On Dec 12, 9:18*pm, John Hall wrote:
In article ,

*Graham writes:

"The 00Z GFS ensemble quite
strongly suggests that there could be a brief cold spell starting as
little as 11 days away, though it doesn't look like lasting for more
than a few days.

But of course it's not there on the 12Z.
Just more fantasy

I don't bother looking more that a few days ahead, complete waste of time & effort!!

Why is it these models can only predict mild conditions 5 to 8 days ahead but are totally useless at predicting cold conditions?

There's not much use looking at the operational run that far ahead, I
agree, but if there's a strong signal from the ensemble then it can
sometimes indicate that something is up. Equally of course, as in this
case, it can prove to be a mirage.
--
John Hall

* * * * * "Whenever people agree with me I always feel I must be wrong."
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *Oscar Wilde

Just as a case in point I saved a chart from the 00z run last
Wednesday when it was hinting that we'd be in the grip of an easterly
blast, complete with -10c uppers, by tomorrow (Thursday) lunchtime.
Instead by this time tomorrow our upper air will most probably be of
Atlantic origin...