mountain shadow

Christmas Eve shaping up well for the North West... http://cdn.nwstatic.co.uk/gfsimages/gfs.20131218/18/138/prectypeuktopo.png I'm dreaming of a...

Wind picking up now in the East. Must be bad out Mayo/Galloway direction.

That was some rain in Belfast. Been on bus 35 minutes andonly gone about 1/2 mile.

Just been hammered with Rain in Belfast. Traffic gridlocked. Wind isn't an issue....yet!

More like a crawl BFTV.

Smithy, The Met Automated forecasts are notoriously inaccurate. The NAE is far more useful. The further North and West with altitude the more likely you are to see something on Thursday. The Glenshane Pass will be horrendous that's for sure. Blizzards likely in showers.

Decent frost this morning in the Castlereagh Hills with an exciting period of weather ahead... Possible severe/destructive low pressure system battering into the Island with snow chances on Thursday and particularly around Christmas. Seriously though, there is a potential for a pretty brutal storm over the next ten to fifteen days.

Well the PV did shift across the Atlantic.. http://cdn.nwstatic.co.uk/gfsimages/gfs.20131216/18/216/h500slp.png Unfortunately only in this country can we have the PV overhead and its still to warm for snow.. http://cdn.nwstatic.co.uk/gfsimages/gfs.20131216/18/216/h850t850eu.png

Polar profile none to shabby there surely? Certainly a chance the PV could split around Greenland sending a segment towards Scandi bringing in colder air just in time for Christmas? http://cdn.nwstatic.co.uk/gfsimages/gfs.20131216/18/129/npsh500.png

I thought it was a very really possibility 4 days ok, there were subtle signs a vortex segment would move East leaving us in the colder Arctic air.

Well more fool you. The EC32 is THE BEST medium range forecasting tool out there and obviously changes each issue depending on the prevailing situation at the time. How else do you expect Matt to forecast then if not by using the best tool out there? Only a fool or a trickster would stick to a forecast that is clearly going to be wrong, like Madden for example.

Well the 12z's have been more amplified and offered more wintry prospects than the 0z's lately, lets hope the trend continues of more amplification in the mid atlantic and pressure loweing in central Europe towards Christmas and thereafter.

For Northern Ireland: Christmas Day starting wet and windy with maxes of 8oc. Around lunchtime a cold front passes through with winds turning North Westerly and temperatures drop to 5oc with rain showers, sleet/ snow over 2000 feet. As the sun begins to set and the turkey settles the wind strengthens and turns more NNW pulling in a biting Arctic wind with showers becoming progessively heavier and more wintry. By 7pm a full blown blizzard is in progress with frequent heavy snow showers and power outages, candles and coal fire are lit, carols are sung and I pound another glass of Port. Come 11pm, there is a foot of snow, drifting in the wind as I fall asleep on the couch...

Once again the 12z's look more promising, will the 0z flatten it all again?

What I have noticed lately is whatever the 12z giveth, the 0z taketh away!

Agreed, he probably champs at the bit to come back on here, unfortunately his knowledge would be a dead give away as he baffles us with his GWO and GLAAM projections.

If that Pacific low remaind deep as it hits the US/Canadian Western seabaord, would this produce a strong Rockies Mountain Torque event, perhaps leading to wave breaking into the Strat. and/or assist the jet in becoming more meridonial?

Strat temp at the pole on its way down again, a pretty sustained period of below averge polar vortex temps. http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/gif/pole30_nh.gif As mentioned by the great Glacier Point, this is not necessarily a bad thing, because when it goes, it could go with a bang!

There remains the hope the big storms modelled around Christmas track a little further South and get East of the meridian. With the cold locked up at the moment this may release some surprise snow for Christmas Day.

Thought as much, seems a decent spike upwards though.

Matty,Have a look on the historic charts for this day in 2004 and then look at Christmas Day. Can't write a White Christmas off just yet.

A return to average or the start of a warming? http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/gif/pole30_nh.gif

The Northern Hemisphere shows a different picture with a disrupted vortex and Heights pushing poleward on the otherside. Maybe a Northerly down the line?

Im staggered by those 12z ECM ens. after the 0z runs. Some turnaround if...If an Easterly does occur.

Well Barry, if we could model the PV more accurately then forecasting would be simpler, that's for sure. I don't believe its simply coincidence that we are now staring down the barrel of a Euro high rather than a Scandi High because of the vortex strength. The models have been underestimating the PV strength which is why they have been so poor of late. By default, the GFS then looked to be performing better by offering a flatter pattern, which is what it always does. Will GEM be correct?, can't see it, and would expect it to back down on the 12z later. If we have a Euro High in place in ten days time then it's a long way back to a colder pattern, 10-15 days at least which would take us towards month end, so yes, it is possible to write of widespread snow this month, even on the 5th.