Tracking potential wind and rain storm for around Thursday 7 Dec overnight into Friday 8 Dec

M.T. Cranium

There is growing cross-model support for a strong low to approach Ireland from the southwest around the overnight hours Thursday-Friday 7-8 Dec.

Once the current cold pattern fully breaks down, one moderately strong low will move past the west coast Wed 6 Dec into early Thursday 7th. This will allow milder air to cover most of Ireland, with intervals of rain likely. A second and more powerful low will then develop in the vicinity of the Azores and track towards southwest Ireland, arriving (at this early point in time) between early evening Thursday to late overnight.

A summary of different model guidance in 00z model suite will follow ... I wanted to post this to encourage a discussion and also to avoid duplication, so fire away, but I will return with a summary of what models are showing. At this early stage I would say the consensus is in the ballpark of a widespread yellow alert with some counties likely orange. I have not seen any really extreme depictions yet anyway. Named storm? Quite possible.

M.T. Cranium

What models are showing now (from 00z suite) ...

GFS __ Faster evolution than most, low tracks up west coast Thursday afternoon, brief interval of very strong SW to W winds gusting to about 120 km/hr, potential rainfalls of about 15-30 mm with limited eastward extent, in additional to a more widespread 10-15 mm on Wednesday.

GEm __ Low is quite intense six hours before landfall, tracks across central Ireland, arriving late afternoon or early evening. Probably more intense for south coast than GFS. A widespread 15-30 mm rain and wind gusts to 110 km/hr near south coast. Could stay quite cold in Connacht and Ulster, hill snow possible.

ECm __ Similar track to GFS, six hours later in evolution, not as intense, would rapidly fill after passing Donegal Bay with remnants heading east over Britain on Friday. Probably a colder scenario in general with 5-10 mm rainfalls, moderate wind gusts.

Arpege __ A stronger version of GEm track and same timing, would bring 120 km/hr gusts to south coast, swath of heavy rainfalls central to Ulster.

UKmO ___ Looks like a 50-50 compromise of coastal and inland tracks above, moderate intensity.

ICON ___ Also quite intense for southwest by Thursday afternoon, south coast all night as track is inland near Galway then veers east to Dublin. Lowest pressure of guidance suite (near 958 mbs off Clare).

JmA ___ A less intense depiction, but following similar evolution to GEm.

Current model blend ... A low of moderate to borderline strong intensity tracking across Connacht with potentially disruptive winds in most regions, details a long way from nailed down at this early stage. Timing most likely to be Thursday late afternoon and evening, could be delayed to overnight.

Hooter23

The jetstream and these systems just need to be closer to each other...the jetstream is strong enough then to turn these systems into storms...still plenty of time to be upgraded if this starts happening..

M.T. Cranium

06z ICON made no big difference, and 06z GFS intense storm for Galway and mayo late Thursday. 956 mbs fierce gradient over Atlantic west of Clifden.

pauldry

Latest GFS quite intense but still no crossmodel support. However GFS has shown this in some shape or form for days now so it's members are more confident.

Potentially Orange Wind warning for the West if it occurs like latest track.

Hooter23

It seems to be more caught up in the jetstream on the latest chart compared to the last chart..causing it to be more intense and pulled more northwards in our direction

M.T. Cranium

12z GFS a bit further out to sea, other guidance has not changed tracks discussed before to any great extent, UK now looking robust near southwest coast. A spread on tracks and onset so cannot really blend this very easily, but looks to be a significant event. Several depictions kill it off rather quickly on Friday over central or even southern England which is odd (Lorenzo the celebrated non event did that).

I suspect guidance is picking up blocking signals and trying to square those with a strong Atlantic disturbance.

Meteorite58

ATM Weds frontal passage looks very windy on some models ,less so on the ECM. Could get very windy in the SW, perhaps 80 to 100 along the coasts for a time and later 70 to 80 km/h overland in general, ARPEGE / ICON showing the strongest of 90 to 110km/h in Munster , more so towards the coasts and very blustery overlnad for a time up to 80km/h or so .

Thurs models for now starting to look a bit more similar with the depression's track and in general for now keeping the strongest winds along the coasts, again ARPEGE showing v strong winds along Southern coastal counties, some models showing around 70 to 80km/h in places at times overland but I think this has a bit to go yet. Initially a deepening depression/ storm on approach just off the coast travelling quickly and then stalls out as it takes on the effects of the Northern and European blocking and hence never pulls up the strongest winds up over Ireland....for now anyway but could change. Currently showing disturbances that could give strong winds on Fri too especially in the SW but a bit to go with that yet.

Rainfall totals looking high especially along the SW, S, SE , W, NE and perhaps parts ot the E again all depends on the track.

squarecircles

o o

nacho libre

I think the main talking point of this system will be the rain. The winds won't impact over land as the system is essentially being forced to a halt by the blocking to the North East. This regime unfortunately means a lot of rain with potential slow moving fronts over the next week or so. After this the weather may settle down again,hopefully.

Supercell

Looks like normal service resumed for the atlantic following this, wet and mild for the foreseeable.

squarecircles

https://www.boards.ie/discussion/comment/121456601#Comment_121456601

NOT MILD THOUGH,JUST DAMP AND MISERABLE WITH NO STORMS AND LOTS OF COLD RAIN.

Supercell

https://www.boards.ie/discussion/comment/121456748#Comment_121456748

True enough, i suppose mild is relative, mild compared to the last week i suppose. But you're right, atlantic muck is another way to describe it. Hopefully the Wicklow mountains will break up some of it for us Dubs!

nacho libre

Well, even the best winters for those of a cold persuasion had milder periods. Let's hope this proves to be one of them!

sdanseo

Looks like most models now showing the frontal wind tomorrow to be almost as strong as Thursday's storm? Up to 130km/h gusts just offshore.

Very fast moving on Weds, whips over the entire country in <6hrs west to east.

Thursday looks like high yellow only, peak gusts mostly under 110km/h, centred on Galway bay. ICON always overcooks winds.

Thursday

Hooter23

Jetstream is not strong enough on thursday to make a proper storm out of that system...it is very strong by friday but the problem by then is there is no system for it a make a storm 🙃

Meteorite58

ICON , UKMO and ARPEGE might show a bit stronger winds but the WRF more in line with the ECM and GFS. Strong and blustery around the coasts at times, SW will see the strongest winds ( strongest on coasts ) but nothing too severe, probably gusting up to 80km/h or perhaps 90km/h in a few elevated areas for a short time, possibly up to 100km/h or so on coasts. Some high rainfall totals as oulined by the charts below especially over higher ground. Might be some strong winds in the SW on Fri morning/ early afternoon, but not looking overly strong at this stage.

Models showing there may be thunderstorms embedded in the fronts coming close to the coasts tomorrow, perhaps a few straying inland.

M.T. Cranium

Looks like a widespread 30-50 mm for western counties, 15-30 eastern, over period of Wed-Friday, will be quite persistent Thursday into early Friday. Winds fairly moderate except in some exposed coastal locations.

System acting like an energy impulse confronted with upper level retrogression, rapid weakening and same cycle starts over again further west. If it continues, could lead to a sudden change in outlook after 20th once models get better handle on retrogression.

Robwindstorm

https://www.boards.ie/discussion/comment/121460082#Comment_121460082

I was just wondering was there a technical name for these type of impulse storms in the Atlantic at the moment. They are small, very intense ,almost hurricane like in size. There's another one showing mid Atlantic on the GFS in a couple of days . The unravel very quickly though and it would probably be impossible to measure windspeeds at their peak?

Meteorite58

https://www.boards.ie/discussion/comment/121461391#Comment_121461391

More models showing potential for very strong winds sweeping across the country on Sunday, going through very quickly but packing a punch on some models. Will just need to keep an eye on the models to see if there is more certainty over the coming days.

Robwindstorm

https://www.boards.ie/discussion/comment/121461435#Comment_121461435

Yes Meteorite, you progged these little depressions. They're very sudden and unpredictable.

David1

Sunday almost looks interesting. Waiting for the ECM to come out.

whatever76

https://www.boards.ie/discussion/comment/121463153#Comment_121463153

Hows it looking for Cork City on Sunday as have an outdoor event ? Yr weather saying currently Windy - rain in morning but looking clear in afteroon

SouthWesterly

Drove from Kerry to Dublin this morning. The rain was heavy and made driving in the dark hard going.

Is summer here yet?

M.T. Cranium

The low ended up about 200 miles further west than the model consensus a few days ago, and so its effects have been fairly moderate. It will remain blustery all day Friday as the low approaches Donegal Bay and begins to fill gradually Friday night. Another squally frontal trough follows along late Friday night into early Saturday. A deeper low is now expected for Sunday and it could merit its own thread perhaps. Looking very windy around Galway on Sunday afternoon (70-110 km/hr).