National Weather Service: Delivering the Forecast to You

Clicking on the WFO map from our  homepage  will instantly present the forecast for the area you selected in both graphical and text formats. These forecasts are geographically specific and represent a 2.5 x 2.5 km area as shown in green on the map to the right.

You can also create your own forecast for a specific area using the "User-Defined Area Forecast" tool. Why would you want to do this? Say you were heading to the mountains for a hike - you can create a forecast for the hike you’ll go on. You plan on going skiing over the weekend? You can create a forecast for the ski area!

It's super easy to use the tool. All you need to do is click "User-Defined Area Forecast" from the drop-down menu under the "Forecasts" tab on our  homepage . Then, simply add your desired points to create a polygon and click "Get Area Forecast".

You can also access meteograms for a specific forecast point, in either graphical or tabular format. A meteogram is a time series of forecast weather data for a particularly station. You can access these meteograms by clicking "Hourly Weather Forecast" under the "More Information" section of a point-and-click forecast.

The weather story is designed to provide a snapshot of the developing weather across our region or emphasize special weather phenomena that is ongoing or expected. It's issued at least once per day and can be found on our  homepage , as well as on  Facebook  and  Twitter .

Wind describes the prevailing direction from which the wind is blowing with speed in miles per hour. The numbers may vary in other parts of the country due to variation in terrain and elevation.

Forecast temperature describes the forecast maximum and minimum temperatures or, in some cases, the temperature expected at a specific time. Temperature is reported in degrees Fahrenheit.

PoP is the likelihood of measurable precipitation (or water equivalent of frozen precipitation) falling during a specified period in the forecast area. Measurable precipitation is equal to or greater than 0.01 inch (0.2 mm) over a period of 12 hours, unless specified otherwise.

At times, NWS forecasters may use “occasional” or “periods of” to describe a precipitation event that has a high probability of occurrence, i.e., they expect any given location in a forecast area to most likely have precipitation, but it will be of an “on and off” nature.

Wind chill describes the rate of heat loss from exposed skin due to the combined effect of wind and cold. As wind speed increases, heat is lost from the body at an accelerated rate lowering the body temperature. A Wind Chill Table is a matrix that uses sustained wind speeds to determine wind chill.

The NWS issues watches 2 to 24 hours in advance of potentially hazardous weather or water incidents, allowing the community time to plan. Watches for long fused events, such as winter storms or river flooding, may be issued up to 2-3 days before the onset of expected dangerous weather conditions. A watch indicates the risk of a hazardous incident has increased significantly but its occurrence, location, and/or timing is still uncertain.

The mission of the SPC is to provide timely and accurate forecasts and watches for severe thunderstorms and tornadoes over the contiguous United States. They also monitor and issue specific products for heavy rain or snow and fire weather incidents across the country. Forecasts of organized severe weather are relayed as much as 3 days in advance, and they are continually updated until the event has ended. SPC issues a variety of products including  Daily Convective Outlooks ,  Severe Thunderstorm and Tornado Watches , and  Mesoscale Discussions .

Advisories highlight special weather conditions that are less serious than a warning. They are for incidents that may cause significant inconvenience and, without due caution, could lead to a dangerous or threatening situation.

Twice a day, seven days a week, nearly 900 stations around the world (including at the NWS WFO in Grand Junction) release weather balloons into the atmosphere to obtain upper air weather information. (Click  here  for a map of stations in the U.S.) Under the helium or hydrogen-filled balloon a small instrument, called a radiosonde, dangles on a string broadcasting continuous weather data back to the launch site. The radiosonde consists of a radio transmitter, GPS, temperature sensor, humidity sensor, and pressure sensor. The winds aloft are computed from the measured elevations and location of the radiosonde at a given pressure (recall pressure decreases with elevation). The height of the balloon is also calculated. So, from this simple instrument, the complete temperature, moisture, wind and pressure field in the vicinity of the launch station can be obtained during its two hour journey to nearly 100,000 feet up into the atmosphere.

Broadcasting accurate and timely weather information is a crucial aspect of the NWS mission and NOAA Weather Radio All Hazards (NWR) is a primary communication link to NWS customers. NWR is a nationwide network of radio stations broadcasting continuous weather information. NWR broadcasts official NWS warnings, watches, forecasts, and other hazard information 24 hours a day on over 1,000 NWR transmitters to 90% of the country’s population. The Grand Junction WFO maintains eight transmitters providing NWR coverage for eastern Utah and western Colorado. Additionally, the Colorado Department of Transportation (CDOT) maintains a network of AM and FM stations that transmit the NWR broadcasts to parts of Colorado.

NWR is an "All Hazards" radio network, making it the only official source for comprehensive weather and emergency information. NWR also broadcasts warning and post-incident information for all types of hazards, including natural (e.g. earthquakes or avalanches), environmental (e.g. chemical releases or oil spills), and public safety (e.g. AMBER alerts or 911 Telephone outages).

Learn more about NWR by visiting the NWR  website . Maps of the transmitters in the Grand Junction forecast area and the CDOT AM/FM repeater stations can be found below.

Imagine this: You’re driving down the highway, humming along to your favorite tunes, when the cell phone stowed in your bag suddenly makes a strange noise. To investigate, you take the next exit and safely pull over to check the screen. Good thing you did: Your phone just alerted you to a tornado a few miles away in same county you’re driving through. Sound plausible? It is. America’s wireless industry is helping to build a Weather-Ready Nation through a nationwide text emergency alert system, called Wireless Emergency Alerts (WEA), which will warn you when weather threatens. No signup is required! Alerts are sent automatically to WEA-capable phones during an emergency.

For more information on NWS WEA, visit  https://www.weather.gov/wrn/wea.  Or, see this handy  FAQ sheet  for more details on what kind of alerts you can receive.