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Forecasting kind of precipitation in winter via Ivens method
 
Theta W max (C)
Theta W surface (C)
Thickness of warm layer (hPa)
Thickness of stable layer (hPa)
Forecasted amount of precipitation (mm)
Duration precipitation (hour)
Is warm layer discontinuous Yes No

Critical amount of precipitation for snow mm
Critical amount of precipitation for wet snow mm
Melting layer parameter mm


 

Used formulas:
 

rc = 0.03 * (Tw * dwl + Twg * dsl)
i = precipitation / duration precipitation
rca = rc - 2.497 * i0.68 - 1.524 * i0.34 - 0.235;
sp = rc - rca

Tw: maximum wet bulb temperature
Twg: wet bulb temperature at surface
dwl: thickness warm layer
dsl: thickness stable layer
rc: critical amount of precipitation for snow
rca: critical amount of precipitation for wet snow
sp: melting layer parameter

Source:
Ivens, A.A.M., Forecasting the kind of precipitation in winter.
Proc. Symp. Mesoscale Analysis & Forecasting, Vancouver, Canada, 17-19 August 1987, ESA SP-282 (August 1987).

 

 

 

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