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FI Charts ( T120+ onwards) Winter 2022/2023 **READ MOD NOTE IN FIRST POST**

  • 22-11-2022 6:31pm
    Moderators, Science, Health & Environment Moderators Posts: 16,326 Mod ✭✭✭✭Gonzo

    Mod Note

    This thread is for posting/discussing/analyzing FI CHARTS ONLY i.e. Charts in the unreliable time frame, generally +T120 onward for Winter 2022/2023.

    If your post does not specifically relate to an FI chart then it doesn't belong here - Off topic posts will be moved



    Ok, I've had enough of this Autumn and with a week of it still to go, I thought it would be a good idea to open the Winter FI thread extra early, as the GFS short range models are already showing us an insight into the first week of December at this stage.

    After what seemed like over a year of relatively dry and high pressure dominated weather, the autumn brought a significant pattern change to something much wetter since September 2nd. We are still currently in this very unsettled Atlantic dominated pattern but it does look like a change could possibly be happening just in time for the gates of winter of swing open!

    The models are currently playing around with high pressure for the 1st week of December but what they are not sure of is the high pressures position. The positioning of the high pressure at this time of the year is critical to how cold or mild it could be. If the high sits right over us expect plenty of frost and maybe fog. If the high sits to our east, expect mild southerlies or south-westerlies. If the high is just off our west expect a cool north-westerly flow from the Atlantic. If the high pulls out to the mid Atlantic expect maybe a cold northerly shot. If the high positions itself between Iceland and Scandinavia, expect some sort of very cold north easterly etc.

    The GFS 12z just rolled out and is showing a rather chilly 1st week to December as heights try to rise towards Greenland. We begin winter December 1st with a rather chilly easterly wind from the Irish/North Sea. This should be a much dryer scenario than what we are currently in. There maybe some showers on Irish sea coasts but at this stage unlikely to be wintry.

    We generally keep this easterly going through the 1st week of December but it is not a proper cold easterly, a rather cool and slightly unsettled easterly so eastern and northern areas would expect showery outbreaks of rain at times, It would feel very raw in this setup but unlikely to be cold enough for snow away from high ground as we are not drawing in a properly cold easterly.

    We finish up with heights trying to rise over Greenland and Iceland.

    This particular run doesn't really get high pressure sitting over us, so less in the way of frost and fog with this one compared to some of the earlier GFS runs I seen over the past few days. There is an overall cooling trend for the first week of December but nothing properly cold either. Overall it looks like we should get a respite from the Atlantic for at least a week, although it may not be completely dry. There is alot of uncertainty to the first week of December as the positioning of the high and the overall strength of it will be key to how dry we get, if it will become chilly and frosty or could we potentially open the doors to something colder from the north or the east. Alot to play for but it does look like we will begin winter on a slightly more seasonal note than usual.

    Once we get the next week out of the way, things should start to become a bit dryer, but not completely dry either. Expect this outlook to change quite a bit over the coming week especially with the positioning of the high pressure. After a very mild to warm and highly unsettled November, these charts make a welcome change and I wouldn't be surprised if the first week to 10 days of December end up fairly chilly and more seasonal.

    Post edited by Gonzo on



  • Registered Users Posts: 77 ✭✭Brendan offaly

    A lot of flip flop with the long range models.

    I see the latest GFS run showing a nice easterly developing.

    There are signs of blocking setting up in December so hopefully the High pressure sits favourable for some wintry weather.

  • Moderators, Science, Health & Environment Moderators Posts: 16,326 Mod ✭✭✭✭Gonzo

    The models are definitely struggling a bit with the first week of December, it's still a week out and the Atlantic will be tough to shift especially for us. If we do get a break from the Atlantic onslaught it may only be for a few days to a week before it's back again.

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  • Registered Users Posts: 8,913 ✭✭✭Danno

    Indeed there is an interesting trend developing...

  • Registered Users Posts: 4,033 ✭✭✭PokeHerKing

    Yous had to go and jinx us didn't yis!

    Hopefully the pub run just got some bad gear!

  • Registered Users Posts: 142 ✭✭Niall145

    Don't worry it's upgraded again.....for now

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  • Registered Users Posts: 232 ✭✭konman

    The parralel run (which becomes the operational in 5 days) looks a bit better.

  • Registered Users Posts: 564 ✭✭✭bazlers

    Probably not the correct place for this but anyhow.

    Back in December 2010 where did the source of the cold originate and what was the temperature there at the time?

    Also in late February 2018 the east midlands seemed to get most of the snow from streamers before Emma moved up along the east of the country. Just wondering did the source of the cold originate from the same area as 2010 and what was the temperature from its origins? Thanks.

  • Registered Users Posts: 4,033 ✭✭✭PokeHerKing

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  • Registered Users Posts: 564 ✭✭✭bazlers

    Cheers, but it doesnt really give the source of the cold or the depth of cold from that source. Just that it was arctic air. Was trying to work out the temperature differential between the Irish sea and air temp of that cold air to produce such convection in 2010 and 2018.

  • Registered Users Posts: 4,033 ✭✭✭PokeHerKing

    Needs to be around a 14 degree difference between airmass and sea temps to produce lake/sea snow.

  • Registered Users Posts: 1,993 ✭✭✭John.Icy

    I believe this should link you to the 24th of November 2010 as the cold starts approaching from the East, 850s shown on this set of charts so you can see depth of cold and also where it's coming from, northern hemisphere view. The next 15 days are loaded on that link but you're free to change them around. The second bout of cold from mid-December came from the north then.

  • Registered Users Posts: 77 ✭✭Brendan offaly

    Perfect time of the winter season for this to happen, ( if it does at all).

    All we need is a little luck.

    Ireland is due a decent cold spell.


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