On Friday, 27 November 2015 11:44:22 UTC, Metman2012 wrote:
On 27/11/2015 10:16, Eskimo Will wrote:

"Dave Cornwell"
On 27/11/2015 07:21, Bob Martin wrote:
Rain radar shows no rain within 100 miles of me in South Hants
yet we've had 1.6 mm in the last hour.

-----------------------------------------
Normally brilliant - today rubbish would be my reply! I've just given
a friend a forecast for Sevenoaks in Kent where he is playing golf
today, saying dry. Imagine my shock when I looked out of the window
and saw puddles on my flat roof. Checked the radar - nothing at all.
On high res some very light small patches around your area but nothing
in Essex or Kent!
Dave, S.Essex

The radar is to be used with caution on Dartmoor. Always misses soaking
heavy drizzle which can give several mm in the gauge and sometimes
overdoes convective rainfall.

Will
See http://www.metoffice.gov.uk/news/in-depth/radar. Drizzle isn't
picked up by radar.

There's more info on
http://www.metoffice.gov.uk/learning...rainfall-radar.

The Met O is upgrading their radar network but whether this includes
drizzle I don't know. There used to be a very good page describing the
strengths and weaknesses of weather radar but I can't find it at the moment.

-------------------------------------------------------------------------------
Met Office Fact sheet No.15:

'Radars under-estimate the rain from clouds composed of smaller-than-average
drops (e.g. drizzle), .......'


http://www.metoffice.gov.uk/media/pd...m=auto,-47,842


Len
Wembury, SW Devon

in patchy heavy drizzle 1230 GMT. Small patchy blue echoes on radar.

------------------------------------------------------------------------------

On 27/11/2015 11:47, Dave Cornwell wrote:
On 27/11/2015 11:37, Tudor Hughes wrote:
On Friday, 27 November 2015 10:51:20 UTC, Freddie wrote:
Bob Martin Wrote in message:

Rain radar shows no rain within 100 miles of me in South Hants
yet we've had 1.6 mm in the last hour.


It has its well-documented limitations.
--
Freddie
Pontesbury
Shropshire
102m AMSL
http://www.hosiene.co.uk/weather/
http://twitter.com/PontesburyWx for hourly reports


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

What proportion of its shortcomings are due simply to the radar
beam passing over the top of very low and shallow precipitating
stratus? This has certainly happened the in the past.
Fairly continuous but light drizzle here up to now (1130). No
hill fog.

Tudor Hughes, Warlingham, Surrey, 557 ft, 169 m.

-------------------------------------------------------------
I'm gonna get some stick from my mate. it's that soaking drizzle that is
a nightmare to play golf in. The forecast was also for dry so the human
intervention didn't work either. Today bears no resemblance to the
impression given by last night's forecast which was for a windy, mild
dry day prior to the rain band arriving later.

Been dry here in sunny Woodford since 0900 and 7/8 Cu since 1030 .so
cheer up lad ,and keep the faith ....

Ron

Bob Martin Wrote in message:

Rain radar shows no rain within 100 miles of me in South Hants
yet we've had 1.6 mm in the last hour.


It has its well-documented limitations.
--
Freddie
Pontesbury
Shropshire
102m AMSL
http://www.hosiene.co.uk/weather/
http://twitter.com/PontesburyWx for hourly reports


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

Tudor Hughes Wrote in message:
On Friday, 27 November 2015 10:51:20 UTC, Freddie wrote:
Bob Martin Wrote in message:

Rain radar shows no rain within 100 miles of me in South Hants
yet we've had 1.6 mm in the last hour.


It has its well-documented limitations.
--
Freddie
Pontesbury
Shropshire
102m AMSL
http://www.hosiene.co.uk/weather/
http://twitter.com/PontesburyWx for hourly reports


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

What proportion of its shortcomings are due simply to the radar beam passing over the top of very low and shallow precipitating stratus? This has certainly happened the in the past.
Most of them, I think, from the perspective of wanting to know
whether it will be dry/wet. Over-reading due to intersection of
the melting layer isn't likely to raise more than the odd comment
of "I was expecting heavier than that". Anaprop is efficiently
removed by software - I can't recall anyone complaining about it
in the past 15 or so years.

--
Freddie
Pontesbury
Shropshire
102m AMSL
http://www.hosiene.co.uk/weather/
http://twitter.com/PontesburyWx for hourly reports


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

On 27/11/2015 12:35, Len Wood wrote:
On Friday, 27 November 2015 11:44:22 UTC, Metman2012 wrote:
On 27/11/2015 10:16, Eskimo Will wrote:

"Dave Cornwell"
On 27/11/2015 07:21, Bob Martin wrote:
Rain radar shows no rain within 100 miles of me in South Hants
yet we've had 1.6 mm in the last hour.

-----------------------------------------
Normally brilliant - today rubbish would be my reply! I've just given
a friend a forecast for Sevenoaks in Kent where he is playing golf
today, saying dry. Imagine my shock when I looked out of the window
and saw puddles on my flat roof. Checked the radar - nothing at all.
On high res some very light small patches around your area but nothing
in Essex or Kent!
Dave, S.Essex

The radar is to be used with caution on Dartmoor. Always misses soaking
heavy drizzle which can give several mm in the gauge and sometimes
overdoes convective rainfall.

Will
See http://www.metoffice.gov.uk/news/in-depth/radar. Drizzle isn't
picked up by radar.

There's more info on
http://www.metoffice.gov.uk/learning...rainfall-radar.

The Met O is upgrading their radar network but whether this includes
drizzle I don't know. There used to be a very good page describing the
strengths and weaknesses of weather radar but I can't find it at the moment.

-------------------------------------------------------------------------------
Met Office Fact sheet No.15:

'Radars under-estimate the rain from clouds composed of smaller-than-average
drops (e.g. drizzle), .......'


http://www.metoffice.gov.uk/media/pd...m=auto,-47,842


Len
Wembury, SW Devon

in patchy heavy drizzle 1230 GMT. Small patchy blue echoes on radar.

------------------------------------------------------------------------------

Thanks Len, the very one, albeit, it's now six years out of date. I was
at the official openings of Cobbacombe Cross and Clee Hill back in the
90s....

On 27/11/2015 11:37, Tudor Hughes wrote:
On Friday, 27 November 2015 10:51:20 UTC, Freddie wrote:
Bob Martin Wrote in message:

Rain radar shows no rain within 100 miles of me in South Hants
yet we've had 1.6 mm in the last hour.


It has its well-documented limitations.
--
Freddie
Pontesbury
Shropshire
102m AMSL
http://www.hosiene.co.uk/weather/
http://twitter.com/PontesburyWx for hourly reports


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

What proportion of its shortcomings are due simply to the radar beam passing over the top of very low and shallow precipitating stratus? This has certainly happened the in the past.
Fairly continuous but light drizzle here up to now (1130). No hill fog.

And then of course you have those instances when precipitation
evaporates before it hits the ground.
--
Col

Bolton, Lancashire
160m asl
Snow videos:
http://www.youtube.com/channel/UC3QvmL4UWBmHFMKWiwYm_gg

On 27/11/2015 19:15, Col wrote:
On 27/11/2015 11:37, Tudor Hughes wrote:
On Friday, 27 November 2015 10:51:20 UTC, Freddie wrote:
Bob Martin Wrote in message:

Rain radar shows no rain within 100 miles of me in South Hants
yet we've had 1.6 mm in the last hour.


It has its well-documented limitations.
--
Freddie
Pontesbury
Shropshire
102m AMSL
http://www.hosiene.co.uk/weather/
http://twitter.com/PontesburyWx for hourly reports


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

What proportion of its shortcomings are due simply to the radar
beam passing over the top of very low and shallow precipitating
stratus? This has certainly happened the in the past.
Fairly continuous but light drizzle here up to now (1130). No
hill fog.

And then of course you have those instances when precipitation
evaporates before it hits the ground.
------------------------------------------------------------
Stephen Davenport gave me a very good explaination of why this can be
missed a couple of years ago although that was partly due to the lack of
stations in East Anglia which wouldn't normally affect here or the S.E.
Dave

On 27/11/2015 07:21, Bob Martin wrote:
Rain radar shows no rain within 100 miles of me in South Hants
yet we've had 1.6 mm in the last hour.

-----------------------------------------------------------
Still not good. Today rain was forecast. Lots of dark blue and orange
echoes passing directly over us, albeit quickly, but no heavy rain and
less than 1mm on all the other local stations as well as mine. The
complete opposite of what happened yesterday!
Dave, S.Essex

Dave Cornwell Wrote in message:
On 27/11/2015 07:21, Bob Martin wrote:
Rain radar shows no rain within 100 miles of me in South Hants
yet we've had 1.6 mm in the last hour.

-----------------------------------------------------------
Still not good. Today rain was forecast. Lots of dark blue and orange
echoes passing directly over us, albeit quickly, but no heavy rain and
less than 1mm on all the other local stations as well as mine. The
complete opposite of what happened yesterday!
Dave, S.Essex


Evaporation within the dry sub-cloud layer, and probably a touch
of the radar beam intersecting the melting layer. They are
well-documented shortcomings, and fairly common.

--
Freddie
Pontesbury
Shropshire
102m AMSL
http://www.hosiene.co.uk/weather/
http://twitter.com/PontesburyWx for hourly reports


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

in 427038 20151129 000039 Freddie wrote:
Dave Cornwell Wrote in message:
On 27/11/2015 07:21, Bob Martin wrote:
Rain radar shows no rain within 100 miles of me in South Hants
yet we've had 1.6 mm in the last hour.

-----------------------------------------------------------
Still not good. Today rain was forecast. Lots of dark blue and orange
echoes passing directly over us, albeit quickly, but no heavy rain and
less than 1mm on all the other local stations as well as mine. The
complete opposite of what happened yesterday!
Dave, S.Essex


Evaporation within the dry sub-cloud layer, and probably a touch
of the radar beam intersecting the melting layer. They are
well-documented shortcomings, and fairly common.

Not that common where I am; radar usually reflects what is happening
very accurately, which is why I mentioned it on Friday.