FI Charts (T120+ onwards) Summer/ Autumn 2018 **READ MOD NOTE IN FIRST POST**

hatrickpatrick wrote: »

Oh my days ðŸ˜ðŸ˜ðŸ˜

The eagle has landed. Possibly the best cold run I have ever seen. The 6z GFS. Hopefully the ECM moves toward it. But OMG

torres9kop wrote: »

What would this mean if it happens??

Cold weather, that GFS chart = snow and a long way to it warming up

kneemos wrote: »

BBC has it turning milder and wet by next weekend.

Even if it does the odds are well stacked for cold weather to be lurking in the near future afterwards

I'd call the 18Z GFS an upgrade on what we've been seeing today. Still not as epic as what we saw earlier this week in FI, but very much all to play for it would seem.

ECM 0z is...... Interesting O_o

Not really sure what to make of this. Very peculiar setup.

I'm still sticking to what I said earlier for the moment. I don't think the low will be quite as deep as what is being shown (maybe closer to 990 or 995 hPa?), we still are pretty far out for now. Also wrt the possible cold spell, I think the ECM should improve but the GFSP should back down a little giving us something close to a halfway house solution. I'm no expert though... my reasoning is because I feel like the factors are too favourable for an ECM solution but the GFSP is too extreme and we rarely get something to that extreme. We shall see.

Ukmo as off 144 hours

Just use image tags...

Chris_5339762 wrote: »

In my (very limited) experience I've found that when the New York area floods with snow (as has happened) it tends to enhance the jet and we end up with storms and bad weather. Wonder if this will happen now and push this cold area back?

That's what *usually* happens when there is a northwest to southeast trajectory of the jet stream across North America. High pressure builds to the west of the US but on the other side low pressure digs down from Canada into the northeast with cold air plunging down from Canada at the same time. This cold air pushes down towards the jet stream and hits the relatively warm waters of the Atlantic Ocean. The contrast in temperature leads to an intensification in the jet stream. This is what happened in Winter 2013-14, the atrociously wet and windy Winter and the wettest ever recorded before 2015-16 came along.

Something like this is usually as a result of the path of the jet stream which I mentioned but also can be as a result of the positioning of the blocking. Around this point in time, it's more the path of the jet rather than the blocking as the blocking has yet to retrogress to Greenland.

Some years the blocking can be very powerful and extensive to the point where it can be cold (even bitterly so) on both sides of the Atlantic. This was the case in 2009-10, 1995-96 and 1962-63. 1977-78 was another Winter that had several instances of such though it was more temporary than prolonged.

A weakening in zonal winds in the stratosphere as predicted by the GFS and CFS ensembles (if they verify obviously) during latter part of November and for some December should result in more extensive blocking over the Arctic but as ever with the weather, it's no guarantee. If more extensive blocking doesn't appear during the said periods and the zonal winds weaken to very slow speeds then I think it should appear around or just after Christmas.

The models are still trying to get a grip on where this blocking to the north will exactly sit as well as where the trough to our southwest will anchor. If I was to make my own educated guess, I'd lean more towards an Atlantic onslaught as I've previously stated, I expect nothing special this side of the Winter. However, I think "very mild" conditions like we have seen for a good part of November are unlikely with this Atlantic onslaught as the jet stream will be more meriodional (due to various factors including the approaching solar minimum) and or on a southerly track.

The pattern is one where slight adjustments can make huge differences. High pressure is trying to get into southern Europe but there is also blocking over Greenland (apart from some GFS runs during the first few days of December which show a strengthening of the Polar Vortex).

Let's wait and see, shall we?

Snowbiee21 wrote: »

Can we get updates as 18z rolls out , please

Trust me, you don't want to know. 🙈

The consensus right now is that the models are only useful out to a few days, because the situation in the Atlantic is very unusual, and thus they're all going a bit haywire trying to resolve it. That big, more or less stationary low anchored to our West is responsible for a lot of the havoc.

A few of the regulars on Netweather have gone so far as to suggest everyone takes a few days off from model watching, since it's so frustrating right now and whatever long term solutions they throw up are genuine all-out FI, with massive flip flops going on all over the place. It's a fascinating battleground scenario if you're just interested in how the models work and how they're going to handle this, but if you're actually hoping for a particular solution and the process of getting to it is less interesting, you don't have much to gain by watching this except causing yourself an unnecessary emotional rollercoaster