air pressure (weather station)

jay28

Hi all,
I got myself a WH1081 weather station today, I have it up and running however im a bit confused as to how to set the air pressure,
Is there anywhere I can find the current air pressure in my area so I can change the settings on my station,
Im in Wicklow and 180m ASL.

Also is it the relative or absolute pressure I change,

Thanks
Jason

Su Campu

Where in Wickow are you exactly? Check the reports from other surrounding stations (Casement, Oak Park, Johnstown Castle, aswell as others on the IWN. Have a look at the forecast chart below too, and set the sea level pressure to what looks a best fit for your location.

Note: This method won't be very accurate on a windy day like today where the pressure gradient is large (ie. a large difference for a small change of location), but with the help of up to date observations and the chart below it should be good enough. The next few days will give a much better opportunity for accuracy as the pressure gradient will become very slack.

I have found with my Oregon that purely setting the altitude and letting it calculate sea level is of no help at all, as it gives whatever number comes into its head! :rolleyes:

jay28

Thanks for that,

I'm in Connary, about 3 miles from Avoca. The closest station to me on the IWN is Ashford, its showing 1013.1 at 3:30pm.
My station at the moment is showing 1010.8
Im at a much higher altitude than ashford, Im guessing that would make a difference?

Su Campu

Going on current observations I'd calibrate it to 1013 now. It should stay roughly at that value for the next 24hrs or so

jay28

Just calibrated it 1013,
Thanks for that.

gbee

Just for the record, I added 4millibars to mine and it is seemingly in line with most of the rest, one does not want to make them exactly the same as there should be microclimactic differences.

My curves are almost identical to most local ones too, so it's probably reasonably accurate, pleased enough after making the adjustment.

Like you found, I could not make the adjustment for the altitude, just did not seem to make any difference, so using the global offset did the trick.

Mothman

jay28 wrote: »

Im at a much higher altitude than ashford, Im guessing that would make a difference?

The pressure you want to set it to is the sea level equivalent. Pressure does decrease with altitude, hence yes the real pressure with you is lower than with me.
You won't be far wrong with the advice from SC earlier.

Deep Easterly

jay28 wrote: »

Just calibrated it 1013,
Thanks for that.

If you are still unsure, you can use XC Weather (click on 'pressure' tab at the side) which shows up to date isobaric information, as does the meteocentre synoptic analysis maps for Ireland & UK.

Best advice, as su campu already has given, is to wait a few days until the pressure gradient slackens in and around Ireland over the next few days and adjust then. That way you can be sure of a reasonably accurate reading to adjust your station with.

jay28

Thanks for the advice guys, I'll wait for a few days and adjust the station then,
Cheers.