Top Down Method

  • Check for ice in the cloud

  • Warm layer aloft – partial melting if maximum temperatures are between +1 and +3 degrees C (can re-freeze to sleet in surface-based cold layer)

  • Warm layer aloft – total melting if maximum temperatures are above +3 degrees C (freezing rain more likely if surface-based cold layer)

Notes:

Let’s start our analysis by examining how effective the “top down” method of precipitation-type forecasting would have been for these two events. The key to the forecast in both of these events was the mid-level warm layer. Deep, warm, mid-level warm layers favor freezing rain, while shallower, colder layers favor snow and or sleet.


Slide 9