Re: Regional Pressures
In broad terms:
Aerodrome QFE is an actual pressure setting based on a recent measurement on site. At 300ft amsl the QFE would differ from an actual QNH at the same site by being about 10mb lower. (1mb equivalent to about 30ft at these levels).
However the regional QNH is
1. a forecast figure and
2. the lowest forecast QNH within the whole of the ASR
For terrain clearance safety reasons both factors drive the figure down. The forecast regional QNH will always be an underestimate. If the pressure differential across the Barnsley ASR is significant it is conceiveable the lowest forecast QNH would be 10mb below the QNH at your airfield. The regional QNH would then be equal to the airfield QFE.
In addition there might be some correlation between the geographical location of your airfield compared to the average pressure distribution across the ASR that produces the coincident figure so frequently.