FI Charts (T120+ onwards) Winter 2018 **READ MOD NOTE IN FIRST POST**

kod87

Well the ECM run seems the more intuitive outcome with regards the high pressure (sitting on top of us before moving into europe and allowing the Atlantic to roar back), previously it had hinted that it may push north giving us an easterly but that always seemed unlikely sadly.

squarecircles

kod87 wrote: »

Well the ECM run seems the more intuitive outcome with regards the high pressure (sitting on top of us before moving into europe and allowing the Atlantic to roar back), previously it had hinted that it may push north giving us an easterly but that always seemed unlikely sadly.

Isn't that what the models generally tend to do after a reliable timeframe,a swift return of the Atlantic regime -their programmed default mode,when they are faced with strong blocking or unusual synoptic patterns.

GFS 12z is more encouraging...the high continue s to push north into Greenland,much colder 850 hpa temperatures flooding south...

BLIZZARD7

GFS is super with a proper ridge through Greenland and into the Arctic, finally showing proper cold uppers flooding south too. UKMO not so good and the differences that cause it to be not as ideal are in the 96hrs to 120hrs time frame. Need a good ECM tonight.

*The UKMO is by no means bad by the way, it's just not ideal if it's a proper snowy cold shot we want.

George Sunsnow

There’s nothing in the 12Z ECM-that would thwart an eventual delivery of snowy cold but it’s 2 weeks away on tonight’s output ie a week+ into FI

If the high sinks south east and by Gor it’s a thin ridge,then it’s curtains for at least 3 weeks
In the medium term there’s going to be some rain showers in that -5c air northeasterly assuming we get it this day week
Snow for lugnaquilla

BLIZZARD7

George Sunsnow wrote: »

There’s nothing in the 12Z ECM-that would thwart an eventual delivery of snowy cold but it’s 2 weeks away on tonight’s output ie a week+ into FI

If the high sinks south east and by Gor it’s a thin ridge,then it’s curtains for at least 3 weeks
In the medium term there’s going to be some rain showers in that -5c air northeasterly assuming we get it this day week
Snow for lugnaquilla

Agreed, somewhat strange to have a sustained flow from a northerly quadrant without lower uppers coming in although I'm sure they would eventually.

It's also impressive how strong the blocking is, there's no chance of that breaking down without a fight and also currently no indication of the PV settling over Greenland which is nice to see.

A seasonal start to winter seems most likely anyway.

George Sunsnow

Ah it’s not strange
I’ve seen that often in the much fabled 80’s winters
Here’s what would happen after a few days of what’s in near FI
You’d have Joanna or Evelyn putting up a chart with a long cold front not yet modeled over Scandinavia and they’d both call it a polar front (met Éireann speak)
It’s behind that you’d have -10 uppers
-8 would do from that direction
It wouldn’t surprise me at all,the question is when,2 weeks 3 weeks,sooner or later either in this phase or in a reload

BLIZZARD7

GFS 18z looking very nice at +120hrs

BLIZZARD7

This time we drag in -7 maybe touching -8c uppers, -10c into Scotland. The northerly flow then gets cut off as the high sort of collapses back over the country - looks like a messy evolution though. All in all not bad and we're in a lucky position where everything is looking better as it moves into the reliable timeframe I.e under 120hrs.

sryanbruen

Ireland having upper air temperatures between -4 to -7c on Wednesday on the ECM 12z :eek:, only +120hrs away.



Did I mention, this is an upgrade from the very cold ECM 00z!

George Sunsnow

Yup
I mentioned it in the general winter thread

Looks like we are entering a pattern if that high does stay that far west

-8 850 air would be enough with current Irish Sea SST’s to pummel the east coast with showers and they would be wintry with quite a lot of settling snow on higher ground and perhaps lower ,isn’t it getting interesting

Easterly Beasterly

George Sunsnow wrote: »

Yup
I mentioned it in the general winter thread

Looks like we are entering a pattern if that high does stay that far west

-8 850 air would be enough with current Irish Sea SST’s to pummel the east coast with showers and they would be wintry with quite a lot of settling snow on higher ground and perhaps lower ,isn’t it getting interesting

Ah GS.. You know how much I love snow but I'm heading to New York on Wednesday for 5 days and it's mild over there, can we not delay it for a few days??

The ECM certainly looks interesting and I think something might be brewing!

highdef

sryanbruen wrote: »

Ireland having upper air temperatures between -4 to -8c on Wednesday on the ECM 12z :eek:, only +120hrs away.



Did I mention, this is an upgrade from the very cold ECM 00z!

Unless I'm reading that chart incorrectly, it looks like -4 to -6 uppers over Ireland with the -8 uppers barely touching the north of Scotland. There are black lines separating temperatures every 4c and no black lines between colours for half way in between the 4 degrees. So 0c would have a black line between colours (0c actually has a thick black line, the rest a thin black line) as would 4c but 2c would have no black line separating the colours. Not sure if I have explained this very well!

kod87

The ecm does what the gfs does and leaves the high basically sitting on top of us. Nothing particularly exciting about those charts atm, it will be cold next week for sure but nothing prolonged and should be relatively dry everywhere. temps slowly rise as the high pressure settles over us.

highdef

sryanbruen wrote: »

You are reading it incorrectly. Firstly, those "black lines" are called isotherms. Isotherms are lines of equal temperature. Look at the key where -8c is on the key below the map (start at 0 and go down the scale to see what I mean if the blues are too similar to your eye sight). The area I have marked here is -8c, which is mostly northeastern Ireland.

I disagree. Firstly, I know that they are isotherms, in a similar vein to isobars.....lines that show equal units of something. I was just trying to keep it simple for everyone by keeping the language simple.

Secondly, the area you highlight is -6 to -8, not -8. This means >6 but <8 so therefore nowhere in Ireland can be at -8. In fact, as it's only the north and parts of the midlands within that particular shade of blue (which then stretches all the way to the very north of Scotland), I would hazard a guess and say that it's unlikely that any part of the island of Ireland is even at -7. As stated, it's only when you get to the very north of Scotland that you hit -8.

If you look off the coast of the northwest coast of Norway in your chart, you can see an area that is a lighter shade of blue to surrounding areas. Within this the 850 hPa temp is greater than -6 but less than -8. This is the same shading that you are referring to over the north of Ireland.

Just to be 100%, I did some colour sampling. The area you refer to over the north of Ireland has a colour of #0036FF. The area beyond the isotherm at the very north of Scotland has a colour of 0000FF - a different shade of blue, looks very similar on either side of that isotherm however it means that north of it, the temp is lower than -8 (between -8 and -10, when using the colour scheme as a reference). South of it is GREATER than -8 (between -6 and -8, when using the colour scheme as a reference). Therefore nowhere in Ireland is under -8 uppers in that chart and most likely are not under -7 either....probably nearer -6.

sryanbruen

highdef wrote: »

I disagree. Firstly, I know that they are isotherms, in a similar vein to isobars.....lines that show equal units of something. I was just trying to keep it simple for everyone by keeping the language simple.

Secondly, the area you highlight is -6 to -8, not -8. This means >6 but <8 so therefore nowhere in Ireland can be at -8. In fact, as it's only the north and parts of the midlands within that particular shade of blue (which then stretches all the way to the very north of Scotland), I would hazard a guess and say that it's unlikely that any part of the island of Ireland is even at -7. As stated, it's only when you get to the very north of Scotland that you hit -8.

If you look off the coast of the northwest coast of Norway in your chart, you can see an area that is a lighter shade of blue to surrounding areas. Within this the 850 hPa temp is greater than -6 but less than -8. This is the same shading that you are referring to over the north of Ireland.

Just to be 100%, I did some colour sampling. The area you refer to over the north of Ireland has a colour of #0036FF. The area beyond the isotherm at the very north of Scotland has a colour of 0000FF - a different shade of blue, looks very similar on either side of that isotherm however it means that north of it, the temp is lower than -8 (between -8 and -10, when using the colour scheme as a reference). South of it is GREATER than -8 (between -6 and -8, when using the colour scheme as a reference). Therefore nowhere in Ireland is under -8 uppers in that chart and most likely are not under -7 either....probably nearer -6.

Sent you a PM to discuss this rather than upsetting others and flooding this thread with irrelevant posts.

George Sunsnow

highdef wrote: »

I disagree. Firstly, I know that they are isotherms, in a similar vein to isobars.....lines that show equal units of something. I was just trying to keep it simple for everyone by keeping the language simple.

Secondly, the area you highlight is -6 to -8, not -8. This means >6 but <8 so therefore nowhere in Ireland can be at -8. In fact, as it's only the north and parts of the midlands within that particular shade of blue (which then stretches all the way to the very north of Scotland), I would hazard a guess and say that it's unlikely that any part of the island of Ireland is even at -7. As stated, it's only when you get to the very north of Scotland that you hit -8.

If you look off the coast of the northwest coast of Norway in your chart, you can see an area that is a lighter shade of blue to surrounding areas. Within this the 850 hPa temp is greater than -6 but less than -8. This is the same shading that you are referring to over the north of Ireland.

Just to be 100%, I did some colour sampling. The area you refer to over the north of Ireland has a colour of #0036FF. The area beyond the isotherm at the very north of Scotland has a colour of 0000FF - a different shade of blue, looks very similar on either side of that isotherm however it means that north of it, the temp is lower than -8 (between -8 and -10, when using the colour scheme as a reference). South of it is GREATER than -8 (between -6 and -8, when using the colour scheme as a reference). Therefore nowhere in Ireland is under -8 uppers in that chart and most likely are not under -7 either....probably nearer -6.

TWO’s chart viewer has the detail at some -7 in NI wenesday but widespread -7 air over the Republic and the Irish Sea thursday
The important thing to note it’s advecting in and not much yet to stop it
No point in arguing over a single degree as ideally we’d like -9 or lower for a while and Spidey senses are telling me that’s entirely plausible eventually ,all good anyway if you get me ?

Floki

George Sunsnow has posted about the Irish Sea temperatures and advection.

So just to remind everyone that the irish sea is currently 13c (warmer than the sea in the west of Ireland) atm.
So if you wanted a perfect scenario for snow, you kind of have it maybe from Tuesday night onwards (for the east coast) with these cold upper air temperatures and warm sea could see a lot of precipitation (looks like snow) coming off the irish sea.
All depends if we get a north easterly and where this HP will be (and obviously cold air and dam line).

Also it would help if there was frost before any snow for snow to stick.
The west and north are getting it atm. Maybe the east will get some next week?

Gaoth Laidir

Highdef is right, the ECMWF shows the -8 isotherm nowhere near Ireland next Wednesday. Here's a zoomed in version of the actual numbers.



Here's the snowline, between 200-400 metres.

sryanbruen

The argument is over and done with. We've discussed it and it was more of a misunderstanding than anything. Leave it behind. As it's sorted now, time to get back to the point of this thread.

Just awaiting on seeing what the GFS 18z will show.

Stetsonfrank

sryanbruen wrote:

Just awaiting on seeing what the GFS 18z will show.

What time is this issued sryanbruen?

sryanbruen

Stetsonfrank wrote: »

What time is this issued sryanbruen?

Now, 9:30.

icesnowfrost

That blocking was kinda showing up a few days ago but run to run between th ECMWF and the Gfs where not in agreement, however it's great to see the GFS come into agreement.
Lots if dry weather though if we could get a few low pressure systems come up against that cold we could get decent snow ❄️

George Sunsnow

-7c 850 air is fringing Antrim on the ECMWF on Wenesday
By Thursday it’s widespread into Leinster and the Irish Sea
That would put the white lad into most showers should they develop in areas like Rathdrum in Co. Wicklow and higher parts of South Dublin

And using my adjacency rule of thumb possibly into Docarchs back garden if he’s not too far from lamb Doyle’s

But anyhow,more changes will happen

If the pattern persists,our forum’s very own air pilot Gaoth Láidir usually has access to paid for aviation weather charts that he will drill into the yea or nae in your back yard specifics with ,as will no doubt MT

sryanbruen

GFS 18z tries to bring in an easterly but fails. But at day 10, it isn’t important anyway. The fact that the model wants to continue cold and blocked conditions is good enough at this stage. Plus it’s still very uncertain when the first ridge next week bringing us the northerly will collapse.

nacho libre

Good grief the latest GFS is very good. It has a stellar Greenland high in place by the 11th of December. If we could only bank this chart:

Meteorite58

Looks even nicer on the next run with a very cold air mass heading our way perhaps. Long way off but certainly trending cold.

The GFS has HP build to our W next week and nudges closer and over us as the week goes on. Presently showing a slow moving area of LP move down through Europe which would bring cold N and NE winds down over Ireland from about Tues, we being sandwiched between Hp and LP .

ATM nothing stormy showing up on the charts for the next week or so.







Tropical Tidbits

BLIZZARD7

AO forecast to go quite deeply negative, the NAO a little bit negative.





Looking like a complete collapse and possible reversal of zonal winds, the Polar vortex is going to stay in tatters for the foreseeable if this happens. We are quite well setup for a prolonged cold spell to kick in, the question is will the blocking continue to be in favorable places...
I expect some serious charts to start appearing on the models over the next few days.

sryanbruen

The GFS 12z is showing signs of retrogression on 3 December before another northerly yet again takes place. Now that's what I call a Greenland block!

sryanbruen

The ECM 12z is pretty much a carbon copy of what the GFS 12z has on offer. High pressure retrogressing on 3 December before a northerly takes place on 4 December.

BLIZZARD7

Indeed, it seems that every time a northerly collapses we have another shot of WAA into Greenland and the subsequent northerly is that bit colder each time, long May it continue!