This Week's Storms - FORECAST, MODEL DISCUSSION ONLY

maquiladora · 10-12-2011 2:14pm

Deep Easterly wrote: »

What the guys at Exeter are thinking at this stage for Tuesday noon:

Gusty and more in line with its own UKMO run as well as GFS. Interesting that the ECMWF have it further north with slacker gradient over Ireland on both the op and en mean. Once off or start of a trend? .

ECM has been showing that now for the last two runs.

Who will bow to who? :pac:

12Z's will be interesting...

Deep Easterly · 10-12-2011 3:16pm

maquiladora wrote: »

Who will bow to who? :pac:

12Z's will be interesting...

The actual 84hr fax shows something slightly different for the same time period: (Tuesday noon)

a bit more in tune with the ECMWF projection with the low centre being more 'complex' in structure but still packing a punch wind wise over Ireland.

Yep, all eyes on the 12z. Swings and roundabouts!

maquiladora · 10-12-2011 3:29pm

Deep Easterly wrote: »

The actual 84hr fax shows something slightly different for the same time period: (Tuesday noon)

a bit more in tune with the ECMWF projection with the low centre being more 'complex' in structure but still packing a punch wind wise over Ireland.

Yep, all eyes on the 12z. Swings and roundabouts!

955mb low right on the NI coast. That probably explains the UKMO warning for the highest winds to be in the southern UK then.

Ahorseofaman · 10-12-2011 4:02pm

maquiladora wrote: »

955mb low right on the NI coast. That probably explains the UKMO warning for the highest winds to be in the southern UK then.

and therefore southern Ireland as well?

ninebeanrows · 10-12-2011 4:06pm

Just before the 12z,

The 6z did look quite blowy for much of Ireland on Tuesday

Widespread gusts from 60-70 knots

irish1967 · 10-12-2011 4:24pm

Lol. I love the use of that phrase.... "quite blowy" that's my kind of technical phrase

M.T. Cranium · 10-12-2011 4:29pm

This thread could probably use an upgraded title to reflect the severity of two storms. It's starting to look like a five-day siege of stormy weather with two peaks of intensity, as there may not be any great let up in wind speeds between Tuesday and Thursday night. Also this inter-storm period could be producing its own brand of disruptive wintry showers.

I think the UK Met warnings are influenced by the upper pattern being so cold that only a southward shift could be logically expected, and they are buying fully into the idea of a southern energy centre which will tend to reduce wind speeds for Scotland as the double-centered low approaches (but it will still be very windy there, just below warning criteria in that scenario). Personally I would put the whole of the UK under the same level of alert at this point and extend the same alert to Ireland. This thing looks intense and I don't think there will be much variation north to south for Ireland. In any case a fairly significant part of the storm comes in the warmer period late Monday so that alone would justify an alert, regardless of how strong the colder westerly portion proves to be.

I'm only starting my day so going back to get a better handle on how this is evolving off eastern Canada now. If there's a continuation of model trends on the 12z then I think our task here switches from speculation to outright warning as we might expect the other sources to be a little more hesitant -- people need to know this is coming especially given that it's a weekend and Monday looks very unpleasant to be outside trying to deal with preparation issues in a driving rain.

For a new thread title, I would suggest something like

Severe windstorms, wintry showers from late Monday 12th to Friday 16th

or anything that alerts to a long-duration, severe set of events.

ninebeanrows · 10-12-2011 4:44pm

M.T. Cranium wrote: »

This thread could probably use an upgraded title to reflect the severity of two storms. It's starting to look like a five-day siege of stormy weather with two peaks of intensity, as there may not be any great let up in wind speeds between Tuesday and Thursday night. Also this inter-storm period could be producing its own brand of disruptive wintry showers.

I think the UK Met warnings are influenced by the upper pattern being so cold that only a southward shift could be logically expected, and they are buying fully into the idea of a southern energy centre which will tend to reduce wind speeds for Scotland as the double-centered low approaches (but it will still be very windy there, just below warning criteria in that scenario). Personally I would put the whole of the UK under the same level of alert at this point and extend the same alert to Ireland. This thing looks intense and I don't think there will be much variation north to south for Ireland. In any case a fairly significant part of the storm comes in the warmer period late Monday so that alone would justify an alert, regardless of how strong the colder westerly portion proves to be.

I'm only starting my day so going back to get a better handle on how this is evolving off eastern Canada now. If there's a continuation of model trends on the 12z then I think our task here switches from speculation to outright warning as we might expect the other sources to be a little more hesitant -- people need to know this is coming especially given that it's a weekend and Monday looks very unpleasant to be outside trying to deal with preparation issues in a driving rain.

For a new thread title, I would suggest something like

Severe windstorms, wintry showers from late Monday 12th to Friday 16th

or anything that alerts to a long-duration, severe set of events.

Thanks MT, you are free to set up any threads you wish!

I will set up a thread maybe this evening after the outputs.

Thanks as usual for your excellent analysis.

ninebeanrows · 10-12-2011 4:51pm

12z GFS perhaps looking for ECM esque with the low set up, but i have no grasp over how this thing makes its moves.

pauldry · 10-12-2011 4:51pm

Thread title : Severe Windstorm turning out not to be as bad as anticipated as it goes too far south and sends the shallow part of the low over us and then fills a bit more as it passes us and the winds just are blowy and then the second storm goes too far north of us and we are left with just a couple of windy days and the wintry showers are hailstones.

Or is that too long for a thread title

Deep Easterly · 10-12-2011 4:54pm

System slowing getting into high res territory now. EMHI 12z output suggests potential for a narrow zone of strong winds aligned with the actual approaching warm front:

Monday Noon:

Horizontal rain territory right there

ninebeanrows · 10-12-2011 5:02pm

The system just sits out to our west growing deeper and deeper! The west coast could have a long period of severe winds.

945mb at this point.

Overall similar path to the 6z with the centre staying to our north.

Winds gusting to 70 knots in place and widely gusts above 60 knots.

TheMilkyPirate · 10-12-2011 5:21pm

Thursdays storm lookin like a bit of a monster

ninebeanrows · 10-12-2011 5:22pm

baraca wrote: »

Thursdays storm lookin like a bit of a monster

Ye but it keeps getting shifted north run by run.

Absolute cane' though.

maquiladora · 10-12-2011 5:28pm

On the 12z gfs, the strongest winds stay offshore then slam into Scotland.

(second system)

Deep Easterly · 10-12-2011 5:29pm

GFS has 2nd potential storm depression down to 938hPa by Friday morn:

Track very uncertain on this one, though almost a week away yet.

nacho libre · 10-12-2011 5:46pm

Weathercheck wrote: »

The system just sits out to our west growing deeper and deeper! The west coast could have a long period of severe winds.

945mb at this point.

Overall similar path to the 6z with the centre staying to our north.

Winds gusting to 70 knots in place and widely gusts above 60 knots.

interesting. if that chart verifies, this could turn out to be like the storm we had back in the early 90s.

M.T. Cranium · 10-12-2011 5:51pm

Sorry about the thread title confusion, I meant this thread needed a new title. I see there's a new thread now. Anyway, here's my take on the 12z GFS and what I saw from the GEM which is similar to 72h.

The solution for Monday-Tuesday looks plausible as analyzed above in the thread here. As seems to be the case quite often, the east and south may see their strongest winds in the warm frontal to occlusion stage late Monday or overnight. I think the potential for this to spin its wheels and unleash very strong winds on the west coast is the main story there. More or less into the countdown phase for this, although as a system it is barely in the infant stages now off Nova Scotia as a developing closed centre (about 1015 mbs at 16z) suspended from a trough in Quebec. By 12z Monday the regional GEM model (usually very accurate for North Atlantic) has it at 952 mbs near 57N 20W. That represents double bombogenesis next 48 hours with 5 mbs and 4 hours to spare.

As to storm number 2, count me among the skeptics on that evolution, a 930 mb low in outer Donegal Bay that raises a 40-knot wind at Belmullet? I don't think that's even possible in terrestrial physics. More likely this is a signal of a very powerful storm heading more towards the northwest coast of Ireland, not reaching the 930s but a more realistic prediction might be just clear of Belmullet at 948 mbs. We shall see ... looks to be cutting too far north for the uppers ahead of it.

tayto lover · 10-12-2011 6:24pm

maquiladora wrote: »

On the 12z gfs, the strongest winds stay offshore then slam into Scotland.

(second system)

Good enough for the Scots.

seanknowsall · 10-12-2011 6:32pm

As exciting as all this is,I expect a complete downgrade of both events. I understand many contributors put alot of time into analyzing the various models and do it very well but the predictions are 99% of the time way overboard. I would love to see a powerful windstorm next week but I refusing to allow myself to get excited about it. Both systems will track more to the north;yes we will have strong winds but nothing extraordinary for Ireland in a typical december. Example of hype... The storm on Thursday earlier this week.... no where near as strong as was being forecasted. The problem is the media trawl through weather related forums like this and pick up all the hype and print outlandish articles about killer storms etc. When they dont materialise the public grow weary....

JanuarySnowstor · 10-12-2011 6:34pm

UKMO has both systems slamming into Ireland
This thinking is also backed by the UK Met Office.

ECM will give clues later on but for now I think the Tuesday system shouldn't be taken as little brother. It looks very severe in it's own right and is much more in the reliable timeframe!

I would watch the UK Met for updates closely

Deep Easterly · 10-12-2011 6:39pm

UKMO 12z has Thursday's storm potential on a slightly more southerly track:

and though way more conservative on the actual pressure values (around 960hPa) still looking fairly explosive if not to the same extent as the GFS.

maquiladora · 10-12-2011 6:50pm

12Z UKMO:

maquiladora · 10-12-2011 6:57pm

12Z GEM...

Tuesday :

and then Thursday :

Sponge Bob · 10-12-2011 7:04pm

Tuesday looks harmless enough to me, a stiff breeze and that is all.

Thursday looks the same, a ta stiffer on the Irish Sea maybe

Deep Easterly · 10-12-2011 7:05pm

ECMWF 12z beginning to roll out now. Please ECM, no more of those slack complexes over Ireland, I'll be your bestest fwend.

Sponge Bob · 10-12-2011 7:12pm

I'll call Tuesday Now. No weather station will break 70KT gusts and the top gust Tuesday will probably be in the 61KT-64KT range in Belmullet. A stiff breeze and that is that.

I'll call Thursday on Monday some time.

maquiladora · 10-12-2011 7:13pm

Some tweets from Ian Fergusson, BBC weather forecaster:

Tues storm threatens severe gales here; gusts 60mph+, but the Thurs-Fri event offers even more concern if it stays as per models

need to see continuity in forecast models to judge areas worst affected by high winds, but high confidence for the 2 storms.

ECMWF prog for 00z Fri.... Troubling. Exact track will be critical... Don't take this latest run as done deal!

ninebeanrows · 10-12-2011 7:16pm

ECM is slightly delayed but still a fairly strong storm progged off the NW coast for Tuesday with very strong winds, 70-75 knots on exposed coasts and 60 knots inland.

maquiladora · 10-12-2011 7:16pm

12Z ECM at 72 hours is similar to GFS. A bit further south and west and just 5mb in the difference. If we had a 78 hour ECM frame it would probably be even closer to the GFS.

nacho libre · 10-12-2011 7:23pm

12_72_mslp500.png?dt=10December%2020111814:29

it seems to me, and i could be wrong, tuesday's system could be notable for the duration of the wind, rather than the strength of the actual gusts.

for a biggie storm, you'd expect gusts of 60- 90mph(potentially even higher). i don't see that happening on Tuesday. The storm later in the week has that potential- again though it could easily not happen. it would be a major disappointment if we don't get one significant storm out of all this.

Pangea · 10-12-2011 7:23pm

For Monday/Tuesdays event are we looking at winds similar to a few days ago for the west coast?
I know Thursday is a good bit away so I wont mention that one.

edit: never mind, question answered above.

Deep Easterly · 10-12-2011 7:28pm

maquiladora wrote: »

If we had a 78 hour ECM frame it would probably be even closer to the GFS.

meteo.si has ECMWF run (MSLP & cloud/rain) in 6hr increments out to 3 days.

Meteo.si

Hasn't updated yet to 12z run but tends to update to latest run more rapidly than vedur.is.

Edit: how badly put that last sentence is!

Edit again: updated to 12z run now.

Pangea · 10-12-2011 7:32pm

I remember the great storm in 1998 aka 'Hurricane Stephen', Gusts of 96 knots -177Km recorded at Malin.
It would take a lot to beat that. We had to get our roof repaired and my neighbour had to get a new roof.
http://www.met.ie/climate-ireland/weather-events/Dec1998_Storm.PDF

M.T. Cranium · 10-12-2011 7:33pm

I took the 12z ECM for Tuesday as an upgrade and feel that we are likely to see a series of slight upgrades now. Suggestions that this will be just a minor event are perhaps missing the key element of cold air wrapping around the circulation, a sign that winds are likely to become very gusty. I would set the over-under for max gust at 80 knots for this storm. Try to keep in mind that the models are working with a very volatile pattern here, given the cold SST anomaly around 30W and the rapid development rate of this cyclone which is barely past its infant stage now. Also, it will be "northern max" the most energetic point in the lunar cycle on Monday. There is often a bit of a sting in the tail of northern max storms. They tend to produce because they get that extra shot of geomagnetic energy.

The UKMO track for Thursday-Friday meanwhile, as per what J.S. was saying, is more or less maxing out potential for wind speeds in the south and east (of Ireland). I'm going to keep that one on the back burner in my thoughts until we get past whatever Tuesday has to offer. But it does look very strong on some of the 12z guidance. Have been watching the ECM come out and I heard that collective "uh oh" when it showed 120h. That's not going to be pretty if that verifies.

JanuarySnowstor · 10-12-2011 7:34pm

ECM keeps the core further South.
Looks very severe for Northern half of the country, indeed for all
Of course plenty time for it to change yet

maquiladora · 10-12-2011 7:38pm

Wow....12Z ECM has the second low down to 932 mb at 132 hours.

http://www.wunderground.com/wundermap/

ninebeanrows · 10-12-2011 7:42pm

maquiladora wrote: »

Wow....12Z ECM has the second low down to 932 mb at 132 hours.

http://www.wunderground.com/wundermap/

How do you get the 12hr segments?

Looks disastrous.

Deep Easterly · 10-12-2011 7:44pm

maquiladora wrote: »

Wow....12Z ECM has the second low down to 932 mb at 132 hours.

http://www.wunderground.com/wundermap/

I am just gettting a map of Roscommon on that link?

maquiladora · 10-12-2011 7:46pm

Weathercheck wrote: »

How do you get the 12hr segments?

Looks disastrous.

Ahorseofaman · 10-12-2011 7:47pm

Deep Easterly wrote: »

I am just gettting a map of Roscommon on that link?

I got Kerry/West Cork

ninebeanrows · 10-12-2011 7:52pm

The storm on the ECM which is associated with a really exceptionally strong jet would bring the potential for gusts to 90-100 knots in exposed northwestern areas.

Widespread gusts to 70knots perhaps upto 80knots.

maquiladora · 10-12-2011 8:04pm

12Z ECM does looks dangerous for the west/northwest. Thankfully it is still 100+ hours away and there is time for a downgrade/track shift.

bb1234567 · 10-12-2011 8:06pm

will a lot of rain come with these high winds?as much rain as during the dublin floods in october?

Su Campu · 10-12-2011 8:07pm

We also need to keep an eye out for possible stingjet events in these systems, which can bring winds of 100 knots or more to the surface. Water vapour imagery tomorrow and Monday will give signs of any such development for Tuesday's system, which would occur near the central spiral.

M.T. Cranium · 10-12-2011 8:14pm

The second storm is a freak of nature, that's for certain ... I don't recall a time when all the models were showing a storm in this region at 120-144h with a sub-940 centre. It will be egg on face for meteorology in general if there's no such animal. Although the GFS and GEM are further north than the two major European models, there isn't a lot of difference for this time scale and I find the Euro models more credible given the large-scale set-up. The jet stream is not likely to rebound as quickly as the N American models are showing after the effects of the Tuesday storm which forces very cold air to circulate as far south as 48-50 N on Tuesday into Wednesday.

I may not see the 18z model run before the 00z run because I'm heading out now for the rest of the day (it's only 11:15 here).

ninebeanrows · 10-12-2011 8:24pm

Our two storms as per ECM.

ninebeanrows · 10-12-2011 8:30pm

A few disturbing ensembles for next Friday on the GFS.

But i note that a number go for a really slam on Tuesday too.

A really violent week ahead.

Deep Easterly · 10-12-2011 8:51pm

6hr'ly forecasts for midweek period for Malin Head as based on the raw ECMWF 12z operational output: (from yr.no)

Has Storm No.2 with higher windspeeds (Mean speeds 27m/s = 53kt / BF 10)
Caution with this one as has already been suggested. Tracking and intensity of the system continues to be very uncertain. Trend is good, specifics not so much so just yet. Nail-bitin' times ahead!

Iancar29 · 10-12-2011 8:55pm

* GOES AND INVESTS INTO WINDPOWER *

:rolleyes::rolleyes::rolleyes:

This Week's Storms - FORECAST, MODEL DISCUSSION ONLY

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