Storm Ciara - Strong Winds & Potential Snow **TECHNICAL DISCUSSION**

Meteorite58

The advancing cold air mass.

Showers turning increasingly wintry Late Sunday early Monday morning, turning more to snow showers during Monday and more so again during Tuesday.







Fairly crude basic maps but ECM did very well predicting the last bit of snow we had. Only a rough guide to where might get some accumulations I reckon.

Monkeynut

Meteorite58 wrote: »

The advancing cold air mass.

Showers turning increasingly wintry Late Sunday early Monday morning, turning more to snow showers during Monday and more so again during Tuesday.

I'll take 0.1cm

Meteorite58

auspicious wrote: »

Should this be a concern?
Roughly where will the 'eye' track overland? How big is it?

That chart is for wind sheer high up, it is one of the parameters when looking for convection and thunderstorms.

From Meteologix ' This map displays the forecast deep layer wind shear in the 0-4 mile (above ground) layer. This is calculated by taking the wind vector at the surface and subtracting it from the wind vector 4 miles above the surface. The more the wind strengthens with height, the higher the wind shear will be, and the more favorable the environment will be for severe thunderstorms. Note that other ingredients are equally important for severe weather, and high shear values do not guarantee severe storm development.'


You can see the the upper winds are moving at a slightly different direction , this aids shear. The center of the system is actually moving up near N of Scotland, see previous charts.

Just a glimpse of thunderstorm possibility, will know a bit more tomorrow evening , hard to predict how much or where but will have some idea of general probability.

Meteorite58

The 528 dam line moving well S of Ireland by Tuesday.

snowgal

Meteorite58 wrote: »

The 528 dam line moving well S of Ireland by Tuesday.

Rougies

snowgal wrote: »

It's a good thing if you like snow :pac:

leahyl

What does that mean exactly?

squarecircles

leahyl wrote: »

What does that mean exactly?

The thickness of the air high up in the atmosphere, 528 usually indicates polar air

leahyl

squarecircles wrote: »

The thickness of the air high up in the atmosphere, 528 usually indicates polar air

Meaning that we would be enveloped by polar air?

snowgal

Rougies wrote: »

It's a good thing if you like snow :pac:

:eek: I can’t read charts for crap so!!!! Thought I was getting a good handle on them... looks too far south for us in that chart??

squarecircles

snowgal wrote: »

:eek: I can’t read charts for crap so!!!! Thought I was getting a good handle on them... looks too far south for us in that chart??

The 528 dam line has cleared Ireland, once we're above
that line we're in an air mass conducive to snowfall

Usually its well to our north

Rougies

leahyl wrote: »

What does that mean exactly?

528 dam (decametres, 5280 metres) between 1000 hPa and 500 hPa atmospheric pressure. Cold air is more dense so there is less distance (thickness) between those two atmospheric pressures as the air in between gets colder. It's a good indicator of snow potential but not a guarantee by any means.

Gaoth Laidir

In a showery setup a thickness of 516 dam guarantees snow at all levels. We'll be in about 520 dam, but more useful thicknesses are the 700-1000 and 850-1000 thicknesses. These are looking closer to the required 282 and 129 dam, respectively later Monday and Tuesday.

kittyn

Hhhmmm GL sounds positive .....

pauldry

There could be thick wet drifts of snow by Tuesday in places and not just hills. Two snowy Tuesdays in one Winter? It couldn't could it.

Meanwhile my rain has stalled at 8mm since the start of the non dry.

nthclare

Lots of Graupel in North Clare this evening in the commons in the Burren

Meteorite58

Nice Sat Pic of the 930 hPa Storm off Greenland and tomorrows weather approaching from the SW








A follow through of the charts up to Sun noon

steirishrover

Have a flight to London at 8.20 in the morning and coming home on flight at 10pm tomorrow night due in around 11pm.

I'm panicking a bit for the flight home after just been looking at the forecast.. not the greatest of fliers.

Anyone shed any hope for me at that time how the storm could be lol..

Deagol

In fairness, the lad who got the yellow card had it absolutely right.

Regular normal bad couple of wintery days in Ireland. A bit windy, a bit wet and a few wintry showers.

I have no idea why this forum seems to be full of people wishing for natural disasters that will cause misery for 'other' people rather than thanking whatever deity you chose for a quiet life.

I ,for one, am glad that as in 80% of the time your doom and gloom predictions of 180km/h gusts and 10cm+ of snow is comprehensively being shown to be complete and utter tosh based on GFS model nonsense. Why anyone who knows anything about weather even looks at the GFS I have no idea as it is 100% time wrong on anything over 24 hours.

nthclare

Deagol wrote: »

In fairness, the lad who got the yellow card had it absolutely right.

Regular normal bad couple of wintery days in Ireland. A bit windy, a bit wet and a few wintry showers.

I have no idea why this forum seems to be full of people wishing for natural disasters that will cause misery for 'other' people rather than thanking whatever deity you chose for a quiet life.

I ,for one, am glad that as in 80% of the time your doom and gloom predictions of 180km/h gusts and 10cm+ of snow is comprehensively being shown to be complete and utter tosh based on GFS model nonsense. Why anyone who knows anything about weather even looks at the GFS I have no idea as it is 100% time wrong on anything over 24 hours.

Lol I get snow days in work so I am in no danger.
Some of us love extreme weather.
And we're prepared for the onslaught.

I am anyhow

pistolpetes11

Deagol wrote: »

In fairness, the lad who got the yellow card had it absolutely right.

Regular normal bad couple of wintery days in Ireland. A bit windy, a bit wet and a few wintry showers.

I have no idea why this forum seems to be full of people wishing for natural disasters that will cause misery for 'other' people rather than thanking whatever deity you chose for a quiet life.

I ,for one, am glad that as in 80% of the time your doom and gloom predictions of 180km/h gusts and 10cm+ of snow is comprehensively being shown to be complete and utter tosh based on GFS model nonsense. Why anyone who knows anything about weather even looks at the GFS I have no idea as it is 100% time wrong on anything over 24 hours.

Please don’t post in this thread again , you’re just looking for a reaction that you’re not going to get

Can we possibly have a separate thread for the 'WHOITE GOOLLLLD' folk?

Three days of sustained wind and rain is a weather event worthy of itself.

Larbre34

steirishrover wrote: »

Anyone shed any hope for me at that time how the storm could be lol..

Not really, the storm will be at something of a peak around then.

I wouldn't be too concerned, the storm is to be so widespread across Ireland and UK alike that if your home airport here is restricted due to the weather, the flight simply will not leave London as there will be nowhere to safely divert to.

Kermit.de.frog

Deleted User wrote: »

Can we possibly have a separate thread for the 'WHOITE GOOLLLLD' folk?

Three days of sustained wind and rain is a weather event worthy of itself.

I have it ready earlier just in case anyone wants a separate thread for the wind and the snow :pac:

MT's thread on Storm Ciara is here

https://www.boards.ie/vbulletin/showthread.php?t=2058051890&page=18

It is due to affect the country for a number of days. There are two very distinct and parallel affects - one is wind which is a big issue, the other is snow particularly in the west.

This thread is for the latter. If you are more interested in the wind or potential flooding please consult MTs official storm thread.

We have had a fairly mild winter so far but early next week the cold embrace of the Arctic will be pointing this way like a big vindictive finger and it's packing high cloud tops and snow showers in abundance.






Sunday night

On Sunday night much colder air will be moving in across the country from the northwest being driven through on very strong northwest winds.

Increasingly heavy showers in Connaught and Ulster quickly turning to sleet and then to snow overnight with accumulations here by Monday morning. Perhaps 2 - 5 cm should be anticipated by morning in many locations here.

Less and much lighter showers further east.

Over Munster and south Leinster showers will probably be more sleety rather than snow overnight.

Monday from sunrise

Early Monday sunrise more significant pulses of rain will move in to the southwest. As this advances through Munster and Leinster it should pretty much immediately turn to snow as it engages the colder air with between 2 and 8 cms likely in many areas across Munster and Leinster. This is potentially disruptive in some places.

After this clears later Monday evening snow showers will continue packing in to the west and north giving appreciable totals which could be in excess of 8 - 10 cms in some place overnight Monday.

Showers lighter and more scattered further east but could contribute more to snow already lying here.

Widespread snow showers through Tuesday. The snow showers die back to western coastal counties on Tuesday night.

To recap Sunday night to Wednesday morning:

Main risk of disruption: Snow showers (longer period of snow through Munster/Leinster on Monday)
Areas most at risk in order: Connaught/Ulster, South Leinster, Munster
Low Temperature: Temperatures will be near or just below freezing during snowfall and over snow cover particularly in the northwest

Some disruption is possible anywhere really.

M.T. Cranium

The 00z models out so far have little new insight, waiting to see the ECM.

What intrigues me is that a very unusual 175 kt reading at 500 mb (90 kt at same location 700 mb) is indicated from Yarmouth NS at 00z. Winds have increased over NS to 80-120 km/hr in the past two hours. The centre of the low (already about 967 mbs) was near western Newfoundland at 04z.

Then bear in mind this quite strong cyclone is being swung around an even deeper 932 mb low west of Iceland. Given those upper level wind anomalies, I think we should be ready to process intensification signals in future model runs, perhaps the ECM will pick up on this potential with the 00z run due out in an hour or so.

The 175 kt reading was not flagged as suspect on the chart. To give some context, readings above 120 knots are unusual (at 500 mb). Also 90 kts at 700 mb is close to an extreme. So there is definitely a low level jet forming as the low about to become storm "Ciara" enters the western Atlantic.

Will be keeping a very close watch on developments as my intuition says this one could over-perform (there is also a massive energy peak on Feb 9th to phase with the storm approaching the Rockall marine zone).

It may well stay within the limits we have been discussing but be prepared for some chance of a red alert being required on this occasion. Would think the 12z model run will pick up any strong potential for upgrades.

Graces7

Good morning; busy night on here..

Just in from the wild outdoors before a loud deluge hit. Round the corner to the sheltered north, torn between the utter silver beauty of the moon, clothed in puffy clouds, and the brutal bitter cold of the wind at my back. Wheezy weather!

Dramatic days ahead.

Foggy Jew

Graces7 wrote: »

Good morning; busy night on here..

Just in from the wild outdoors before a loud deluge hit. Round the corner to the sheltered north, torn between the utter silver beauty of the moon, clothed in puffy clouds, and the brutal bitter cold of the wind at my back. Wheezy weather!

Dramatic days ahead.

Stay safe Grace

JanuarySnowstor

Monday is starting to look quite disruptive from snow. It really has upgraded over the last 24 hours particularly for the Southern half of the country. I see no reason why that front can't quickly turn to snow. The parameters for snow are just about ticked but then the heavy ppn should sway the matter. Amazing stuff really in its own right.....it's not every day we get snow from the southwest.....IF indeed it does happen. An orange warning for snow is not impossible and for once it's bypassing the media with the election and stuff going on!

Graces7

Foggy Jew wrote: »

Stay safe Grace

Thanks and I am! Ten years on a North Sea island where there were similar three day events and a few years out here..Veteran…. Safer here where there are no trees... Will be happy when all my cats are safe inside; they are acting up, a sure sign of disturbance in the weather.

Has eased a little. Emptied the cat litter tray and did not end up wearing it

Graces7

JanuarySnowstor wrote: »

Monday is starting to look quite disruptive from snow. It really has upgraded over the last 24 hours particularly for the Southern half of the country. I see no reason why that front can't quickly turn to snow. The parameters for snow are just about ticked but then the heavy ppn should sway the matter. Amazing stuff really in its own right.....it's not every day we get snow from the southwest.....IF indeed it does happen. An orange warning for snow is not impossible and for once it's bypassing the media with the election and stuff going on!

If this is the same system as is hitting Newfoundland? My family report they are being obliterated and severe cold with it. Get ready, folks!