Many times, we receive questions about our Grid point forecasts. They come in many forms, and often some are related. The frequently asked questions are listed here. If you need more in depth information about the gridded forecasts, be it the 7-day Forecast, Hourly Weather Graph or the Tabular Forecasts, see the help sections of those documents.

1. How often does the map update?

The map updates when the forecast is updated. However, there is no auto-refresh. You will have to reload the page to see the latest forecast. At a minimum, the forecast is updated by 4 am and 4 pm. The last time the forecast was updated is above the 'Forecast at a Glance' shown in Fig. 1.

Fig. 1. Image showing where the last time the forecast was updated is shown on the page.

2. What is the size (in miles) of the forecast red grid box?

The grid box is approximately 1.5 miles on each side; an area of approximately 2.25 square miles.

3. Can I save (bookmark) my forecast site then always get updated/future forecasts? (e.g. I want to bookmark 8 miles E of Yerington for future forecasts)

Yes. You can use the bookmark option in your browser to do this. You can rename the bookmark to "My Forecast" if you wish, but be sure to leave the address of the page as is.

4. I live in south Reno, near Mount Rose Highway. When I click my location on the map (it may be South Lake Tahoe, Truckee, etc.), the location selected shows that I am 6 miles south of Reno. I live in the city limits so this doesn't make sense to me. Why does it show this?

This is the design of our database where only one grid point is defined as Reno, or Sparks, Susanville, etc. Since some towns and cities cover many square miles, the weather on one side of town may be much different than the other. In some cases, the elevation across the city or town varies by 1,000 feet or more! Imagine the confusion if 25+ grid points within the Reno city limits all stated Reno, NV. Other than the map, there would be no way to know which part of the city that forecast is valid.

The points defined for each city or town are in reference to the city or town center, typically the 'downtown' area. In the case of Reno it is the intersection of Virginia Street and the Truckee River. Therefore, in this example, the grid point you clicked on is approximately 6 miles south of the center of Reno (Fig. 1a and 1b).

Fig. 4a. Your location at the top of the page.

Fig. 4b. You location in the right on the map. Here, 'Reno' is over the downtown area.

5. Your forecast said it would snow for my location, but it is raining right now and has been doing so for several hours. I live at 6700 feet, and the snow level from the zone forecast says it will be 7,000 feet. I would expect rain at my house based on the zone forecast, but I thought the point-and-click was supposed to be more accurate? Why is there this difference?

In mountainous areas such as the Eastern Sierra and Western Nevada, there can be large elevation changes over short differences. While each grid point represents an square approximately 1.5 miles on each side and is fairly small, there are cases where the elevation will change 1,000 feet, 2,000 feet or more! Your location may be in one of these boxes. For example, look at this grid box, which is for Incline Village, NV (Fig. 2):

Fig. 5. Grid box for a portion of Incline Village, NV. The map on the left is the default while the map on the right is zoomed in to show the contours.

This point off of Mount Rose Highway (NV 431) has a large difference in elevation across it. At the north end of the box, the elevation is over 9,000 feet in places, while portions of the south end are near 7,000 feet. The average elevation of the box is displayed below the map. This box's average elevation is 7,865 feet, and this is the elevation that is used for the forecast. If the snow level is 7500 feet, the forecast for this box will say snow. However, if you live near 7,000 feet at the south end of the grid box, you will see rain instead. Sometimes, the snow level is displayed in the forecasts for each box in varied terrain while in other cases it is not.

6. Why is the forecast so different when I click just outside of the grid box?

You are getting a forecast for another grid box. Depending on the terrain involved, the average elevations for the two adjacent grid boxes may be very different. For example, the grid box north of the grid box used in Question 5 is used. Note in the figure below that the average elevation is much different which will result in a different temperature, wind, and snow/rain forecast.

Fig. 6. Maps for adjacent points near Incline Village, NV. Note the difference in elevation between the two points at

7. When I click on the map for a forecast, I get a forecast for a completely different area. Why?

Pay close attention to the location shown at the top of the forecast. It is difficult to click on the same grid box every time, so this may be why you are getting a different forecast. In the example below, the forecast is for '3 miles NW of Dollar Point, CA.'

Fig. 7. The location descriptor shown at the top of the page.

This location description will show up every time for this forecast grid box. Another forecast grid box will have a different location descriptor, but not always. A second, and better way to check is to look at the map on the right hand side. Make sure the red box is in the same location you are used to. If not, you can click on the map to select the point you would like.

8. The wind forecast for my location is almost always too strong and the directions can be off. Why?

This question is related to #5. The wind forecast is averaged over the grid box at the elevation shown. There are many areas in the grid box where the forecast wind is not representative due to small scale terrain effects. For example, using the map in question 5, the winds on the north side of the box at the higher elevations will be stronger, while the lower elevations at the south end of the box may be lighter. The wind directions may also be quite different due to prominent canyons or ridges that will alter how the air flows in and around them.