NOAA/NWS Frequently Asked Questions (FAQ) |
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1. What exactly is the NOAA/National Weather Service? The National Weather Service is an agency of the federal government. It is actually part of the Department of Commerce, with its parent organization being the National Oceanic and Atmospheric Administration. You may be familiar with its acronym NOAA, which is pronounced “Noah”. Our office is staffed 24 hours a day, every day of the year, protecting life and property of Iowa citizens residing in our 51 county area of responsibility. The website for the Des Moines office can be found at http://weather.gov/desmoines. |
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2. What is the difference between Partly Cloudy and Partly Sunny?
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3. What are heating and cooling degree days? Heating and cooling degree days are a measure of how much the average daily temperature deviates from a baseline of 65 degrees. The average temperature is crudely computed by averaging the high and low temperatures for the day, so a high of 70 and a low of 50 would result in an average daily temperature of 60 and 5 heating degree days. Conversely, a high of 90 and a low of 65 ((90 + 65)/2 = 78 rounded up) results in 13 cooling degree days for that particular day. These degree days are sometimes used by utility companies to get a rough idea of how much you may by using your heating or air conditioning. |
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4. Does the NOAA/National Weather Service activate the tornado siren in my town? The NOAA/National Weather Service does not have direct control over any tornado or severe weather sirens. They are typically activated by city or county officials, usually police, fire department or emergency management personnel. Some officials wait for the issuance of a tornado warning, while others wait until a tornado has been identified by spotters. The NOAA/National Weather Service in Des Moines recommends siren activation with the first occurrence of either a Tornado Warning with favorable path-cast references, or an impending tornado identified by trained, credible spotters. |
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5. The forecast says there is a 30 percent chance of rain. That means it probably won’t rain, or if it does it will be light, right?
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6. Can the NOAA/National Weather Service in Des Moines provide certified records regarding weather phenomena that occurred on a particular day?
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7. We had storm damage and large hail at my house a few weeks ago. Where can I find out information about past severe weather events? For information from 1950 up to a few months ago, please visit NOAA’s National Climatic Data Center (NCDC) website at www.ncdc.noaa.gov. Input “storm events” in the search field window and follow the links to the appropriate information. For more recent information, please visit the NOAA/Storm Prediction Center (SPC) website at www.spc.noaa.gov. Click on the “Storm Reports” link on the left hand side under Weather Information. |
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8. Are tours of the Des Moines NOAA/National Weather Service office available? Yes. Tours can be arranged by calling 270-2614 weekdays between 700 am and 300 pm. We prefer groups limited to 25 people or less, and ages of 9 years (3rd Grade) and older. |
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9. Can the NOAA/National Weather Service please remove those watches and warnings from my favorite broadcast and cable TV station? They keep interrupting my shows.
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10. I’ve heard that an inch of rain would fall as 10 inches of snow. Is that always true?
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11. Your forecast has periods that begin Today, Tonight, Tomorrow night, etc. When do those periods begin and end exactly?
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12. My weather radio doesn’t alarm for Amber Alerts. Is there something wrong with my NOAA All Hazards Weather Radio? There are two kinds of alerts that can be received by weather radios. The older legacy weather radios only alarm when they hear a 1050 Hz tone. This only activates the radio, and does not include any information about counties affected or duration of the hazard. Newer weather radios take advantage of SAME, or Specific Area Message Encoding. This details what counties are affected and how long the watch or warning is valid. More advanced SAME radios can also be programmed to only alert for specific products in particular counties. If you are not receiving Amber Alerts, you likely either have an old legacy weather radio which does not receive SAME information, or your newer All Hazards SAME Weather Radio is not programmed to alarm for Amber Alerts. NOAA/National Weather Service national policy is to not send the 1050 Hz tone with Amber Alerts. |
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13. Where is the best place to get information on current river stages and forecasts? Does this have anything to do with AHPS?
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14. We had torrential rains last night with frequent lightning and a severe thunderstorm warning wasn't issued. Why is that? The issuance criteria for Severe Thunderstorm Warnings is soley based on wind speed or wind damage potential and hail size. The intensity of rain or frequency of lightning are not factors.
Severe Thunderstorms are defined as those producing wind damage, having wind speeds of 58 mph or greater (50 knots), or containing hail 3/4 of an inch diameter or greater (penny size). A storm meeting any of these critiera, even if there is little rain or lightning activity, is categorized as a severe thunderstorm. In situations where very heavy or excessive rains are expected to cause flooding, Flood Warnings or Flash Flood Warnings would be issued. |
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15. Does the National Weather Service have any educational materials that I can use in the classroom or even just for my own personal interest? Yes, there is a very detailed educational webpage with information on multiple topics. This online weather school, called JetStream, can be found at www.srh.noaa.gov/jetstream.
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