You can see the rain pushing in on Stormtracker above, and it will be around tonight through Sunday morning.  Temperatures will temporarily fall into the upper 30s in the rain due to what we call “evaporational cooling”  in the rain (I’ll explain that below, and then rise back into the low 40s by daybreak.

On Sunday, morning showers will give way to mostly cloudy skies with some peaks of sun during the afternoon and temps warming to the low 50s for highs.

Evaporational cooling can occur when rain falls into very dry air (our dew point in in the upper teens, and that’s pretty dry).  Some of that rain evaporates, and evaporation is a cooling process.  That’s why when you get out of a swimming pool you feel cool as the evaporating water draws heat out of your skin.  In the same way, the evaporating rain pulls heat out of the air.

This entry was posted on Saturday, December 12th, 2009 at 6:22 pm and is filed under Forecasts. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.