By Sue KILPATRICK
“Can such things be
And overcome us like a summer’s cloud,
Without our special wonder?”
– William Shakespeare, “Macbeth”
Persons reading this quotation in India and southern Asia would not understand the significance and “wonder” of a cloud on a summer’s day. Living in a Mediterranean climate as we do in Southern California, our summers are sunny and dry. Typically, there is little or no rainfall from May through November. In sharp contrast, most regions worldwide receive their highest rainfall totals in the summertime. This year is no exception – summer and its appropriate climate is right on target here in the Foothills. Temperatures were on the rise to start the week, peaking at close to 100, but nighttime temperatures thankfully cooled to the mid 60s. By mid-week, there had been a possibility of a weather phenomena referred to as the North American Monsoon or the Southwest Monsoon. With anticipation and excitement, I looked forward to some variation in our weather. But, the meteorologist with the National Weather Service cancelled this forecast. Now they are predicting the same for the middle of next week. Look for white bellowing thunderheads rising over the mountains to the northeast. Can these actually be a summer clouds?
The word monsoon conjures up an image of torrential rains beating down in the steamy jungles of the equatorial regions. Sounds like an exotic travel adventure, but its effects can result in devastation and loss of life. Monsoons happen in several locations around the world, including a large portion of the American Southwest – Texas, New Mexico, Arizona, Nevada and parts of California.
These storms in the U.S. can bring up to 70% of the year’s rainfall. Southern California is not included, for it is on the western most border and does not receive the full effects of the monsoon. We can feel the humidity and heat, see the clouds and receive an occasional thundershower, but not much more.
This time of year, as the sun heats up the desert floors warm air rises and an area of low pressure forms. Concurrently cooler moist air from the gulfs of Mexico and California takes shape. To put the complex into simple: this air mass as it crosses northern Mexico and into the U.S. is lifted high in the atmosphere by the rising hot air in the deserts and mountains. You may hear the term Monsoonal Flow used in referring to this. By afternoon the results of these interactions are in place – clouds and thunderstorms.
With the CV Weekly arriving Thursday morning, so shall the marine fog. Temperatures will cool into the 80s for the remainder of the week. By Sunday, break out the iced tea again! Next week … well, even the meteorologists at the NWS are undecided. With Hurricane Dora in Mexico holding strong, pushing cool moist air northeast and a strong high pressure in the west, it is a tough one to call.
I can assure you that either way, it will still be summer!
Sue Kilpatrick is a Crescenta
Valley resident and Official Skywarn Spotter for the National Weather Service. Reach her at