Interesting overnight temperatures

The graph above shows temperatures (green line) and wind speeds (blue line) from midnight to 7:00 AM Tuesday (times shown are UTC; EST is -5 hrs). The prominent feature of the graph is the dip in temperatures that bottomed out around 4:00 AM. Notice also that for the few hours preceding and proceeding this time, winds were completely calm. These two are related.

Warm air rises and cold air sinks. We in the Merrimack Valley are located at a low elevation, so at night when the sun is no longer heating the earth, the air the cold sinks down into the valley while the warm air rises above our heads. When there is wind, these layers are stirred up thus keeping temperatures at the ground a bit warmer. This phenomenon obviously happened overnight and is very well depicted in the graph. Something neat I wanted to share:-D

The weather will be quiet for most of this week. Temperatures will actually get quite warm, rising above 40 on Wednesday, Thursday, and Friday. Rain will fall Friday, and some thunderstorms may even move through later in the day as a very strong cold front pushes through. If the rain leaves any puddles on the ground, they will quickly freeze Friday night. Arctic air will come POURING in behind the cold front and we will see some of the coldest air we have seen all season long. Highs Saturday and Sunday will not get out if the 20s if they get there at all and lows Saturday night will likely fall below zero. After we moderate some early next week, another snowstorm may come our way. Stay tuned and enjoy the mild air while it makes its brief return. Happy Valentine's Day!