Utah Mesonet: Monitoring Weather Conditions in the Intermountain West

Personnel: B. White, M. Splitt (CIMMS), C. Clements

Project began during 1994 with support from COMET. Continued funding from NWS

Surface observations obtained from local, state, and federal agencies and private firms

Considerable interaction with SLC NWSFO to operate and maintain

Deployment of sensors as part of joint project with NWS Western Region and NSSL for high elevation radar project and in support of 2002 Winter Olympics

15 minute processing cycle

Quality control measures in place

Fall 1998: port files into WFO Advanced via LDADS for use at the SLC NWSFO

On-line information: U. Utah, SLC NWSFO

References:

• Stiff, C. J., 1997: The Utah Mesonet. University of Utah M.S. Thesis. 120 pp.
• Slemmer, J. W., 1998: Characteristics of Winter Snowstorms near Salt Lake City as Deduced from Surface and Radar Observations. University of Utah M.S. Thesis. 138 pp.
• Splitt, M. E., and J. Horel, 1998: Use of multivariate linear regression for meteorological data analysis and quality assessment in complex terrain. Tenth Symposium on Meteorological Observations and Instrumentation. Phoenix, AZ

Utah ARPS Data Analysis System (ADAS)

Personnel: S. Lazarus and C. Ciliberti

Develop local analysis at high temporal (1 h) and spatial resolution (2 km)

Provide near real-time high resolution data over the complex terrain of northwes t Utah

Based on the Oklahoma ADAS (ARPS Data Analysis System) developed by the Center for Analysis and Prediction of Storms (CAPS)

Incorporation of large-scale and local data:

• Rapid Update Cycle Version 2 (RUC2) analysis used to initialize ADAS
• Utah Mesonet available at 15 minute intervals
• NWS rawinsonde provides upper air data at 0 and 12 GMT
• NWS WSR-88D velocity and reflectivity data obtained at 5-10 minute intervals (NIDS products)
• Visible and IR Satellite imagery used to specifiy cloud water

Summer 1998: Use ADAS to initialize the Advanced Regional Prediction System (ARPS) to provide high resolution forecasts of mesoscale events

On-line Information: ADAS

References:

• Lazarus, S., C. Ciliberti, and J. Horel, 1998: Application of a local analysis system in highly variable terrain. 16th Weather and Forecasting Conference. Phoenix, AZ.

Validation of Operational and Research Models

Personnel: K. Cook, B. McDonald, B. White. Supervision by J. Steenburgh, J. Horel, and J. Paegle respectively

Evaluate forecast skill of operational and research mesoscale models in regions of complex terrain

• Eta model at all available resolutions (48, 29, and 10 km)
• MM5
• Utah LAM

Focus on validation of precipitation and 3-D circulation

On-line information:

• www.met.utah.edu/jimsteen/mm5_val/mm5_validation_page.html
• www.met.utah.edu/jimsteen/meso_val/meso_validation_page.html
• Eta Evaluation
• www.met.utah.edu/jpaegle/validation

References

• McDonald, B. E., J. D. Horel, W. J. Steenburgh, and C. J. Stiff, 1998: Observations and simulations of three downslope wind events over the northern Wasatch mountains. 16th Conference on Weather Analysis and Forecasting. Phoenix, AZ
• McDonald, B. E., and J. D. Horel, 1998: Evaluation of precipitation forecasts from the NCEP's Nested Eta Model. 16th Conference on Weather Analysis and Forecasting. Phoenix, AZ
• White, B. G., 1997: Short-term forecast validation of six models for winter 1996. University of Utah M.S. Thesis. 99 pp.
• White, B. G., W. J. Steenburgh, J. Paegle, J. D. Horel, R. T. Swanson, and J. Miles, 1998: Short-term forecast validation of six models for winter 1996 16th Conference on Weather Analysis and Forecasting. Phoenix, AZ
• White, B. G., W. J. Steenburgh, J. Paegle, J. D. Horel, R. T. Swanson, and J. Miles, 1998: Short-term forecast validation of six models for winter 1996. Wea. Forecasting. Accepted.
• Cook, L. K., 1998: Mesoscale Model Validation in the Intermountain West. University of Utah M.S. Thesis. Summer '98.

Summary: Precipitation Evaluation

Validation of model skill requires attention be placed on the quality and uncertainty contained in observational data sets

In regions of complex terrain, models should be verified on their native grids with minimal postprocessing

Objective skill measures should be consistent with subjective, visual evaluations. The ETS may be misleading in some instances, since overforecasting precipitation is rewarded while slight underforecasting is penalized.

Models that resolve the terrain of the western United States tend to have higher skill during winter for moderate-to-large precipitation totals. Less skill is evident during spring.

Skill for coarse resolution models improves if model precipitation is readjusted across grid squares to conform to monthly PRISM climatology

Forecast skill is higher along West Coast than over Intermountain region