METEOROLOGIST JEFF HABY
Frost is like dew in that it is not produced by precipitation. Frost and dew both form from the temperature dropping to the dewpoint and
continued cooling causing moisture to condense out of the air and onto the ground and other outside surfaces. Frost is different from dew
in that it forms when the dewpoint is below freezing and thus frost is in the frozen state instead of the liquid state. On some cold
mornings, frost can be thick enough to look like a light snow fell. Frost can collect on cars causing drivers to have to spend time
scrapping the ice off the windows. A frost advisory will be issued when dangers can result from the frost. This most often occurs in
one of the first frosts of the year, when frost occurs at a location where frost is infrequent or when frost has the potential to damage
vegetation, especially if it is an early spring season frost that could damage newly sprouted vegetation.
A freeze advisory/warning does not require that frost occur. What is required is that temperatures drop to at or below freezing. Just like
the frost advisory, the freeze warning will be issued when dangers to vegetation and pipes can result. Freeze warnings will also occur
most often when it is one of the first or last freezes of the year and when freezing occurs at a location where freezing temperatures
are infrequent. The warning is also more likely to be issued if the temperature is expected to drop well below freezing. This makes
damage to vegetation and pipes more likely and can cause dangers for people and animals that are outside.
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