Diagnosis of Medium-Range Predictability Enhancement During Anomalous Winter Zonal Flows Over Western North America
Abstract
This investigation analyzes medium range predictability enhancement during winter cases of anomalous, upper troposphere zonal flows over western North America. Time correlations based upon a 50 year record of reanalyses suggest that winters with anomalously strong zonal winds are wetter over the region, while years with anomalously weak zonal winds are relatively drier. Forecasts are selected based upon anomalously weak and strong zonal flows during January. Results from 15 day simulations using a variety of operational and research global model configurations are presented to diagnose the predictability of precipitation and large scale features. Model forecasts of precipitation accumulation delineate qualitatively between wet and dry events at both 5 and 10 days. Anomaly correlations of the geopotential height field reveal useful predictability for some ensembles extending to 9.5 days. Uniform resolution forecasts are compared with two model configurations which employ rotated variable resolution. Uniform and variable resolution forecasts maintain representative precipitation into the second week over the western U.S.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2003
- Accession Number
- ADA424127
Entities
People
- Lee A. Byerle
Organizations
- University of Utah