Some Snow Surprises?Added : Monday at 14:15 Ahh snow forecasting in the UK. Nine times out of ten, the scenario is usually fairly complex and marginal. If you cast your mind back to last week when the models threw some bitterly cold air in from the North, well, those situations are fairly easy, but in the real world the evolving picture is usually a little warmer with a few more caveats.
A chilly start to the week with high pressure across the UK and some residual colder air which came South over the weekend parked across the region :-
Into the second half of the week and some colder air once again comes in from the North :-
Snow across the mountains and hills, but rain at lower levels. The GFS ► then bringing in another low from the Northwest on Friday :-
In situations like this, we tend to look for either undercutting (where colder air coming around the low pressure undercuts the fronts associated with the system) :-
The other thing we look for is weather systems running in from the West. Not only to they run into colder air with snow on the leading edge, but the trajectory of the systems is incredibly important with snow on the polar side of the low, but rain on the tropical side :-
The GFS ► then keeping it chilly for much of next week. The risk of snow certainly there, but a very messy scenario and likely to be day to day forecasting for most. That said, just a reality check... Always remember the decameter lines, they are there to ensure sanity in forecasters. Light blue 528dm line means snow for hills, 510dm means snow at sea level (roughly anyway).
The caveats usually come in terms of heavy rain/sleet mix as well as the trajectory of any low pressure systems coming through.
But some interesting weather for the next week or two regardless.
METEOROLOGIST : MARSH |