‘Humbling’: Why even meteorologists were stumped by this week’s weird weather
Storm moving in Friday afternoon should provide rainy start to Saturday, according to forecast
As it turns out, weather forecasting is a difficult business.
“It’s a humbling experience trying to forecast these systems,” said Rick Canepa, a National Weather Service meteorologist. “This is definitely a much more complicated system (than normal).”
After forecasts that promised significant-if-not-overwhelming showers gave way to mostly dry skies this week, the storm that began moving over the Bay Area on Friday afternoon promised real rain overnight, lasting at least part of Saturday.
According to the NWS, the midday tally didn’t exceed a quarter-inch for the week anywhere south of the Golden Gate Bridge before showers began picking up Friday afternoon.
Canepa explained that storms that formed far north of the Bay Area in places like the Gulf of Alaska this week failed to pick up significant amounts of moisture as they approached land. Because offshore winds and other pockets of low pressure pushed and pulled the water in different directions, the low-pressure system that fueled the storms didn’t pick up that water vapor.
Simply put, this weather system did bring more precipitation; it just happened to rain a lot more over the Pacific Ocean than it did in the San Francisco Bay Area.
“The two (systems) just kind of worked against each other,” he told me. “It’s just incredible meteorological complexity that even the best forecast models in the world are struggling with.” So we’re trying to make heads or tails of the system every day.”
Before leaving for good, the complex and difficult-to-predict weather system left meteorologists with just one more challenge: Saturday. The rain was expected to arrive late Friday for a prolonged stay, lasting through much of Saturday.
“We’re looking at increasing the chances of showers,” said Canepa. “It looks like it’s in line.”
Saturday’s rainfall totals in San Jose, Oakland, San Francisco, and the rest of the Bay Area could reach a quarter inch.
Saturday could see some thunderstorms pop up around the Bay Area, as a consolation to an otherwise underperforming rain week, according to the NWS. Lightning activity, like rain, would be variable, according to Canepa, but could be accompanied by brief downpours.
“It’s hinging on a lot and this system has been so complex, a really good example of the complexity of the atmosphere,” he went on to say.
According to early NWS forecasts, the rain events were expected to end by Saturday evening, clearing the way for a sunny start to the week.
