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

tbayers

lucernarian wrote: »

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:

Yup, just posted. On mobile so can't see numbered post but it was posted at 15:08. Don't know how to copy posts either.

Cantona's Collars

highdef wrote: »

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?

That band seems to be just arriving in Wexford now.

revelman

Donegal Storm wrote: »

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

Snow measurements should not be taken on grass given that air space will overstate the measurement. It should be taken on a flat concrete surface where possible. I've taken measurements in 'flat looking' parts of a field here near Kinsale and have also got 30cm. The driveway outside my house is currently giving me 18cm while the top of the car is giving me 16cm though more seems to be blowing off this. Btw, Cork airport is only 20 minutes north of here and am amazed that they had only 5cm.

Interesting guidance on snow measurements can be found here: http://www.nws.noaa.gov/os/coop/reference/Snow_Measurement_Guidelines.pdf

Oneiric 3

Here is where the Met Éireann model has the snow by 10pm this evening:




And mean windspeed forecast for the same time:

Gaoth Laidir

3 pm snow depths, in general on the decline but most likely due to blowing snow. Still, the Casement and Dublin airport are not reporting drifting in the description, just "even covering of dry snow covering all of the ground".



Same picture in the UK. 3 cm reported in Guernsey, and snow is falling also in far northwest Brittany.

ThaitaniumM

I noticed something in nearly every model recently it seems to me that there's a circular area around the Shannon that's biased towards significantly less precipitation. Is this an anomaly or a glitch?

12Z GFS.



Seems better than its 6Z equivalent for the same time.

George Sunsnow

Weathercheck wrote: »

You're in for some night

Am I too ?

ninebeanrows

George Sunsnow wrote: »

Am I too ?

Harmonie surely overdoing it - giving you 60mm of liquid by 5pm

Comhrá

Latest ME radar shows a lot of precip showing up now in a large swathe from Cork to Tipperary. Looking like a sort of pre-frontal area of snow?

demakinz

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.



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

Is this snow accumulated from just Emma or does that include the snow dumped by the streamers also?

George Sunsnow

Comhra wrote: »

Latest ME radar shows a lot of precip showing up now in a large swathe from Cork to Tipperary. Looking like a sort of pre-frontal area of snow?

Yes and thats not even the front!

Casualsingby

Big upgrade for munster on latest GFS. It has the highest widespread depths.

06z and 12z for comparison

kod87

Casualsingby wrote: »

Big upgrade for munster on latest GFS. It has the highest widespread depths.

06z and 12z for comparison

There is already more snow than that indicates in several places. Is that just hourly falls?

wakka12

Pentecost wrote: »

Any danger of parts of Dublin city missing out at this point (or more specifically the south side!)? Doesn't look like it from the radar forecasts but I am far from knowledgeable on these things.

It looks as though the entire county dublin will experience heavy snow

I know how you feel though its nearly hard to believe this snow is coming for us as practically every streamer is hitting north dublin and missing most of the south city

munsterlegend

Casualsingby wrote: »

Big upgrade for munster on latest GFS. It has the highest widespread depths.

06z and 12z for comparison

Those GFS figures tie in with Hirlam for Munster anyway.

Slydice

The rainfall radar linked in the other thread url]http://www.meteoradar.co.uk/realtime-rainradar[/url
has me thinking we haven't seen the start of Emma yet. Is that it down in Cornwall right now?

12Z Hirlam.



6Z equivalent. 12Z pushes precipitation up a bit more along the east coast. But not much of a change further west it seems. Little bit more intensity north of Dublin into Meath.

George Sunsnow

Weathercheck wrote: »

Harmonie surely overdoing it - giving you 60mm of liquid by 5pm

Wow
By 5pm tomorrow in Arklow :eek:
it’ll be making up for lost time by the artic load literally,no pun intended
What’s that in cm’s :eek:
(Pelting it down here off the Irish Sea in the last hour)

cherryghost

HIRLAM follows other models, slightly further east. Now going over 40cm in Wexford, Wicklow (over 2ft on mountains), Dublin. 20-30 in Munster and 10-20 elsewhere. Tomorrow night Munster has a 2nd blast of heavy snow, heavy snow showers elsewhere.

Drifting will be immense later.

Full picture now. Waterford and cork may see over 1ft by Saturday morning. More or less upgrade across the board.

munsterlegend

cherryghost wrote: »

HIRLAM follows other models, slightly further east. Now going over 40cm in Wexford, Wicklow (over 2ft on mountains), Dublin. 20-30 in Munster and 10-20 elsewhere. Tomorrow night Munster has a 2nd blast of heavy snow, heavy showers elsewhere.

Drifting will be immense later.

How often is Hirlam updated?

MJohnston

Does anyone (Meteorite maybe?) know when we might see some high resolution satellite imagery of the snow conditions around the country?

cherryghost

lawred2 wrote: »

showers of rain?

Edited. No sign of the cold mass and dew point going anywhere til at least Sunday

MJohnston

munsterlegend wrote: »

How often is Hirlam updated?

https://imgur.com/a/WCiKM

revelman

cherryghost wrote: »

Edited. No sign of the cold mass and dew point going anywhere til at least Sunday

Evelyn seems to think that this will be falling as rain in Munster tomorrow night.

4068ac1elhodqr

Only a slightly technical image, but is S/W'England about to get battered also, and have a M.Fish moment?

cherryghost

revelman wrote: »

Evelyn seems to think that this will be falling as rain in Munster tomorrow night.

Looks very borderline but latest forecast has cold air mass further south. I'd be reasonably confident saying sleet/rain breakdown on south until Saturday morning/afternoon.

JanuarySnowstor

cherryghost wrote: »

Edited. No sign of the cold mass and dew point going anywhere til at least Sunday

What are dew points tomorrow morning??

JanuarySnowstor

We're moving from -15 uppers to -4.
Don't expect snow on the south coast tomorrow morning with an onshore wind

ninebeanrows

Disappointing that the models havent went inline with last nights EC, looks like it will now turn milder from Monday.