Storm Agnes Wed 27 Sept 2023.

amandstu

weather.png

Does this look bad this far out?

amandstu

https://www.boards.ie/discussion/2058314623/a-bad-storm-on-the-night-of-the-26th

The chart is from met.ie

Jim_Hodge

Follow the track on through, past where you paused it, and you'll see it depends on where you are.

amandstu

https://www.boards.ie/discussion/comment/121133573#Comment_121133573

Can't be too accurate so far out,can it.?Looks like a proper storm to me though ( force10? force11?) but quite short lived and hitting the North West the hardest the way it is set up now.

.Donegal.

Winds gusting 140km/h offshore. 120km/h coastal locations in the West. Far out so could amount to nothing or deepen further.

pauldry

It will keep West. Maybe skirt the NW but prob 120kph tops. They rarely trend worse usually better.

adocholiday

Looks a nasty system on the latest ECM but I'd say it will downgrade as we get closer.

For the 26th/27th the ECM, GFS and ICON show the remnants of Nigel and another low from the Newfoundland area coming together in the Atlantic to our W/NW over the weekend; then another separate low coming out of Newfoundland gets pulled across and into the same system off our west coast on Tuesday night into Wednesday morning. The ECM shows this resulting in cyclogenesis (weather bomb, a drop of 24mb+ in 24 hours) and the GFS has the same overall pattern but a much less severe forecast. ICON has a more complex series of lows but a more or less similar pattern. That whole system hangs around NW of Ireland for the week then. The GEM is showing a different outcome, with Nigel and the second low heading NE and then that third low comes in later much further to our West not impacting us at all.

ECM cyclogenesis (can't see the frames before the first image but the pressure drops from 993 to 965 in 24 hours):

GFS:

ICON

GEM

adocholiday

And just for the sake of showing how much things change this far out in a forecast, ECM have backed off entirely on this in the run that just came out, GFS deepens the system but keeps it well offshore, and GEM deepens it too and brings it closer but still stays much too far west to impact us. There's not much point really worrying about these things until a few days out because they can change so much from run to run.

Meteorite58

Certainly an interesting time ahead for the weather watcher, lots going on out in the very active Atlantic, Jet very fast and close to or over us, remnants of Hurricanes and tropical features moving into the mix forming large areas of LP /storms and wave depressions possibly growing from these. A good way off yet, changes to timings, tracks and strengths, +120hrs , some big rainfall predictions coming in also with heavy frontal rains at times.

pauldry

It's a nasty feature alright but will it roll over us or miss us. I fear the Northwest won't escape it or the West coast. We could be looking at Orange warnings if it makes landfall. After this it will be fairly mild to warm

squarecircles

The storm system is back again on the latest ecm and has been on the last two runs of the gfs,

this time affecting more the south and east of the country, undergoing rapid development while crossing the country.

amandstu

And here is met.ie

weather.png

Coming up from the South West

pauldry

That thing can feck right off. I've to travel that day. Hope the jet carries it thru Tuesday night or wel be orange. Could go even more South n hit England. (Even better)

Hooter23

Thats very bad if it deepens at the last minute it will not change the track and will not have any time to curve northwards and miss us 😶

pauldry

Gone from last GFS run. See what next brings. Standard breezy showery weather on offer. That's OK.

adocholiday

As of now the ICON and GEM have a direct hit Wednesday afternoon with some very high winds affecting various parts of the country. GFS, ECM and UKMO evening runs showing nothing more than a windy day really.

All of the models are in agreement on the low coming out of the Newfoundland area on Monday and then as it crosses the Atlantic it gets picked up by the rotating remnants of Nigel but as of this evening the GFS and ECM both now have the low on a slightly more southerly track and moving up our direction later where it is a much less powerful system. There's a lot of dynamic elements to this system, and a lot will depend on how Nigel behaves and how far South the low coming across can go before being pulled back up towards us.

Cork2021

Already seeing eejits saying Ophelia 2.0

NIMAN

Could someone explain why I'm reading figures of 120km/h on this thread, yet Gerry Murphy just said on the weather forecast that it'll be blustery, and the graphic for the NW had a figure of 45.

.Donegal.

https://www.boards.ie/discussion/comment/121140557#Comment_121140557

I mentioned 120km/h based off yesterday mornings ecm run with the caveat that it’s far away so could amount to nothing or deepen.

NIMAN

When rte weather shows 45km for example, is that average speed expected or max gust expected.

Jim_Hodge

https://www.boards.ie/discussion/comment/121140782#Comment_121140782

They're saying gusts of 45kmh.

adocholiday

I didn't watch the forecast but was he talking about Tuesday or Wednesday? This thread title says the night of the 26th but most of the models showing any impact is for Wednesday afternoon and evening. And both the main models (GFS and ECM) have backed off the stormy stuff in their latest runs

JanuarySnowstor

Storm is back on this morning with all models!! Let's see what ecm does..

Supercell

Fax charts show blowy on Monday but nothing unusual for the time of year, then systems track to the NW. One to watch for sure.

cheezums

Is ICON reliable? Showing gusts of 160km

squarecircles

Someone over on netweather said the ukv model is now showing a severe storm on wednesday with 100 mph gusts off the west coast.

amandstu

Met.ie seems to be showing it coming up from the South to the NE.

The west doesn't seem to be getting strong winds from this system on whatever model(s) they are using for now.

aidanodr

https://www.boards.ie/discussion/comment/121140162#Comment_121140162

Yip .. its in CorkBeo headline .. Ophelia that is

https://twitter.com/corkbeo/status/1705199448391885166

adocholiday

ICON almost always way over estimates the winds. I rarely put any stock in their max gust values.

GFS and GEM both showing a similar shape and track, with it passing to our South and not really bothering us other than maybe clipping Cork, Waterford and Wexford.

UKMO doesn't roll out until around 8pm but their midday run show gusts of over 200km/h off the Galway coast. I don't know much about that model so not sure how accurate their modelling is for winds etc 5 days out.

ECM comes out between 7 and 8 so let's see what that says. Their morning run has a gusty day for the East coast that's about it.

As for Galway Beo, Cork Beo and those other online rags, the less said about their 'weather reporting' the better!

Hooter23

The fact the storm is to our south on the most recent charts is probably even worse...because storms usually pull away to our north and miss us on charts closer to the day...it is still 5 days away and charts will still change alot by then...so the fact its not a direct hit right now is actually a bad thing...it can only get worse if the charts go the way they usually go near the day 🙃

M.T. Cranium

All forecasts will be somewhat speculative until perhaps 12-18z Sunday runs, let newly formed Ophelia (2023 version) show its actual intentions after looping around south of Long Island by Sunday, interacting with lows further east, then the model guidance may be more reliable for western Europe downstream. Almost any outcome is possible, including no significant storm, but Tues-Wed period bears close watch. Surrounding seas are very warm especially North Sea at 18-20 C in places.

Meteorite58

Mod Note : Thanks amandstu for starting the thread, I will change the thread title now to Watch for storm potential Tues 26 - Wed 27 Sept 2023. Can amend it further if one develops and if/ when we get a better idea of timing.

Meteorite58

Watching the energy from Tropical Storm Ophelia as it glances off the East coast of the US and gets taken along by the Jet over towards us. How will it interact with the other LP systems ? Could be a wet one also, if it keeps the winds South then we could get a lot of rain North of the System, so far models showing somewhere between 20mm to 35mm, GFS 50 mm in parts of the S of the country but a way to go yet. Models certainly pointing towards a lot of energy maybe becoming a storm but if it does form could miss us.

ECM storm off the coast, very windy along the coasts Weds/ Thurs

GFS potential storm well off the S coasts, some strong winds along the coasts

UKMO full on storm overland Weds

ICON Weds storm off the coast, Windy along the coastal areas, some Southern counties windy

GEM Storm Weds, very strong overland

ACCESS-G ( Australian ) Weds Full on storm overland

So the models certainly showing potential for a storm but very early to know for sure of track, strength, projected rainfall accumulations etc

Tides will be starting to get high as the week goes on, Spring tides next weekend .

.Donegal.

Access-G a new model? Never seen it mentioned before.

pauldry

This storm has been showing for days now even weeks back. There's also another Oct 4th that's pretty severe for the North and West. If we are still stormless after the 1st week of October I will be amazed.

Still the one on Wednesday might develop too late to affect us and be a 1987 type storm over England...or not. Wait till Sunday to see if it's still there.

Meteorite58

https://www.boards.ie/discussion/comment/121144850#Comment_121144850

Been keeping an eye on it, grand as part of a suite to compare.

Cork2021

Is the storm potential gone!?

adocholiday

https://www.boards.ie/discussion/comment/121146505#Comment_121146505

GFS and ECM both in their latest runs keep it well South of us with no significant impact. ICON, UKMO and GEM all going for a strong cross-country storm. As MT said though, there are a lot of factors influencing this so there won't be any certainty for a while yet.

Cork2021

https://www.boards.ie/discussion/comment/121146606#Comment_121146606

Thanks

pauldry

It all gets caught in the jet so there could be nothing or a short sharp burst of winds. Nothing set in stone yet but its Trended Southeast a while now. Maybe gales for South and East and nothing elsewhere.

amandstu

https://www.boards.ie/discussion/comment/121146895#Comment_121146895

Is there a reason it has trended South so far?

Or are there just too many variables to identify a particular ( or set of) reasons?

squarecircles

Met Eireann alluding to it in their latest forecast...

While details are still uncertain, current indications suggest that WEDNESDAY could be a very windy

or possibly stormy day with heavy rain and very strong winds in all areas for a time.

Meteorite58

ECM 06Z only runs to 01.00 Weds looking very similar now to the UKMO at that time frame, ECM would be more conservative than than the UKMO with wind speeds especially at this range, UKMO often comes down a peg more in line with the ECM and GFS closer to the off, GFS less developed and sends the system in over the UK, Very windy for Southern UK but nothing on how strong the UKMO is.

ACCESS-G very stormy

ICON Stormy

GEM Stormy

UKMO Very stormy

( will change the thread title to Weds )

Meteorite58

This was posted by squarecircles earlier from Met Eireann 'While details are still uncertain, current indications suggest that WEDNESDAY could be a very windy or possibly stormy day with heavy rain and very strong winds in all areas for a time.'

squarecircles

The storm system is much,much stronger, more developed and further north on the latest 12z GFS

coming more inline NOW with what ICON AND UKV ARE SHOWING.

Would be a very severe storm for the south and east if this were to transpire.

squarecircles

the south and east of the country bearing the brunt of it...

Chris_5339762

Arpege in line with GFS too - but with 160kmh gusts around Dingle.

pauldry

Tomorrow there'll be 10 percent more certainty with this. Its on and off the charts half the time. But when met eireann has stormy on forecast it is now more likely there'll be warnings somewhere than not. Hopefully itl pass through pretty fast.

squarecircles

The APERGE model has 100mph gusts hitting the southwest

Cork2021

https://www.boards.ie/discussion/comment/121147540#Comment_121147540

And so does the UKMO

highdef

https://www.boards.ie/discussion/comment/121147540#Comment_121147540

Already mentioned just two posts back...... Except the speed mentioned was not in British Imperial Units 😜