Emir wrote:
I don’t see much difference between BKN and OVC.
The amount of Oktas in actual/forcast does make a difference when you are flying VFR with a PPL 
But yes, as you descend through it should not matter (weather actual/forcast reports are more tailored for IFR traffic)
TBH when descending and entering cloud layer from above for instrument approach, I don’t see much difference between BKN and OVC.
Just spotted another one
EDNY 101100Z 1012/1112 VRB03KT 5000 -RA BR SCT005 OVC020 TEMPO 1012/1016 4000 RADZ BKN010 BECMG 1017/1020 03008KT BECMG 1020/1022 OVC012 BECMG 1107/1109 BKN015 TEMPO 1109/1112 04013KT
It is definitely rare.
From earlier today…
TAF EGBB 200457Z 2006/2106 01005KT 9999 OVC025
TEMPO 2021/2106 8000
PROB30 TEMPO 2100/2106 4000 BR BKN006=
I have never seen a OVC in a UK TAF, FWIW.
Peter,
no, it is allowed and used regularly.
What I see in my experience is that a real stratiform overcast is pretty rare, particularly if you measure it. On the multiple sensor array we have at ZRH, 99% of the times you’ll see a broken condition, as difference between sensor readouts are often such that you can actually see a layer above the supposed overcast. My METARS will therefore read BKN most of the time, unless I get a situation where it’s really within tolerance.
Maybe that is why you see BKN more in TAF’s as well
You thought wrong!
EGMD 200459Z 2006/2015 03012KT 9999 BKN020 TEMPO 2006/2009 BKN009
LFAT 200500Z 2006/2015 04008KT 9999 OVC020
I thought OVC was not allowed in TAFs. OTOH I can’t see why not…
