Federal Department of Home Affairs FDHA Federal Office of Meteorology and Climatology MeteoSwiss Operational thunderstorm nowcasting in the Alpine region using 3D-radar severe weather parameters and lightning data Alessandro Hering 1 , Urs Germann 1 , Marco Boscacci 1 , Stéphane Sénési 2 1 MeteoSwiss, Locarno-Monti, Switzerland 2 Météo-France, Toulouse, France.
Operational thunderstorm nowcasting in the Alpine region using 3D-radar severe weather parameters and lightning data. Alessandro Hering 1 , Urs Germann 1 , Marco Boscacci 1 , Stéphane Sénési 2 1 MeteoSwiss, Locarno-Monti, Switzerland 2 Météo-France, Toulouse, France. - PowerPoint PPT Presentation
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Federal Department of Home Affairs FDHAFederal Office of Meteorology and Climatology MeteoSwiss
Operational thunderstorm nowcasting in the Alpine region using 3D-radar
severe weather parameters and lightning data
Alessandro Hering1, Urs Germann1, Marco Boscacci1, Stéphane Sénési2
1 MeteoSwiss, Locarno-Monti, Switzerland2 Météo-France, Toulouse, France.
2
Montreux, Lake Geneva, 18.7.2005
Source: Webcam Hotel Splendid, Montreux, Switzerland
3
Montreux, Lake Geneva, 18.7.2005
Source: Webcam Hotel Splendid, Montreux, Switzerland
4
Montreux, Lake Geneva, 18.7.2005
Source: Webcam Hotel Splendid, Montreux, Switzerland
5
TRT (Thunderstorms Radar Tracking)
TRT Cell tracking
Montreux (webcam)
TRT Cell-based VIL(Vertically Integrated Liquid)
18.7.2005 (12:50-14:35)
220
km
13dBZ 25dBZ 40dBZ 55dBZ
6
TRT (Thunderstorms Radar Tracking)
TRT Cell tracking TRT Cell-based VIL(Vertically Integrated Liquid)
18.7.2005 (12:50-14:35)
220
km
13dBZ 25dBZ 40dBZ 55dBZ
7
TRT (Thunderstorms Radar Tracking)
TRT Cell-based VIL(Vertically Integrated Liquid)
18.7.2005 (12:50-14:35)
TRT Cell tracking
220
km
13dBZ 25dBZ 40dBZ 55dBZ
8
Scan geometry, Orography
• Scan geometry of Swiss radar La Dôle situated on a mountain top (1680 m a.s.l.) near Geneva
• Orography roughly in the direction of the hail swath on 18 July 2005
Montreux (webcam)
9
TRT (Thunderstorms Radar Tracking)
• TRT: real-time object-oriented tool for thunderstorms nowcasting based on multiple-radar composites
• 2003: TRT operational at MeteoSwiss• Detection: Dynamic reflectivity thresholding scheme• cells detected at individual thresholds: 36-48 dBZ
• 2004: Improved cell position extrapolation
• 2005: Lightning data added → multiple-sensors system
• 2006: 3D multiple-radar derived storm properties
cell-based (time series), grid-based (2D horizontal fields):• VIL (Vertically Integrated Liquid)• EchoTops 15/45 dBZ• Max storm reflectivity altitude
10
Operational view: cell-based attributes
VIL, 15/45 EchoTops, storm altitudes:
• Cartesian composite 3 C-band Doppler radars
• 20 elevation scan (-0.3° / 40°)
• 12 CAPPI between 1 and 12 km
• 5 min
Lightning data:• CG positive/negative
11
The severe hailstorm on 18 July 2005
• One cell, 11:00-15:00 UTC, developed to a supercell hailstorm moving over Lake Geneva to western Switzerland
• 250 km track• hail swath 1200 km2 • 8 people injured• 15'000 cars damaged• several vineyards destroyed• Insured claims > €70 millions
12
Hail swath on 18 July 2005• Hail crop damage claims (Swiss Hail Insurance)• Daily maximum grid-VIL• Daily maximum grid-VIL > 10 [kg/m2]
[kg/m2]0 20 40 60
540
km• Squares: communities where hail reported at least once
VIL distribution145 trajectories (2630 cells); max >= 57 dBZ, duration >=30 min
25
3639
26
11
53
0
5
10
15
20
25
30
35
40
45
10-20 20-30 30-40 40-50 50-60 60-70 70-80
VIL [kg/m2]
Nu
mb
er
18
Conclusions and outlook
• Reliable operational thunderstorms identification, tracking and 3D characterisation in Alpine area needs:• high resolution in height / time: 20-elev. (-0.3° / 40°) in 5 min
• dynamic reflectivity thresholding scheme: TRT
• multiple-radar composites
• Nowcasting in Alpine area: • use 3D storm attibutes VIL, 15/45 EchoTops, max storm refl.
altitude, CG for assessing the severe weather potential of thunderstorms
• combine grid-based 2D-animations and cell-based time trends
• Outlook Alpine area:• VIL: determine typical values, thresholds for occurrence of hail
• explore use of POH!? (Probability of Hail, Waldvogel et al.)
• extend time series analysis to forecast thunderstorm development (stage in its life cycle)