Storm Desmond - High Winds 4/5 December 2015

FWVT

The 12Z ECMWF shows 50-kt 10-metre and 80-kt 925 hPa winds off the far west coast on Friday 12Z. Over land the 925 hPa level is around 700 metres in that area but the winds are at most 60-70 kt.

For comparison, Barney, which gave a 68-kt gust at 5 pm at Oak Park, had 925 hPa winds of 80 knots over land (yellow area) but this level was lower, at around 600 metres. This Friday's system will be no match for Barney over land, however I would not like to be out to sea in it.

Tactical

Chris_5339762 wrote: »

Vanilla GFS is showing a good lot of rain all over the weekend. Torrential for ~30 hours in places.

Torrential rain for approx 30 hours? Surely that's overcooked? That would be quite serious given the recent rain we've had, even taking into account a dry day or two.

Can you elaborate on this?

FWVT

Chris_5339762 wrote: »

Vanilla GFS is showing a good lot of rain all over the weekend. Torrential for ~30 hours in places.

??

Clonmel1000

Met Eireann not quite as strong in this as I'd have thought having read this thread.

DOCARCH

Clonmel1000 wrote: »

Met Eireann not quite as strong in this as I'd have thought having read this thread.

Still a little early to call it. ME would be on the cautious side.

km79

DOCARCH wrote: »

Still a little early to call it. ME would be on the cautious side.

MTC holding off on major rainfall too
I hope they are right

M.T. Cranium

The guidance suggests heavy orographic rainfall (on south-facing hills) which might be level two rain or flood potential locally for small streams that drain those hills. Lowland rainfall does not look overly heavy. Would expect possible changes as details of the frontal stall zone become clarified.

From the guidance I looked at, would suggest 50-75 mm rainfalls on hills in west but only 15-30 mm over most lower terrain. So unless you live close to those hills or have a stream nearby that rises in nearby hills, the flood potential may not be especially great. This is not meant to be a comment on the Thursday rainfall in the southeast which is being discussed in a separate thread.

I can edit posts but I can't change thread titles so if there is a change in my thinking it will show up in posts before the thread title.

Oneiric 3

Latest HIRLAM has a zone of mean wind speeds of near gale or gale pushing into Connacht later on Friday. Here imby, it is showing a period of mean wind speeds reaching near gale for period of at least 6 hours which would be unusual event in recent climate history. Gust speeds not projected to be excessive though away from the coast.

maquiladora

18Z ARPEGE max gusts up until 6am Saturday. 130 km/h gusts shown for northwest Mayo.

maquiladora

Here's a comparison, for what it's worth, between the max gusts up until Saturday 6pm on NMM WRF and what the same model showed for Barney's max gusts.

Barney :



This weekend :

kittyn

maquiladora wrote: »

Here's a comparison, for what it's worth, between the max gusts up until Saturday 6pm on NMM WRF and what the same model showed for Barney's max gusts.

Barney :



This weekend :

Looks a fair bit worse than Barney or are my eyes deceiving me???

Isaiah

Hi folks, have a ferry crossing Holyhead to Dublin this Friday afternoon.

What's the verdict ? Look like a cancellation?

Oscar Bravo

Jerry Murphy on Radio 1 there "very wind or possibly stormy friday night", not much more detail on it.

Isaiah

Oscar Bravo wrote: »

Jerry Murphy on Radio 1 there "very wind or possibly stormy friday night", not much more detail on it.

Hopefully we get in before it kicks off.

Oneiric 3

maquiladora wrote: »

18Z ARPEGE max gusts up until 6am Saturday. 130 km/h gusts shown for northwest Mayo.

Felt a pang of excitement in my stomach looking at that chart

maquiladora

kittyn wrote: »

Looks a fair bit worse than Barney or are my eyes deceiving me???

Winds over a wider area and a longer duration than Barney but I doubt winds will be stronger than Barney in the inland areas where Barney was strongest.

ninebeanrows

Latest EC data suggests widespread 50-60mph wind gusts. Western coastal fringes ~65/70mph gusts... A small slice of 75/80mph gusts into the north-west.

Oneiric 3

Weathercheck wrote: »

Latest EC data suggests widespread 50-60mph wind gusts. Western coastal fringes ~65/70mph gusts... A small slice of 75/80mph gusts into the north-west.

I don't think gusts will be the biggest issue in this event, but more the persistence of high mean speeds, which would be more typical of warm sector conditions in similar set ups I think.

mickger844posts

I'm surprised Met Eireann/UkMo haven't come out and called this Storm Desmond yet. Looks on a par or stronger than previous named storms this season. Guess there is still time but it seemed like they named previous storms a few days earlier.

Irish Steve

Isaiah wrote: »

Hi folks, have a ferry crossing Holyhead to Dublin this Friday afternoon.

What's the verdict ? Look like a cancellation?

Depends on which company/ferry you are travelling on. If it's Irish Ferries, then the Swift fast craft is likely to be hiding in Dublin port for a number of days, but Ulysses, their largest Cruise ferry is probably going to be operating, I don't think they've cancelled a sailing because of weather with that ferry since it entered service, though some wind directions can cause issues at Holyhead when getting on and off the berth.

I have no recent experience of the Stena craft that are operating the route now, they're both decent size ships, so should be OK, but your best bet is to check with the operators for an update

FWVT

mickger844posts wrote: »

I'm surprised Met Eireann/UkMo haven't come out and called this Storm Desmond yet. Looks on a par or stronger than previous named storms this season. Guess there is still time but it seemed like they named previous storms a few days earlier.

The worst winds will be out to sea so with no real damage or disruption on land they're unlikely to name it.

JCX BXC

FWVT wrote: »

The worst winds will be out to sea so with no real damage or disruption on land they're unlikely to name it.

Has something changed to the 130km/h gusts I had been seeing on the coasts???

FWVT

Carnacalla wrote: »

Has something changed to the 130km/h gusts I had been seeing on the coasts???

That was only around Belmullet and in any case the 00Z ECM has downgraded winds in that area. Yesterday its strongest winds were for 12Z Friday and showed numerous 50-kt barbs offshore and just at the coast, however now it's more like 45 kt.



Later in the afternoon and evening the winds move onshore but weaken all the time. I would expect the strongest gusts of about 60-65 kt in Mace Head - Malin Head in the afternoon but much less than that overland (45-55).

FWVT

FWVT wrote: »

That was only around Belmullet and in any case the 00Z ECM has downgraded winds in that area. Yesterday its strongest winds were for 12Z Friday and showed numerous 50-kt barbs offshore and just at the coast, however now it's more like 45 kt.



Later in the afternoon and evening the winds move onshore but weaken all the time. I would expect the strongest gusts of about 60-65 kt in Mace Head - Malin Head in the afternoon but much less than that overland (45-55).

This was the 12Z output yesterday.

maquiladora

0Z UKMO for 6pm Friday has the strongest winds on the southwest coast, 90 km/h sustained. Quite strong inland over southwest coastal counties too. Just one model though, most have the strongest winds further north up the west coast.

Meteorite58

Expecting a lot of wind along the Western Seaboard for a good part of Fri ( 12 hours or more ? ) which looks like an Orange warning and again for parts of Sat that could also possibly warrant an orange warning. Strong SW winds in Southern counties on Sat too with a lot of water flowing out the rivers will lead to some high levels, although just coming out of neap tides atm.

maquiladora

Yes, more notable for the duration of the winds than the forecast strength. Long duration of winds + saturated ground from periods of heavy rain means trees will be down in places.

km79

yr.no is still giving my area 60 mm from friday night to Sunday morning
not a hilly / mountainous area
I hope MTC is correct in his forecast . does not seen to be going for anywhere near this amount

maquiladora

06Z GFS also spins up a deep low off the northwest coast on Monday, though it's too far off shore to have any impact here unless the track shifts.

Weatherproof79

Wind warning issued for NI. Gusts of 45-55mph, locally 60mph. Nothing out of the ordinary