This Week's Storms - FORECAST, MODEL DISCUSSION ONLY

Su Campu · 08-12-2011 6:47pm

Monday/Tuesday's storm now looks much further north than previous runs, so if that were the case it would be nothing special for Ireland, just another normal windy day in the northwest Tuesday. Still a very low core pressure though, but it remains to be seen if it goes that low. Still a lot of scope for change with systems this deep.

EDIT: Didn't see Jerry's post!

ninebeanrows · 08-12-2011 7:26pm

Although the ECM 120hr chart would bring widespread gales and severe gales.

I dont think it would pack that real punch as it is matured, although a secondary could form to squeeze the isobars and creates something extreme.

Needs close watching.

Also as the low arrives the gradient does tighten up ahead of the fronts up the Irish sea which would bring some severe gales.

Harps · 09-12-2011 12:43am

Some real monster storms showing up on the GFS runs for next week, ensembles for Malin show there's still no real agreement on just how low the pressure will drop but sub 945mb showing up regularly

Don't think I've ever seen a 925mb in FI never mind just 4 days away!

M.T. Cranium · 09-12-2011 1:01am

This is a rare and volatile pattern developing where a large pool of unusually cold water in the mid-Atlantic is likely to reinforce a very strong jet stream aimed directly at Ireland and Britain (see, I'm learning) as illustrated by the very latest SST observations:

http://www.osdpd.noaa.gov/data/sst/anomaly/2011/anomnight.12.8.2011.gif

The storm in question develops at the most energetic point in the lunar cycle, after the double peak of full moon and northern max (which are separated by about 24h at this point). As I've mentioned before with regard to the research, there is a strong low pressure signal at winter full and new moon but more importantly, the lunar energy tends to be constrained by the large-scale pattern so if we were seeing a weak jet stream or a split flow or even a raging southwest flow into the Norwegian Sea, this energy peak would not be of great concern for Ireland.

As things stand, the models have been trending towards a very strong storm outcome and track is of course dependent on central pressure in terms of how much of a high impact storm it would be. A 970 mb low (today's earlier value as the storm crossed 10W) would have considerably less impact than a 945 mb low on the same track.

People commented that today's storm went further north than the models, which may be the case but in the past few years, this track has become almost a standard route for low pressure, it may be somewhat further north than climatology because of a gradual northward shift of the grid. However, all depends on where the polar vortex sets up in the wake of today's storm. Since we are now approaching 96 hours to storm onset, the 00z model run should begin to clarify the scenario. The extreme winds of 70-80 knots in the wake of the storm today (I have decided that the ship reports earlier were probably realistic given the location and satellite imagery) may have shifted the SST anomaly pattern more towards a linkup of the central Atlantic and Faeroes cold pools leaving the Biscay warm anomaly intact. This really spells trouble for Ireland and Britain and the Monday-Tuesday event is probably the most likely to deliver as the Friday 16th energy is beginning to show a southward drift on model runs and may turn into a problem for France.

tylercollins · 09-12-2011 1:19am

If you guys had to book a day off work for this... Would you take the Monday or Tuesday?

markfla · 09-12-2011 1:55am

I'm flying to the states on Tuesday afternoon, should I be worried?

Harps · 09-12-2011 3:25am

tylercollins wrote: »

If you guys had to book a day off work for this... Would you take the Monday or Tuesday?

Judging by your previous posts I'm guessing you'd like a day of storm chasing? At the moment Tuesday looks like it'll have the stronger winds

markfla wrote: »

I'm flying to the states on Tuesday afternoon, should I be worried?

Too early to say but you definitely need to keep an eye on it, there's a chance of severe winds nationwide on Tuesday so keep a close eye on this thread and it'll give you an idea

There's no real confirmation whether the low will actually give us a direct hit yet so this could all turn out to be a bit of a non-event yet! At the moment it looks severe but it could turn out to just give a few stormy but rather typical December days

Redsunset · 09-12-2011 4:24am

Joe Bastardi

The UK will get slammed yet again in the coming days and I think the next one will be further south.
Its cause there is so much cold air aloft. Look at the next threat ( notice N atlantic water cold)

M.T. Cranium · 09-12-2011 11:29am

Surprised no new comments, 00z models were aggressive enough, but 06z GFS has 942 mb low in Donegal Bay 00-03h Tuesday and a gradient wind of about 60 knots sustained with potential for gusts to 90-100 knots, in all exposed locations. Time frame keep in mind is now 84h.

This cannot upgrade more than 10 knots so we'll be watching for signs of reliable fixed track and intensity now. It makes sense from both large-scale and research perspectives. And I rather hope it's wrong since it would do considerable if not enormous damage. Galway Bay storm surge would be one obvious risk, let's hope this solution is too extreme.

Tom Cruises Left Nut · 09-12-2011 11:31am

M.T. Cranium wrote: »

Surprised no new comments, 00z models were aggressive enough, but 06z GFS has 942 mb low in Donegal Bay 00-03h Tuesday and a gradient wind of about 60 knots sustained with potential for gusts to 90-100 knots, in all exposed locations. Time frame keep in mind is now 84h.

This cannot upgrade more than 10 knots so we'll be watching for signs of reliable fixed track and intensity now. It makes sense from both large-scale and research perspectives. And I rather hope it's wrong since it would do considerable if not enormous damage. Galway Bay storm surge would be one obvious risk, let's hope this solution is too extreme.

Everyone could be too scared to comment !! :eek:

WolfeIRE · 09-12-2011 11:36am

Lowest mean sea level pressure: 931.2hpa at Limerick on 28th November 1838.

leahyl · 09-12-2011 11:39am

This is sounding more ominous by the day:eek:

ninebeanrows · 09-12-2011 11:41am

Has the potential to be bad alright but on current charts any real extreme winds restricted to the northwest.

However if this undergoes that last phase of intensification a little later and further south then trouble is afoot.

Also there is the concern that there could be a few secondary centres which will buckle around the centre really tightening the gradient.

Definitely one to watch for any southerly movement. Although i think the areas that would be affected by the system as currently progged would be able to cope with sustained 50-60mph winds and gusts to 70-80mph as shown on the 6z. I notice that the 925hpa winds predicted for this storm are much lower than say for yesterdays storm, indicating the gust ratio will be lower but the sustained speeds will be higher.

Speak Now · 09-12-2011 11:41am

WolfeIRE · 09-12-2011 11:44am

M.T. Cranium wrote: »

Surprised no new comments

tntn is not far off the mark

This storm has been showing up for the past 4-5 days. The fact that it is continuing to hold 84 hrs out is notable. Storm surges in the shannon estuary and galway bay could cause significant flooding in the setup shown on the 00hz gefs. Another thing to note is that the rain that will fall saturday night, monday and before and after this storm will further compund flooding concerns in various parts of the country. I know here in Clare the Council has warned of high river levels and warned public that flooding could occur along the fergus and shannon if the rainfall continues at the rate we have seen in the past fornight.

M.T. Cranium · 09-12-2011 11:50am

If the storm came off exactly as depicted on these charts, I would expect maximum wind gusts near 90 knots, and close to 70 knots even as far south as Valentia. Sub-950 mb centre would be one indicator, very steep lapse rate below 925 mbs due to ocean modification would contribute also. However the bigger question for me is whether these models are even close yet to the solution. We've seen big windstorms go "pear shaped" at this time range before. Anyway, would imagine we won't have any debates about ship reports if this comes off because no ship will be anywhere near this baby.

leahyl · 09-12-2011 11:53am

M.T. Cranium wrote: »

If the storm came off exactly as depicted on these charts, I would expect maximum wind gusts near 90 knots, and close to 70 knots even as far south as Valentia. Sub-950 mb centre would be one indicator, very steep lapse rate below 925 mbs due to ocean modification would contribute also. However the bigger question for me is whether these models are even close yet to the solution. We've seen big windstorms go "pear shaped" at this time range before. Anyway, would imagine we won't have any debates about ship reports if this comes off because no ship will be anywhere near this baby.

Whats you're feeling on this so MT? Do you think this could actually happen or is the likelihood that it will not be as bad as the current models are showing?

WolfeIRE · 09-12-2011 11:54am

Met Eireann not concerned at this point. They mentioned 'storm' for Tuesday in yesterday's report but just 'windy' today

"Heavy rain will spread from the west during the second half of the day and it will be a wet and windy Monday evening. Tuesday is another cold, windy and very showery day right across the country."

ninebeanrows · 09-12-2011 11:54am

M.T. Cranium wrote: »

If the storm came off exactly as depicted on these charts, I would expect maximum wind gusts near 90 knots, and close to 70 knots even as far south as Valentia. Sub-950 mb centre would be one indicator, very steep lapse rate below 925 mbs due to ocean modification would contribute also. However the bigger question for me is whether these models are even close yet to the solution. We've seen big windstorms go "pear shaped" at this time range before. Anyway, would imagine we won't have any debates about ship reports if this comes off because no ship will be anywhere near this baby.

Do you think 850hpa winds could reach the surface?

6z showing just a small band of 80knot 925hpa wind along the north coast
Mostly below that. For most of the country just 50-60knot figures, and we had alot higher
yesterday.

I am not doubting you just wondering what sort of charts your using!

leahyl · 09-12-2011 11:56am

WolfeIRE wrote: »

Met Eireann not concerned at this point. They mentioned 'storm' for Tuesday in yesterday's report but just 'windy' today

"Heavy rain will spread from the west during the second half of the day and it will be a wet and windy Monday evening. Tuesday is another cold, windy and very showery day right across the country."

Was just gonna mention that WolfeIRE - Met Eireann don't seem to be worried at all! Just being cautious at the moment maybe. It is still 3 days away after all

ninebeanrows · 09-12-2011 12:02pm

Flicking through the 6z Ensembles and plenty of scope for this thing to move further south and bring the extreme winds further onshore.

Sponge Bob · 09-12-2011 12:15pm

I'd wait till sunday before warning. Furthermore the odds are greater that it will come in at 970 or 980 pressure and a corresponding stiff breeze than the 925 the GFS cooked up yesterday....at least in my opinion. Even the GFS has bounded itself at 950 minimum in the 06z for Mon-Wed inclusive.

Forgot to mention, the epic GFS wind event on the 18th and 19th has been replaced by a heatwave in the 06z run. Everyone else seems to have forgotten too so I thought I'd mention it.

A real snow melter from the look of it and continuing till christmas.

Spindle · 09-12-2011 12:15pm

Weathercheck wrote: »

Flicking through the 6z Ensembles and plenty of scope for this thing to move further south and bring the extreme winds further onshore.

This might be the one that does not follow the normal track over the last few years of heading north and smack us more full on. It will be interesting to see how low the pressure of this system will go.

Su Campu · 09-12-2011 12:22pm

Weathercheck wrote: »

I notice that the 925hpa winds predicted for this storm are much lower than say for yesterdays storm, indicating the gust ratio will be lower but the sustained speeds will be higher.

Just remember though that in this case, 925 hPa will be almost at ground level (around 50 metres) near the 931 hPa storm centre, whereas yesterday it was above 300 metres (near the 955 hPa centre over Scotland).

maquiladora · 09-12-2011 12:25pm

For what its worth, here are the 06Z GFS gust charts.

80-85mph gusts on the exposed west coast, 70mph gusts inland in the west.

Later, strongest winds move to the northwest, 60mph (red) gusts fairly widespread.

Ensembles for central Ireland...

Most of the ensembles with lower pressure than the op. Look at the mean and the control.
12Z could be interesting.

Hells Belle · 09-12-2011 12:46pm

Our Mariners use this website a lot, it's usually conservative, but it seems to be picking up on Tuesday's storm albeit a good bit further North. 944 centre.

http://www.xcweather.co.uk/GB/forecast

M.T. Cranium · 09-12-2011 12:57pm

Just in response to a couple of questions earlier, first of all, don't have any strong feeling that a downgrade is likely with this, some minor variations no doubt, but would say odds on for a strong windstorm event.

My numbers for wind speeds are probably based on how I think the situation really plays out rather than the operational run charts but also to some extent pattern matching with past storms that I have studied. We should however just speak in generalities at this early stage, and the bottom line is that the charts are showing potential for damaging winds.

I'm showing 100% certain potential for falling asleep very soon and as there will be no new guidance until 1500h or so, hope to return after that.

dexter647 · 09-12-2011 1:59pm

M.T. Cranium wrote: »

I'm showing 100% certain potential for falling asleep very soon and as there will be no new guidance until 1500h or so, hope to return after that.

We've just got to get that man over to Ireland:D

gothwalk · 09-12-2011 2:05pm

I haven't checked the data to back this up properly, but it seems to me that a number of the recent storms have followed a pattern - the models have them headed for Ireland, on a bearing due east from somewhere in the North Atlantic, and then they strengthen and move off further north instead. Obviously, depressions that get deeper will veer left - but I think it's three in a row now that have done that now. None of the recent ones have weakened and veered right, for instance.

Is that something consistent enough to fold back into a forecast model yet, or is it still in the realm of coincidence?

(Or is Tír na nÓg rising from beneath the Atlantic waves, causing ocean surface warming west of Ireland?!1!)

maw368 · 09-12-2011 2:20pm

I see UKMO have also updated forecasts which include the strong winds that you guys have been expecting. So is this looking more certain yet or is it still early days

This Week's Storms - FORECAST, MODEL DISCUSSION ONLY

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