Downslope Windstorms - RAL - UCAR

More documents

Recommendations

Info

The effect of a mountaintop The effect of a mountaintop inversion Figure from Durran (1990)
Other forecast factors Other forecast factors • Ideal terrain for windstorms are long ridges with gentle windward slopes and steep lee slopes (effective terrain shape can be modified by upstream blocking) • Low humidity is better (moisture seems to reduce amplitude) • Nighttime or early morning more likely (stability changing during this time?) • Klemp and Lilly (1975) found that the strongest downslope events occur in Boulder when a one-half wavelength phase shift was present between ground and tropopause (partial reflection mechanism of linear theory) • Durran (1986a) ran simulations of the 11 January 1972 event – this condition appears necessary, but not sufficient for strongest windstorms • Elevated inversions might be required for breaking waves to form • Lee et al (1989) found that the presence of cold pools in the lee of the mountain could have a strong determinant in whether downslope winds would make it to the mountain base – it also altered the overall structure of the mountain wave in simulations (different lower boundary, change in scale?) • In some cases, precipitation effects could play a role? (e.g. the 3 July 1993 Fort Collins windstorm case)
Page 1 and 2: Downslope Windstorms Downslope Wind
Page 3 and 4: Naming conventions and Naming conve
Page 5 and 6: A few notes on the Chinook A few no
Page 7 and 8: Windstorm Damage Windstorm Damage
Page 9 and 10: Figure from Kuettner and Lilly (196
Page 11 and 12: Composite soundings at onset of Com
Page 13 and 14: Observations from the 11 January Ob
Page 15 and 16: Figures from Lilly (1978)
Page 17 and 18: Downslope Windstorm Downslope Winds
Page 19 and 20: Supercritical case Supercritical ca
Page 21 and 22: Hydraulic jump case Hydraulic jump
Page 23: General development General develop
Page 27 and 28: RAMS Model Simulation Figures from
Page 29 and 30: Fort Collins Windstorm Climatology
Page 31 and 32: FC Windstorm Climatology, cont’d
Page 33 and 34: Wind trace of windstorm at Fort Col
Page 35 and 36: Rotors Rotor: a region of reversed
Page 37 and 38: Rotor observations from Sierra Roto
Page 39 and 40: Figure from Grubiši and Lewis (200
Page 41 and 42: Rotor formation, cont’d Rotor for
Page 43 and 44: Figure from Doyle and Durran (2004)
Page 45 and 46: References, Cont’d Hamann, R. R.,
Page 47: References, Cont’d Raphael, M. N.

Downslope Windstorms - RAL - UCAR

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?