FI Charts ( T120+ onwards) Winter 2024/2025 **READ MOD NOTE IN FIRST
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can we keep this thread to chart discussion please. There are other threads for general winter discussion.
Overall, we are looking at modest chances of colder weather by mid month. I would put it at around 50% at best. A depression over the Benelux countries is a key factor later next week as is the extent to which the jetstream gets fired up by cold weather in NE USA. The linking up of heights between Scandi and Greenland is the one constant. We need to see how the Atlantic and Benelux depressions interact with the heights. The latest GFS is not hugely supportive of a cold outcome for us in comparison to the other models, but there is much to play out.
www.weatheire.com
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Latest data shows the main weather models easing off on the prospect of a colder spell of weather next weekend.
Much of Europe is set to cool down significantly as the coming week progresses while, at the same time, Atlantic systems will track closer to Ireland's west coast. As things stand, the average of all output places Ireland on a boundary between a milder Atlantic airmass and a much colder airmass.
The outlook for our weather for next weekend into the following week splits 3 ways in terms of % likelihood:- Average conditions with temps 6-9c, small rainfall totals, generally overcast with light to moderate winds (50%)
- Much colder conditions with an easterly component (25%), temps 2-5c, some wintry precipitation, cold windchill effect
- Milder and more unsettled conditions with a south-westerly to westerly component, wind and rain, temps 8-11c (25%)
Data analysis
The data in the first graph relates to daytime highs for Mullingar, County Westmeath over the next 9 days, based on the latest output from four of the main weather models. The main theme is for a general rise in temperatures next weekend. Individual features of the data include the sharp drop in temperatures for Friday on the ECM with a risk of wintry precipitation, the continuation of cool weather beyond the weekend on the GEM, and the ACCESS-G (UKMO) indicating significantly milder weather from the weekend.
Meanwhile, analysis of the last 16 runs of the GFS for Mullingar for midday on Monday, 17th February suggest rather benign conditions with little rainfall and average to slightly above temperatures for the time of year.
Looking ahead
We are very much in a wait and see scenario in terms of how the models adjust to the anticipated amplification of heights over Scandinavia toward Greenland, and the positioning and interaction of depressions to our west and over the Benelux countries with the high pressure. Small adjustments to these features could significantly revise upward or downward the likelihood of the 3 possible outcomes identified at the top of the post.
The uncertainty regarding our weather is further emphasised in Met Éireann’s met.ie outlook, which does not extend beyond Thursday.www.weatheire.com
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Just thought I'd share a post from a poster called Catacol on Netweather who seems to be very knowledgeable and not into the run by run dramas that go on there at times. A lot of it I don't fully understand but we do see the Atlantic taking another backward step on the models this morning.
"The chances of a beasterly departed when we didnt see the vortex split and reverse. At that point deep cold became an outside bet. But it was also flagged that the latter half of this month was possible, and this remains the case. Why? Because:
1. The vortex may not have reversed but it is about to split. See this at 50hpa from the Berlin charts
2. As it splits, downwards frictional support for westerlies ceases. Hence that low in the atlantic that winds itself up and then sort of lacks any interest at moving anywhere. Meanwhile the Siberian half of the vortex also becomes isolated, and rather sits still. The ridge created from the pacific by the lagged impacts of this big spike in momentum therefore dominates our weather
3. This was all fairly predicable. Folk hoping for a big undercut or a raging beasterly did not read the tea leaves.
But as we get beyond the initial split and the momentum that caused it fades, it nevertheless gets intriguing. Observations:
a. Without that downwards westerly frictional support for an atlantic onslaught, we have no atlantic conveyor. But that doesnt mean that an isolation of the ridge wont happen. In fact, given the collapse in relative momentum now, I'd expect the lagged impact of that to allow the possibility of the undercut through next week grow in strength. The models do show it.
b. Without dominant westerly influence, and without the usual vortex forcing in place, we have models struggling. We dont have the usual dominant element. So they are finding a resolution very difficult. Anyone saying "game over" is simply not reading the situation nor grasping the context.
c. High pressure tends to move slower than modelled in my observations, and cold air is often more resilient. So in general I'd suggest the bowling ball low in the atlantic will be kept at bay...
d. ...and from that I'd punt on the air mass to the east continuing to inch our way. Frustratingly slow - but on its way.
e. The MJO is entering favourable phases and it looks as though the amplitude is fair. And I'm still expecting another bounce up in AAM, though it is a day or so slower than I expected. But overall I expect pacific drivers to remain favourable for blocking.
Conclusion? I dont think the atlantic is arriving. The cold in the east will never be a beasterly because we lost the SSW, but the chances of it getting here remain decent. So we can expect a cold spell, possibly an extended spell, with snow chances. They will only become visible at very short range.
Was this not what was always on the cards once the SSW was lost? The only thing I dont understand in here today is why people are so distraught. Perhaps the bar was set too high in the eyes of some, but I think this is playing out broadly as expected. And snow is still in the forecast even without 2018 synoptics. Remember we live in the UK in the days of AGW. Any cold with flakes is to be celebrated. The 1980s this is not and will not be again in our lifetime."
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Yep, in and around.
Analysis of subsequent runs of the Global Forecast System (GFS) weather model from Saturday evening through to this afternoon’s run indicate that the prospects of a cold spell of weather from later this week into the beginning of next week remain low at 30%, a slight rise on yesterday's potential risk.
Much of Europe is set to cool down significantly as the coming week progresses while, at the same time, Atlantic systems will track closer to Ireland's west coast.As things stand, the average of all output places Ireland on a boundary between a milder Atlantic airmass and a much colder airmass. There is a 50% likelihood of such an outcome.
The outlook for our weather for late this weekend into the following week splits 3 ways in terms of % likelihood:
- (50%) Average conditions with temps 5-8c, low rainfall totals, generally overcast with light to moderate winds (50%)
- (30%) Much colder conditions with an easterly component, temps 2-5c, some wintry precipitation, cold windchill effect
- (20%) Milder and more unsettled conditions with a south-westerly to westerly component, wind and rain, temps 9-12c.
The GFS model model runs four times a day, and produces forecasts for up to 16 days in advance, but with decreased spatial resolution after 10 days. The below data is based off the output of the 32 members, which include operational and control runs and 30 lower-resolution members, referred to as the GEFS ensemble.
www.weatheire.com
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