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

nacho libre

Donegal Storm wrote: »

Already been blizzard-like whiteout conditions here in Kildare for the past number of hours with significant extra accumulation on top of the already significant accumulation from earlier. If tomorrow actually happens as per some forecasts it could go down as the biggest snow event I'll ever see in this country, incredible synoptics. Even what's happened in the past few hours is something I've very rarely, if ever experienced before in this country!


This is what Arome makes of things up to Friday morning, worth noting that it hasn't even picked up on the current streamers so add another 10cm probably to the totals in the east. The front is far from finished at that point as well so there'd be further accumulations through Friday

How many cms of snow do you have there?

SleetAndSnow

nacho libre wrote: »

aha! and he did mention about us experiencing Canadian weather in an earlier update. Is there no end to the man's talents:pac:

meanwhile the jet is still on a scenic route around us:

Its still so amazing to see that. The jet coming down from the north. How often do we see that!

Donegal Storm

Haven't actually measured anything since this morning, had 8cm first thing this morning then 11cm at midday. We had a slight thaw back to probably about 8cm by 5pm and since then its been coming down heavy with significant drifting. Looks like the streamer might clear fairly soon so I might brave it then :pac:

Meteorite58

Slow moving system coming up against the colder air and gradual mixing .

Meteorite58

WRF - NMM showing much stronger winds then the ARPEGE. Strange the difference between them. The WRF is one not to exaggerate nor is the ARPEGE one to be far off. Another couple of runs eh...

sean555

In light of the 12z precipitation models it surely only has to be a matter of time before Galway, Roscommon and maybe Mayo are added to the red warning.

Gaoth Laidir

I've just measured 12 cm here in Celbridge, 2 of which fell in the past hour. At 8 am this morning I had 13 cm. Wasn't here to measure any during the day but will keep an eye on it from now on.

Casement is now up to 17 cm at 8 pm, the highest of the day. Dublin is at 7 cm, the highest it's been at too. Cork 5 cm.

sryanbruen

Perhaps some similarities with the way the Polar Jet is going next week to March 2013?

sunflower3

Wow....I just checked yr.no for next week. Into the freezer again. It completely changed its forecast. Also non stop snow on Friday. Again, a bit of an upgrade?? Seems to reflect the posters here discussing the ECM etc.

Is anyone prepared to predict when a thaw will happen? Getting a bit nervous now!

Snowaddict

As someone who has a true affinity for cold and extreme weather this has been long coming! I look on from overseas in North America for all fellow Irish posters!

We recently had a major frontal snow event in the US Midwest that is shaping up just like what is happening in Ireland right now.

GFS and others originally predicted a snow to rain event and an immediate transition to mild southwesterly winds across Chicagoland. What transpired was 30 hours of snow giving 12-15 inches generally with localized amounts of two feet.

There is a definitive shift to a more serious evolution tomorrow night into Friday. Should this transpire; that combined with the already exceptional snowfall totals will leave this as a once in generation event.

Very interesting to see if the latest ECMWF 12Z Op modelling is mirrored overnight.

Savour these charts! I would place my bets on HIRLAM - it has been excellent so far in modelling precip amounts.

sryanbruen

The downwards trend in the zonal winds after a recovery continues with the latest update of the ensembles.

gozunda

Meteorite58 wrote: »

WRF - NMM showing much stronger winds then the ARPEGE. Strange the difference between them. The WRF is one not to exaggerate nor is the ARPEGE one to be far off. Another couple of runs eh...

The winds appear to be predominantly from the East or South East for most of that run if that is correct?

Meteorite58

ICON 18Z :eek: That is bigger snow totals predicted than earlier runs.

Gaoth Laidir

That's the last of the intense showers for us. Upper levels (700 & 500 hPa) are starting to warm significantly from midnight, and 850 hPa stay pretty much stationary. Convection will be much shallower, as already evident from the much warmer cloutops over UK and Irish Sea. Light streamers will continue, but the heaviest sea-effect event has passed.

adam240610

Gaoth Laidir wrote: »

That's the last of the intense showers for us. Upper levels (700 & 500 hPa) are starting to warm significantly from midnight, and 850 hPa stay pretty much stationary. Convection will be much shallower, as already evident from the much warmer cloutops over UK and Irish Sea. Light streamers will continue, but the heaviest sea-effect event has passed.

Not good news for north Wicklow and south Dublin then, just as a few are slowly lining up from Wales now. What kind of reduction are we talking about?

Daniel2590

GFS pub run has Storm Emma about 50-100 km east compared to the 12z!

sdanseo

18Z GFS brings more of the intense precip up to the Northwest:



HIRLAM shows showers intensifying rather than dying out off the Irish sea after 12pm?

Rougies

adam240610 wrote: »

Not good news for north Wicklow and south Dublin then, just as a few are slowly lining up from Wales now. What kind of reduction are we talking about?

I wouldn't worry about it. 60 minutes under a moderate streamer would drop the same amount of snow as 30 minutes under a twice as intense one (going by my high level mathematic formula). And moderate streamer is certainly a lot better than an intense one missing you to the north!

Gaoth Laidir

adam240610 wrote: »

Not good news for north Wicklow and south Dublin then, just as a few are slowly lining up from Wales now. What kind of reduction are we talking about?

Still showers on and off, and as usual coverage will depend on subtle wind direction, but we won't be seeing the hail and heavy graupel we saw today. With very low dewpoints upstream over the UK raising cloudbases as the warmer upper levels lower cloud tops, saturated levels will be shallower, Still some light snow and snow grains, a bit like we had yesterday.

Lepidoptera

Is that just for tonight or do you mean that we've seen the last of the intense showers for the rest of the week?

sdanseo

sdanseo wrote: »

HIRLAM shows showers intensifying rather than dying out off the Irish sea after 12pm?

18Z appears to keep them going.

Gaoth Laidir

Lepidoptera wrote: »

Is that just for tonight or do you mean that we've seen the last of the intense showers for the rest of the week?

For the rest of the week.

Gremlin

Deleted User wrote: »

18Z appears to keep them going.

..also the radar doesn't look like there is any real loss in intensity. If anything it looks like its ramping up between IOM and Anglesea.

patneve2

-14 at 850 over 7 deg sea..lets see what the next hour brings

WolfeEire

Hirlam precip accumulation by Friday eve

Gaoth Laidir

Gremlin wrote: »

..also the radar doesn't look like there is any real loss in intensity. If anything it looks like its ramping up between IOM and Anglesea.

The coldest 500 hPa pool has already passed the east coast. The 700 hPa will follow at around 3 am, so the next few hours will see a gradual decline in intensity, but by morning I can't see anything near as heavy as we've seen in the past 18 hours.

Gaoth Laidir

patneve2 wrote: »

-14 at 850 over 7 deg sea..lets see what the next hour brings

It's been -14 all day and if anything will warm slightly by the morning.

Meteorite58

Looks like a steady supply of snow overnight.






They are like eddies in the wake off the W coast of Ireland



The cold pool spreading well into the Atlantic

pad199207

Pressure was around 1025mb last night when we were getting buried here in Kildare. Pressure is now 1017mb so i think at least moderate snow can be expected in many of the showers added with blowing and drifting snow.

Elmer Blooker

Less than 2 hours of meteorological winter left and every single ME station below freezing from Malin at -1 to Knock at -5.
Now that's what I call winter going out in style!