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

Reversal

HighLine wrote: »

Are the greens and blues trailing over the south west corner of England and towards us a worry? That would suggest the precipitation will turn wet earlier than expected?

No. The precipitation type radars are just modelled parameters overlayed onto the rainfall radar. They give no new information compared to the last run of whatever model they use.

Oneiric 3

Elmer Blooker wrote: »

Advice please.
Chart for noon tomorrow, is that the front to the southwest of England thats meant to give us blizzards? Its nowhere near us and I don't like the look of that warm sector either but it doesn't surprise me, there would have to be one to complicate matters.

This is a chart that befuddles me as well. It doesn't look right. For what it's worth, the forecast chart from KMNI for the same time looks a bit more 'logical'.

sryanbruen

Snow and ice cover charts for the past two days.

28 February:



1 March:

M.T. Cranium

Re map and radar interpretations in past few pages:

The blizzards will be ahead of the occlusion which is acting basically like a warm front. The fronts further south will be dragged west tomorrow and not affect Ireland.

Hence the rain approaching southwestern England will likely track northwest more than north, it may skim along the south coast of Cork and Kerry later tomorrow. I do expect some mixing with sleet and ice pellets in south coast and low elevations of southeast at times during this event but not in organized bands, just precip types wavering back and forth. Accumulations may therefore be held down in a few places mostly within a mile or two of the coasts but more like below 150m in general in Kerry and southwest Cork.

If this low veers a bit north and comes inland over Kerry then I think the only effect will be to shift the northern margins of the snowfall further north and add a few cms of snow in higher terrain. For Kerry itself, your forecast is very track-dependent, the sequence will probably be sleet to snow, heavy snow, back to sleet, ice pellets, rain, strong southeast winds but dry for a time, then back to rain, sleet and light snow. It will be messy in other words. Higher parts of the southwest will be mostly snow with some sleety mixtures as low passes.

Oneiric 3

For anyone wishing to keep an eye on the track of where the snow is falling overnight, and where it is likely to fall, you could do worse than keep an eye on this precipitation intensity chart from Met Éireann:



Which updates every hour on this page: http://www.met.ie/forecasts/3hour.asp

Roofs have turned white here with 'drizzle snow' Feeling colder than it did today though temps are the same.

Latest Euro4 run good for the east. This model has upgraded throughout the day.

kerrycork13

3 inches of snow here in East kerry, cork border 150 asl exactly. Only snowing 3 hours and bear in mind we had absolutely nothing before that!!! Could be interesting if this keeps up!!!

wicklowdub

Temps and DP's on the rise in Wicklow

sdanseo

2300Z Dublin TAF pushes the moderate snow out to beginning at 00Z and continuing right through to tomorrow midnight.

00Z to 09Z still +SN but as a PROB40 as opposed to no PROB earlier

TAF: EIDW 012300Z 0200/0224 08030G45KT 2000 -SN BKN008
TEMPO 0200/0224 0400 SN OVC002 - moderate snow for the full day 2nd, visibility 400m
PROB40 TEMPO 0200/0209 0200 +SN BKN001 - heavy snow 40% chance 00Z to 09Z, visibility 200m (a drop from projected 300m earlier, a sign that they expect it to perhaps be slightly more intense)
TEMPO 0203/0208 08035G52KT - wind gusting 52kt 0300 to 0800
BECMG 0209/0212 08025G40KT - wind gusting 40kt 0900-1200
TEMPO 0212/0224 08022G35KT - hopefully you get the picture at this stage :pac:

Gremlin

Anyone like to comment on the effect (or not) of convection on the frontal precip over the Irish Sea?

Storm 10

Is this pushing more West and North than was forecast

kerrycork13

Even though it's snowing here in East kerry for 3 hours it's not that windy and visibility isn't bad!! Will the winds pick up? Will it snow heavier? Anyone she's any light on this? 150 asl cork/Kerry border

sean555

Storm 10 wrote: »

Is this pushing more West and North than was forecast

Hirlam and Arpege have been forecasting that since yesterday.

lucernarian

sean555 wrote: »

Hirlam and Arpege have been forecasting that since yesterday.

And not ICON I note. Emma is aligning itself to really dump snow over Leinster and Munster and I suspect there's a warm upper front involved which is is acting synergistically with the convection in the Irish Sea. Incredible set of circumstances tbh.

piuswal

teddybones wrote: »

Roughy 30cm = 1ft

see previous post also

someone seems to be mixing mms an cms!

Meteorite58

I think the foretasted winds may not be as strong( apart from coastal areas ) as originally thought, still gusty no doubt blowing snow about.








Latest WRF 18Z showing rain / Sleet pushing on to the S coast Sat morning after a lot of snow.

DOCARCH

The wind and snow/snow grains are really really full on now in Dublin 16. I can hear the wind howling both to the front and back of the house now!

If this does last 24 hours, at this intensity, I can't see any issue getting a 100cm+

Gaoth Laidir

Heavy snow at Johnstown Castle at midnight. Visibility 400 metres, temp -1.0, dewpoint -1.2.

Depths on the way back up around Dublin now.

gugsy

I feel a mix between the harlim and aprege have been bang on harlims intensity is slightly over but its spread is perfect as the aprege is the oppostite both models so far are doing the best IMO

sdanseo

The bank of higher intensity precip seems to have just completely stalled over the Irish Sea. It's like its hit a wall and releasing only bits of rain at a time.

Never seen anything like it before. Anyone hazard a guess at what's causing it?

wakka12

sdanseo wrote: »

The bank of higher intensity precip seems to have just completely stalled over the Irish Sea. It's like its hit a wall and releasing only bits of rain at a time.

Never seen anything like it before. Anyone hazard a guess at what's causing it?

Could it just be a model glitch?

snowstorm445

sdanseo wrote: »

The bank of higher intensity precip seems to have just completely stalled over the Irish Sea. It's like its hit a wall and releasing only bits of rain at a time.

Never seen anything like it before. Anyone hazard a guess at what's causing it?

Are you looking at the Netweather radar? If you are, its fairly useless for the South Irish sea for whatever reason (hence why there might appear to be a wall), the Met Éireann radar picks it up far better.

Donegal Storm

sdanseo wrote: »

The bank of higher intensity precip seems to have just completely stalled over the Irish Sea. It's like its hit a wall and releasing only bits of rain at a time.

Never seen anything like it before. Anyone hazard a guess at what's causing it?

Just radar interference, the netweather radar always gets very messy in these setups when theres vast areas of precip, presumably because of how overlapping signals are handled. Met Eireann radar picks things up better and shows light to moderate precip steadily progressing NW'ward

Gaoth Laidir

This 18Z radiosonde sounding from Larkhill in southern England shows a very heavy snow setup. Cold surface layer but deep warm saturated inversion just below zero, meaning a lot of precipipitable water content. 850 hPa temperature and dewpoint were both just -1.6 , but as the whole profile is below zero it just shows that in some cases -1 is enough for snow.

A Major Incident has been declared in Avon and Somerset this evening as a result.

ThaitaniumM

Still a long way to go yet, Emma's main band has yet to give us her heavy load :pac:

Gaoth Laidir

Tonight's midnight sounding from Camborne down near Land's End. Upper warm front at 850 hPa leading to heavy cold rain in that area, confirmed by surface reports.

ThaitaniumM

Recent satellite imagery shows that big blob of white off the SE coast. Should make the next few hours interesting :eek::D

lucernarian

GFS 0z rolling out, showing prolonged snow still hanging around this evening...

harr

Can I ask what is stopping the snow from making its may further inland, a huge gap in centre of country for the last few hours .
Looking at the radar snow goes so far and then it’s like a sudden block.
Unfortunately I am smack bang in middle of this big gap .,

M.T. Cranium

General trend on early 00z models is to weaken Emma somewhat faster through late Friday, may have pros and cons for snowfall totals, pro would be less coastal incursion of milder air, con would be less dynamic system in general. May be a slight "downgrade" net but a downgrade of something off the scale so not sure how we'll know, really.