11/2/11 A quiet week & Franklin's Storm 1743

This week will feature tranquil weather with high pressure in control for at least the next 5-7 days. A weak dry front will push temperatures lower this weekend, but will rebound to above normal reading by early next week.

High pressure will keep New England dry for the next few days. A storm in Colorado, which is bringing snow to that area will split into two, going north and south of us.

Franklin's Storm!

Think back to a time when weather was just thought to happen in one place, almost pop up and die down at one location or move with the prevailing surface wind flow.  That is how most meteorologists/scientists thought back in the 18th century.

On November 2, 1743, a full eclipse of the moon was predicted, and Benjamin Franklin was eager to see the eclipse from his home in Philadelphia.

However as  the afternoon wore on, the sky darkened and what appeared to be a hurricane bore down on the east coast, and Philadelphia was struck with heavy rain and high winds from the northeast. At the time it was thought that such a storm, which had happened in the past, must have come down from the northeast! Franklin never saw the eclipse.

He wrote his brother in Boston of his disappointment and assumed that since the storm came in from the northeast, that his brother also missed the eclipse. However in later letters and newspaper accounts, the people of Boston observed the eclipse which would have occurred at the same time,  but was then followed by a 'terrible storm with great tides and a northeast wind'.

Franklin noticed the difference in the time between the onset of the storm in Philadelphia and Boston and believed that it indeed was the same storm. However, he rationed that the storm must have moved in a curve, against the prevailing winds from the southwest to the northeast. (Note: is was not until the 1800's that the term cyclone was adapted and used to describe a circular wind storm, therefore the counterclockwise motion of the wind around a hurricane was not fully understood during Franklin's time)

Franklin's Storm. It was thought all storms moved with the wind. So a northeast wind would bring a storm from the northeast (Boston to Philadelphia). However Franklin observed Philadelphia was onset first by the storm then Boston by using the time of an eclipse of the moon. He rationed that the storm had to of moved from the southwest to the northeast. Inset: It was not clear that storms had winds in a counter clockwise motion.

 
This changed the course of weather forecasting significantly, especially along the eastern seaboard and Franklin helped establish the what would become known as the "law of storm motion".