Winter Weather Spotter Course

1. Winter Weather Spotter Course National Weather Service Northern Indiana

2. Course Outline • Introduction to NWS Winter Weather Advisories/Watches/Warnings • Snow Spotters – our network today • Reporting real time information – what do we need to know about? • What to report after the storm is over • How to measure snow • How to report your information

3. Definitions • Freezing Rain – Rain falls as liquid and then freezes on contact • Sleet– Rain drops freeze into ice pellets priorto reaching ground. • Snow – An aggregation of many ice crystals • Graupel – Snowflakes which have been heavily rimed. Also called snow pellets, soft hail, and hominy snow. Looks like uncooked white grits.

4. Definitions (cont.) • Snowfall – Amount of new snow which has fallen. Measured to the nearest tenth of an inch. • Snow Depth – Total amount of snow on the ground (old and new). Measured to the nearest inch.

5. Precipitation Type Diagram

6. Dec 5, 2002 Raleigh, NC

7. Jan 30, 2002 North Webster, IN

8. NWS Winter Weather Products

9. Watches/Warnings/Advisories • Hazardous Weather Outlook • Winter Storm Watch • Winter Storm Warning • Lake Effect Snow Warning • Blizzard Warning • Winter Weather Advisory

10. Hazardous Weather Outlook • Issued each day between 5am and 6am • Outlines potential weather hazards expected over the next 7 days • The potential for major storms beyond 2 days will be discussed in the HWO

11. Winter Storm Watch • Typically issued 24 to 36 hours in advance of the storm • Issued when potential exists for: • 6inches or more of snow in 12 hours • 8inches or more of snow in 24 hours • Significant mixed precipitation

12. Winter Storm Warning • Typically issued 6 to 12 hours in advance of the storm • Issued when the following are likely: • 6 inches or more of snow in 12 hours • 8 inches or more of snow in 24 hours • 0.25 inches or more of freezing rain

13. Lake Effect Snow Warning • Same criteria as a Winter Storm Warning • 6 inches in 12 hours • 8 inches in 24 hours • Lake effect snow warning implies the localized nature of the heavy snow – in most cases not everyone in a county will receive warning criteria snowfall

14. Blizzard Warning • Wind speeds of 35 mph or greater AND • Visibility of ¼ mile or less in blowing snow • Conditions must persist for at least 3 hours • Blizzards may or may not be accompanied by falling snow (Ground Blizzard)

15. Winter Weather Advisory • Typically issued 6 to 12 hours in advance of storm • Issued when the following are likely: • 4 to 5 inches of snow in 12 hours • Light accumulation of freezing rain (less than 0.25 inches)

16. Where We are Today Existing Snow Spotter Network At NWS Northern Indiana

17. Existing Coop Spotters

18. 2002 Snow Spotters

19. Need for More Spotters • Existing COOP network is evenly spread over our County Warning Area (CWA) • We need to fill in the gaps between COOP and official NWS observing sites – as you well know, snowfall can vary widely within the same county, especially in areas which receive lake effect snow • This is where YOU come in!

20. Reporting Real time Information What type of Information can be useful to us?

21. Real Time Information • Heavy Snow – for example, snow falling at the rate of 1 inch per hour • Precipitation type change – snow to rain, rain to snow, freezing rain, etc. • Is the precipitation causing problems on roads? • Significant Blowing and Drifting Snow – Is drifting making travel difficult (or impossible)?

22. Freezing Rain • Is there a glaze accumulation on roads and sidewalks or only on elevated surfaces, such as trees and power lines? • How much ice has accumulated on surfaces. This can be difficult to measure directly, but can be easily estimated. • Measuring trick – Crack a piece of ice off a railing and measure the thickness.

23. What to Report After the Storm

24. When the Snow Lets Up • Get a final measurement. • Report your total snowfall for the event, and how long it was snowing. • For example: 7 inches in 10 hours. • In the case of freezing rain, also report the total amount of glaze on surfaces.

25. What Do We Use Your Reports For? • Update forecasts, warnings, and advisories to better match conditions being reported • Our updated forecasts and warnings in turn allow local officials to make better decisions • We use storm total snowfall and ice accumulation data to verify forecasts and warnings

26. How to Measure Snow Yes, that says 54 inches!

27. Before the Snow Flies • Place a snowboard outside. Choose a location away from trees, shadows, and known drifting areas. • A snowboard can be any light colored board, about 2 feet by 2 feet. A piece of plywood painted white works great! • Mark the snowboard location with a stake so you can find it easily in the snow.

28. Typical Snow Board

29. Measuring the Snow • If it is windy, it can be more accurate to take several measurements on the board and take an average. • After you measure, sweep the snow board clean. • You can clean the snow board off up to 4 times in 24 hours, but no more than once in 6 hours.

30. Take a Measurement

31. Sweep the Snow Board

32. Special Cases • If snow falls and accumulates, then melts, the total snowfall will be the maximum measured before the snow melts • If snow falls and melts on contact, never reaching 0.1 inch depth, a trace of snow is recorded. • Sleet counts towards the snowfall total, but freezing rain does not.

33. Let the Snow Fly!