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

patneve2

Not bad at all and can't complain at this type of output.



We should know our fate by lunchtime Saturday

Kermit.de.frog

nacho libre

phew. Much better
I need a drink after waiting for this run.

gerrybhoy

nacho libre wrote: »

phew. Much better
I need a drink after waiting for this run.

I've been off it since new years eve,don't study the models and even I'm gagging for a pint after all the shenanigans

nacho libre

The high just about makes make it to the tip of greenland in FI. That should lead to a reload hopefully.

Although a very messy picture up to that point. It could be showing something different on the next run.

I should have said potentially a beautiful mess.

BLIZZARD7

Not the first run today to show a potentially very good snow event days 8-10 sort of timeframe.

nacho libre

BLIZZARD7 wrote: »

Not the first run today to show a potentially very good snow event days 8-10 sort of timeframe.

If you recall the GFS was showing something similar a few days ago. Could it be that it comes to pass?

snowstorm445

BLIZZARD7 wrote: »

Not the first run today to show a potentially very good snow event days 8-10 sort of timeframe.

All hypothetical obviously but given the cold temperatures at the surface what sort of uppers would be required for that to turn to snow? Would it need to be the standard -8 or could it conceivably fall at a higher temp (thinking of the south coast there in particular)? Not sure it would be as marginal as your standard northwesterly.

BLIZZARD7

snowstorm445 wrote: »

All hypothetical obviously but given the cold temperatures at the surface what sort of uppers would be required for that to turn to snow? Would it need to be the standard -8 or could it conceivably fall at a higher temp (thinking of the south coast there in particular)? Not sure it would be as marginal as your standard northwesterly.

Nowhere near as marginal as a northwesterly- South Coast might be marginal though, it would depend on if surface winds are offshore or not I would think. It can snow with uppers just below 0c as long as there is no warmer air between there and the surface. Hopefully if we get to such a situation we are discussing possible snow depths rather than any marginalty.

Kermit.de.frog

ECM ensemble average at 168







Most of Ireland is sub -8c at 850 hpa through to at least next weekend...

BLIZZARD7

Savage mean, -10's entrenched over the east- Next week is gonna be a shock to the system for most people.

Meteorite58

Yes looking very cold up until and maybe over the following weekend and perhaps the most precipitation at the end of next week too going by the present run.

Iancar29

510 dam line over Ireland. Pretty marginal for snow

-13 dew points...yup, too marginal for me...



:pac:

Elmer Blooker

Awful ECM, the block moves so far west .... well, its no longer a block.
Well into FI but a dog's dinner of a chart.

JCX BXC

Ignoring the low pressure just to the South of Ireland bringing NE/E winds and likely snow are we?

pistolpetes11

JCX BXC wrote: »

Ignoring the low pressure just to the South of Ireland bringing NE/E winds and likely snow are we?

Yup I don't think it looks that bad at all to be honest

typhoony

a couple of silly runs from Gfs yesterday, ECM is the one to watch, most of the runs yesterday could be binned however the 0z ECM looks a very plausible scenario of a Low coming up from the South, in the past and I mean a long time ago certainly not in recent memory when we had entrenched very cold air ,a low like the one progged by the ECM would dump a load of snow in the East and SE and the rest of the country would get very little

nacho libre

pistolpetes11 wrote: »

Yup I don't think it looks that bad at all to be honest

He is focused on the longetivity(?) of the cold. If a west based nao does comes to pass it could happen. For me it's like the netweather posters back on December 16th 2010 immediately focusing on the breakdown in fi, rather than nine days of snowy charts before it. It might sound cheesy, but this is a classic example of learning to enjoy the moment- and as we all can see those ecm charts would bring much joy to us snow mad folks for four or five days!

Elmer Blooker

nacho libre wrote: »

He is focused on the longetivity(?) of the cold. If a west based nao does comes to pass it could happen. For me it's like the netweather posters back on December 16th 2010 immediately focusing on the breakdown in fi, rather than nine days of snowy charts before it. It might sound cheesy, but this is a classic example of learning to enjoy the moment- and as we all can see those ecm charts would bring much joy to us snow mad folks for four or five days!

Correct.
This 06z is quite similar to the chart I posted earlier, blocking to N and NE gone. Everyone has different expectations from this coming spell and mine is for a memorable long spell after a SSW of such magnitude and not a snap lasting about a week at most.

lucernarian

nacho libre wrote: »

He is focused on the longetivity(?) of the cold. If a west based nao does comes to pass it could happen. For me it's like the netweather posters back on December 16th 2010 immediately focusing on the breakdown in fi, rather than nine days of snowy charts before it. It might sound cheesy, but this is a classic example of learning to enjoy the moment- and as we all can see those ecm charts would bring much joy to us snow mad folks for four or five days!

Nothing wrong with focusing on what lies ahead but I wouln't call that an awful ECM chart either

Compared to the start of December with the "Iceland High" arrangement, the PV dropping south was a heartstopper to forecast as each subtle change in wind direction made a dramatic difference for each area forecast to get streamer heaven. I made many a post warning about the perils of upper air wind direction

BLIZZARD7

Elmer Blooker wrote: »

Awful ECM, the block moves so far west .... well, its no longer a block.
Well into FI but a dog's dinner of a chart.

Elmer I thought you liked snow? The ECM shows copious amounts of snow in the next 10 days, how can you call it awful?

After the changes we have seen in the last week anything can and will happen, FI is about 120hrs at the moment I feel - The cold is definitely coming, the angle of attack somewhat uncertain still though, likely somewhere is going to be buried looking at all the charts though.

patneve2

Cannot take my eyes off that ECM run. Ok, the cold breaks down eventually, but Eastern areas would still get 3/4 days of snow showers, with 2 of those days seeing frequent snow squalls with temps at or below zero. If it came to fruition the ECM run would easily dump 20+cm of snow at my location.

I'm still considering this FI though. Even a 20/30 degree difference in wind direction can mean 0cm here and 25cm in Louth or vice-versa. ECM mean looks pretty good though I have to say.

gabeeg

Have the models reached a consensus on the arrival time yet?

Seems to be narrowing to around Monday morning/afternoon

lucernarian

The ECM has really gone out of its way to ease our worries today!

And what about this for a jet stream pattern next week:


I've never seen one like this historically or otherwise (though I'm sure similar exist somewhere in the archives)

Kingswood Rover

Woe a north easterly wind coming off the Atlantic, never seen that before west is the best in that setup.

Fantastic charts the last few days it has to be said. In Dundalk, so for any lake effect snow here the wind direction is key. Anything north of an easterly and the Cooley/Mourne hills will block out any precipitation. South of an Easterly is good for us.

JFKIRELAND

Guys,
Can someone educate me here.
I understand all of your excitement with the various runs - I'm in too.
However, I have it in my head that anything above 528 DAM is not great for snow.
530's can produce if the air is cold enough (which it likely will next week) but 540 - 550 DAM as in the UKMO chart above?
Am I missing something?

lucernarian

JFKIRELAND wrote: »

Guys,
Can someone educate me here.
I understand all of your excitement with the various runs - I'm in too.
However, I have it in my head that anything above 528 DAM is not great for snow.
530's can produce if the air is cold enough (which it likely will next week) but 540 - 550 DAM as in the UKMO chart above?
Am I missing something?

That's geopotential height, which is typically lower in low pressure areas as well as colder airmasses. What you're thinking of is thickness.

Thickness is a direct measure of the distance between the 500hPa (in your example) and 1000hPa levels. There's less distance when the air is colder (and therefore denser).

For snow in maritime areas like here, the 850-1000 thickness charts are a better predictor. (128 dm is a good number on those charts)

JFKIRELAND

Ah ok,
With you now, so I was looking at the GeoP Height chart instead of the 850-1000 Thickness chart.
Thanks so much Lucernarian for helping us out:p
JK

nacho libre

Elmer Blooker wrote: »

Correct.
This 06z is quite similar to the chart I posted earlier, blocking to N and NE gone. Everyone has different expectations from this coming spell and mine is for a memorable long spell after a SSW of such magnitude and not a snap lasting about a week at most.

Well unfortunately those are very hard to come by, even with the background signals we have. A west based negative nao should it transpire, after the age of a postive nao, is kind of sods law. however, i'm still not buying a breakdown until i see the UKMO long range forecast change to reflect this outcome. They are steadfast so far in this being a potracted cold spell. I will need to be committed if it's a short spell and somehow end up being exclusively dry, but that looks unlikely now. Some places are going to see snow next week, maybe not as great amounts as the current runs suggest, though.