possibly there will be winds up to 100 km/h, much less than 170 recorded on southern Irland during Ophelia, but enough to ruin your Saturday walk...
But possibly it could also totally miss Irland and hit UK.

Nettle Soup

Trying to decide whether to cancel an underage hurling match at 3pm on Saturday in Galway. What do ye think?

Strangegravy

Samaris wrote: »

Guess storm season is here

Roughly 6 - 8 weeks of Atlantic based weather before a big pattern change and then beasterly easterlies all the way for Christmas and January.

(What.... I can hope can't I??) ðŸ˜

Irish Steve

Nettle Soup wrote: »

Trying to decide whether to cancel an underage hurling match at 3pm on Saturday in Galway. What do ye think?

Way too early to call it, there's too much possibility for significant change in the outcome of the track of this storm.

MJohnston

Nettle Soup wrote: »

Trying to decide whether to cancel an underage hurling match at 3pm on Saturday in Galway. What do ye think?

Wait until Friday morning before deciding is my advice.

Annie get your Run

MJohnston wrote: »

It is a storm, but a storm is a very broad definition.

Anyway, here's a quick noobs guide to reading the model charts (and I'm writing this as a total novice myself, so I hope this doesn't come across as condescending or useless!).

Thank you MJohnston, very informative!

Steopo

Annie get your Run wrote: »

Just to add to the thanks for all the information on this thread, most of it I don't understand (yet!). Are we to understand that currently the forecast is predicting wet and windy weather but not a storm for Friday and Saturday? There have been a couple of queries from my parkrun colleagues about whether our events might need to be cancelled this week. We're in Dublin but other queries from Clonmel too. Any advice would be much appreciated!

Well it certainly looks like been very wet & windy in Dublin on sat morning/afternoon but depends if you're worried about comfort or safety. Current projections would not indicate any major safety dangers in Dublin but obviously if you're running in a park with lots of loose branches since Mondays storm there is a risk.

Regarding flights current projections again would not indicate any disruption potential for Dublin Airport.

Strongest winds in Dublin likely in late Sat afternoon/evening

Clonmel and the South will be much more in the firing line so one to watch closely if the storm moves further North. Still early on this one.

noisenotmusic

Keeping an eye on this as I'm flying out to London on Friday morning from Dublin but my mother and sister are flying out from Shannon which could be cutting it close though the projections make it look like it won't be too bad until Saturday.

Oscarziggy

Think this one will track over the top of us this time in Pembrokeshire.
It doesn't bode well for my local beach at Newgale which has a pebble bank between the road ,pub and the sea.
This bank was washed across the road last Sunday but this coming week end the tides are much higher.
Stay safe .
Regards

spookwoman

https://twitter.com/bbcweather/status/920616223926255618

Paully D

Any danger of cancellation to a 6am flight out of Dublin on Friday morning from this per current forecast?

pjohnson

Paully D wrote: »

Any danger of cancellation to a 6am flight out of Dublin on Friday morning from this per current forecast?

Similar question for 4.30pm Saturday.

And general question so I can somewhat monitor myself, What level warning/wind speed is needed before flights start to come into question?

Rodar08

Hi guys

Thanks for all the fab info as usual. Great job all through Ophelia. Bring on snow watch season. Always my favourite time of year on boards ðŸ˜

I’m supposed to drive from North east Donegal to Galway on Saturday morning then back on Sunday afternoon. Advisable? I’m worried about trees already weakened by Ophelia and just don’t know what to do. Would I be better making my decision on Friday? Tia

Clonmel1000

Good forecast by Johanna on radio 1 now. Storm Brian has not been named yet. The amount of utter nonsense about a hurricane this weekend is frightening but in the fb fake news world unsurprising.

MJohnston

pjohnson wrote: »

Similar question for 4.30pm Saturday.

And general question so I can somewhat monitor myself, What level warning/wind speed is needed before flights start to come into question?

It's not as simple as Wind Speed unfortunately. It's more about the gusts and the wind direction - I can't remember the exact operating limits (Paging JCX BXC!) but it's something like 40 knots cross-winds before they will stop operations.

However, the airlines are a different story - some will cancel flights maybe 24 hours ahead of time if they see a particularly windy system is likely to arrive, even if the airport itself continues operating and the conditions aren't as bad as forecast.

Keep an eye on the wind charts being posted, look for 40kts+ winds at cross-directions to the Dublin runways, and keep an eye on the Terminal Aerodrome Forecasts for DUB too:
http://en.allmetsat.com/metar-taf/united-kingdom-ireland.php?icao=EIDW

pjohnson

MJohnston wrote: »

It's not as simple as Wind Speed unfortunately. It's more about the gusts and the wind direction - I can't remember the exact operating limits (Paging JCX BXC!) but it's something like 40 knots cross-winds before they will stop operations.

However, the airlines are a different story - some will cancel flights maybe 24 hours ahead of time if they see a particularly windy system is likely to arrive, even if the airport itself continues operating and the conditions aren't as bad as forecast.

Keep an eye on the wind charts being posted, look for 40kts+ winds at cross-directions to the Dublin runways, and keep an eye on the Terminal Aerodrome Forecasts for DUB too:
http://en.allmetsat.com/metar-taf/united-kingdom-ireland.php?icao=EIDW

Thanks!

0byme75341jo28

Maybe I'm just uneducated but this doesn't look like anything *too* out of the ordinary. I don't think there will be any need to cancel trips/car journeys etc., to me it seems like little more than a wet and windy weekend for most of the country.

Have ye no faith in Met Eireann? They're predicting a fine start to Friday with unsettled weather to the southwest coming in in the afternoon - highly unlikely your flight gets cancelled unless something drastic happens. Saturday looks a bit less clear but doesn't look like anything too serious either at the moment.

pjohnson

Sierra Bitter Dropout wrote: »

Maybe I'm just uneducated but this doesn't look like anything *too* out of the ordinary. I don't think there will be any need to cancel trips/car journeys etc., to me it seems like little more than a wet and windy weekend for most of the country.

Have ye no faith in Met Eireann? They're predicting a fine start to Friday with unsettled weather to the southwest coming in in the afternoon - highly unlikely your flight gets cancelled unless something drastic happens. Saturday looks a bit less clear but doesn't look like anything too serious either at the moment.

I'm the guy with the Saturday flight hence my worry.

TheMilkyPirate

Sierra Bitter Dropout wrote: »

Maybe I'm just uneducated but this doesn't look like anything *too* out of the ordinary. I don't think there will be any need to cancel trips/car journeys etc., to me it seems like little more than a wet and windy weekend for most of the country.

Have ye no faith in Met Eireann? They're predicting a fine start to Friday with unsettled weather to the southwest coming in in the afternoon - highly unlikely your flight gets cancelled unless something drastic happens. Saturday looks a bit less clear but doesn't look like anything too serious either at the moment.

Standard winter wet and windy scenario. Yeah it'll be gusty and very wet but absolutely nothing out of the ordinary

TopOfTheHill

MJohnston wrote: »

However, the airlines are a different story - some will cancel flights maybe 24 hours ahead of time if they see a particularly windy system is likely to arrive, even if the airport itself continues operating and the conditions aren't as bad as forecast.

Ryanair had a flight due to land in Cork at 12:10 on Monday lunchtime (right when storm was due to hit). Even though all Aer Lingus flights were cancelled the previous evening, and most Ryanair flights were cancelled, this one was not cancelled until we were in the queue to board the plane. Every dog in the street knew there was no way of landing at that time, but maybe airline had a different view on what was possible - however, this is a story for another thread.

So, you can never count on a flight being cancelled, even in the worst weather situations.

Steopo

From my read it's very unlikely to have any flight cancellations from Dublin on Fri/Sat and even with last Mondays more extreme winds there were very few diversions/cancellations

But these 'will my flight be cancelled' questions are impossible to answer as there are so many factors - direction of the wind, wet or dry, type/size of aircraft, airline decision, whether it's taking off or landing, length of runway etc... it takes a lot to close Dublin Airport and cross winds are normally the reason. When it gets over 40knts (75kph) you're probably more likely to see disruption and some aircraft are not allowed open their doors if >45knts. Incidentally the new North Runway at Dublin Airport will give them more options as they'll be able to vary the take off and landing depending on the wind direction so reduces the likely cancellations down even further