Downslope windstorm in High Tatras, 19 November 2004
Downslope windstorm in High Tatras, 19 November 2004 Downslope windstorm in High Tatras, 19 November 2004
Mesoscale diagnostics• Theory of downslope windstorms:• Supercritical flow: Froud number 1• Several analytical models an criterions …• Mostly:Less stable airFr =UN HShallow water hydraulic model:adapted from Holton (1992)Stable airSupercritical flowFr 1turbulent adjustmentto subcritical environment
Mesoscale diagnostics• Increase of stability withheight• Below 3000 m Froudnumber > 1 (air can flowover mountains)Froud numberBV x 100RiFr=1wind shear and “θ”Fr=1Froud number0 0,02 0,04 0,06 s -1 K
- Page 1 and 2: Downslope windstorm in High Tatras1
- Page 3 and 4: Impact of the 19 November windstorm
- Page 5 and 6: Local observations• Gusty charact
- Page 7 and 8: Success of the operational forecast
- Page 9 and 10: 2.5 km hydrostatic run with physics
- Page 11 and 12: 2,5 km non- hydrostatic run• Time
- Page 13: Sensitivity testsMax. gust 40 m/s33
- Page 17 and 18: Conclusions: points of view• NWP
Mesoscale diagnostics• Theory of downslope <strong>w<strong>in</strong>dstorm</strong>s:• Supercritical flow: Froud number 1• Several analytical models an criterions …• Mostly:Less stable airFr =UN HShallow water hydraulic model:adapted from Holton (<strong>19</strong>92)Stable airSupercritical flowFr 1turbulent adjustmentto subcritical environment
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