FI Charts ( T120+ onwards) Winter 2020 **READ MOD NOTE IN FIRST POST**

Snowbiee21

Rebelbrowser wrote: »

Thread! Thread! Thread!

https://touch.boards.ie/thread/2058155857/1/#post116132645

Reversal

That 12z ECM is pretty much a 2018 repeat. Plenty of scope for a storm Emma in there.

Gonzo

my god the ECM is knocking it out of the park.

nacho libre

That is a run that keeps on giving. Save it for posterity.

We have a consensus between the main players now, but still potential for it to go belly up at this stage. I'll only really believe it if we see these charts at 48 hours out

Kermit.de.frog

Worth noting such a scenario would be occurring a good 3 - 4 weeks prior to same in Feb 2018. Less thawing on certain surfaces in any sunshine and more ice days potential.

We do need to iron out the differences in the models at day 4 though in terms of eta of the deeper continental cold.

Gonzo

The ECM has blown open that freezer door and it persists right up to 240 hours. Chart of the day and is potentially even better than the GFS. This is really looking good but we have to maintain calm as I feel we need this trend to be maintained for the next 2 days.

Fitzo123

All tentative yet I know but is this looking like an all-island event or one primarily confided to the East Coast.

Storm Emma brought a staggering 1cm of snow to Sligo....

nacho libre

What i really like about this run is we could extend the cold spell if the ECM day 10 chart verified.

Nqp15hhu

Fitzo123 wrote: »

All tentative yet I know but is this looking like an all-island event or one primarily confided to the East Coast.

Storm Emma brought a staggering 1cm of snow to Sligo....

Yes, I don’t get much out of easterlies either.

With this event, it will depends on the wind direction and whether or not any troughs will be embedded. Troughs can cover the whole island and encourage widespread showers or prolonged snow.

An easterly wind with convective showers will be limited to the eastern third. However a NE wind can bring snow showers to the eastern half and northern parts.

Reversal

Fitzo123 wrote: »

All tentative yet I know but is this looking like an all-island event or one primarily confided to the East Coast.

Storm Emma brought a staggering 1cm of snow to Sligo....

All streamers on this run.

mickger844posts

A peach of a run there from the ECM. We have seen the progression from Saturdays 12z to an improving picture with yesterdays 12z to todays pretty much perfect scenario. I would be still be to a bit cautious as the deep cold still 6 days away. If we can see a mirror of this 12z this time tomorrow then a great chance of something special.

nacho libre

Fitzo123 wrote: »

All tentative yet I know but is this looking like an all-island event or one primarily confided to the East Coast.

Storm Emma brought a staggering 1cm of snow to Sligo....

The East will get the most snow, but in such an unstable flow other areas may well will see snow at times from features that pop up.

Also later on if there is an attack from the Atlantic at some stage it could cause a more widespread snowfall across the country

Sweet divine Lord
This would lead to an almighty snowfest of snow streamers in East Leinster
Just one week away
Thunder Snow and Ice days

ninebeanrows

ECMWF would vastly underestimate the showers coming in from the Irish Sea also, if that run was converted into an HARMONIE run with same boundary conditions it would be twice that much snow

snowstorm445

Good day of model watching, hopefully something big is on the cards Snow looks like it's coming Ireland's way soon.

I will say the ECM is much better for me personally being based here in Belgium, the other models have the low pushing too far north leaving me in the mild sector lol, the ECM brings in proper cold uppers :P But all the models look excellent from Ireland's point of view

Gonzo

Sleety_Rain wrote: »

ECMWF would vastly underestimate the showers coming in from the Irish Sea also, if that run was converted into an HARMONIE run with same boundary conditions it would be twice that much snow

yep, if the ECM run verifies, right now that is still a big IF, snow depths would be far in excess of 10cm over a 4 to 5 day period of streamers. In perfect conditions away from the shadows it wouldn't be unusual for half a foot of snow over a few hours. 20 to 30cm and beyond of snow would be achievable in many low lying areas if the Irish sea is a snowmaker for 4/5 days.

nacho libre

Let's just hope the ECM is not an outlier- well a mild outlier would be acceptable:)

froog

question - i get the "uppers" temperature requirement for snow. but what about the moisture requirement? is it possible to get the requisite cold but not have enough moisture for snow? or is that moisture always there this time of year, waiting to be tapped into?

Reckless Abandonment

If the ECMWF is right we might need a "Npset" National public snow emergency team ..

Zogabomb

froog wrote: »

question - i get the "uppers" temperature requirement for snow. but what about the moisture requirement? is it possible to get the requisite cold but not have enough moisture for snow? or is that moisture always there this time of year, waiting to be tapped into?

From my limited knowledge, the moisture is created by the contrast between the very cold upper temps and the relatively warm Irish Sea. It creates convective showers particularly affecting the coast. If you google "Lake Effect Snow" it will give you the general gist.

Nqp15hhu

froog wrote: »

question - i get the "uppers" temperature requirement for snow. but what about the moisture requirement? is it possible to get the requisite cold but not have enough moisture for snow? or is that moisture always there this time of year, waiting to be tapped into?

Yes if the air pressure is high (say 1020mb) precipitation will be limited. And the corresponding 850hPa level will be higher than the typical altitude.

Snowbiee21

The great thing about this cold spell,Like Kermit said, IF it comes off, is that it is in early February rather than late Feb/early March like the last BFTE. It was a bit bizarre having sub zero temperatures and heavy snow showers only for much of it to melt when the sun came out.

Gonzo

Snowbiee21 wrote: »

The great thing about this cold spell,Like Kermit said, IF it comes off, is that it is in early February rather than late Feb/early March like the last BFTE. It was a bit bizarre having sub zero temperatures and heavy snow showers only for much of it to melt when the sun came out.

This is why we are always want potent cold spells no later than the second half of February. By the final week of February snow melt becomes much more of a concern and that is exactly what happened during the BFTE/Storm Emma. If it happened first/second of February the snow depths would have been even greater and it would have stuck around for longer.

IF this cold spell verifies like this evenings ECM expect more of a December 2010/February 1991 over a Storm Emma in terms of cold. Forget about the snow levels for now until we lock in this spell.

Kermit.de.frog

The OP run on the ECM is on the colder side of the ensembles but there are colder runs there mid term. It is a cold outlier at the end though but that's out in cuckoo land anyway.

ninebeanrows

The moyenne at 168hrs is decent

Cw85

Is there still a possibility the Atlantic could kick back in given this is still 7 days out? I'm afraid to get positive as there have been too many letters downs in the past

TheMilkyPirate

Cw85 wrote: »

Is there still a possibility the Atlantic could kick back in given this is still 7 days out? I'm afraid to get positive as there have been too many letters downs in the past

This can very much still go wrong, yes.

Gonzo

Cw85 wrote: »

Is there still a possibility the Atlantic could kick back in given this is still 7 days out? I'm afraid to get positive as there have been too many letters downs in the past

The Low Pressure on Thursday/Friday is essential, it is a trigger low. This needs to sink well south into France or Spain to bring the winds in from the east/north-east. If this low sits around Ireland/UK and fails to sink south, we can forget about the potent cold spell and will have to wait another turn.

Oneiric 3

Fitzo123 wrote: »

All tentative yet I know but is this looking like an all-island event or one primarily confided to the East Coast.

Storm Emma brought a staggering 1cm of snow to Sligo....

Hard to tell what we got as the dust was blowing all over the place and tended to pile up against walls and stuff. This picture was taken by my brother a couple of miles outside of town here. Not near as much as they got up the Wicklow Mts in the east but not bad for easterly either for all the way west.

Oneiric 3

Sleety_Rain wrote: »

ECMWF would vastly underestimate the showers coming in from the Irish Sea also, if that run was converted into an HARMONIE run with same boundary conditions it would be twice that much snow

Possibly, but I have found that the ECMWF generally overestimates snowfall accumulations. Anyways, still literally a week to go yet so plenty more swings and roundabouts to come.