I agree with a Julian Mayes post about the lack of an appropriate
presentation of such a storm system on television stations. The kind of
debate that is being discussed here could be covered on a weather channel or
a hybrid of it. i.e. combine travel(roads and rail etc), air port info etc
with weather as it happens.
A glance at the radar and Sferic information during the afternoon clearly
showed the favoured areas for development. Yet forecasts continually
mentioned the Southeast and as Julian stated this prevailed well into the
evening. At a key time yesterday meteorologically the News 24 Channel missed
two broadcasts on the half hour and hour due to a live broadcast featuring
the Prime Minister answering questions set by journalists. Yes he should
answer questions but perhaps it could be on BBC 2 etc.
There are sacrosanct areas of the Media. Not even nuclear war would shift
the Archers from being broadcast.
Of course what is needed is a Weather channel. Information is available,
there is an interest but it is regarded by the top media moguls as not being
"sexy" rather "anorakish". Perhaps though it could be combined , yes a `Big
Brother Weather Channel'.
Ian Currie- Coulsdon.
www.Frostedearth.com
"Joe Hunt" wrote in message
...
"Waghorn" wrote in message
...
Widespread showers can and indeed often do apparently crop up more or
less
randomly. But clearly it cannot be a simple random process. Factors
such
as convergence, locally higher dewpoints, etc must be at work.
Jack,
haven't followed closely as rather busy but-
I have saved some streamlines from the GFS and NMM 22km from y'day and
they clearly show convergence
in the warm,moist plume from the south (let me know if want a look).I
imagine the MO mesoscale
model wld have done an even better job.Engagement of the slow moving
trough in the west with this
plume and convergence triggered the heavy showers ,wind shear wld have
been enough to turn the cold
pools away from the updrafts and allow a degree of organisation into a
smallish Mesoscale Convective
System.This shows a comma like appearance in radar imagery later in it's
lifecycle.
I wonder if CSIP were up for this-
http://www.env.leeds.ac.uk/csip/
were up for this.Anybody Know?
Hi David/Jack,
It certainly was an interesting event. The showers around the Bristol area
were indeed triggered through dynamic ascent ahead of the upper trough
moving E through the strong SW flow aloft. Winds were sampled at 75-80kts
at
300mb on many 22/11Z ascents along with considerable speed shear and
directional shear in the lowest layers. A closer look at the 12Z WV images
and jet stream maps shows the storm complex lying in the right entrance of
a
jet streak, an area of maximum acceleration of air, further inducing
ascent.
It is these dynamic features that helped maintain the complex for such a
long period and hence an MCS may have formed.
http://www.sat.dundee.ac.uk/pdus/BW/...21200BW1_g.jpg (12Z WV)
http://www.sat.dundee.ac.uk/pdus/BW/...21800BW1_g.jpg (18Z WV - jet
streak visible Manchester-Cornwall)
Also of note from the above is the developing wave that ran along the cold
front moving ENE which gave NW areas some heavy rain for a few hours (3hrs
of moderate showery rain at EGNH Blackpool). An associated dry slot (PV
max)
ushering the storms NE and providing further ascent.
The following soundings show the conditional instability in the atmosphere
at 11Z yesterday. Inversions at between 650-700hPa cap the energy at the
surface which is fuelled by reservoirs of moisture (WBPT 16degC), however
it
is at Watnall where a large amount of potential instability was probably
released when the inversion was broken.
http://weather.uwyo.edu/cgi-bin/soun...F%3ASKEWT&YEAR
=2004&MONTH=7&FROM=2212&TO=2212&STNM=03354&STNN=No ttingham%2FWatnall
(22/11Z Watnall)
http://weather.uwyo.edu/cgi-bin/soun...F%3ASKEWT&YEAR
=2004&MONTH=7&FROM=2212&TO=2212&STNM=03743&STNN=La rkhill
(22/11Z Larkhill)
The lack of home-grown thunderstorms in the SE was most likely due to
subsidence from both the "MCS" over central UK and the area of
thunderstorms
that skimmed the far SE coast.
In short, convergence (which has already been covered), several forcing
elements from aloft, abundant moisture, surface heating all seem to have
played a part. Bristol may have been a foci of moisture due to surface
convergence and hence all the "ingredients" occurred here first.
What is interesting is the cells that spawned over the
Cambridgeshire/Rutland area on the E side of the storm, flanking lines ?
Joe