"Will Hand" wrote in message
...

"Brian Wakem" wrote in message
...
Will Hand wrote:

1953 GMT

Rate 1.5 mm/h
Total rain 8.4 mm

Radar at 1930 GMT had zero rainfall rate over us (as far as I can tell
squinting at the Met Office maps). Actual ground truth was 1.5 mm/h

It has been continuous moderate rain now for over 3 hours (occasionally
heavy).

2100 GMT

9.9 mm total now
Rate 2.3 mm/h

Radar had zero rain at 2030 GMT , actual rate on the ground 1.6 mm/h


Radar rate at 2100 very light but now some heavy rain spreading in on the
display.

2145 GMT

Total now 12.4 mm
Rate 11.4 mm/h
Turning into a dirty wet night now.

One reason why radar may have been under-reading was the old problem of rain
falling from shallow cloud being orographically enhanced over high ground. Radar
beam overshoots the low cloud and misses the rain. This is more of a problem if
a radar goes out of the network as it then has to be replaced with radar data
from a more distant radar which would be looking higher up. I cannot tell
whether this was the case this evening. Anyhow the thicker cloud seems to be
coming in now and it looks like we are in for a big fall in Devon. I fear the
worst re the flooding situation it does seem inevitable given that the moor this
morning still had streams running down the paths which should normally be dry.

Fingers crossed.

Will.
--

" Ah yet another day to enjoy "
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