Where did that rain come from on the radar in the SE ?

Also, the TAFs have changed somewhat from a nice day expected at 22Z
TAF EGLL 122220Z 130624 34004KT 7000 SCT045 PROB40
TEMPO 0608 2000 BR
BECMG 0912 9999

to a more unsettled one at 04Z

TAF EGLL 130425Z 131206 04004KT 9999 BKN030 PROB30
TEMPO 1215 4000 +SHRA TS BKN025CB PROB30
TEMPO 1517 8000 SHRA
BECMG 0003 7000 PROB30
TEMPO 0406 3000 BR

Phil


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,Where did that rain come from on the radar in the SE ?
I think this is upper air driven.In WV a weakish vortex has spun up on the PV streamer moving SE
across the country.
The AVN T+18 VT 06Z today has the core of the vortex displaced somewhat NE,if MetO had similar error
this wld account for the poor forecast
http://met.psu.edu/trop-cgi/avntc2.c...ity&hour=018hr

Rather sharp,mod heavy shower in SE London ~17Z from v leaden sky ,otherwise rather nice with TCU
around.No rain so far this morning,

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regards,
david
(add 17 to waghorne to reply)

"Waghorn" wrote in message
...
,Where did that rain come from on the radar in the SE ?
I think this is upper air driven.In WV a weakish vortex has spun up on the
PV streamer moving SE
across the country.
The AVN T+18 VT 06Z today has the core of the vortex displaced somewhat
NE,if MetO had similar error
this wld account for the poor forecast

http://met.psu.edu/trop-cgi/avntc2.c...ity&hour=018hr

Rather sharp,mod heavy shower in SE London ~17Z from v leaden sky
,otherwise rather nice with TCU
around.No rain so far this morning,


There was indeed an upper trough expected to drive east on Monday leading to
destabilisation and a scattering of showers. Yesterday's mesoscale runs
continued this theme and were also indicating a more organised dynamically
generated feature in the far SE, although admittedly not of the intensity of
this morning's radar returns.

Jon.

"Jon O'Rourke" wrote in message
...

There was indeed an upper trough expected to drive east on Monday
leading to
destabilisation and a scattering of showers. Yesterday's mesoscale
runs
continued this theme and were also indicating a more organised
dynamically
generated feature in the far SE, although admittedly not of the
intensity of
this morning's radar returns.


.... always the risk at this time of year of disrupted portions of upper
troughs (puddles of colder air wandering around with a life of their own
at / above 700 mbar), and with the potentially strong heating as spring
advances .... poof! Up they go. I'm always surprised the models do so
well as they do, particularly with fewer routine upper air ascents
nowadays to keep them on track. The models in the past always warmed
such features a little too fast - modern iterations are better, but
because it is such a fine balance (between surface heating / trigger and
mid-tropospheric thermal & humidity structure), the potential for things
going awry is huge!

Martin.

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