FREEZING DRIZZLE TUTORIAL
FREEZING DRIZZLE TUTORIAL
This is an example of a sounding that indicates a strong possibility of freezing drizzle at the surface.
INTRODUCTION
This freezing drizzle tutorial begins with an actual freezing drizzle event from January 2002. After describing the event, the tutorial takes the reader through the steps of forecasting freezing drizzle using this January 2002 event as an example.
Event Description:
Weak surface Low (with strong cold front) passed directly overhead MSP around 27/18Z, moving to the East. Clouds over MSP being to deepen in cyclonic flow. Surface temperature is 32F.
First round of freezing drizzle starts at 28/0250Z and lasts until 28/0706Z, with surface temperatures 27-30F. Cloud depth is about 3000ft at 28/00Z, and surface temperature is 31F. (VIEW MSP METARS HERE)
By 28/12Z, surface low over ORD and MSP into northeasterly flow. Cold air is advecting into southern MN. Cloud depth is 5000ft, and surface temperature is 21F.
Second round of freezing drizzle begins at 28/1747Z (surface temperature is 20 F), and this lasts until 29/0522Z. At 29/00Z, cloud depth is still at 5000ft. (VIEW MSP METARS HERE)
By 29/0522z, surface temperature has fallen to 18F and precipitation changes over to snow.
