Moisture transport during the inland penetrating atmospheric river of early November 006 in the Pacific Northwest: A high-resolution model-based study Michael J. Mueller 1 and Kelly Mahoney 1 Cooperative Institute for Research in Environmental Sciences (CIRES) CU-Boulder National Oceanic and Atmospheric Administration International Atmospheric Rivers Conference 016 11 August 016
Case Background & Motivation Series of storms in Pacific Northwest early November 006 5-7 November: Record-breaking rainfall in Cascades and interior mountains (Neiman et al. 008) Extreme rainfall and snowmelt caused destructive flooding at Montana s Glacier National Park (Bernhardt 006) Fraction of heavy precipitation events attributable to atmospheric rivers ( AR fractions ) largest along Pacific coast Elevated AR fractions extend to the interior of North America north and south of the High Sierras (Rutz et al. 015) including the Pacific Northwest Investigate how and where water vapor penetrated the Pacific Northwest using a highresolution weather modeling system Glacier National Park Courtesy: National Park Service
Case Background & Motivation Series of storms in Pacific Northwest early November 006 5-7 November: Record-breaking rainfall in Cascades and interior mountains (Neiman et al. 008) Extreme rainfall and snowmelt caused destructive flooding at Montana s Glacier National Park (Bernhardt 006) Fraction of heavy precipitation events attributable to atmospheric rivers ( AR fractions ) largest along Pacific coast Elevated AR fractions extend to the interior of North America north and south of the High Sierras (Rutz et al. 015) including the Pacific Northwest Investigate how and where water vapor penetrated the Pacific Northwest using a highresolution weather modeling system Glacier National Park Courtesy: National Park Service
Model Configuration Model Terrain Height (x1000 feet) Model System Weather Research & Forecasting (WRF-ARW) Version 3.6 WRF Model Terrain Height Domain Single domain (00km x 00km) km grid spacing 53 terrain-following vertical levels No cumulus parameterization scheme Simulation 00 UTC 3 November 006 00 UTC 9 November 006 (1 hours) LBC/ICs: Climate Forecast System Reanalysis Columbia River Gorge C.R. Basin Glacier National Park Verification Precipitation: Livneh et al. (013) dataset based on NOAA COOP data in CONUS
WRF Verification: Precipitation Accumulated Precipitation (inches) Livneh WRF 1 3 GNP General agreement in distribution and magnitude Major regions of precipitation align with mountains Coastal Ranges: 10-15 ; 0 + high ridges and mountains Interior Ranges: 5-7 ; 10 + high ridges
WRF Precipitation Plumes Accumulated Precipitation (inches) 00z N3 00z N 00z N5 00z N6 00z N7 00z N8 00z N9 1 Area-averaged Accumulated Precipitation 1 3 GNP 1 10 8 1 6 GNP 3 0 Antecedent precipitation 1- Main event: 00 UTC 6 Nov 1 UTC 7 Nov (Coast) 1 UTC 6 Nov 00 UTC 8 Nov (Interior)
WRF Synoptic Overview: Upper Air 300 hpa 500 hpa 1 UTC 6 Nov 00 UTC 7 Nov 1 UTC 6 Nov 00 UTC 7 Nov 700 hpa 1 UTC 6 Nov 00 UTC 7 Nov 1 UTC 7 Nov 00 UTC 8 Nov 1 UTC 7 Nov 00 UTC 8 Nov 1 UTC 7 Nov 00 UTC 8 Nov 70 90 110 130 150 Wind Speed (knots) 0 5 30 35 0 Abs. Vorticity (x10-5 s -1 ) 70 80 90 95 Relative Humidity (%)
WRF Synoptic Overview: Upper Air 300 hpa 500 hpa 1 UTC 6 Nov 00 UTC 7 Nov 1 UTC 6 Nov 00 UTC 7 Nov 700 hpa 1 UTC 6 Nov 00 UTC 7 Nov 1 UTC 7 Nov 00 UTC 8 Nov 1 UTC 7 Nov 00 UTC 8 Nov 1 UTC 7 Nov 00 UTC 8 Nov 70 90 110 130 150 Wind Speed (knots) 0 5 30 35 0 Abs. Vorticity (x10-5 s -1 ) 70 80 90 95 Relative Humidity (%)
WRF Synoptic Overview: Upper Air 300 hpa 500 hpa 1 UTC 6 Nov 00 UTC 7 Nov 1 UTC 6 Nov 00 UTC 7 Nov 700 hpa 1 UTC 6 Nov 00 UTC 7 Nov 1 UTC 7 Nov 00 UTC 8 Nov 1 UTC 7 Nov 00 UTC 8 Nov 1 UTC 7 Nov 00 UTC 8 Nov 70 90 110 130 150 Wind Speed (knots) 0 5 30 35 0 Abs. Vorticity (x10-5 s -1 ) 70 80 90 95 Relative Humidity (%)
WRF Synoptic Overview: Surface 1 UTC 5 Nov 00 UTC 6 Nov 1 UTC 6 Nov 0 kts 1 10 00 UTC 7 Nov 1 UTC 7 Nov 00 UTC 8 Nov 8 6 0 Interior precip: 1 UTC 6 Nov 00 UTC 8 Nov -Meter Water Vapor Mixing Ratio (g/kg) 1
Moisture Transport Diagnostics Integrated Water Vapor (IWV) Total water vapor in column Summed over each model level Units: centimeters Integrated Vapor Transport (IVT) Horizontal water vapor flux Calculated as 50-hPa layer averages Summed over layers Units: kg m -1 s -1 Water Vapor Mass Flux (QFLUX) Total water vapor mass moving through vertical unit cross section Calculated at each model level Units: kg s -1
Moisture Transport Diagnostics Integrated Water Vapor (IWV) Total water vapor in column Summed over each model level Units: centimeters Integrated Vapor Transport (IVT) Horizontal water vapor flux Calculated as 50-hPa layer averages Summed over layers Units: kg m -1 s -1 Water Vapor Mass Flux (QFLUX) Total water vapor mass moving through vertical unit cross section Calculated at each model level Units: kg s -1
Moisture Transport Diagnostics Integrated Water Vapor (IWV) Total water vapor in column Summed over each model level Units: centimeters Integrated Vapor Transport (IVT) Horizontal water vapor flux Calculated as 50-hPa layer averages Summed over layers Units: kg m -1 s -1 Water Vapor Mass Flux (QFLUX) Total water vapor mass moving through vertical unit cross section Calculated at each model level Units: kg s -1
WRF Integrated Water Vapor 1 UTC 5 Nov 1 UTC 6 Nov 00 UTC 6 Nov Approach, landfall, penetration, and decay of AR Oriented WSW to ENE Most intense phase: 00 UTC 7 Nov 1 UTC 7 Nov 00 UTC 8 Nov Centered on Ore./Wa. border -5cm IWV at coast 3-cm IWV in C.R. Basin Decaying phase: Moving south to N. Cal. 3-cm IWV at coast cm IWV in NE Ore. Location of moisture, not transport 1 3 IWV (cm) 5 Interior precip: 1 UTC 6 Nov 00 UTC 8 Nov
WRF Integrated Vapor Transport: Plan View IVT (kg m -1 s -1 ) Landfall at Ore./Wa. border 1 UTC 5 Nov 00 UTC 6 Nov 1 UTC 6 Nov Penetration occurred across length of Cascades 600 kg m -1 s -1 Maximum penetration through C. R. Gorge and over terrain immediately south of it Follow this corridor with time series 00 UTC 7 Nov 1 UTC 7 Nov 00 UTC 8 Nov Interior precip: 1 UTC 6 Nov 00 UTC 8 Nov
WRF Integrated Vapor Transport: Temporal Plumes Integrated Vapor Transport (in kg m -1 s -1 ) 00z N3 00z N 00z N5 00z N6 00z N7 00z N8 00z N9 100 Offshore, C. R. Gorge, C. R. Basin, Glacier Nat l Park 100 1000 800 600 00 1 3 1 3 Lesser AR before main event Progressively less transport from Cascades eastward 100 1000 Maximum IVT at Point 00 600 00 1 3
WRF Water Vapor Mass Flux: Plan View Vertically Integrated Water Vapor Flux (x 10 9 kg) 8-hour total water vapor flux Isolates main AR from initial landfall to decay Corridor of penetration ~150km C.R. Gorge and south Terrain south of Gorge 3-k feet and ~50km wide Terrain north of Gorge -6k feet and ~100km wide Water Vapor Flux (00 UTC 6 Nov 00 UTC 8 Nov) 7 6 5 3 1
WRF Water Vapor Mass Flux: Plan View Model Terrain Height (x1000 feet) Vertically Integrated Water Vapor Flux (x 10 9 kg) 1 10 8 6 7 6 5 3 1
WRF Water Vapor Mass Flux: Plan View Model Terrain Height (x1000 feet) Vertically Integrated Water Vapor Flux (x 10 9 kg) 1 7 10 8 W R E 6 5 6 3 W R E Cross-Sections 1
WRF Water Vapor Mass Flux: Cross-Sections Height (km) West of Cascades Cascades Ridge East of Cascades Core flux under 3km Northern half of OR 5 W W R R E E WA OR WA OR WA OR 3 1 C. R. Gorge 100 00 300 00 500 8-hour Total Q Flux (kg m - )
WRF Water Vapor Mass Flux: Cross-Sections Height (km) West of Cascades Cascades Ridge East of Cascades Core flux under 3km Northern half of OR Through C.R. Gorge Over Cascades, esp. in OR Flux through Gorge similar to that west of Cascades 5 W W R R E E WA OR WA OR WA OR 3 1 C. R. Gorge 100 00 300 00 500 8-hour Total Q Flux (kg m - )
WRF Water Vapor Mass Flux: Cross-Sections Height (km) West of Cascades Cascades Ridge East of Cascades Core flux under 3km Northern half of OR Through C.R. Gorge Over Cascades, esp. in OR Flux through Gorge similar to that west of Cascades Core of flux downwind of Gorge Notable weakening of flux 5 W W R R E E WA OR WA OR WA OR 3 1 C. R. Gorge 100 00 300 00 500 8-hour Total Q Flux (kg m - )
WRF Water Vapor Loss Over Cascades.0 Total Water Vapor Mass Flux (x 10 1 kg) 1.5 1.0 31% reduction 5% reduction 0.5 West Ridge East
WRF Water Vapor Loss: 00 km Segments Upstream Downstream Upstream Downstream Upstream Downstream 0.6 0. Total Water Vapor Mass Flux (x 10 1 kg) 5% reduction 18% reduction 18% reduction 0. Northern Cascades Gorge Corridor Southern Cascades
Summary Intense inland penetrating AR in Pacific Northwest early November 006 Record rainfall and flooding over interior mountains (Glacier Nat l Park) Water vapor breached length of Cascades (3-7k foot ridge) 5% water vapor transport reduction across Cascades Main corridor for water vapor penetration ~150 km wide from Columbia River Gorge south Greater reduction north of Gorge (5%) vs. south of Gorge (18%) Next Steps Follow moisture transport to interior mountains Calculate moisture transport including hydrometeor mass Modify terrain to close Gorge, increase barrier height
Acknowledgements Funding from the Bureau of Reclamation Cooperative Agreement with CIRES Kelly Mahoney: co-author at NOAA University of Colorado s Research Computing (Janus supercomputer) Weather Research and Forecasting modeling system