Weather Bomb
 

I see the BBC are talking about a weather bomb as being a drop of 24 hPa in 24 hours. In respect of the low pressure system about to hit NW Scotland they are expecting a weather bomb of 50 hPa and a minimum pressure of 930 hPa.

In my day we only had settings on our altimeters down to 950 hPa and I remember the initial confusion back in the early 80's amongst the helicopter operators out of ABZ when one day the QNH for altimeter settings on the track system dropped well below 950. Does the more modern glass cockpit kit cope with pressure down to 930?

Shouldn`t be a problem if the ATC unit decides to operate on 1013.2mbs..

Wow!! A chance to use QNE at last!

Aberdeen went down 27mb in 8 hours this afternoon, 14 of them between 1150 and 1450.

Why would QNH not work?

Too hard on your gray matter to figure out where the ground is?

When the wheels go bump....read the number....even with QNE it odds are it will not be reading Zero anyway.

If you can't wind your altimeter down far enough to set it?

936.4mb
 

BBC news is reporting that it was 936.4mb at midday today in Stornoway. This is the lowest "central pressure" (of a weather system) recorded in UK for 127 years (Dec 1886).

I seem to remember coming across the problem of the subscale stopping at 950 many years ago (think it was on the Wessex) and we got round it by adding 37 mb to the pressure we were given and then taking 1000' off the altimeter reading. Complicated, but better than nothing.