At about 0645 BST this morning the pressure fell by 5.5mb inside the hour.
This is shown on my barograph and also on my AWS Vantage pro, so there is no
instrument failure. The pressure has now recovered, but the change on my
barograph looks like some major feature has passed through. I have not seen
a pressure change of this magnitude in such a short time scale- I can only
assume it was a storm cell that was very close by.

Rob
Farsley
near Leeds

"Rob Brooks" bogus wrote in message
...
At about 0645 BST this morning the pressure fell by 5.5mb inside
the hour. This is shown on my barograph and also on my AWS Vantage
pro, so there is no instrument failure. The pressure has now
recovered, but the change on my barograph looks like some major
feature has passed through. I have not seen a pressure change of
this magnitude in such a short time scale- I can only assume it was
a storm cell that was very close by.

Rob
Farsley
near Leeds

.... similar change was picked up at Leeds/Bradford as well (the 'Q'
group at the end of the observation shows the QNH, or mean sea level
pressure). Later obs at top ...
EGNM 280650Z 02009KT 350V070 3500 -RA BKN001 BKN003 10/10 Q1004
EGNM 280620Z 01025G36KT 340V060 2000 RA BKN001 BKN003 10/10 Q1002
EGNM 280550Z 02013KT 360V070 0800 R32/P1500 RA BKN001 BKN002 10/10
Q1005
EGNM 280520Z 04009KT 010V090 0500 R32/1000 -RA BKN001 BKN002 10/10
Q10070520Z = QNH 1007 mbar: 0620Z = QNH 1002 mbar.As you state,
obviously associated with an active cell within the very 'pokey'
system running north late last night.Martin. -- Martin RowleyWest
Moors, East Dorset (UK): 17m (56ft) amslLat: 50.82N Long: 01.88W
NGR: SU 082 023

[ sorry about the poor formatting ... resent as a 'reply' below ]

"Rob Brooks" bogus wrote in message
...
At about 0645 BST this morning the pressure fell by 5.5mb inside
the hour. This is shown on my barograph and also on my AWS Vantage
pro, so there is no instrument failure. The pressure has now
recovered, but the change on my barograph looks like some major
feature has passed through. I have not seen a pressure change of
this magnitude in such a short time scale- I can only assume it was
a storm cell that was very close by.

Rob
Farsley
near Leeds


"Martin Rowley" wrote in message...

... similar change was picked up at Leeds/Bradford as well (the 'Q'
group at the end of the observation shows the QNH, or mean sea level
pressure). Later obs at top ...
EGNM 280650Z 02009KT 350V070 3500 -RA BKN001 BKN003 10/10 Q1004
EGNM 280620Z 01025G36KT 340V060 2000 RA BKN001 BKN003 10/10 Q1002
EGNM 280550Z 02013KT 360V070 0800 R32/P1500 RA BKN001 BKN002 10/10
Q1005
EGNM 280520Z 04009KT 010V090 0500 R32/1000 -RA BKN001 BKN002 10/10
Q1007

0520Z = QNH 1007 mbar: 0620Z = QNH 1002 mbar.
As you state, obviously associated with an active cell within the
very 'pokey' system running north late last night.

Martin.



--
Martin Rowley
West Moors, East Dorset (UK): 17m (56ft) amsl
Lat: 50.82N Long: 01.88W
NGR: SU 082 023

Hello Rob

The same rapid fall occurred here in the Yorkshire Dales at a similar time.
The pressure dropped from 1006.3mb to 1002.0mb. It was accompanied by a
short lived heavy burst of rain and a wind gust of 22mph. Pressure then
quickly rose by 2mb but is now falling again.

Trevor Smith.


"Rob Brooks" bogus wrote in message
...
At about 0645 BST this morning the pressure fell by 5.5mb inside the
hour. This is shown on my barograph and also on my AWS Vantage pro, so
there is no instrument failure. The pressure has now recovered, but the
change on my barograph looks like some major feature has passed through. I
have not seen a pressure change of this magnitude in such a short time
scale- I can only assume it was a storm cell that was very close by.

Rob
Farsley
near Leeds

On 28 May, 09:14, "Trevor Smith" wrote:
Hello Rob

The same rapid fall occurred here in the Yorkshire Dales at a similar time.
The pressure dropped from 1006.3mb to 1002.0mb. It was accompanied by a
short lived heavy burst of rain and a wind gust of 22mph. Pressure then
quickly rose by 2mb but is now falling again.

Trevor Smith.

Same here at same time wind backed from NNE to NNW and gusted to 26mph
during burst of rain.
Ken
Copley, Teesdale

On 28 May, 11:01, Ken Cook wrote:
On 28 May, 09:14, "Trevor Smith" wrote: Hello Rob

The same rapid fall occurred here in the Yorkshire Dales at a similar time.
The pressure dropped from 1006.3mb to 1002.0mb. It was accompanied by a
short lived heavy burst of rain and a wind gust of 22mph. Pressure then
quickly rose by 2mb but is now falling again.

Trevor Smith.

Same here at same time wind backed from NNE to NNW and gusted to 26mph
during burst of rain.
Ken
Copley, Teesdale

Don't think that bar fall was confined to just Yorkshire,,I recorded a 4mb
drop between 0500-0600 this morning,dunno what the wind was doing though.
must be all this GW that's about.


RonB


"Rob Brooks" bogus wrote in message
...
At about 0645 BST this morning the pressure fell by 5.5mb inside the
hour. This is shown on my barograph and also on my AWS Vantage pro, so
there is no instrument failure. The pressure has now recovered, but the
change on my barograph looks like some major feature has passed through. I
have not seen a pressure change of this magnitude in such a short time
scale- I can only assume it was a storm cell that was very close by.

Rob
Farsley
near Leeds

On May 28, 8:20*am, "Rob Brooks" bogus
wrote:
At about 0645 BST this morning the pressure *fell by 5.5mb inside the hour.
This is shown on my barograph and also on my AWS Vantage pro, so there is no
instrument failure. *The pressure has *now recovered, but the change on my
barograph looks like some major feature has passed through. I have not seen
a *pressure change of this magnitude in such a short time scale- I can only
assume it was a storm cell that was very close by.

Rob
Farsley
near Leeds

It sounds as if it was thunderstorm-related but extremely rapid
falls can be caused by gravity waves. One of these affected west
London (Sunbury) on about 19 Jan 1977. We had a mercury barometer in
the laboratory and you could actually just about see the mercury
surface falling. I cannot remember the exact figures (it has been
written about, probably in "Weather") but 8 mb in 5 minutes seems to
ring a bell. There were gusts to 30 kn but nothing more in an
otherwise breezy cloudy SW'ly. The expected End Of The World did not
happen.

Tudor Hughes, Warlingham, Surrey

On May 28, 8:20 am, "Rob Brooks"

At about 0645 BST this morning the pressure fell by 5.5mb inside the
hour.
This is shown on my barograph and also on my AWS Vantage pro, so
there is no
instrument failure. The pressure has now recovered, but the change
on my
barograph looks like some major feature has passed through. I have
not seen
a pressure change of this magnitude in such a short time scale- I
can only
assume it was a storm cell that was very close by.

Rob
Farsley
near Leeds

.... I can't now remember the criterion or exact details of the
warnings structure, but I *do* remember that in the days when this
country had a vibrant coal mining industry, such events had to be
'warned' to the NCB (as was) by the various MMOs and/or Weather
Centres around the UK. Very difficult to predict of course -
essentially monitoring the observations (actually quite easy to do in
the days when we had hand-plotted hourly charts) and being alert &
quick! (The mines would actually have barometers at the pit head, so
we were actually a second-line of defence really).

I believe that it was a rapid *fall* of pressure that was critical:
such would unbalance the atmospheric pressure 'environment' in deep
mines, allowing potentially explosive gases from old workings
(nominally sealed off - but always slightly porous) to mix with the
air in the operational part of the mine. The problem was diagnosed as
far back as the end of the 18th century according to one search I've
just done.

Another area that caused problems with such events was the issue of
the Regional Pressure Settings (FOQNH/minimum pressure setting for
safe operation of aircraft altimeters) - a rapid, unexpected fall in
such could cause panic in CFO!
[ I'm sure it's much better now ;-) ]

Martin.

--
Martin Rowley
West Moors, East Dorset (UK): 17m (56ft) amsl
Lat: 50.82N Long: 01.88W
NGR: SU 082 023

A closer look at the event revealed that the wind gusted to 30 mph and swung
round from NE to SW in the space of 30minutes - we had suprisingly little
rain of around 3.0mm in the hour. Intensity of rain was higher prior to the
fall in pressure.

"Rob Brooks" bogus wrote in message
...
At about 0645 BST this morning the pressure fell by 5.5mb inside the
hour. This is shown on my barograph and also on my AWS Vantage pro, so
there is no instrument failure. The pressure has now recovered, but the
change on my barograph looks like some major feature has passed through. I
have not seen a pressure change of this magnitude in such a short time
scale- I can only assume it was a storm cell that was very close by.

Rob
Farsley
near Leeds