Winter 20/21 - General Discussion

Nqp15hhu

munsterlegend wrote: »

That’s a dusting man! I had more than that in Cork the other morning.

Well suit yourself but don’t think you’re a snowier location than here.

Gaoth Laidir

Nqp15hhu wrote: »

Yes we did..

Ok, I thought that was somewhere else on your way to work. Your posts seemed to imply you were frustrated not to be getting some in your immediate location but if you got some, fair play.

Gaoth Laidir

Nqp15hhu wrote: »

Where did you get this? I used to be able to see it.

Met Office General Aviation subscription.

munsterlegend

Nqp15hhu wrote: »

Well suit yourself but don’t think you’re a snowier location than here.

Kind of missing the point though. You have had a northerly flow and not exactly been snowed in.

Kermit.de.frog

munsterlegend wrote: »

That’s a dusting man! I had more than that in Cork the other morning.

I had a bit more than that in north Dublin.

The concept of inland and coastal, on shore wind and off shore wind seems to be lost here somewhere...

giveitholly

Nqp15hhu wrote: »

Yes we did..

I can see the grass verges on the side of the road

pad199207

-2.8°c in Kildare now. A hard frost.

Kermit.de.frog

pad199207 wrote: »

-2.8°c in Kildare now. A hard frost.

Looking good for the freezing white gold graupel rain

Gaoth Laidir

Light rain at Malin Head. Temp/Dewp/WBT 4.6/2.9/3.8.

Moderate rain shower at Magilligan and freezing rain at Lough Fea.

Wet-bulbs well down low across most of the country, but of course because there's no precip...:rolleyes:

Rock Lesnar

-3c in Meath, beautiful night out there

pad199207

Gaoth Laidir wrote: »

Light rain at Malin Head. Temp/Dewp/WBT 4.6/2.9/3.8.

Moderate rain shower at Magilligan and freezing rain at Lough Fea.

Wet-bulbs well down low across most of the country, but of course because there's no precip...:rolleyes:

You can have one but you can’t have the other :rolleyes:

Gaoth Laidir

At 11 pm, this was the difference between the 4 stations around the Dublin/Meath area.

-2.6 Casement
-1.8 Dunsany
-1.4 Dublin Airport
-0.7 Phoenix Park

Quite a variation on a calm, clear night.

redsteveireland

Currently - 3, wonder can we beat the - 4.4? Lovely crisp frost out there.

Danno

Actually, the latest GFS has perked my interest, the 850s show a tight core of warm sector fully enveloped in a shallow low running due south through Tipperary.

The morning looks most interesting for another bout of ninja snow for much of Leinster and southern Ulster.

Nqp15hhu

Snowing on hill behind me despite 600 metre freezing level

https://trafficwatchni.com/twni/cameras/static?id=23

Gaoth Laidir

Nqp15hhu wrote: »

Snowing on hill behind me despite 600 metre freezing level

https://trafficwatchni.com/twni/cameras/static?id=23

Forget looking at just one freezing level chart on nights like this. It doesn't show the full picture. There can be two or more freezing levels, and right now it's a few tens of metres above the surface as there is a very sharp inversion above the sub-zero surface layer.

This is the ICON forecast sounding for Casement for now. It has forecast a surface temperature and dewpoint of +0.5/-0.5 C when in actual fact they're both 3 degrees colder than that right now (-3 at 1 am). So the model is not correctly getting a hold on the surface cooling taking place.

Extrapolate the surface actual temperature and dewpoint (-3/-3) onto that sounding and you'll get a different profile in the lowest 100 hPa. That means that the warm inversion is not as deep as forecast, meaning any snow falling through it could survive more easily. A typical descent rate is 1 m/s, so if the bottom say 100 metres are below zero then that's 100 seconds less it has through warmer air.

Kermit.de.frog

Aye and if it does snow, as I think it will for some of us first thing, it won't be the fine grains it will be bigger messier flakes - but as long as that fell on frozen ground it really makes no difference tbh.

For my own location I expect a mix of grauple, sleet, snow IF we actually get precipitation - we might get nothing.

And freezing rain is possible as well...

Nqp15hhu

Gaoth Laidir wrote: »

Forget looking at just one freezing level chart on nights like this. It doesn't show the full picture. There can be two or more freezing levels, and right now it's a few tens of metres above the surface as there is a very sharp inversion above the sub-zero surface layer.

This is the ICON forecast sounding for Casement for now. It has forecast a surface temperature and dewpoint of +0.5/-0.5 C when in actual fact they're both 3 degrees colder than that right now (-3 at 1 am). So the model is not correctly getting a hold on the surface cooling taking place.

Extrapolate the surface actual temperature and dewpoint (-3/-3) onto that sounding and you'll get a different profile in the lowest 100 hPa. That means that the warm inversion is not as deep as forecast, meaning any snow falling through it could survive more easily. A typical descent rate is 1 m/s, so if the bottom say 100 metres are below zero then that's 100 seconds less it has through warmer air.

I am just thinking about the top layer.. if it is at 600 metres and up to 2c below that it will turn to rain or sleet.

Gaoth Laidir

Nqp15hhu wrote: »

I am just thinking about the top layer.. if it is at 600 metres and up to 2c below that it will turn to rain or sleet.

Ok.

Gaoth Laidir

Met Éireann aviation chart for 06Z (just issued) has a very weak trough slowly moving down through north Connacht and across to the east midlands. They're giving rain and sleet showers, with snow confined to high ground.

Kermit.de.frog

The satellite imagery seems a bit out of whack with what I was expecting in terms of cloud cover, is more extensive...presumably there is little activity underneath

Snowbiee21

Kermit.de.frog wrote: »

The satellite imagery seems a bit out of whack with what I was expecting in terms of cloud cover, is more extensive...presumably there is little activity underneath

You can snooze your alarm Kermit :O

Gaoth Laidir

Kermit.de.frog wrote: »

The satellite imagery seems a bit out of whack with what I was expecting in terms of cloud cover, is more extensive...presumably there is little activity underneath

Yes, that's only jet cirrus. There's very little activity underneath it. Some light rain reported in the Hebrides but not much else. Malin Head light rain shower and overcast at 1300 ft.

Nqp15hhu

It’s been raining periodically here...

Gaoth Laidir

00Z Castor Bay sounding shows why it's raining. Although the surface is cold the warm layer extends several hundred metres. The 0.5-degree wbt snowline is at around 975 hPa (~370m).

http://www.meteociel.com/cartes_obs/sondage_display.php?id=3918&map=2&date=1609542000&map2=2

Kermit.de.frog

Right off to bed :eek:

JCX BXC

Took a while to cool down, was still 1.7°c at midnight, but it's dropped to a cool -2.2°c now.

icesnowfrost

Don’t you just hate when rain washes away lovely white frosty roads and footpaths. Although it’s already starting to refreeze, could be dangerous as a result.

Graces7

Bitterly lung-achingly, hand -numbingly cold.

pad199207

Very light flurry of flakes here now going past the garden sensor light. That will probably have to do