The Springtime Jet
Yesterday started off very cold and damp, however it quickly shifted to sunny weather and temperatures slightly above 70°F. If you are curious about the source of this springtime variability, at least part of it is due to the jet stream that is currently located over Boston. The jet acts as a guide for smaller scale perturbations that can potentially cause weather variations over a few hours. Also, since the jet stream in the upper atmosphere is concomitant with a large temperature gradient near the surface and lower atmosphere, to be close to the jet is also to be close to the boundary between the polar air masses and the tropical air masses. This is yet another source of variability since it provides the potential for rapid changes in temperature due to air crossing over either from the pole or from the equator side of the boundary.
The situation for the next few days will be quite variable, although the highs will remain above 50°F. Some time Wednesday morning we expect the rapid passage of a short wave that will bring cloudy skies and precipitation. Temperatures will remain on the cool side, with mostly clear skies on Thursday and Friday.
Tonight: Mostly cloudy. Chance of precipitation after midnight. Low 43°F (6°C).
Tomorrow: Mostly cloudy in the morning. Chance of rain and areas of fog in the morning varying to partly cloudy late afternoon. High 54°F (12°C).
Tomorrow night: Mostly clear. Low 44°F (7°C).
Thursday: Mostly clear and pleasant. High 63°F (17°C).
Friday: Mostly clear. High 63°F (17°C).