Cold Spell - Feb 7th to 13th 2021 - Technical Discussion

Meteorite58

EURO 4 can overdo it a bit but has upgraded from earlier runs, bringing the snow more into the W , NW, midlands and a good shot of it along the S and SE in away from the coasts on hillier terrain.

Time will tell....

Oneiric 3

Aunty Snow's readings sort of highlights a phenomena I have noted for a good while and that is that humidity readings in general a good amount of time tend read lower at coastal locations that they do inland, both in summer and winter. You would think that the opposite would be true, given that they are closer to huge bodies of water.

Snowbie

mickger844posts wrote: »

Models at this range are only a guide. Its a nowcast for sure. First port of call for me when i wake up tomorrow is check the radar. Best of luck to everyone

Yup I agree, nowcast for sure but time for it all go belly up for east tomorrow evening and north midlands. My money still on south midlands to do well, also lots of orographic lift on the Sth Wicklow Mtns, Blackstairs, Comeraghs possibly Castlecomer too.

Anywhere just to the lee of these hills (NW side) may be in a shadow and little or less precipitation falls, this is always stretched out if the predominant wind direction is strong which its forecast to be.

Due to the slow progress of the front moving up across the island, there is very little veering of the wind at the passage of the front and it is very possible that places in the high risk zone are in the shadow of the hills/Mtns gets very little precip, very possible.

M.T. Cranium

I was aware of Aunty Snow's location, just thought there might be more than one person posting here from east slope locations, so how high above sea level are you there AS?

My hunch is that this overperforms, especially with the little twist in the thermal structure indicated on 18z GFS, that will tend to keep the cold surface layers in place a bit longer.

Snowbie

JanuarySnowstor wrote: »

I don't think there is any chance of freezing rain MT.

I see Met Eireann have kept the warnings at yellow!!
Will it prove to be case

They wont issue an orange warning unless a wider area has 5cm to 10cm likely. The precip is not all that heavy, its just persistent. It will thaw from the south in Munster as the Atlantic air moves in.

Snowbie

Snowbie wrote: »

You always did get very low Dp there, impressive.

Is Croghan close to you? Are you on the downslope or close by etc

Croghan us about 5kms west
Usually low dp's if the wind is west or NW or north off the mtns
My dp and humidity today is mirroring the met wow station at the Dublin end of the Arklow bypass which overlooks the sea
It has to be the fast travelling surface feed from wales and the low 850 temp combining for this as its very unusual
I said on this thread yesterday or the day before that this weather reminded me of the day before the start of the jan 82 snowstorm
Obviously not a hope of a millionth of that snow going to come but feels exactly similar, I remember it like it was yesterday and can remember exactly what I was doing the day before it started complete with the conversation with my grandfather
He was 95 in Jan 82,he'd seen a lot and I remember him saying many times as he wandered round the yard(at that age in a blizzard doing jobs!) In his Diocese of Kerry accent 'Is it ever going to stop
That was the first time I experienced thundersnow

RobertKK

https://twitter.com/MetEireann/status/1359654046001414144?s=20

Snowbie

AuntySnow wrote: »

Croghan us about 5kms west
Usually low dp's if the wind is west or NW or north off the mtns
My dp and humidity today is mirroring the met wow station at the Dublin end of the Arklow bypass which overlooks the sea
It has to be the fast travelling surface feed from wales and the low 850 temp combining for this as its very unusual
I said on this thread yesterday or the day before that this weather reminded me of the day before the start of the jan 82 snowstorm
Obviously not a hope of a millionth of that snow going to come but feels exactly similar, I remember it like it was yesterday and can remember exactly what I was doing the day before it started complete with the conversation with my grandfather
He was 95 in Jan 82,he'd seen a lot and I remember him saying many times as he wandered round the yard(at that age in a blizzard doing jobs!) In his Diocese of Kerry accent 'Is it ever going to stop
That was the first time I experienced thundersnow

Brilliant memory to have and of an epic event also. Thundersnow too, you got spoilt

M.T. Cranium

M.T. Cranium wrote: »

I was aware of Aunty Snow's location, just thought there might be more than one person posting here from east slope locations, so how high above sea level are you there AS?

My hunch is that this overperforms, especially with the little twist in the thermal structure indicated on 18z GFS, that will tend to keep the cold surface layers in place a bit longer.

Just 62 metres and 2kms inland
However I have a reporter located 6kms west behind croghan mtn in a raised valley at 170 metres Asl
Will be sharing reports and video from there too
They're roughly 8kms inland

MJohnston

ECM 18z (later frames haven't shown up yet):

MJohnston

Later frames here (seems to me like the mild is winning out a bit earlier on this run, snow depths less generous):

Rougies

M.T. Cranium wrote: »

I was aware of Aunty Snow's location, just thought there might be more than one person posting here from east slope locations, so how high above sea level are you there AS?

My hunch is that this overperforms, especially with the little twist in the thermal structure indicated on 18z GFS, that will tend to keep the cold surface layers in place a bit longer.

Most east Wicklow towns are coastal or fairly low lying < 150m. A couple of places that I would regard as higher "eastern slope" towns would be Roundwood (238m) and Glencullen (276m) and will probably get high snowfall totals over the next few days.


Here's a good map of the area with contour lines (if you zoom in close you can see the contour altitude values)


https://www.openstreetmap.org/#map=10/53.0676/-6.3810&layers=C


Roundwood:


https://www.openstreetmap.org/search?query=roundwood#map=12/53.0656/-6.2298&layers=C


Glencullen:


https://www.openstreetmap.org/search?query=glencullen#map=14/53.2211/-6.2181&layers=C

lucernarian

Meteorite58 wrote: »

EURO 4 can overdo it a bit but has upgraded from earlier runs, bringing the snow more into the W , NW, midlands and a good shot of it along the S and SE in away from the coasts on hillier terrain.

Time will tell....

Euro4 is a pretty good model for these scenarios tbh.

JCX BXC

Worth noting the TAF's for tomorrow.

EINN 102300Z 1100/1124 10015KT 9999 FEW020 BKN040
TEMPO 1100/1108 10018G28KT
BECMG 1108/1110 11021G34KT 5000 -SN BKN012 TEMPO 1108/1114 3000 -SN BKN006
PROB40 TEMPO 1109/1113 1200 SN BKN003
TEMPO 1114/1122 4000 -RASN BKN008
PROB30 TEMPO 1114/1118 2000 -SNRA BKN004
BECMG 1117/1119 11016KT
TEMPO 1119/1124 11017G27KT

Light snow from 8am until 2pm, followed by sleet at Shannon. Possibly moderate snow from 9 until 1.

Cork just has sleet, Dublin has no mention of any precipitation and Knock has no available TAF at the moment. Shannon is by far the most hopeful. From a West Clare perspective, that's good for me.

Snowbie

ECM 18z upgrades precip again and moves it quicker up the island. Midnight run will be interesting

SeaBreezes

Just rain on south coast at the moment.

Gaoth Laidir

The 03Z ICON Flash is awful for northern Leinster. Massive Wicklow shadow and practically nothing making it to Dublin or the midlands north of Kildare. The southeast is the only place that has anything semi-respectable later.

All eyes on Munster this morning and the northwest later.

https://meteologix.com/ie/model-charts/deu-hd-3h/ireland/significant-weather/20210211-0800z.html

Gaoth Laidir

Shannon are expecting light snow with 4-km visibility in the next 2 hours.

METAR EINN 110800Z 10018KT 9999 FEW028 BKN032 OVC050 01/M04 Q1015 BECMG 4000 -SN BKN010=

Light sleet at Cork Airport now

METAR EICK 110800Z 12028G38KT 5000 -RASN FEW008 BKN010 02/00 Q1013 TEMPO 3000 BKN005=

Mount Vesuvius

Updated HARMONIE

https://twitter.com/MetEireann/status/1359761421752533000?s=19

Cloudio9

https://twitter.com/OwensDamien/status/1359606511354474500?s=20

noobsnow95

Spitting snow here in Limerick City, currently very light.

Gaoth Laidir

noobsnow95 wrote: »

Spitting snow here in Limerick City, currently very light.

Light snow at Shannon. Light drizzle at Kerry Airport.

METAR EINN 110900Z 10020KT 8000 -SN FEW022 BKN030 01/M02 Q1015 WS RWY06 BECMG 4000 -SN BKN010=

SPECI EIKY 110901Z 11013G23KT 080V150 9999 -DZ BKN013 OVC020 03/01 Q1012=

Gaoth Laidir

Visibility is pretty low now at Shannon, down to 600 metres.

METAR EINN 110930Z 10018KT 0600 R24/1300 R06/1300 -SN SCT008 OVC010 00/M00 Q1015 TEMPO BKN003=

Kermit.de.frog

Gaoth Laidir wrote: »

Visibility is pretty low now at Shannon, down to 600 metres.

METAR EINN 110930Z 10018KT 0600 R24/1300 R06/1300 -SN SCT008 OVC010 00/M00 Q1015 TEMPO BKN003=

The wind must be whipping up some grains.

Gaoth Laidir

Slightly better now

METAR EINN 111000Z 09016KT 2500 -SN OVC005 00/M00 Q1015 TEMPO BKN003=

Gaoth Laidir

Airport warnings for Knock, Shannon, Casement and Cork, respectively.

EIKN AD WRNG 02 VALID 111400/120200 SNOW FBL 1 to 3 CM FCST=
EINN AD WRNG 01 VALID 110800/111400 SNOW FBL 1 to 3 CM FCST=
EIME AD WRNG 01 VALID 111600/111900 SNOW FBL LESS THAN 1 CM FCST=
EICK AD WRNG 02 VALID 110700/111500 SNOW FBL LESS THAN 1 CM FCST=

Meteorite58

Light sleety rain here near Tralee, a bit of wet snow earlier. Breezy

2.6C

AROME still showing the snow to intensify in the W and midlands in the afternoon / evening and the SE early Fri morning looks like getting wintry precipitation.

DOCARCH

Gaoth Laidir wrote: »

EIME....LESS THAN 1 CM FCST=

Whoopywoo! Can.....not.....wait! :P

Gaoth Laidir

DOCARCH wrote: »

Whoopywoo! Can.....not.....wait! :P

I should have added that that warning is valid up to 7 pm this evening.

Danno

Live Stream from Johnstown in N Kilkenny: https://www.youtube.com/watch?v=mNw2V0HU-Q0