Status: Finalised Material from: Linus, Jonny, Fernando
1. Impact
On 13-14 January the windstorm Brendan hit the Ireland and UK.
https://www.bbc.co.uk/news/uk-england-berkshire-51117465
2. Description of the event
The plots below show analyses of MSLP and 6-hour precipitation forecasts every 12h hour between 12 and 15 January. The main cyclone formed on 12 January and brought strong winds to Ireland and Scotland on 13 January. A secondary wave brought strong winds to southern England on 14 January.
3. Predictability
3.1 Data assimilation
The two charts below show the increments computed at the begin of the 4DVar window (21-09) on 12 January (then the cyclone rapidly deepened) which exceed the the 90-precentile of the model increments CDF of the last 30 days. The top panel shows the magnitude of the wind increments ahead of the cyclone while the bottom panel shows a cooling (deepening) near the centre of the storm at the model level 100 (~600 hPa). One could speculate that the region where we detect the wind increments (ahead of the trough/low) might be related with the adjustments in the warm conveyor belt circulation. We have computed the wind field relative to the storm translation speed at model level 100 (~600 hPa) and is from the figure we can see a region ahead of the cyclone where the winds are from S-SW consistent with what is expected along the warm conveyor belt.
3.2 HRES
The plots below show observations of 24-hour maximum wind gusts valid 13 January 00UTC to 14 January 00UTC (first plot) and HRES forecasts valid at the same period. The forecast plots also includes MSLP valid 13 January 12UTC.
The plots below show observations of 24-hour maximum wind gusts valid 14 January 00UTC to 15 January 00UTC (first plot) and HRES forecasts valid at the same period. The forecast plots also includes MSLP valid 14 January 12UTC.
3.3 ENS
The plots below show EFI and SOT for wind gusts valid 13 January.
The plots below show EFI and SOT for wind gusts valid 14 January.
The plots below show the cyclone feature plots valid 13 January 12UTC, with the colouring of the dot marking the maximum wind speed within 600 km. At this time the primary low was north-west of Iceland, and the secondary wave started to form over the central Atlantic.
The plot below shows the evolution of forecast for 24-hour maximum wind gusts valid 13 January 00UTC to 14 January 00UTC for a point on the Irish north-western coast (lat=64.25, lon=-10)). The plot includes ensemble (blue box-and-whisker), HRES (red dot) and model climate (red box-and-whisker).
3.4 Monthly forecasts
The plots below show the weekly MSLP anomaly valid 13-19 January.
