Cold Spell Late Feb/ Early March Technical Discussion only MOD NOTE POST #1

cherryghost

leahyl wrote: »

According to the HIRLAM?

Yes


So basically all models say 'more cold, extended snow, less thaw'

ninebeanrows

Imagine 30-40cm in Dublin CC with easterly gales - the drifts !!

ascophyllum

With most models showing continous snowfall in Connacht tomorrow daytime its puzzling why the red alert finishes at 6am Friday, on that basis you could resume transport for work, school etc. (we won't) but it would be far more hazardous than today.

sdanseo

leahyl wrote: »

Imagine 30-40cm in Cork CC with easterly gales - the drifts!! :-P

Doesn't look like imagination will be necessary for much longer!

gozunda

leahyl wrote: »

Imagine 30-40cm in Cork CC with easterly gales - the drifts!!

As the front is coming in on a Easterly / South Easterly track I reckon that at least some areas will be shielded from the worst of the snowfall by local topography notably the mountain ranges along the South coast and their hinterland.

nacho libre

ascophyllum wrote: »

With most models showing continous snowfall in Connacht tomorrow daytime its puzzling why the red alert finishes at 6am Friday, on that basis you could resume transport for work, school etc. (we won't) but it would be far more hazardous than today.

Connacht will get little from storm Emma directly. It will be showers, but usually low pressure kills off shower activity ahead of it.
I could be wrong but a red warning for connacht seems wrong, but then they are the professionals.

Gaoth Laidir

nacho libre wrote: »

I know this will seem like a pissing contest, but what are the snow depths like now? Has anyone recorded 25cms of snow yet?

Depths up to 1 pm.

Rebelbrowser

Gaoth Laidir wrote: »

Depths up to 1 pm.

still no idea how Cork airport was steady from 3pm to midnight last night. It snowed for 90% of that time. strange

Gaoth Laidir

25 cm at Glennane (160 m) and 37 cm at Glasgow!

davidsr20

nacho libre wrote: »

Connacht will get little from storm Emma directly. It will be showers, but usually low pressure kills off shower activity ahead of it.
I could be wrong but a red warning for connacht seems wrong, but then they are the professionals.

So Galway should get away? Are they not saying a line between galway and dublin south. I’m around 17km east galway.(Craughwell)

JanuarySnowstor

Rebelbrowser wrote: »

still no idea how Cork airport was steady from 3pm to midnight last night. It snowed for 90% of that time. strange

Because it's a joke of a chart and completely inaccurate

Gaoth Laidir

JanuarySnowstor wrote: »

Because it's a joke of a chart and completely inaccurate

What's a joke of a chart? The map is made up of official depth reports. Mine is too, apart from my own measurements.

nacho libre

davidsr20 wrote: »

So Galway should get away? Are they not saying a line between galway and dublin south. I’m around 17km east galway.(Craughwell)

Yes you will be on the edge of it. I think most of Connacht will escape the best or worst of it depending on your perspective

JanuarySnowstor

Gaoth Laidir wrote: »

What's a joke of a chart? The map is made up of official depth reports. Mine is too, apart from my own measurements.

It snowed for hours in Cork last night and the airport didn't open because of it so how can it be seen as anything else?

nacho libre

JanuarySnowstor wrote: »

Because it's a joke of a chart and completely inaccurate

There is an argument that there are not enough official stations to record depths, but also a lot of people don't measure snow deposits accurately, so depths can often be inflated, particularly with drifting conditions

Donegal Storm

Snow measurements are fairly arbitrary in these conditions I'm finding, whatever about the official readings the actual depths people are seeing are highly variable depending on exposure to the wind. Some sheltered areas here have over 30cm while theres other places I can nearly see the concrete as its all blown away

Gaoth Laidir

https://twitter.com/MetEireann/status/969212575425683456

highdef

Looking at very recent radar returns and satellite imagery would suggest there may be a separate band of snow trying to develop ahead of the main system. It's currently aligned from NW Wales, across to Wicklow and then down through Carlow, Kilkenny, West Waterford and East Cork. Is this an unexpected development?

Gaoth Laidir

Snow depths are measured on an open, flat surface, away from buildings and other sources of turbulent eddies. It should not be measured in drifts, only a representative area of flat cover.

There are not enough depth reports in the Republic. Only the manned stations give reports. In the UK most of the automatic stations have ultrasonic depth-measurement instruments.

Casualsingby

Gaoth Laidir wrote: »

It's a strange one alright. 16 cm of snowfall fell midnight to 6 am at Casement with only 0.3 mm registered.

How is that possible Gaoth? That's a crazy liquid to snow rate. Maybe something to do with the drifts? I've no idea

Reckless Abandonment

Gaoth Laidir wrote: »

https://twitter.com/MetEireann/status/969212575425683456

Why dont they us that radar display on their website. looking at the amination
is so much better

Oneiric 3

Donegal Storm wrote: »

Snow measurements are fairly arbitrary in these conditions I'm finding, whatever about the official readings the actual depths people are seeing are highly variable depending on exposure to the wind. Some sheltered areas here have over 30cm while theres other places I can nearly see the concrete as its all blown away

I agree. There is 2 inches of snow lying in my front garden, which is sheltered from the NE wind, and on parked cars etc; yet out the back, which is far more exposed to the current wind direction, cover only amounts to between 1 & 5 cm, depending on where one was to measure.

garyha

Vxlks wrote: »

Judging from any updated charts now, how is dublin looking?

Much the same, expect the frontal/heavy snow to hit Dublin around 9pm with a chance of some heavier convective showers in advance.

garyha

stephenjmcd wrote: »

Over on the event thread a few minutes ago 1 person said it wont snow in greystones and another said a weather app showing rain for wicklow, no charts to back this up.

I find it quite annoying given met are saying this is coming. sorry, rant over.

However is there any alliance between the charts as to how far north the snowline will be ?

Agreed, don't know where people are getting this info from. Nothing has changed on the latest guidance in fact if the latest HIRLAM was to verify it's an upgrade. Below is the anticipated snow accumulation by Saturday from all of this.



I believe the snow line is currently a line between Galway and Louth.

Donegal Storm

28cm in the field behind the house here, thats the most accurate representation I can find where there's fairly uniform cover. A lot deeper in some places and a lot shallower on concrete exposed to the wind

lawred2

garyha wrote: »

Much the same, expect the frontal/heavy snow to hit Dublin around 9pm with a chance of some heavier convective showers in advance.

snowing for the last three hours in Portmarnock so to say that the heavy snow hasn't hit yet is rather scary/exciting

tbayers

Gaoth Laidir wrote: »

https://twitter.com/MetEireann/status/969212575425683456

It's been hammering down in Tramore all day not one second of a let up. Going from that chart nothing hit at all. Hence my question earlier , but that was answered. Never seen anything like and it's picked up a notch now

mirrorwall14

garyha wrote: »

Agreed, don't know where people are getting this info from. Nothing has changed on the latest guidance in fact if the latest HIRLAM was to verify it's an upgrade. Below is the anticipated snow accumulation by Saturday from all of this.

(Image removed from quote)

I believe the snow line is currently a line between Galway and Louth.

Is that straight up cm of snow or is it measuring precipitation where you are supposed to use a multiplier?

cian1500ww

Outer bands of Emma are approaching the South East now, a while away from the heavier snow bands yet though

lucernarian

tbayers wrote: »

It's been hammering down in Tramore all day not one second of a let up. Going from that chart nothing hit at all. Hence my question earlier , but that was answered. Never seen anything like and it's picked up a notch now

Did you post any images in the main chat thread out of interest? Yeah the wind direction would suit many parts of Waterford to get very significant amounts of snow, and that's before Emma hits.

Good old HIRLAM is offering snowfall potential >20 cm for tonight/tomorrow in most parts of Leinster and Munster, with some locations flirting with 50cm :eek: