This week’s pattern of sunny, seasonable weather will continue through the weekend, with a strong high pressure system forecast to move in from the northwest. High pressure systems, or anticyclones, tend to be associated with calm, sunny weather, since their clockwise motion (in the Northern Hemisphere) induces large-scale subsidence, or downward motion of air from the upper troposphere. The air warms as it descends due to the increase in atmospheric pressure, and it remains dry, since air in the upper troposphere cannot retain much water vapor.
An anticyclone currently over eastern Canada will be located directly over New England by tomorrow evening. The result will be a continuation of the current pattern of clear skies and moderate temperatures for the next few days. The next chance for rain will come at the beginning of next week, as a low pressure system is forecast to form somewhere off the coast — but with a few days to go, there is still a good deal of uncertainty concerning this storm.