Forecasting Lee Side Forecasting Lee Side Spillover Spillover Precipitation Precipitation Resulting in Major Resulting in Major Flooding in an Urban Flooding in an Urban Valley Location Valley Location Michael L. Kaplan, Phillip J. Marzette, Michael L. Kaplan, Phillip J. Marzette, Christopher S. Adaniya and K.C. King Christopher S. Adaniya and K.C. King Division of Atmospheric Sciences Division of Atmospheric Sciences Desert Research Institute Desert Research Institute Reno, Nevada Reno, Nevada S. Jeffrey Underwood S. Jeffrey Underwood Department of Geography Department of Geography University of Nevada Reno University of Nevada Reno Reno, Nevada Reno, Nevada
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Modeling and Forecasting Lee Side Spillover Precipitation Resulting in Major Flooding in an Urban Valley Location Michael L. Kaplan, Phillip J. Marzette,
Counter-Rotating Meso-γ Scale Lee Side Vortices (~10-20 km/3-6 hours or less) Lee side blocking of upstream unsaturated flow function of dry Froude Number (linear theory) u=2000 m MSL average (valley-crest) cross-mountain top wind velocity N=2000 m MSL average (valley-crest) Brunt-Vaisalla frequency H = Average upstream mountain height (~1000 m for Carson Range between valley (1500 m) and crest (2500 m) MSL)
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Modeling and Forecasting Modeling and Forecasting Lee Side Spillover Lee Side Spillover
Precipitation Resulting in Precipitation Resulting in Major Flooding in an Urban Major Flooding in an Urban
Valley LocationValley Location Michael L. Kaplan, Phillip J. Marzette, Michael L. Kaplan, Phillip J. Marzette, Christopher S. Adaniya and K.C. KingChristopher S. Adaniya and K.C. King
Division of Atmospheric SciencesDivision of Atmospheric SciencesDesert Research InstituteDesert Research Institute
Reno, NevadaReno, Nevada
S. Jeffrey UnderwoodS. Jeffrey UnderwoodDepartment of GeographyDepartment of GeographyUniversity of Nevada RenoUniversity of Nevada Reno
Reno, NevadaReno, Nevada
Presentation OverviewPresentation Overview1. Formation of meso-Γ scale vortices in blocked flow1. Formation of meso-Γ scale vortices in blocked flow
2. Meso-Β/Γ scale observations (Reno) during the 2. Meso-Β/Γ scale observations (Reno) during the 2005 flood2005 flood
3. Simulated counter-rotating vortices during the flood3. Simulated counter-rotating vortices during the flood
4. Sensitivity to model initial conditions during the flood4. Sensitivity to model initial conditions during the flood
5. Summary and key conclusions5. Summary and key conclusions
Counter-Rotating Meso-γ Scale Lee Side Counter-Rotating Meso-γ Scale Lee Side Vortices (~10-20 km/3-6 hours or less)Vortices (~10-20 km/3-6 hours or less)
Lee side blocking of upstream unsaturated flow function of dry Froude Number (linear theory)
u=2000 m MSL average (valley-crest) cross-mountain top wind velocity
N=2000 m MSL average (valley-crest) Brunt-Vaisalla frequency
H = Average upstream mountain height (~1000 m for Carson Range between valley (1500 m) and crest (2500 m) MSL)
Urban scale prediction in complex terrain is Urban scale prediction in complex terrain is difficult reflecting larger scale Froude difficult reflecting larger scale Froude number and simulated blocking errorsnumber and simulated blocking errors
Blocking may be key to organizing lee side Blocking may be key to organizing lee side vortices and convergence zones on the vortices and convergence zones on the urban scale, which control precipitationurban scale, which control precipitation
Better initial data, resolution and Better initial data, resolution and microphysics are likely key to improving microphysics are likely key to improving flooding prediction for spillover precipitationflooding prediction for spillover precipitation in a lee side urban valley regionin a lee side urban valley region