St Patrick's Weekend Snow Risk - Technical Discussion Only - READ MOD NOTE POST #1

Gaoth Laidir

Snow now being reported at Manchester airport and Hawarden, Cheshire.

ninebeanrows

I am expecting the first flickers from the Irish Sea around 5/6pm, all lit up from midnight through to 9am with frequent well stacked streamers, merging into continuous snowfall at times, this snow moving inland tomorrow afternoon and clearing from the east coast.

However, increasingly likely some streamers will return to parts of east coast on Sunday night and into Monday morning.

S. Dublin, Wicklow, Wexford and parts of Kildare will be the jackpot winners this time I feel.

Calibos

Weathercheck wrote: »

I am expecting the first flickers from the Irish Sea around 5/6pm, all lit up from midnight through to 9am with frequent well stacked streamers, merging into continuous snowfall at times, this snow moving inland tomorrow afternoon and clearing from the east coast.

However, increasingly likely some streamers will return to parts of east coast on Sunday night and into Monday morning.

S. Dublin, Wicklow, Wexford and parts of Kildare will be the jackpot winners this time I feel.

Excellent. Was getting worried as MT's forecast read like he favoured Dublin North, Meath, Louth and Ulster for the heaviest falls. What are the models saying about windspeeds? Are coastal districts going to get a decent bite of each streamer cherry or will high winds take them inland too quickly before they slow down due to Orographic Braking? Also are the winds going to be high enough to lift Salty Sea Spray aloft which could dampen accumulations close to the east coast shorelines.

highdef

Calibos wrote: »

Excellent. Was getting worried as MT's forecast read like he favoured Dublin North, Meath, Louth and Ulster for the heaviest falls. What are the models saying about windspeeds? Are coastal districts going to get a decent bite of each streamer cherry or will high winds take them inland too quickly before they slow down due to Orographic Braking? Also are the winds going to be high enough to lift Salty Sea Spray aloft which could dampen accumulations close to the east coast shorelines.

Looking at the charts, I have a suspicion that two things will happen:

1. Areas very close to the coast will have very little, if any lying snow.
2. The snow showers/bands will get more inland than the charts are currently showing, with the greatest snowfalls and depths occurrings a little bit inland (say 10 - 30/40km inland), much like the recent event a few weeks ago.

cherryghost

Yes its almost identical situation now to a few weeks ago. Crazy really, we'd pray for something like this for years and it happens twice within 3 weeks of each other. Inland constant snowfest until Monday morning from tonight onwards

pad199207

cherryghost wrote: »

Yes its almost identical situation now to a few weeks ago. Crazy really, we'd pray for something like this for years and it happens twice within 3 weeks of each other. Inland constant snowfest until Monday morning from tonight onwards

Took the words right out of my mouth

ninebeanrows

Hirlam is beauty-

Wind slightly weaker this time so coastal margins may do better than last event.

pad199207

Weathercheck wrote: »

Hirlam is beauty-

Wind slightly weaker this time so coastal margins may do better than last event.

Hopefully still enough kick in it to carry them into Kildare

Gaoth Laidir

Still pretty shallow convection upstream over the North Sea. The pool of coldest uppers is currently extending west from Denmark so we should see cloudtops cooling as that moves further over the North Sea.

200motels

Weathercheck wrote: »

I am expecting the first flickers from the Irish Sea around 5/6pm, all lit up from midnight through to 9am with frequent well stacked streamers, merging into continuous snowfall at times, this snow moving inland tomorrow afternoon and clearing from the east coast.

However, increasingly likely some streamers will return to parts of east coast on Sunday night and into Monday morning.

S. Dublin, Wicklow, Wexford and parts of Kildare will be the jackpot winners this time I feel.

Don't forget Waterford.

Alun

Weathercheck wrote: »

I am expecting the first flickers from the Irish Sea around 5/6pm, ..

Up in the Wicklow Mountains 4 hours ago ...

https://www.facebook.com/groups/1893153657680055/permalink/1957300644598689/

Looks like the viewing spot up at the Wicklow Gap to me.

M.T. Cranium

The consensus of our snap forecast contest (twelve entries) was along these lines ...

Maximum snowfall 29 cm

Maximum snow at Dub A or Casement 14 cm

First report of thunder/lightning (83% predicting some) at 1824h

Max wind gust 51 knots most likely Dublin or south coast

Min overnight temp --8.3 most likely Mullingar or Ballyhaise (and while not asked for this, probably Monday or Tuesday)

My own forecasts are either similar or a bit more extreme although not much.

Would say looking at UK radar it will be game on around 1630-1700h.

M.T. Cranium

If anything the UK radar looks more active now than it did at any time during the streamer portion of the Beast 1.0 + Emma event. There are wintry showers if not outright snow covering about half the landmass of GB from north to south. This is the link I use:

http://www.weathercast.co.uk/radar/united-kingdom.html

Some 15z temps for your interest:

London (several locations) 0 to -2 in south downs

B'ham A at --0.8 C

Manchester A at --2.0 C

coldest low elevation reading I can find in UK is -3.2 C at Loftus on east coast

at higher elevations, -3 C Lake Vyrnwy Wales (360m), -5 C Glen Ogle Scotland (564m) and -8 Great Dun Fell (847m), -10 Cairngorm Scotland (1245m).

strongest gusts at low elevations 89 km/hr at Donna Nook (Lincs) and 86-87 at two other east coast locations ... remains quite gusty all across well exposed portions of Britain to near 70 km/hr on west coast. On Great Dun Fell max gusts 136 km/hr.

Gonzo

if Leinster can get streamers similar to whats over in the UK all through tonight, could be some very decent coverings by the morning. The streamers do look much more widespread and beefy compared to the Beast.

M.T. Cranium

The 12z GFS indicates widespread snow in south late tonight and Sunday morning associated with low near Brittany, probably enhanced sea effect rather than snow spreading in from that system.

Also of note, a real sting to the tail of the Thursday frontal system with gale to storm force northwest winds indicated for Friday on this run. Cold enough in the wake for wintry showers. One thing after another.

highdef

Gonzo wrote: »

if Leinster can get streamers similar to whats over in the UK all through tonight, could be some very decent coverings by the morning. The streamers do look much more widespread and beefy compared to the Beast.

Looks like snow should have begun for you, assuming you're at home.

Gonzo

highdef wrote: »

Looks like snow should have begun for you, assuming you're at home.

not at home, currently near Shannon where its dry and cool. Very unlikely to see snow in this area. I'm hoping to see some snow on the ground by the time I make it back on Monday.

teddybones

Feckin anglesea shadow scuppering us here in wicklow town again...grrrrrrr...a few miles north getting some streamer action. Someone please tell me the wind is due to change more in our favour.

M.T. Cranium

M2 buoy showing all signs of prime streamer potential now.

Temp only 2.9 C, dew point --3.7 C.

wet bulb at rough estimate is -1 C.

wind 074 deg 32 knots gusting 41 ... ideal speeds for streamer formation

sea temp n/a but around 7 or 8 C probably (M5 further south is 8 C)

expect gradual increase in streamer development now to 10 p.m. with max overnight and Sunday morning.

IOM shadow predicted to fall around Balbriggan, so heavier snow either side of the IOM-Meath/Dublin border vector.

Probably favours south Dublin inland above 100m.

I see some signs of a slight turn in wind direction later to about 060 deg, pushing heavier squalls a bit further south into north Wicklow at times. Oscillating wind directions tend to remove the shadow effects too (all in with a shout).

More clear patches than we saw in last outbreak, some lower inland temps may result.

Gaoth Laidir

1-3 cm snowfall forecast for Dublin and Casement up to midday Sunday.

EIDW AD WRNG 04 VALID 180001/181200 SNOW FBL 1 TO 3CM FCST =
EIME AD WRNG 03 VALID 180001/181200 SNOW FBL 1 TO 3CM FCST =

Gaoth Laidir

<1 cm of snow forecast at Cork (EICK) and Shannon (EINN) airports up to 7 pm and 3 pm, respectively.

EICK AD WRNG 01 VALID 180800/181900 SNOW FBL < 1CM FCST =
EINN AD WRNG 01 VALID 180700/181500 SNOW FBL < 1CM FCST =

Birdie Num Num

2010 or 1982?