In order to keep AccuWeather.com a free service, we need to use advertisers to cover the cost of operating the best weather site on the web. We understand your concerns and will forward them to our internet department. We do, however, offer an ad-free service called Premium AccuWeather.com -- for more information click here.
We've worked hard to find the best balance of advertising and content, and it was our intention to separate content and advertising more completely with the new site. This results in a column for content (left side) and the column for advertising (right side). It's our hope that by pulling the advertising out of the content we've created a better experience for people scanning quickly for the weather.
AccuWeather offers an ad-free service called Premium AccuWeather.com -- for more information click here.
In order to keep AccuWeather.com a free service, we need to use advertisers to cover the cost of operating the best weather site on the web. We understand your concerns about the rate of pop-under ads, and recently, we have taken steps to reduce the number of pop-under ads that appear, and a user should not get more than 2 in a particular 5 minute session. This rate of pop-under ads is similar to many other major sites on the Internet. We offer an ad-free service called Premium AccuWeather.com -- for more information click here.
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Although our forecasts are for tens of thousands of unique points, we rely on the National Weather Service for Current Condition reports. Each city is related to the nearest (in mileage) official NWS reporting station, or an estimation of what is going on between them, and these only come in once per hour. For some locations, especially in the West, this can lead to a current data report that is not directly in your backyard, but where the weather at that moment is different.
There have been tremendous improvements in the accuracy of longer range forecasts over the past several years. A forecast for the 7th day today is as accurate as it was for the 4th or 5th day 10 years ago. Further, there is now skill in forecasting out through 15 days, something that was not possible a few years ago. Still, a forecast for the 15th day is not going to be as accurate as a forecast for tomorrow. The best advice would be to look for trends of the weather from days 11-15....that is, will it be warmer or colder, wet or dry.
AccuWeather is always working to provide more accurate forecasts. Right now the computing power available to the private sector limits the actual number of forecast points, so actual city forecasts may be a forecast for a nearby forecast point, and this may be off base because of elevation differences, especially in Western US States.
We are updating our database soon to include thousands more points, towards a goal of one million points worldwide. Most of our competitors' web forecasts are drawn from a couple thousand points while ours are in the tens of thousands, and again in the future should reach one million.
As noted on the AccuWeather.com 15-Day Forecast Page, These National Weather Service forecasts are provided as an additional "voice" to consider and compare with the AccuWeather.com forecast. They are not written by AccuWeather.com forecasters, and may disagree with the official AccuWeather.com forecast.
NEXRAD (NEXt generation of weather RADar) Doppler radars have been installed throughout the country to replace the outdated network of conventional weather radars that were installed in the late 1950s. AccuWeather is offering access to the full network of nearly 150 NEXRAD Doppler radars, as each site is installed and test data made available from it by the government. NEXRAD's ability to detect wind patterns in storms and provide real time rainfall amounts are revolutionizing the way we keep up with and ahead of rapidly changing weather.
Each NEXRAD radar generates dozens of data types, including higher resolution reflectivity data, storm total rainfall amounts, wind speeds and direction, wind gusts and much more, including early tornado detection capability.
AccuWeather has the most NEXRAD products available (20 basic products plus value-added mosaics, StormTimer™ and numerous other value-added products) from the most NEXRAD sites, all in real time. AccuWeather's NEXRAD products will provide you with superior resolution, more detail, higher accuracy and a wide range of information than ever before available from existing radar technology.
If you see data on your NEXRAD Doppler Radar but that location is not receiving precipitation, this could be for a number of reasons.
The most common explanation for the seemingly anomalous data on the image is "ground clutter." Ground clutter usually appears near the center of the radar image when the radar beam intersects trees, buildings, mountains, insects, pollution, etc. near the site. Every NEXRAD radar has ground clutter, but it is much more evident when the radar is operating in Clear Air Mode (explained above). This non-precipitation data may also affect the MAX dBZ reading so be sure to use the color scale to confirm the MAX dbZ reading if ground clutter is present.
Anomalous data, often high in intensity, which is not limited to a circular pattern near the radar site may be "anomalous propagation," or "AP." AP occurs when atmospheric conditions cause the radar beam to be reflected back to the earth, where it bounces off the ground and reports the terrain back as radar echoes. It is often hard to distinguish from actual precipitation data.
Precipitation not reaching the ground (virga) may be occurring. Also, the NEXRAD Doppler radar's sensitivity also allows users to view cold fronts, sea breeze fronts and thunderstorm outflow boundaries that have no precipitation associated with them. Boundaries such as these appear as thin continuous lines on the Base Reflectivity product at reflectivities of 10 dBZ or lower. Other non-weather related phenomena are also detected periodically in NEXRAD reflectivity data due to the high sensitivity and high resolution of the radar, such as smoke plumes from grass and forest fires and movements of large flocks of migrating birds.
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