Any insights into the model discomfort?
A complete split in the models, GFS and Arpege have the low hanging west
of Ireland and coming over the UK 22 May, ECMWF, Germany/Canada are
still with 20 May.
To me it looks as though 19 May GFS is entraining a mid-Atlantic warm
plume and the others are not. NHC has not had its interest piqued,
although the origin of this storm was not far from the approx 26 deg
warm surface Gulf Stream finger of this SST image, passing off Cape Hatteras
https://coralreefwatch.noaa.gov/data/5km/v3.1/current/daily/gif/cur_coraltemp5km_sst_large.gif


--
Global sea level rise to 2100 from curve-fitted existing altimetry data
http://diverse.4mg.com/slr.htm

On Monday, 17 May 2021 at 09:45:04 UTC+1, N_Cook wrote:
Any insights into the model discomfort?
A complete split in the models, GFS and Arpege have the low hanging west
of Ireland and coming over the UK 22 May, ECMWF, Germany/Canada are
still with 20 May.
Model differences are due to small differences in jet streak strength and orientation emanating from the USA. The jet streaks are being heavily influenced by the severe convection occurring over the USA.

--
Freddie
Alcaston
Shropshire
148m AMSL
http://www.hosiene.co.uk/weather/
Stats for the month so far: https://www.hosiene.co.uk/weather/st...cs/latest.xlsx

On 17/05/2021 11:16, Freddie wrote:
On Monday, 17 May 2021 at 09:45:04 UTC+1, N_Cook wrote:
Any insights into the model discomfort?
A complete split in the models, GFS and Arpege have the low hanging west
of Ireland and coming over the UK 22 May, ECMWF, Germany/Canada are
still with 20 May.
Model differences are due to small differences in jet streak strength and orientation emanating from the USA. The jet streaks are being heavily influenced by the severe convection occurring over the USA.


So whether the blocking loop develops around the UK about 21 May or does
not.

--
Global sea level rise to 2100 from curve-fitted existing altimetry data
http://diverse.4mg.com/slr.htm

On Monday, 17 May 2021 at 13:21:02 UTC+1, N_Cook wrote:
On 17/05/2021 11:16, Freddie wrote:
On Monday, 17 May 2021 at 09:45:04 UTC+1, N_Cook wrote:
Any insights into the model discomfort?
A complete split in the models, GFS and Arpege have the low hanging west
of Ireland and coming over the UK 22 May, ECMWF, Germany/Canada are
still with 20 May.
Model differences are due to small differences in jet streak strength and orientation emanating from the USA. The jet streaks are being heavily influenced by the severe convection occurring over the USA.

So whether the blocking loop develops around the UK about 21 May or does
not.
What's a blocking loop?

--
Freddie
Alcaston
Shropshire
148m AMSL
http://www.hosiene.co.uk/weather/
Stats for the month so far: https://www.hosiene.co.uk/weather/st...cs/latest.xlsx

On 17/05/2021 13:25, Freddie wrote:
On Monday, 17 May 2021 at 13:21:02 UTC+1, N_Cook wrote:
On 17/05/2021 11:16, Freddie wrote:
On Monday, 17 May 2021 at 09:45:04 UTC+1, N_Cook wrote:
Any insights into the model discomfort?
A complete split in the models, GFS and Arpege have the low hanging west
of Ireland and coming over the UK 22 May, ECMWF, Germany/Canada are
still with 20 May.
Model differences are due to small differences in jet streak strength and orientation emanating from the USA. The jet streaks are being heavily influenced by the severe convection occurring over the USA.

So whether the blocking loop develops around the UK about 21 May or does
not.
What's a blocking loop?


An Omega block

--
Global sea level rise to 2100 from curve-fitted existing altimetry data
http://diverse.4mg.com/slr.htm

On Monday, 17 May 2021 at 13:29:07 UTC+1, N_Cook wrote:
On 17/05/2021 13:25, Freddie wrote:
On Monday, 17 May 2021 at 13:21:02 UTC+1, N_Cook wrote:
On 17/05/2021 11:16, Freddie wrote:
On Monday, 17 May 2021 at 09:45:04 UTC+1, N_Cook wrote:
Any insights into the model discomfort?
A complete split in the models, GFS and Arpege have the low hanging west
of Ireland and coming over the UK 22 May, ECMWF, Germany/Canada are
still with 20 May.
Model differences are due to small differences in jet streak strength and orientation emanating from the USA. The jet streaks are being heavily influenced by the severe convection occurring over the USA.

So whether the blocking loop develops around the UK about 21 May or does
not.
What's a blocking loop?

An Omega block
--
Oh okay. There is no omega block over the UK in that timeframe. In the upper air I see a progressive pattern with short-wave ridges and troughs, albeit with a southward shift relative to normal.

--
Freddie
Alcaston
Shropshire
148m AMSL
http://www.hosiene.co.uk/weather/
Stats for the month so far: https://www.hosiene.co.uk/weather/st...cs/latest.xlsx

On 17/05/2021 15:35, Freddie wrote:
On Monday, 17 May 2021 at 13:29:07 UTC+1, N_Cook wrote:
On 17/05/2021 13:25, Freddie wrote:
On Monday, 17 May 2021 at 13:21:02 UTC+1, N_Cook wrote:
On 17/05/2021 11:16, Freddie wrote:
On Monday, 17 May 2021 at 09:45:04 UTC+1, N_Cook wrote:
Any insights into the model discomfort?
A complete split in the models, GFS and Arpege have the low hanging west
of Ireland and coming over the UK 22 May, ECMWF, Germany/Canada are
still with 20 May.
Model differences are due to small differences in jet streak strength and orientation emanating from the USA. The jet streaks are being heavily influenced by the severe convection occurring over the USA.

So whether the blocking loop develops around the UK about 21 May or does
not.
What's a blocking loop?

An Omega block
--
Oh okay. There is no omega block over the UK in that timeframe. In the upper air I see a progressive pattern with short-wave ridges and troughs, albeit with a southward shift relative to normal.


Comparing representatives of the 2 camps, 06Z outputs for 300mB wind, I see
GFS about 84h to 96h an omega block around the UK
DWD about 84h to 96h no such block

--
Global sea level rise to 2100 from curve-fitted existing altimetry data
http://diverse.4mg.com/slr.htm

On 17/05/2021 16:16, N_Cook wrote:
Comparing representatives of the 2 camps, 06Z outputs for 300mB wind, I see
GFS about 84h to 96h an omega block around the UK
DWD about 84h to 96h no such block

GFS 12Z output has shifted that omega block to the Baltic allowing
stronger wind over the UK for 21 May , perhaps by the next run or two
loosing the residual block and the ground level wind regime back to
closer to 20 May for the UK overpass and the other models.

--
Global sea level rise to 2100 from curve-fitted existing altimetry data
http://diverse.4mg.com/slr.htm

On Monday, 17 May 2021 at 17:09:26 UTC+1, N_Cook wrote:
On 17/05/2021 16:16, N_Cook wrote:
Comparing representatives of the 2 camps, 06Z outputs for 300mB wind, I see
GFS about 84h to 96h an omega block around the UK
DWD about 84h to 96h no such block
GFS 12Z output has shifted that omega block to the Baltic allowing
stronger wind over the UK for 21 May , perhaps by the next run or two
loosing the residual block and the ground level wind regime back to
closer to 20 May for the UK overpass and the other models.


An Omega block persists for several days, so wouldn't shift anywhere in a hurry. When I look at the GFS model charts I see a south-shifted jet with a large upper low to the north. There is a short-wave upper trough-ridge-trough moving quickly east. This is driving the system in question. There is no evidence of an Omega block.

--
Freddie
Alcaston
Shropshire
148m AMSL
http://www.hosiene.co.uk/weather/
Stats for the month so far: https://www.hosiene.co.uk/weather/st...cs/latest.xlsx