One of the delights of travel is reading and watching the local news, particularly the weather reports. Several days in the San Francisco area this past week had me studying just how meteorologists hook readers and viewers into their coverage when, to the average Joe, forecasts don't seem to change for months.
It doesn’t rain in the Bay Area in the summer. The last measurable precipitation in San Francisco was May 21, when one-tenth-of-an-inch fell. That actually ended a stretch when it rained six out of seven days, highly unusual in May. Usually meteorologists can put away their rain gauges in April and not dust them off until the fall, if then.
So how do forecasters keep casual viewers tuned in?
They zero in on the ever-present summertime fog, trying to predict when it will roll in through the Golden Gate, and how widespread it will become day to day. It’s an inexact science, sort of like trying to predict where pop-up thunderstorms will pop up in New England, without the obvious trigger of an approaching cold front. As we well know, it can be pouring in Swanzey and sunny in Keene on a humid, summer afternoon.
Likewise, San Francisco is awash in micro-climates when it comes to fog. You could be shivering in one neighborhood and sweating in another, depending on where the fog bank settles that day. It is startling to see the daily temperature ranges — here a general forecast may call for highs of 70 to 75; there, the average summer spread is 65 to 95.
Almost always the densest fog will be along the coast, but it can spread inland and drop temperatures 15 degrees in minutes. And like humidity here makes it feel warmer than the actual temperature, fog there makes it feel colder.
One of the coolest websites is fog.today, which captures the movement of fog, via satellite, in real time as it rolls in and out of the Golden Gate and spreads through the Bay Area. You can also put it on a timing loop, similar to how radar tracks precipitation. Called the GOES-16 satellite, it’s the same technology used to track wildfires in California. But its future is, well, foggy because the program is on a list of potential budget cuts by the Trump administration to NOAA’s National Environmental Satellite, Data and Information Service.
Returning to the Monadnock Region, once the remnants of Hurricane Dorian clear the coast, we should be in for decent weather for several days. Saturday and Sunday look to be partly sunny with temperatures in the low 70s. That should continue through much of the week, though a stray thundershower is possible Wednesday. High temperatures will hover in the high 60s, low 70s range, with lows in the 40s and 50s.
If you’re seeking some sizzle, head south, where an expanding heat wave is expected to push temperatures into the high 90s, and near 100 in some parts, Texas through South Carolina. Not exactly optimum football weather as the NFL opens its season this weekend, and colleges strike up the bands with a full slate of games.
As for the tropics, they’ll be quiet for the next several days, but a disturbance that came off the coast of Africa could stir up trouble starting next weekend. The National Weather Service says conditions are favorable for development into a tropical system by late in the coming week as it treks across the Atlantic toward the Lesser Antilles. It’s a classic setup for a typical September tropical storm or hurricane to form.