[QUOTE=Oneiric 3;116272299]My humble theory is that Thursday's front, coming up against a dry and relatively cold easterly, was regularly 'enhanced' (given its near stationary status) by "orogenic uplift' as it pushed up against the eastern side of the western coastal uplands, which I think may explain why it was regions close by got the greater snow totals, given what little energy this front contained was constantly being forced into that particular corner of the country for hours on end]
My own visual observations and experience on the day would definitely support this explanation. My own location is not too far east of Castlebar.
Like many else on this forum, I was keenly awaiting the arrival of this particular weather front as it moved up into the cold air.
Living here in the West, I like to watch the weather fronts roll in and then eventually clear. It was interesting to see this front quiet noticeably being stalled in its tracks during the early afternoon on Thursday 11th. The dividing line between the cold and dry air to the north and the frontal cloud and its associated precipitation to the south seemed to sit over us for a few hours. Reports were coming in of decent snowfall from the west of the county and from places like Westport around midday and just afterwards. It was at least another 4 hours before it settled into proper snowfall in this location despite an hour of two of flakes being blown around in that very strong and cold south easterly wind beforehand. On the ground here, it was as if you could see the front struggling to make any further inroads into this cold air that was being driven by that strong wind.
I could see what I knew was snow falling from posters reports out to the west and southwest but meanwhile the drier air held its ground further north.
The picture above was taken at 12.28pm on Thursday looking due west. The light coloured cloud with a faint orangey hue in the bottom left of the photo is actually snowfall over towards Westport. The more obvious grey precipitation to the left of the centre of the photo is snowfall out towards Newport and west Mayo. Towards the bottom right is Nephin mountain and the drier air out to the north and northwest. For a few hours here, you could see what looked to me like somewhat of a dividing line or a battleground between the respective airmasses.
It was interesting to look at but made even more interesting when the snowfall eventually got going here.
Thanks to Gaoth and Oneiric for the more technical and informed explanations as to what unfolded on that day. I know we are always looking forward as to what might unfold weather wise, but I certainly find it interesting to rake back over what was or indeed sometimes what could have been!