Winter Precipitation Types
- Rain – moisture condenses into drops and then falls.
- Freezing Rain – rain that freezes when it lands on surfaces below freezing.
- Sleet – frozen precipitation melts and refreezes into ice pellets.
- Snow – water crystalizes and falls to the ground without any melting.
- Radar can make a “best guess” at the precipitation type, but it could still change before it hits the ground underneath the radar beam.
- Snow to sleet, sleet to rain, rain to freezing rain, etc. but wait till the change has “taken hold.”
- Thunder during a snow event.
- Measured radially from the twig, grass blade, fence, etc.
- Report accretion starting at ¼″
- Can cause a lot of damage to trees and power lines due to the added weight of the ice
- If the ice is uneven, measure both sides and take the average.
- Report rain when temperatures are below 30°F.
- Structural damage
- Coastal flooding
Measuring Snow Fall
- First 2″ of snow
- Every additional 2″-3″ of snow
- 1”/hr or greater snow
- If total snowfall is less than 2″ just report final depth.
- Always report final total, don’t leave NWS hanging!
Proper methods to measuring snow depth:
- Measure in several places that are not affected by trees, buildings, or other local obstructions.
- Areas that are clear, flat and open. Avoid drifts and bare areas.
- Average your numbers together and report to the nearest 0.1″. For example 3.25″ becomes 3.3″.
Should you clear your spot?
- Not necessary.
- If you do decide to clear, wait 6 hours between clearings.
- Useful during larger storms as snow compaction can lessen total snowfall amounts.