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

nacho libre

We need to be mindful that we are the last port of call for a Scandi High. If a robust Scandi High does exert its influence over us, it could eventually move across to Greenland. If this does come off it will prove me wrong that you can't have cold in the north east of America and here at the same time. Also if it does come to fruition the discussion of over hodographs, thickness, the temperature at the 700 hpa level might fizzle out:p

nacho libre

ninebeanrows wrote: »

Remember with a nice continental feed 850hPa temps largely become irrelevant for surface cold.

Yes. As well as that snow from any frontal event could fall for several hours even with rising uppers, which of course wouldn't happen if the flow was reversed.

PokeHerKing

nacho libre wrote: »

We need to be mindful that we are the last port of call for a Scandi High. If a robust Scandi High does exert its influence over us, it could eventually move across to Greenland. If this does come off it will prove me wrong that you can't have cold in the north east of America and here at the same time. Also if it does come to fruition the discussion of over hodographs, thickness, the temperature at the 700 hpa level might fizzle out:p

Open to correction but I'm pretty sure 2010 has already proved you wrong. NE and even SE coast of the USA had a pretty harsh winter that year if memory serves me.

nacho libre

PokeHerKing wrote: »

Open to correction but I'm pretty sure 2010 has already proved you wrong. NE and even SE coast of the USA had a pretty harsh winter that year if memory serves me.

You are right! I'm just reading about it now:
The winter season saw winter storms and very cold temperatures affect a large portion of the continental United States, even as far south as the Texas Panhandle. By far the most notable event was a historic blizzard that impacted areas from Oklahoma to Michigan in early February which broke numerous snowfall records, and one of the few winter storms to rank as a Category 5 on the Regional Snowfall Index.

Gonzo

very interesting charts this morning. This started with the GFS yesterday and now looks like all models are going for possibly another cold event next week edging closer to us. There is still some way to go with it and we may not get it at all, but there is every possibility that over the next few days this cold spell could end up continuing and merge into the next one. Fingers crossed because the upcoming current spell isn't great for us in terms of snow.

nacho libre

Gonzo wrote: »

very interesting charts this morning. This started with the GFS yesterday and now looks like all models are going for possibly another cold event next week edging closer to us. There is still some way to go with it and we may not get it at all, but there is every possibility that over the next few days this cold spell could end up continuing and merge into the next one. Fingers crossed because the upcoming current spell isn't great for us in terms of snow.

You could end up surprised yet. You are unlikely to get a foot of snow, but you could have a decent covering by Wednesday all the same.

compsys

Frontal systems delivering snow are so rare in Ireland.

So while there's been a slight upgrade for a 'big' snow event on Thursday I'm concerned about the downgrade to streamer activity.

Streamer activity would at least almost guarantee the Dublin region (and a quarter of the entire population) some nice snow. Even parts of Cork could get in on the action if the wind was right.

But frontal systems rarely come off in terms of snow.

Inland places like Cavan can sometimes strike gold once in a blue moon but anywhere remotely near the coast is rarely lucky.

Slashermcguirk

By the way before this snow events starts, a big thanks to some of the great contributors on here who called this out from about a week ago. Some really interesting discussions and you would learn a lot from just reading what the more knowledgable posters have to say.

Dreary times and events like this are certainly good entertainment among the madness. Hoping everyone gets some snow from this, even maybe the glass half empty types :-)

nacho libre

compsys wrote: »

Frontal systems delivering snow are so rare in Ireland.

So while there's been a slight upgrade for a 'big' snow event on Thursday I'm concerned about the downgrade to streamer activity.

Streamer activity would at least almost guarantee the Dublin region (and a quarter of the entire population) some nice snow. Even parts of Cork could get in on the action if the wind was right.

But frontal systems rarely come off in terms of snow.

Inland places like Cavan can sometimes strike gold once in a blue moon but anywhere remotely near the coast is rarely lucky.

I would not get too concerned just yet. The next runs could upgrade streamer activity. Keep in mind also there maybe an element of imbyism creeping into some posts as well. We are not going to get the amounts of snow some places in England will get, but some locations here will have done reasonably well by Wednesday.
Regarding frontal snow, didn't some places in Dublin do ok a few weeks back?

Arduach

Showers, by their nature, are difficult to predict, no matter what the weather and temperature. Some will be luckier than others.

TheMilkyPirate

ICON also raising heights towards Scandi at +180

sryanbruen

Really interesting evolution on models this morning indeed with what I consider a classic example of a cold spell prelude. Heights begin to rise over Scandinavia in advance of a southerly airflow bringing milder air but this is advected northward (warm air advection). Really classic stuff and we last saw it in 2018 when we had a milder prelude coming up to the developments of the Scandi High and we got gradually colder as the high retrogressed courtesy of the completely reversed zonal flow being forced by the sudden stratospheric warming event at the time. It's not like this week's cold snap that we're relying on a wedge of heights to our north to fend off low pressure systems from the Atlantic and undercut to Europe.

I'm showing latest ICON for illustration sakes of what I mean for those that rather a more visual approach than reading long paragraphs of waffler. The warm air advection (WAA) on the western side of the ridge to our east inflates the ridge into a blocking high which in turn sends cold air south on its eastern side as the airflow is clockwise around high pressure. This cold air is brought westward as a result but the exact positioning of the block is key to where gets the cold air.



Absolutely classic stuff here. FI for now but surprised at just how much this signal has advanced overnight like that. The UK Met Office MOGREPS model with its signal of shorter-mid range models underestimating the high latitude blocking might be right about this.

Lots to keep our eyes on at the moment, certainly not in any way boring. Whatever the end result is of this week's easterly or the potential of this Scandinavian High, we'll keep watching!

Billcarson

Would be nice though if we stayed cold in between,
or cold enough for any lying snow to hang around from the upcoming
spell till hopefully the next one though perhaps that's being greedy and unrealistic.

Dazler97

sryanbruen wrote: »

Really interesting evolution on models this morning indeed with what I consider a classic example of a cold spell prelude. Heights begin to rise over Scandinavia in advance of a southerly airflow bringing milder air but this is advected northward (warm air advection). Really classic stuff and we last saw it in 2018 when we had a milder prelude coming up to the developments of the Scandi High and we got gradually colder as the high retrogressed courtesy of the completely reversed zonal flow being forced by the sudden stratospheric warming event at the time. It's not like this week's cold snap that we're relying on a wedge of heights to our north to fend off low pressure systems from the Atlantic and undercut to Europe.

I'm showing latest ICON for illustration sakes of what I mean for those that rather a more visual approach than reading long paragraphs of waffler. The warm air advection (WAA) on the western side of the ridge to our east inflates the ridge into a blocking high which in turn sends cold air south on its eastern side as the airflow is clockwise around high pressure. This cold air is brought westward as a result but the exact positioning of the block is key to where gets the cold air.



Absolutely classic stuff here. FI for now but surprised at just how much this signal has advanced overnight like that. The UK Met Office MOGREPS model with its signal of shorter-mid range models underestimating the high latitude blocking might be right about this.

Lots to keep our eyes on at the moment, certainly not in any way boring. Whatever the end result is of this week's easterly or the potential of this Scandinavian High, we'll keep watching!

Oh yes please

JanuarySnowstor

There's only one boss on tonight's 12z gfs
It's the beast and it's the Freezer!!
Makes mince meat of the Atlantic...

munsterlegend

JanuarySnowstor wrote: »

There's only one boss on tonight's 12z gfs
It's the beast and it's the Freezer!!
Makes mince meat of the Atlantic...

Looks good alright but all in FI!

Gonzo

fantastic GFS 12z so far. A monster of a beast flooding south-westwards clipping the SE of England and on to France and Spain. It wouldn't take alot of adjust this over us eventually. Even if we don't get it, we could be under a nice area of high pressure with night time frosts and crisp chilly days. The Atlantic looks like it's bag's are packed for some time to come.

TheMilkyPirate

Maybe this week might just be the starter



I've 8 days off work from today and absolutely nothing to do. Hopefully a great week of model watching coming up

Gonzo

next few frames, the high over Ireland is making a bee line to Greenland.....

Gonzo

TheMilkyPirate wrote: »

Maybe this week might just be the starter

I've 8 days off work from today and absolutely nothing to do. Hopefully a great week of model watching coming up

this cold spell over the next few days is just mildly interesting, what we are seeing right now in FI is far more exciting. So much potential.

TheMilkyPirate

Cold has barely left the east coast by next Saturday on the GEM with heights building over Scandi, a strong signal being picked up by the models today

Captain Snow

TheMilkyPirate wrote: »

Maybe this week might just be the starter



I've 8 days off work from today and absolutely nothing to do. Hopefully a great week of model watching coming up

Bit of a Ramp But Shades of an Omega Block.

snowstorm445

GEM also creating a strong Scandi high but the low to the west is a bit more stubborn unfortunately.

Gonzo

The GFS 12z is a complete and utter failure of the mild/Atlantic push. Looking at the predicted temperatures, the mild doesn't get much further than the Irish midlands and then retreats back into the Atlantic.

Temps still in the low single digits in parts of Leinster up to Saturday.



Sunday is chilly with temperatures close to freezing in Leinster. The UK is absolutely frozen.



Following week is very cold, low daytime temperatures and below freeezing at night, plenty of frost.

Davaeo09

Isn't that MT and Oneiric?
https://www.iweatheronline.com/2021/02/cloudy-with-chance-of-snowballs.html

Gonzo

GFS control run places us back in the freezer early to mid week next week. A few other members going for similar.

Gonzo

If this was to verify, the south coast would get plastered most likely. It would be sub zero by day and night everywhere.

nacho libre

The much maligned CFS predicted this outcome. We are not there yet, of course, but it looks promising. Let's see what the ECM has in store.

Gaoth Laidir

Davaeo09 wrote: »

Isn't that MT and Oneiric?
https://www.iweatheronline.com/2021/02/cloudy-with-chance-of-snowballs.html

The old WolfeIre

Captain Snow

Gonzo wrote: »

If this was to verify, the south coast would get plastered most likely. It would be sub zero by day and night everywhere.