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

Mickeroo

Reckless Abandonment wrote: »

One or the other of them might be a typo .

They would surely have left it as a country wide red rather than splitting it into two warnings that both finish at 18:00 surely? There doesn't seem to be much snow expected in that part of the country from what I've seen so maybe they're leaving red as a precaution rather than outright downgrading and having to upgrade again if the outlook changes?

Gonzo

went outside again and I can only describe what is like an 'ice' storm outside. It's not snow, its not rain, it's not hail, it ain't graupel either. Sheets of fine ice that shines in the light. Windows at the back of the house are all caked in ice particles and snow dust.

DOCARCH

Horrendous now in Dublin 16 (...by that I mean ...). Strong winds and a fog of that fine snow, with the fog being added to with snow being blown off roofs! -1.1c.

I was skeptical...but I think this may be the real deal!!!

RuthieRose

sean555 wrote: »

I can see why they might for the Northwest [did that part of the country ever warrant a red?] but most of the models give Galway lots of snow tonight.

I would in my humble opinion beg to differ. I’m very near Cavan Town. We have a massive amount of snow on the ground. We have more to come. The terrain here is very hilly. We can only access the top of our estate with a 4x4 just about. I know I’m not a weather forecaster but with compacted snow and freezing temperatures I think the red should have stayed in place till at least sunrise. If only to keep people at home and safe. The initial orange warning on Wednesday was ignored by most schools and businesses and they closed early as if it was red. We are used to snow here but this I haven't seen before. Just my opinion.

Meteorite58

Some model predictions, Some huge amounts to fall up along the SE and E

Zoney

Amazing how most of the models leave a "hole" right over Limerick in the heavy accumulations. Is it just the topology (river basin, galtees, silvermines) combined with front direction? As such is it likely to be a valid prediction of way less snow than just a few miles any direction outside Limerick city?

Edit: right now there's super fine snow falling, leaving a fine sparkling dust over the dry car roof and driveway.

BLIZZARD7

DOCARCH wrote: »

Horrendous now in Dublin 16 (...by that I mean ...). Strong winds and a fog of that fine snow, with the fog being added to with snow being blown off roofs! -1.1c.

I was skeptical...but I think this may be the real deal!!!

Same here DOC, this is the BIG SNOW for this generation. Already pretty horrendous conditions out, is there much word from SW of England yet?

Charts showing insane amounts of snow for the east and south now.

DOCARCH

BLIZZARD7 wrote: »

Same here DOC, this is the BIG SNOW for this generation. Already pretty horrendous conditions out, is there much word from SW of England yet?

Charts showing insane amounts of snow for the east and south now.

Bear in mind I was around for 1982! I will let you know tomorrow morning if this is the 'big snow'!

ninebeanrows

Latest 18z Harmonie liquid totals by 6pm Friday

Swords 38mm

Howth 57mm

Dundrum 109mm

Foothills 132mm

Arklow 60mm


I'll now and go and get a large whiskey.

kittyn

Weathercheck wrote: »

Latest 18z Harmonie liquid totals by 6pm Friday

Swords 38mm

Howth 57mm

Dundrum 109mm

Foothills 132mm

Arklow 60mm


I'll now and go and get a large whiskey.

So what does that translate to in terms of feet WC??

teddybones

kittyn wrote: »

So what does that translate to in terms of feet WC??

Roughy 30cm = 1ft

ninebeanrows

kittyn wrote: »

So what does that translate to in terms of feet WC??

1 foot, 2 foot, 3 foot...4

jay28

Weathercheck wrote: »

Latest 18z Harmonie liquid totals by 6pm Friday

Swords 38mm

Howth 57mm

Dundrum 109mm

Foothills 132mm

Arklow 60mm


I'll now and go and get a large whiskey.

Sorry if this a dumb question but what's the mm liquid to cm of snow ratio?

BLIZZARD7

kittyn wrote: »

So what does that translate to in terms of feet WC??

For Dundrum if we assume a x10 ratio (it could be more than this) that's 110cm or 3.3 feet. :eek:

If you're in the foothills, that's more like 4 foot +...

Elmer Blooker

Shouldn't we be getting worried by dew point temps?
+1.2 at buoy M2 east of Howth.

nacho libre

BLIZZARD7 wrote: »

Same here DOC, this is the BIG SNOW for this generation. Already pretty horrendous conditions out, is there much word from SW of England yet?

Charts showing insane amounts of snow for the east and south now.

http://www.camsecure.co.uk/combe_martin_webcam.html

Devon is suppose to be getting buried in it. Although it does not look too severe on the above cam?
Anyway good luck to you. Your patience has been rewarded. Those long nights of fretting over models runs are over! Enjoy!

sdanseo

NW Radar is starting to show the first wave (or is it the second wave) generating huge precip of the Irish Sea heading straight for us. They seem to be convected because they're appearing over the sea and not moving north from beyond the UK coast.

sdanseo

Weathercheck wrote: »

Latest 18z Harmonie liquid totals by 6pm Friday

Swords 38mm

Howth 57mm

Dundrum 109mm

Foothills 132mm

Arklow 60mm


I'll now and go and get a large whiskey.

kittyn wrote: »

So what does that translate to in terms of feet WC??

Assuming wet snow, roughly x10 at minimum, so basically those figures but in cm. Possibly up to double that if it was drier snow but that's unlikely.

Then allow for drifts, there are going to be entire towns cut off in the mountains.

Give me some of that Whiskey!

Elmer Blooker wrote: »

Shouldn't we be getting worried by dew point temps?
+1.2 at buoy M2 east of Howth.

M2 is at 5.5W, 30km out to sea. We'll be fine.

Gaoth Laidir

UKMO 18Z analysis. It's very different to the 24-hr forecast from yesterday. The upper warm front has not materialised, and that may have been the source of the thunderstorms that Met Éireann mentioned. Pressure is 4 hPa higher. In reality things are a bit behind the schedule of the forecast, with the warm front still only in the Channel. It's a big difference for only 24 hours and a sign of how complex Emma is.

Analysis


Forecast

Meteorite58

Very slow moving and a long way off yet.







Latest ICON 18z

pistolpetes11

THIS IS THE MODEL TECHNICAL DISCUSSION THREAD CAN WE PLEASE KEEP IT TO THAT , IM FED UP REMOVING POSTS

Oneiric 3

Gaoth Laidir wrote: »

UKMO 18Z analysis. It's very different to the 24-hr forecast from yesterday. The upper warm front has not materialised.

Odd, considering that the 12z had a very marked upper warm front on the 12z:



Given how we are seeing the prep becoming more widespread over the east and south at the mo, there would be evidence that while it may well have weakened a good deal in the 6hrs up to 18z, that it is still, in some form, active.

Another curious one is that the DWD 18z analysis has the main warm front centred over central/north France, and not the Channel.



And to further complicate things, the KNMI 18z analysis has the warm front further south still, while showing an upper over the Channel:



As you suggest, it's complicated...

sdanseo

sdanseo wrote: »

M2 is at 5.5W, 30km out to sea. We'll be fine.

Risen again at 2100. Temp is +3.7 C. DP is +2.5 C. Is there a warm sector out there that wants to cause trouble?

teddybones

Oneiric 3 wrote: »

Odd, considering that the 12z had a very marked upper warm front on the 12z:

Yes but i am wondering what does that mean...upgrade downgrade, is it stalling, slowing, warming

Oneiric 3

teddybones wrote: »

Yes but i am wondering what does that mean...upgrade downgrade, is it stalling, slowing, warming

https://www.youtube.com/watch?v=TiE14GQJzVg

wakka12

So is there actually still valid concerns that this may turn out to be rain?

ninebeanrows

wakka12 wrote: »

So is there actually still valid concerns that this may turn out to be rain?

There is a risk right on the coast but maybe 20% but just a mile inland and full snow

Daniel2590

wakka12 wrote: »

So is there actually still valid concerns that this may turn out to be rain?

Not overnight

Edit: sorry I'm slightly misinformed!

gozunda

The weather Forecaster on the RTE six News said we were in for "

Record breaking snow especially for Southern and Eastern Coastal counties and especially on on the Lee side of mountains stretching from Louth all the way down to Wexford

Now correct me if I'm wrong on my technical understanding of the Lee or Leeward side of mountains - which as far as I remember is the sheltered side away from the prevailing wind. It is the opposite Windward side which would normally get deposits of precipitation as the wind meets the elevated mountain topography.

So how is it that the Forecaster is suggesting that it is the other - Leeward side which will be getting the record breaking snow - when it is the windward side of those mountains which will be meeting the winds from an East and South Eastern direction?



Anyone else spot this tonight?

Elmer Blooker

Deleted User wrote: »

Risen again at 2100. Temp is +3.7 C. DP is +2.5 C. Is there a warm sector out there that wants to cause trouble?

There must be. I posted a chart earlier inquiring why the far southwest of England was much colder than northern England. My opinion was that it was a warm sector. I thought someone more knowledgable than me might have had an answer but no one answered my post.
I just pointed out a few mins ago that Valentia and Sherkin are colder than the Phoenix Park.