GFS Goes Off On One....Added : Tuesday at 12:18 Some rather interesting charts coming through on the 6z GFS ► this morning and we have held back the discussion as the ECMWF ► model output was delayed this morning, but take a look at this chart from the GFS ► :-
The GFS ► has been a little over enthusiastic about opening the arctic pipeline next week with low pressure swinging down the from Northwest and bringing a plunge of colder Arctic air South. One thing which is firmly at the back of our mind, and should be too for many of you who have followed this model over the years is how the GFS ► seems to love promoting this scenario in the medium range of the output, only to back away a few days later as it brings in a new area of low pressure from the West which cuts off the flow. The issue comes from the GFS ► constantly wanting to over emphasise the mid Atlantic ridge which rarely happens.
This is the ECMWF ► output for the same timeframe :-
The ECMWF ► doesn't buy the Northerly plunge at all. The low pressure to across Scandinavia is far less organised and there seems far less organisation around the Greenlandic Sea.
This brings us back to the GFS. A few years back and a couple of model upgrades ago, the GFS ► was notorious for developing Northerly plunges which were tamed further and further back as the date got closer. Is the new version of the GFS ► revisiting old habits?
The GEM model seems to be the voice of reason. A half way scenario between the GFS ► and the ECMWF ► :-
So, certainly looking like the weather will turn colder towards the end of next week from the North, but most likely scenario is some of the white stuff for higher mountains of Scotland and perhaps Northern England. But a few things to remember before you take too much notice of the GFS ► 6z output :-
- The ground (or undersoil) is warm after summer and autumn.
- Northerlies can be cold but rarely deliver snow away from Northern facing coasts and high ground
- The GFS ► might very well be going off on one and overplaying that ridge.
As ever, more runs are needed to see how this scenario develops, but something which we are keeping an eye on.
METEOROLOGIST : MARSH |