This product, developed for the Reno National Weather Service Forecast Office (NWSFO), is based upon results obtained from the COMET Partners project "Integrating Weather and Climate for Improving Outlooks and Forecasts During the Nevada Fire Season". It includes the climatology of Remote Automatic Weather Station (RAWS; e.g., Redmond, 1991) historical data for the period of record through 1995 at 131 stations located within Nevada and approximately one degree spatially surrounding the state. This area covers all of the Reno NWSFO forecast zones and adjacent area. The climatology for temperature, humidity, wind speed, and wind direction is summarized in map form for each hour of each month.

The data were extracted from the Western Regional Climate Center’s (WRCC) RAWS database. Sites within Nevada and surrounding vicinity were selected using the station’s NESS (National Environmental Satellite Service) identification number (ID). Un fortunately, the NESS ID is not always unique for each station during its operational period. It was found that in several cases the NESS ID was different depending upon the particular time period the station was in use. Thus, station ID’s were checked manually to establish the spatial location, and to determine whether or not two or more stations were actually one site, but with different ID numbers. For all station locations in the attached graphical displays and index table, the most recent record of latitude, longitude, and elevation was used.

Once the sites were identified, a low-level quality control (QC) was applied to the data. Two types of problems were found in the original data. First, March 1995 was intermittently contaminated with non-numeric characters due to electronic transmission problems. If it was possible to preserve the data of interest for the hour with a known problem, then the bad characters were removed and valid data values retained. If it was not possible to preserve the data for the hour while correcting for the non-numeric characters, all of the station’s values for that particular hour were deleted. Overall this only amounted to a less than 1% removal of bad data. The second QC check included examination of values exceeding a predetermined set of ranges; temperature -20 °F to 120 °F, humidity 0 to 100%, wind speed 0 to 99 mph, and wind direction 0 to 360 degrees. Values found to exceed these ranges were set to missing. Only a very small portion of the values were flagged in this manner.

Mean hourly values were calculated by taking the sum of all values for a particular variable (i.e., temperature, humidity, wind speed, and wind direction) for each hour of each month, then dividing by the total number of hours. For a station to be included in the analysis, the period of record had to exceed one year.

Mean temperature, humidity, and wind speed values are presented in contour plot form. Gray scale shaded contours highlight regions of equal value, and labeled contours are overlaid for shading identification. A Cressman analysis scheme (Cressman, 1959) was applied to convert the irregularly spaced data into a regular grid. Wind direction is shown as equal length vectors graphically representing the mean direction for that hour. All graphical displays were made using the Grid Analysis and Display System (GrADS) from the University of Maryland’s Center for Ocean-Land-Atmosphere Studies.

It is important to be aware that the dataset as a whole lacks homogeneity - in particular, the number of observation hours vary by station. For example, a station might contain hourly data for the two-year period 1985-86, and a nearby station for the five-year period 1990-1994. In the graphical summaries these are combined as if all the stations have identical periods of record. For some types of analyses this might have to be accounted for. However, all of the plots show reasonable spatial consistency, and a good qualitative assessment of RAWS climatology can be achieved.

Included with the climatology figures is a station location map, and a station index. RAWS stations are denoted as black dots with a nearby index number. This number may be used with the station index table to obtain specific information regarding the site. The table includes the site name, most recent latitude, longitude, and elevation, the station start and end dates, and the number of missing months. An ending date of 12/95 only reflects the last month used in this project, not necessarily the closing of a station.

Cressman, G., 1959: An operational analysis system. Mon. Wea. Rev., 87, 367-374.

Redmond, K., 1991: A User’s Guide to RAWS Products, July 1991. WRCC Report #91-02, Western Regional Climate Center, Desert Research Institute, Reno, NV, 28 pp.