Atlantic Storm Watch: December 2013

M.T. Cranium

The 06z GFS looks rather close to some of the stronger 00z perturbations and would almost certainly produce 80-90 kt gusts in most exposed locations, trending to 60 knots in the southeast. But this is still only an approximation. There are some real warning signs on the maps already. The 250 mb winds over central Quebec are shown at 216 knots, a very high value. The developing low is currently a weak 1008 mb low (wave actually) just southeast of Newfoundland. Once the core of that jet arrives it can start to deepen rapidly.

Another disturbing feature is that the 498 dm height contour is progged to drop south into central Ireland by 48h as the low reaches Donegal Bay. Heights closer to the low centre will be 480 dm or so. These are truly arctic values that would imply a potential for severe cyclogenesis over 10-12 C ocean water. Except for the ocean temps, these are set-ups you might see around southeast Baffin Island which sees some very high wind gust values in deep cyclones (not quite as deep as this one).

Whatever the exact details of actual shape and gradient, there's a chilling effect to consider that this low is now progged to become within 10 mb as deep as the 1839 storm with a rather similar overall track and shape. I think that it would now take a very weak solution like a 945 mb centre and flabby gradient to prevent this from evolving into a severe windstorm at least for west coast and exposed locations elsewhere.

Then there's the second low which is going to evolve out of an already well-developed low crossing Ohio at the present time. This one has produced a lot of extreme weather in the past 24 hours such as 125 mm rainfalls in Kentucky, 5 cm ice accretion in eastern Ontario, severe storms in the eastern U.S. and the temperature contrast is extreme, warm sector has 21 C temps north to DC and 17 C in NYC, behind the storm is a surge of -15 to -25 C air. Although it is not yet deep or surrounded by strong wind fields, this will be easy to arrange once phased into the Atlantic jet.

So this second low timed for night of 26-27 Dec actually concerns me equally, many different depictions show it crossing Ireland rather than swerving north and the strongest winds would likely hit Cork and then Dublin. So even if it's not quite as strong as the first one, it has more ominous loading of severe gust potential.

Final point, agree that there is some snow potential during the colder phase of the strong winds and would stress disruption potential mainly in areas above 200m but travelers should expect to run into severe squalls of hail, sleet or snow almost anywhere on the 24th. It should be easing off considerably by Christmas morning, but the opening phases of the late 26th storm could be snow or sleet in parts of the north before milder air rushes in, then there could be severe storms with this one, so another difficult travel period around Friday morning (this could change considerably though).

maquiladora

06Z GFS has 80-90mph gusts for northwest areas Christmas Eve morning.

iwantmydinner

Apologies if this isn't the place to ask. I've followed the thread for three days but can't really follow what's being said.

I'm driving from Tralee to Galway today and driving back tomorrow, probably mid-morning or early afternoon. What can I expect to face?

I'm an experienced driver with a solid car, weather doesn't usually phase me but I'm uncharacteristically anxious about conditions today for some reason, so thanks in advance for any forecasts.

cherryghost

iwantmydinner wrote: »

Apologies if this isn't the place to ask. I've followed the thread for three days but can't really follow what's being said.

I'm driving from Tralee to Galway today and driving back tomorrow, probably mid-morning or early afternoon. What can I expect to face?

I'm an experienced driver with a solid car, weather doesn't usually phase me but I'm uncharacteristically anxious about conditions today for some reason, so thanks in advance for any forecasts.

Early afternoon should be fine. Worst is Monday night into Tuesday morning.

iwantmydinner

cherryghost wrote: »

Early afternoon should be fine. Worst is Monday night into Tuesday morning.

Great, very much appreciated!

maquiladora

iwantmydinner wrote: »

Apologies if this isn't the place to ask. I've followed the thread for three days but can't really follow what's being said.

I'm driving from Tralee to Galway today and driving back tomorrow, probably mid-morning or early afternoon. What can I expect to face?

I'm an experienced driver with a solid car, weather doesn't usually phase me but I'm uncharacteristically anxious about conditions today for some reason, so thanks in advance for any forecasts.

There will be heavy rain along with some strong gusts tomorrow morning but that should be cleared by early afternoon.

billie1b

[Deleted User] wrote: »

Netweather has severe gales for Tuesday morning.

Can I be a total noob here and apologise in advance but how do I read this?

naughto

Red is bad that's all I no

M.T. Cranium

Perturbations 2 and 20 on the GFS run create nearly unimaginable chaos with 920 mb lows for storm 2. Some other members of the ensemble are as weak as 970 mb. The range for storm 1 is narrowing a bit, I think.

Billie, you read that map by comparing the colours to the legend on the right, that gives you wind speeds in mph, and the direction can be found by following the streamlines on the map. The map is a forecast for 0900h on Tuesday 24th.

Gonzo

heavy driving snow here at the moment, wasnt expecting that, doing its best to stick after all the rain we've had.

weisses

cherryghost wrote: »

Early afternoon should be fine. Worst is Monday night into Tuesday morning.

I'm driving from Dingle to Cork Airport and back then .... leaving at 2 AM Tuesday morning... Could be in for a rough trip so

fontenoy7

Heavy hail with snow mixed in in Dublin 15...Castleknock.

maquiladora

10 January 1993. The most intense pressure ever recorded anywhere on earth outside of tropical storms & tornadoes. 916mb, estimated at 913mb :



06Z GFS at 48 hours shows this low about 10mb less intense than that historic storm, but its also much closer to Ireland/UK than the Braer storm at its peak.

bcmf

Big snow flakes mixed with rain in North County Dublin.

billie1b

M.T. Cranium wrote: »

Perturbations 2 and 20 on the GFS run create nearly unimaginable chaos with 920 mb lows for storm 2. Some other members of the ensemble are as weak as 970 mb. The range for storm 1 is narrowing a bit, I think.

Billie, you read that map by comparing the colours to the legend on the right, that gives you wind speeds in mph, and the direction can be found by following the streamlines on the map. The map is a forecast for 0900h on Tuesday 24th.

Thanks M.T appreciated

billie1b

bcmf wrote: »

Big snow flakes mixed with rain in North County Dublin.

Same here in Blanch

maquiladora

The Decemeber record for pressure recorded in Ireland is 942.8mb.

06Z GFS has the northwest coast within a couple of mb of that at 48 hours.

M.T. Cranium

When was that record set?

ninebeanrows

Now these would be interesting solutions for Friday...

These type of storms would be similar to the 'Big Wind' event.

maquiladora

M.T. Cranium wrote: »

When was that record set?

http://www.met.ie/climate-ireland/weather-extremes.asp

It doesn't say, but I'm guessing it was Malin Head, Dec 26th 1998.

Maybe someone knows?

Reckless Abandonment

http://magicseaweed.com/UK-Ireland-Surf-Chart/1/
50ft waves anyone...

maquiladora

06Z GFS is very similar to the Met Office's new 4km resolution EURO4 model at 48 hours.

GFS :



EURO4 :

howlinwolf

I know this system is still not nailed on yet in terms of location and pressure but I find met.ie forcast for tomorrow and Tuesday very strange, considering as maq has said that its very very rare to have such a very low pressure system coming close to our shores.... I can understand met playing it safe, after all if it moves further north the winds will probably be nothing exceptional, but there is no mention of this pretty historic low in there forecast .... You would think this is the type of weather they get out of bed in the morning for... At least give it a mention even if your not sure of its path ?

Harps

The storm report on the met website says that the 98 storm was below 950hPa and had the highest recorded pressure falls in 40 years (19hPa in 3 hours) but no mention of the lowest pressure on record. The storm on Dec 13th 2011 wasnt far off 945hPa if I remember it correctly..? On my phone so awkward to be checking records

maquiladora

Harps wrote: »

The storm report on the met website says that the 98 storm was below 950hPa and had the highest recorded pressure falls in 40 years (19hPa in 3 hours) but no mention of the lowest pressure on record. The storm on Dec 13th 2011 wasnt far off 945hPa if I remember it correctly..? On my phone so awkward to be checking records

Yes, would have been about 955 at Malin Head.

Edit : Just looked at the Met Eireann Dec 2011 report. Lowest pressure was 963.1 at Malin.

And on the December 1998 report it says Malin was 955.1.

So I'm not sure when the 942.8mb December record is from.

M.T. Cranium

Well I don't know what their period of record is, but suspect the pressure might have been close to 940 mb on 8 Dec 1886 when a very deep low crossed the north and was responsible for severe damage and maritime casualties on both sides of the Irish Sea (night of 8-9 Dec).

Deleted User

Deleted User wrote: »

Netweather has severe gales for Tuesday morning.

billie1b wrote: »

Can I be a total noob here and apologise in advance but how do I read this?

Put simply it shows the windspeed (colour) and direction expected at 9AM Tuesday morning. The Irish midlands can expect average winds of 24 mph and off the coast of Donegal it is expected to be over 70!

Redsunset

Reposting this from jirafa.

https://www.youtube.com/watch?v=2ICeK53znag

maquiladora

howlinwolf wrote: »

I know this system is still not nailed on yet in terms of location and pressure but I find met.ie forcast for tomorrow and Tuesday very strange, considering as maq has said that its very very rare to have such a very low pressure system coming close to our shores.... I can understand met playing it safe, after all if it moves further north the winds will probably be nothing exceptional, but there is no mention of this pretty historic low in there forecast .... You would think this is the type of weather they get out of bed in the morning for... At least give it a mention even if your not sure of its path ?

Well the 06Z HIRLAM has it as a sub-930mb low like the other models, but seems to be less intense in terms of strong wind potential over Ireland. GFS has a close to 30mb pressure gradient over Ireland, HIRLAM is closer to 20mb.

_Whimsical_

From the BBC forecast it looks like the UK are preparing for this as a big storm. Is it possible that it will affect them but not us?

Sky saying that UK rail and undergrounds will allow people travel today on tickets they have booked for trains tomorrow because of the weather warning.