There's a good test coming up for the reliability of the automated forecast
system. The current issue for Tideswell predicts 27 hours of continuous snow
from 2300 this evening, much of it heavy, with the temperature stuck on zero
deg. The last time there was a prediction like this, on 17th Feb, the
temperature turned out about 2 degrees higher than forecast and we had a long
spell of sleet and rain. Getting the forecast temperate right is crucial in such
a marginal situation.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
http://peakdistrictweather.org

Norman Lynagh Wrote in message:
There's a good test coming up for the reliability of the automated forecast
system. The current issue for Tideswell predicts 27 hours of continuous snow
from 2300 this evening, much of it heavy, with the temperature stuck on zero
deg. The last time there was a prediction like this, on 17th Feb, the
temperature turned out about 2 degrees higher than forecast
I was just thinking last night that there had been a bit of a cold
bias in the model's forecast temperatures this winter - as I have
been caught out more than once anticipating snow, which
materialised as cold rain. I'm glad it isn't just me who has
noticed this.

Having said that, the models IIRC seem to handle the temperatures
okay in the warmer/milder spells - so maybe it's not a simple
bias, but occurs in particular situations?

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

On Thu, 3 Mar 2016 08:08:30 +0000 (GMT+00:00), Freddie
wrote:

Norman Lynagh Wrote in message:
There's a good test coming up for the reliability of the automated forecast
system. The current issue for Tideswell predicts 27 hours of continuous snow
from 2300 this evening, much of it heavy, with the temperature stuck on zero
deg. The last time there was a prediction like this, on 17th Feb, the
temperature turned out about 2 degrees higher than forecast
I was just thinking last night that there had been a bit of a cold
bias in the model's forecast temperatures this winter - as I have
been caught out more than once anticipating snow, which
materialised as cold rain. I'm glad it isn't just me who has
noticed this.

Having said that, the models IIRC seem to handle the temperatures
okay in the warmer/milder spells - so maybe it's not a simple
bias, but occurs in particular situations?

The yr.no forecast for Tideswell for the same period is predicting continuous
rain and sleet with the temp hovering around +1 deg. I think yr.no is based
largely on the ECMWF model. It's all highly marginal and so dependent on that
difference of 1 deg in the temperature. It's so important to get that just right
and I'm not convinced that the models can be relied on to that level of
precision.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
http://peakdistrictweather.org

On Thursday, March 3, 2016 at 8:08:31 AM UTC, Freddie wrote:
Norman Lynagh Wrote in message:
There's a good test coming up for the reliability of the automated forecast
system. The current issue for Tideswell predicts 27 hours of continuous snow
from 2300 this evening, much of it heavy, with the temperature stuck on zero
deg. The last time there was a prediction like this, on 17th Feb, the
temperature turned out about 2 degrees higher than forecast
I was just thinking last night that there had been a bit of a cold
bias in the model's forecast temperatures this winter - as I have
been caught out more than once anticipating snow, which
materialised as cold rain. I'm glad it isn't just me who has
noticed this.

Having said that, the models IIRC seem to handle the temperatures
okay in the warmer/milder spells - so maybe it's not a simple
bias, but occurs in particular situations?

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

Maybe the higher than normal SSTs around the UK much of the winter has had an effect not fully taken into account? Certainly, with the wind from the N-NW the temperatures have been well above those forecast of late in Penzance, and the SST has been well above normal to from around SW England, to the Irish Sea & beyond http://polar.ncep.noaa.gov/sst/rtg_l...maly_oper0.png

Back in Dec/Jan SSTs off SW England where near record levels for the time of year, certainly the highest in the record I've been keeping over the last 10 years or so (from places like Sevenstones / Perranporth & Porthleven buoys etc). They've dropped back somewhat now.

Graham
Penzance

On Thu, 3 Mar 2016 04:05:59 -0800 (PST), Graham Easterling
wrote:

On Thursday, March 3, 2016 at 8:08:31 AM UTC, Freddie wrote:
Norman Lynagh Wrote in message:
There's a good test coming up for the reliability of the automated forecast
system. The current issue for Tideswell predicts 27 hours of continuous snow
from 2300 this evening, much of it heavy, with the temperature stuck on zero
deg. The last time there was a prediction like this, on 17th Feb, the
temperature turned out about 2 degrees higher than forecast
I was just thinking last night that there had been a bit of a cold
bias in the model's forecast temperatures this winter - as I have
been caught out more than once anticipating snow, which
materialised as cold rain. I'm glad it isn't just me who has
noticed this.

Having said that, the models IIRC seem to handle the temperatures
okay in the warmer/milder spells - so maybe it's not a simple
bias, but occurs in particular situations?

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

Maybe the higher than normal SSTs around the UK much of the winter has had an effect not fully taken into account? Certainly, with the wind from the N-NW the temperatures have been well above those forecast of late in Penzance, and the SST has been well above normal to from around SW England, to the Irish Sea & beyond http://polar.ncep.noaa.gov/sst/rtg_l...maly_oper0.png

Back in Dec/Jan SSTs off SW England where near record levels for the time of year, certainly the highest in the record I've been keeping over the last 10 years or so (from places like Sevenstones / Perranporth & Porthleven buoys etc). They've dropped back somewhat now.

Graham
Penzance

The latest issue of the automated forecast, issued at 1100, now predicts heavy
snow for every hour between 2300 on Thursday evening to 2200 on Friday evening
then slight snow till 0600 on Saturday morning. The temperature is predicted as
zero deg throughout (except -1 deg at 0700 on Friday). Force 4 winds are
predicted. If this forecast proves to be correct it'll be an event of
considerable significance. It's a very big 'IF', though :-)

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
http://peakdistrictweather.org