First page Back Continue Last page Overview Graphics
4. Three changes are made to the cloud microphysics:
- During melting precipitation ice particles are assumed to have the same mean diameter (1 mm) as at the freezing level.
- Two changes intended to increase the presence of supercooled liquid water and improve forecast products for use in aircraft icing algorithms:
a. The temperature at which small amounts of supercooled liquid water, if present, are assumed to be glaciated to ice was lowered from -30C to -40C.
b. The temperature at which ice nucleation is allowed to occur was lowered from -5C to -15C based on aircraft icing observations
5. allow horizontal diffusion between neighboring grid points with a slope of less than or equal to 54 m / 12 km (9x that in operational NAM).