Stephen Davenport wrote:
On Mar 12, 10:01 am, Scott W wrote:
The temperature on my AWS in Wanstead, east London, fell to a low of
2.7C at 0718z today, by 0738z it had risen to 4C. Is this normal for
the time of year? I would normally put it down to solar radiation but
there is thick low cloud here.
Also on the ride home from central London last night I noticed thick
patchy fog had formed over Wanstead Flats - quite unexpected from the
forecast - and the air also "felt" colder than I was expecting it to
be from the forecast.
My wife remarked that the air outside felt very "cold - colder than it
should do" as she walked the girls in this morning - anyone else
notice anything strange... Are these phenomena cause by us being slap
bang underneath a high pressure? It would be interesting to see how
low the usual frost hollows got last night - Chipstead Valley in
Surrey, Benson, Oxon etc

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A slight puff of wind would induce some mixing which might account for
the 20 minute temperature rise but a bit of incoming radiation
wouldn't hurt either.

Relatively moist air under high pressure in early spring with plenty
of overnight radiation = ideal conditions for stratus and fog (so I'm
not sure how unexpected it was - any forecast that didn't mention fog
was not a good one!)

I can't comment much on the physiological aspects (how cold it
"felt"). But Benson's minimum was +0.9, Farnborough's +0.6,
Charlwood's -0.1 and Chesham's -0.8. For comparison, High Wycombe's
minimum was +4.1 and Kenley's +4.7. Fog/low cloud formation prevented
greater falls in temperature, and it may develop earlier tonight so it
might be less cold.

Stephen.
---------------------------
Countryfile with Peter Gibbs didn't handle it too well to be honest. He
intimated that temperatures will depend on where the sun breaks through
the cloud but never actually mentioned fog or mist. He also said that
East Anglia and the S.E would fair well again today with the most
sunshine but in fact there was zero sunshine hours today with a late
maximum of 9.8C compared to 16.1C. Always a tricky one I know but
looking at that small HP stagnated right over us mist and fog was always
likely I think.
Dave