FI Charts ( T120+ onwards) Winter 2023/2024 **READ MOD NOTE IN FIRST

Here come the -10s on a north easterly!

The -10's from Canada are going to join in yet!

On the dividing line, there is Athlone going ....

GFS at the very latter stages is very reminiscent of December 1981 to January 1982

Despite producing a 'mad' operational run at 18z, the GEFS is only slightly colder than the 12z in the second half of the run. The only notable aspect of the 850s is the absence of any strong signal for much milder weather over the next 16 days along with the lack of support for severe and lasting cold. Notable cold from Sunday through Thursday has roughly 30-35% support. This was higher in the 00z GEFS despite the latter's operational run looking much milder.

It will be shortly time to move into the 'up to 120hrs' thread.

Fairly solid agreement in the 18Z ECMWF ensembles that cold air will extend down across Ireland from Sunday into Monday. Only change from the 12z was a slight shift east of heights toward Ireland meaning that the sinking airmass will initially bring little in the way of precipitation.

850s ensembles for Belfast, Dublin and Cork as the airmass sinks south

Below is the 850s up to 144hrs for The Midlands

UKMO

Another consistent run from the UKMO with a northerly introducing colder air from Sunday into Monday. There is a warm (less cold) sector to the west but on the other side the Iberian heights drop while the Azores low isn't as far north.

GEM

Similar to 120 hrs as the UKMO after which the same idea of a brief warm sector dilutes the cold somewhat for 12-18 hours before another plunge of cold. Looks nice and blocked to the end of the run

GFS

Not dissimilar to the ICON with that warm sector from the UKMO and GEM repeated here. It stays cold into the following weekend (at least) with battleground scenarios popping up and the 'neige' chart getting a pasting. Throw in some dartboard lows too. A cold op run but as always with GFS, the ensembles are key.

SUMMARY

Cold overnight runs with a coming together of output (ECM not out yet). Each has a slightly less cold sector on Tuesday before colder air arrives from Iceland. All show potential for high impact weather (disruptive as the UK Met says) and in general the op runs significantly extend the cold spell.

And in the words of Met Éireann on met.ie

Stick it in the LOUVRE!!

I'd have thought the theme of this morning's runs is:-

1. Progress of the cold southwards is looking more complicated, and

2. Getting closer to model concensus

While 2 is welcomed, 1 is a disappointment and you would be afraid the cold spell will get further watered down.

The GFS in its outer stages looks interesting. Some would be happy if that is the direction of travel. Although it could be a case of de ja vu with that

In the more immediate timeframe, it is complicated to get the cold in but that is the scenario whereby some parts of Ireland could get a dumping. I just wouldn't be confident of it staying on the ground for long in this setup. We could get snow to rain events too. If that's the case I would prefer to miss out altogether

Yeah if that’s the case then the low can stay well south of us. Do NOT want rain. And snow to rain is pointless.

Hope to see heights increase and maintained over Greenland. Make things easier for us to get as much cold over us as possible before any moisture from the south comes up. That would lead to better frontal snow prospects for us.

Yeah gfs 6z looking completely different .. much better.

This run certainly seems left of field. A rogue run or a new signal courtesy of the models getting a handle on recent events in the strat and the impact on the trop' from them.

A northerly of old! With a possible polar low in the flow . Bank!

I think that chart is based on the UKMO 12z from yesterday so we will be seeing the updated version of that later which will be the 96z. You can understand the UK Met's bullishness when you see straight northerly with troughs like that.