Winter Reporting Procedures


From the NWS Baltimore-Washington Forecast Office

Reporting Snowfall

  1. Call if snow is falling and accumulating, but not in the forecast...Or...the snowfall depth has exceeded what is currently forecasted by our office.
  2. Call when 4 inches of snow has fallen. (However, reports are never turned down).
  3. Most Important! Call or e-mail your final snowfall total. This data is critical for proper documentation of the event. Please do not embelish your total snowfall... accuracy is very important to us.
  4. If you are receiving heavy snow, greater than 4 inches, call when you feel it is an appropriate time to give us an update.

Reporting Ice

Know the difference
  1. Sleet is frozen rain or ice pellets. When it strikes the ground, it usually bounces. Sleet can accumulate like snow and cause slick roads. In February 1994, some areas reported 4 to 7 inches of sleet!
  2. Freezing rain is rain that freezes after it strikes a cold surface such as a tree, a sidewalk, or a car. It forms a sheet of ice and is extremely dangerous.
  3. When measuring ice, measure the thickness of the glaze on trees or wires. Report what is on the ground separately since it might be a mixture of snow, sleet, and ice or a different thickness due to surface temperature differences. (e.g. Ice might be accumulating on trees and wires but the pavement is just wet because it was warmer and above 32°F. On the other hand, there are times that the pavement is colder and slick spots are forming on the road, but above the ground at tree level, the temperature is above 32°F and no ice is forming.) Please tell us as much as you can.
When to Call
  1. Call when a glaze of ice begins to accumulate on trees and wires, or on roadways and walkways. Ice is extremely hazardous and sensitive to your local temperature. Reporting ice might save a life.
  2. Call when ice accumulates a half an inch or more on trees and wire. At this point, the weight of the ice may be enough to bring down tree limbs and utility lines.
  3. Contact us (if still possible) when ice reaches one inch thick.
  4. Call or e-mail your ice total, final thickness of the ice, on the trees.

Reporting Changing Weather and Other Unusual Winter Phenomena

It is hard to define all the right times to call the National Weather Service with a report. You are often the best judge since you know what is normal and what is very usual for your area. Below is a list of a few things that our office is interested in.
  1. If you notice the weather is differing greatly from the forecast.
  2. If, for instance, the forecast is calling for flurries, but you now have a few inches on the ground, or instead of rain, it is now sleeting out. In the rural areas, we have very little "ground-truth" data that tells us what precipitation type is falling or what is happening on the ground.
  3. If the temperature falls below zero and you know what your minimum temperature was.
  4. If you have an anemometer (measures wind speed) and it gusts to 50 mph or higher
  5. If high winds cause any damage such as trees or wires down, or damage to structures.
  6. If it is snowing and you see lightning or hear thunder.
  7. If it is snowing and the wind is gusting to 35 mph causing white out conditions.
  8. If heavy drifting of snow is occurring and you can tell us the depth of the drifts.

How to View Spotter Data during or after an Event

The information that you provide is often used in Special Weather Statements, updates to warnings and advisories, and broadcast over NOAA Weather Radio and SKYWARN Amateur radio networks. However, summary information such as unusually cold temperatures, snowfall or ice amounts, high winds reports, etc. is posted in the "Public Information Statement". For historical data, look on our local historical events site or archives and you can get Storm Data from the National Climatic Data Center.

Page Last Updated, 05/08/09

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