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Desert Research Institute: "An application of local data to analysis and forecasting in the Truckee Meadows

Final Report


The primary goals of this project were to 1) provide the Reno National Weather Service Forecast Office (NWSFO) with a real-time analysis of meteorological fields using the Local Analysis and Prediction System (LAPS), and 2) improve the LAPS analysis over complex terrain. The Reno NWSFO receives data real-time from several mesonets in western Nevada and eastern California. LAPS provides a capability to ingest these data and perform an objective analysis of numerous meteorological fields such as temperature, winds, humidity, etc. It was desired to understand how well LAPS works in the complex terrain of the northern Sierra Mountains and valleys in western Nevada. Four main conclusions can be reached as a result of this project: 1) LAPS will likely need to be run at 1 to 3 km over complex terrain in order to provide for realistic analyses; 2) it is very important to incorporate high elevation mesonet data (e.g., RAWS) into the analysis; 3) the LAPS temperature analysis is not as realistic over complex terrain compared to smoother elevation regions; 4) a potential temperature analysis method developed for LAPS shows improvement over the surface temperature analysis.


2.1 Introduction

The primary objectives were to install and run LAPS operationally in the Reno NWSFO, and to improve the LAPS analysis over complex terrain. The bulk of the work was done by Brian Brong, a Masters graduate student in the Atmospheric Sciences Program (ASP), Desert Research Institute (DRI), University of Nevada (UNR). Dr. Timothy Brown, DRI Atmospheric Sciences Center and Dr. John McGinley (NOAA Forecast Systems Laboratory (FSL)) served as project advisors. Mr. Brong's primary tasks were to obtain and become familiar with the LAPS computer code, establish a database for ingest into LAPS using operational mesonet sites, installing and making LAPS operational on a NWSFO HP workstation, generating GEMPAK displays of the LAPS output, and developing an improved analysis method for temperature for use in LAPS. This latter task has been the basis for a Master's thesis project, of which Dr. McGinley has served as the research advisor.

Mary Cairns, Reno NWSFO SOO, also served as a principal project advisor. She worked directly with Mr. Brong during the implementation stages of LAPS, developing output graphical displays, providing data ingest from the hydrometeorological mesonet, and working with the forecasters to obtain feedback and product evaluation.

2.2 Description of research/development accomplishments.

This project has lead to four major recommendations/conclusions/accomplishments.

1) Running LAPS at a 10-km resolution may not be appropriate for the Western U.S. This has important implications since it is currently running in AWIPS at 10 km. Our experiments in running LAPS at finer spatial resolutions (i.e., 3 km) have suggested that even this might not sufficient. In complex terrain settings, it might be necessary to run an objective analysis at as little as 1 km. In the western U.S., a 3-km horizontal distance can easily equate to a 3000 to 5000 foot elevation change. We would recommend that LAPS within AWIPS be set to finer spatial resolution (at least 3 km minimum) in complex terrain regions, or allow the office to set a scale which seems to work best for their local needs.

2) Reno WSFO provides a unique opportunity for testing an objective analysis scheme in the Western U.S. in that the area has both a diverse mixture of mesonets (i.e., hydromet, surface, ALERT, SNOTEL and RAWS) and complex terrain. Based upon the analyses performed during this project, benefit is seen in having additional high elevation sites such as SNOTEL and RAWS. As the AWIPS version of LAPS is implemented around the West, we would recommend that the local offices ingest as much mesonet data as possible into LAPS, especially high elevation stations. While this statement may seem like overstating the obvious, it is important to recognize that forecasting over complex terrain offers challenges quite different from those in the plains and coastal regions. These additional high elevation sites offer critical information for use in the analysis and subsequent forecasting.

3) We believe that improvements can be made in the analysis of certain LAPS fields. Wind and temperature are two variables most likely to be influenced by terrain. We have focused considerable effort on surface temperature. This field is highly susceptible to complex terrain as considerable temperature change can be observed over short horizontal distances due to elevation affects. The tendency for a sparse observing network in mountainous regions adds to the problem. During this project, we began work on developing an analysis scheme for potential temperature. It is felt that potential temperature is more suited for complex terrain than a surface temperature analysis. Potential temperature is conserved for adiabatic flow and will vary smoothly over mountainous terrain. During the day surface potential gradients near frontal boundaries are well defined. The biggest drawback to potential temperature is at night, when these boundaries can disappear as cool air settles in the valleys.

4) The research involved in developing a potential temperature analysis has become the Masters thesis work of Mr. Brong. The thesis has not been completed as of this report date. However, significant progress has been made. In his initial work, Mr. Brong has provided evidence that a potential temperature analysis offers improvement over a surface temperature analysis. This analysis method is intended to complement the existing surface analysis, not replace it. Mr. Brong has been evaluating his method for different seasons and applying statistical verification techniques. This work is near completion, but is not anticipated to be fully summarized and written for publication until late 1999 or early 2000 (see section 5.1 below).


DRI and NWS made an effort to ensure interaction on this project. The student spent time at the Forecast Office learning forecast operations, installing the software, and hydrometeorological data management. Mr. Brong interacted with the Service Hydrologist, working together to update the hydrometeorological data in the HYDROMET system which is used by the entire staff. This included quality control of local data.

Dr. John McGinley, Chief, Local Analysis Branch, Forecast Systems Laboratory, visited Reno and made a presentation of LAPS to the forecast staff at the NWS. This hour long seminar focused on the current status of LAPS and plans for AWIPS and beyond.

As a result of this project, Dr. McGinley was awarded graduate faculty status in the Atmospheric Sciences Program, University of Nevada, to serve on Mr. Brong's Masters degree committee.


Brong, B.S, 1999: Development of a Potential Temperature Analysis for LAPS. University of Nevada Atmospheric Sciences Program Masters Thesis (in progress).

Brong, B.S., M.M. Cairns, and T.J. Brown, 1998: An Application of the Local Analysis and Prediction System to the Complex Terrain of Western Nevada. Preprints, 16th Conf. on Wea. Forecasting, Amer. Meteor. Soc., Boston, MA, 490-494.

Brong, B.S, T.J. Brown, and M.M. Cairns, 1997: An Application of the Local Analysis and Prediction System to the Complex Terrain of Western Nevada. Presentation at the 22nd Annual meeting of the National Weather Association, 18-24 October 1997, Reno, NV.

Cairns, M.M., 1997: Project overview presentation to the NWS Western Region Science and Operations Officer's workshop in SLC, December 1997.


5.1 University's perspective

The greatest benefit to DRI has been the opportunity to train a student in specialized forecast issues, in particular meteorology over complex terrain. The project has complemented many other DRI research areas including fire weather, cloud seeding, and air quality. The project as also provided Mr. Brong with an excellent career opportunity. In May 1999 Mr. Brong was offered a one-year full-time temporary position with the Corpus Christi National Weather Service Office. That position was offered to a large extent because of Mr. Brong's skills acquired in working with NWS related computing packages such as GEMPAK and his research work on objective analysis of meteorological fields. His accepting this position has been the primary reason for the delay in completing the thesis work. It is hoped that this work will be completed soon, and a journal article submitted sometime in 2000.

In early 1999 FSL provided a modest amount of funds to pursue the potential temperature analysis. The grant provided funds for Mr. Brong during the spring semester. This award was made through the Cooperative Institute for Atmospheric Science and Terrestrial Applications (CIASTA), which is a cooperative institute between the University of Nevada and NOAA. Thus, this project has benefited DRI in furthering participation between UNR and NOAA.

5.2 NWS perspective

This project was begun three years ago to both install and run LAPS in the Reno Forecast Office, and to evaluate how well LAPS would perform in the complex terrain of Western Nevada. The Reno area was unique in that the NWSFO had access to a number of local mesonets that would help augment the surface analysis while being located in a complex terrain environment.

The installation and running of LAPS was not as smooth as hoped. Delays were encountered due to both computer problems and software support from the LAPS group at FSL. FSL is not to be blamed, as this project was begun with the understanding that Dr. McGinley's group did not have the resources for full support of the software.

Several benefits were realized from this project. First, in the course of software installation and data gathering, the student discovered errors with our office hydrometeorological database that is used in forecasts and warnings. The student spent time making corrections to the database, something that was a great benefit to the forecasters. Second, the surface analysis was used in local forecasting, the first objective of this study. Several forecasters used the products on a regular basis, particularly in the summer months to observe and forecast convection. The upper air analysis was used infrequently due to problems with the conversion of LAPS to a 3-km 3-dimensional analysis.

The third and most important benefit of this program has been to open up discussions with the NWS concerning analyses in AWIPS. LAPS is currently run at 10 km, and is limited as to the data sources. It was discovered in this project that even at 3 km an objective analysis package such as LAPS might not perform very well in complex terrain. This is one finding which prompted the actual topic of the students' thesis - to improve the surface analysis of temperature (a second goal of this project). It has been suggested in numerous discussions among other SOOs in Western Region and with the WR SSD that scales of 1 km might be necessary to capture the details necessary for meteorological analysis on a local scale.

Even though LAPS was not a total success in running real-time over a long period of time, many good points were brought out due to this project. We feel that the project has been a success, and that the major objectives were met.