Chris.R

It’s 25th Jan 2013 all over again!

Torrential ice pellets with the odd flake. More flakes now.

Very heavy ice pellets. It seems my theory was correct.

Mainly ice pellets now. Think there’s a lot of sub-zero air above me but the inversion is developing now.

Temp down to 0.8°C. Accumulation starting to develop, mainly ice pellets. Notice ice was forming before the rain was beginning to freeze from earlier.

Really heavy all of a sudden, massive flakes.

Flakes getting bigger.

Proper snowflakes now with ice pellets mixed in. Hardly any rain drops left. Get in.

Watch out for those ice pellets as that’s a sign that the 850s are above freezing if they become the dominant precipitation type.

Here we go it’s turning.

Apps show heavy snow for me now as well.

:-) Brilliant! I’m going to be the last one at this rate.

Quite a strange mix of partially melted snowflakes, some ice pellets and raindrops now. Getting heavier again.

Sleet now with a few ice pellets. 1.4°C

Heavy rain now. Think it’s just about to turn.

Wow nothing here yet. Well done

Temp now on a steady fall but rain has almost stopped.

Freezing levels were supposed to fall all morning down to about 800 feet by 11:00 as that layer of cold air just above the surface grows.

One or two massive snowflakes mixed in with the rain

Light rain now.

Light sleet here, not far away. Dewpoint dropping.

Liverpool taf has rain/snow from 7:00 to 11:00, then freezing rain until 13:00. Manchester has rain/snow followed by snow followed by freezing rain.

Right then. Sorry I’m late, was out for longer than expected. My thoughts on this morning then; hope there’s someone still around to read this. It is a rather interesting and slightly complex set up so I think it will be best to look at it in terms of layers of the atmosphere. As we go through the early hours, The wind backs into the East-south-east and temperatures at the surface are near or below freezing. At first there is nothing unusual about the atmosphere, it gets colder the higher up you go. As we get towards 05:00 however, a layer between about 2000-8000 feet begins to get colder. At the same time, the air above this begins to warm as the Atlantic waa arrives. although still remains below freezing all day. By about 09:00, when the precipitation has already got going, the top of the middle layer (4000-8000 feet) begins to warm substantially and by around 11:00 rises above freezing. This is an inversion layer. In the meantime, there is still a substantial layer of sub-zero air between about 800-4000 feet and this doesn’t get mixed out untill the early afternoon. Thus as we go through the morning, precipitation is likely to start as snow for mostwhen most of the atmosphere is below freezing. As the inversion layer develops however, snowflakes falling through it will melt and then refreeze as they fall into the sub-zero layer below. This gives the rare potential for ice pellets. As this inversion grows The precipitation will have less and less time to refreeze on its way down to the surface and so freezing rain or just rain is then more likely. In summary: this is not your average Atlantic invasion, there are some interesting atmospheric dynamics at play here. Let’s see what happens.

0.4°C now, on a free-fall. About to get 8th air frost of the season.

Down to 1.0 C already. Colder than forecast by far. A good sign.