FI Charts ( T120+ onwards) Winter 2020 **READ MOD NOTE IN FIRST POST**

Happy New Year to everyone on the weather forum, particularly those whose names I like to see pop up regularly on the FI threads during the winter cos it can quite often mean that a certain type of weather could be on the way ;-) hope 2021 is good to you all!

JanuarySnowstor wrote: »

Does anyone else feel we are just going around in circles!!
Cold but not cold enough, frosty but no snow!!
Like in a way if it's not going to snow what's the benefit to this cold....argh!!

Some places have seen snow already, and some more places could get some over night, and over the next seven days.

If this very cold air could sink south and pay us a visit, i think we'd all be happy

JanuarySnowstor wrote: »

Does anyone else feel we are just going around in circles!!
Cold but not cold enough, frosty but no snow!!
Like in a way if it's not going to snow what's the benefit to this cold....argh!!

It will snow just not in Cork

Nah only kidding.

There will be opportunities for snow in various places over the next 10 - 14 days i'm sure. All the models show just that.

pad199207 wrote: »

We will give him a chance, just say the 13th for now

Ah sure you'll get your fix tomorrow morning, should keep you going for a couple of days. Try and hang in there :cool:

Gonzo wrote: »

this cold spell is fairly pathetic and looks like very little change with just low level cold until the mild rolls back after next weekend. Hopefully we get another shot in February.

It certainly has been a let down who jumped at big snowfall forecasts in FI but it’s far better than mild muck from the West.

I would caution that we had an SSW event last year that didn’t do anything for snow fans so an SSW doesn’t promise anything but it does increase chances and I think the second half of January offers hope, but that’s all it is for now.

God lads, it's FI for a reason. I understand the disappointment but there is no need to get your knickers in a twist. In blocking situations, there will always be many changes to the exact scenarios. Remember how long it took before models latched on this coming week's easterly? People have rose tinted glasses now on the 2018 Beast from the East event being smooth sailing. Let me tell you, it certainly was not. It too had its changes every now and then with many comments on models backdating instead of things being brought forward. I remember this vividly because there was so much pessimism leading up to it. There were 3 peaks of uncertainty as well and each one coincided with 3 peaks in stratospheric warming before it started to calm down and the certainty built after 17 February with the odd run showing the anticyclone too far south.

Those 18z runs discussed previously were highly unlikely. They just were, those were best case scenarios. Same with some other runs. Perfect amplification to allow the flooding of cold air south. Whilst it is looking now that the GFS FI suggesting height rises over Europe may verify for mid-January, it was quite ridiculous to think of such with amplified blocking to our north. That is not looking the case now as the trend of late since my last post has been more of a mid-Atlantic ridge than a full on Greenland blocking feature. This will mean a flatter pattern overall and not enough to descend the country into the much plead for (on here) big freeze which was again unlikely, that some runs suggested.

As for sudden stratospheric warming, it is ongoing and set to become a major event (reversal at 60N) in a few days or so time. The stratospheric polar vortex is in the process of displacing from the North Pole at a similar time to that of the 2013 major SSW event and likely to reverse at a similar time too. The 2013 event took a week before it evolved into a split. If we do see a split this time, the similarities are likely to continue there.

What does the SSW event mean for us? Well it is all about where those vortices sit, displaced or split. Stratosphere and troposphere placements of ridges and troughs do not always correlate but with a major SSW event like this, more than likely they will. Historically, stratospheric warming events increase the risk of blocking in the higher latitudes which gives an increased risk of cold spells for Europe but it's not always as straightforward as that due to a few things:

1. Where the blocking sits.
2. If the warming downwells to the troposphere.

The 2018 SSW event was an extreme example of both a monster anticyclone to the north that retrogressed from Siberia to North America in the space of 2 weeks going completely against the zonal flow and the severe cold airmass associated that was brought in from Russia via a polar continental airflow. It was also an example of a quick tropospheric response with the major SSW event central date (day of reversal) being on 12 February 2018 and impacts were felt as soon as 9-10 days after as the Scandinavian High began to form. There is no comparison to that at the moment. 2013 is a better comparison but at the same time, all major SSW events are unique.

If we see downward propagation, which models like the Glosea5 do show occurring, the SSW event is likely to either prolong or reinforce the blocking unless we see something like a 2018 where the retrogression is strong enough to play against chances of a very cold spell in Europe. It is this that I am watching out for to result in a displacement (or retrogression) of the stubborn Russian high that has been chillaxing in its hammock for the past two months over there. We usually see a milder period before the effects of a major SSW event are felt down on the surface as happened in 2018 after a cold start to February. Again only using this as a reference point, not a comparison so do not start thinking a 2018 repeat on the way, definitely not.

Let the SSW do its thing and watch out for where the blocking sits in the second half of January if we do see a tropospheric response. If we don't and see a sudden collapse of all the blocking, it would possibly be the biggest flop there has been and bigger than December 2012. Fortunately (or unfortunately depending on your point of view with cold spells/snowfalls), that is highly unlikely.

sryanbruen wrote: »

God lads, it's FI for a reason. I understand the disappointment but there is no need to get your knickers in a twist. In blocking situations, there will always be many changes to the exact scenarios. Remember how long it took before models latched on this coming week's easterly? People have rose tinted glasses now on the 2018 Beast from the East event being smooth sailing. Let me tell you, it certainly was not. It too had its changes every now and then with many comments on models backdating instead of things being brought forward. I remember this vividly because there was so much pessimism leading up to it. There were 3 peaks of uncertainty as well and each one coincided with 3 peaks in stratospheric warming before it started to calm down and the certainty built after 17 February with the odd run showing the anticyclone too far south.

Those 18z runs discussed previously were highly unlikely. They just were, those were best case scenarios. Same with some other runs. Perfect amplification to allow the flooding of cold air south. Whilst it is looking now that the GFS FI suggesting height rises over Europe may verify for mid-January, it was quite ridiculous to think of such with amplified blocking to our north. That is not looking the case now as the trend of late since my last post has been more of a mid-Atlantic ridge than a full on Greenland blocking feature. This will mean a flatter pattern overall and not enough to descend the country into the much plead for (on here) big freeze which was again unlikely, that some runs suggested.

As for sudden stratospheric warming, it is ongoing and set to become a major event (reversal at 60N) in a few days or so time. The stratospheric polar vortex is in the process of displacing from the North Pole at a similar time to that of the 2013 major SSW event and likely to reverse at a similar time too. The 2013 event took a week before it evolved into a split. If we do see a split this time, the similarities are likely to continue there.

What does the SSW event mean for us? Well it is all about where those vortices sit, displaced or split. Stratosphere and troposphere placements of ridges and troughs do not always correlate but with a major SSW event like this, more than likely they will. Historically, stratospheric warming events increase the risk of blocking in the higher latitudes which gives an increased risk of cold spells for Europe but it's not always as straightforward as that due to a few things:

1. Where the blocking sits.
2. If the warming downwells to the troposphere.

The 2018 SSW event was an extreme example of both a monster anticyclone to the north that retrogressed from Siberia to North America in the space of 2 weeks going completely against the zonal flow and the severe cold airmass associated that was brought in from Russia via a polar continental airflow. It was also an example of a quick tropospheric response with the major SSW event central date (day of reversal) being on 12 February 2018 and impacts were felt as soon as 9-10 days after as the Scandinavian High began to form. There is no comparison to that at the moment. 2013 is a better comparison but at the same time, all major SSW events are unique.

If we see downward propagation, which models like the Glosea5 do show occurring, the SSW event is likely to either prolong or reinforce the blocking unless we see something like a 2018 where the retrogression is strong enough to play against chances of a very cold spell in Europe. It is this that I am watching out for to result in a displacement (or retrogression) of the stubborn Russian high that has been chillaxing in its hammock for the past two months over there. We usually see a milder period before the effects of a major SSW event are felt down on the surface as happened in 2018 after a cold start to February. Again only using this as a reference point, not a comparison so do not start thinking a 2018 repeat on the way, definitely not.

Let the SSW do its thing and watch out for where the blocking sits in the second half of January if we do see a tropospheric response. If we don't and see a sudden collapse of all the blocking, it would possibly be the biggest flop there has been and bigger than December 2012. Fortunately (or unfortunately depending on your point of view with cold spells/snowfalls), that is highly unlikely.

Regards the 2013 ssw Ireland got nothing out of it. The uk got a fairly decent cold spell though nothing special during 2nd half of Jan. The cold didn't make it across the irish sea,so frustrating.

Roots 2020 wrote: »

Belfast was under snow for 10 days from 22/23 March! March was a record cold month. Plenty of snow. Waterford on 12th March. Where it was a rarity near the coast.

Wasnt forgetting march 2013. But was a bit late for my location.

Snow showers would be piling on to the east coast with this next Friday. There is a good few opportunities in the next week or so for some snow in various parts of the country.

Some are definitely letting the perfect be the enemy of the good. These are good charts for Ireland in any winter (depending on perspective of course). Just roll with it and if the SSW event comes in to play later then all the better.