"Keith Wassell" wrote in message
...
On Fri, 27 Aug 2004 15:34:29 +0100, "Martin Rowley"
wrote:

... yes, it certainly is marked. All I can come up with atm is that
the

snip

Staggers back confused by all the two and three letter acronyms, camly
opens another stella, and says

whats all this mean in laymans terms?

.... he, he: sorry about that! We're just trying to decide on the
'where's and 'why,fors' of the discrete line of, for a time, intense
convection that broke out across the north & NW Home Counties, well to
the north of the main rain area (and underneath that latter's cloud
shield) that slowly came south over southern England today.
You can find a simple (I hope) explanation of some of the terms in the
FAQ/Glossary (see my sig file), but in broad terms, I was trying to
imply (subject to correction), that the showers were set off because the
upper cloud thinned enough to allow the still strong sun to warm the
ground, lifting the temperature high enough to start cumulus clouds
growing, there being high humidity [i.e. dew points] (i.e. plenty of
'fuel' to let the cloud/rain droplets grow) available. The +ve PVA stuff
is short-hand to indicate that the windflow in the air above this area
is such that it encourages these things to both grow (vigorously) in an
organised fashion - as opposed to a 'pulse' (or 'here and there') way,
and become strung out in the manner that they did along the flow.

HTH [ & no doubt the Stella will make all clear ;-), though I prefer a
Guinness ]

Martin.


--
FAQ & Glossary for uk.sci.weather at:-
http://homepage.ntlworld.com/booty.weather/uswfaqfr.htm