Several readers have asked me, does it rain more at night than during the day?
I thought a perfect place to start was the Pacific Gas and Electric Co.’s Diablo Canyon Power Plant weather forecasts. And I got my answer.
After reviewing the last 25 years of forecast when the weather was unsettled, I discovered that we do receive more rain during the night than during the day.
There are a few factors to consider. First, there is less daylight during the winter months. On the first day of winter — Dec. 21 — we have about 14 hours and 15 minutes of nighttime and only nine hours and 45 minutes of daylight at our latitude.
Of course, as the winter progresses, the days become longer until the first day of spring, where daytime and nighttime are about equal. Another factor to consider is the San Joaquin Valley’s geography with coastal mountains to our west and the Sierra Nevada to the east.
Another factor is the development of thunderstorms in the Sierra Nevada, which often occur during the afternoon and evening hours due to surface heating. This condition often produces more rain during the daylight hours.
However, taking these factors into consideration, we still receive more rain during the night than during the day.
One reason is the top of the clouds cool during the night, allowing the air mass to reach its dew point more readily and producing greater amounts of precipitation. But the most interesting facet is there seems to be a greater occurrence of frontal passages (rain) near 9 p.m., with another peak about three hours before dawn. I have asked around to some other meteorologists why they thought this happened, and no one seemed to know. This may have to be left as a mystery.
Regardless of what it is, it does add to the amount of rain that we receive during the “0-dark” hours (this is an old Navy term to describe the early morning hours).
In the very near future, we will be able to track nighttime and daytime rainfall events much more accurately; a new spacecraft was successfully slung into orbit on March 1 from Cape Canaveral and will be the most revolutionary one yet, especially for those who live along the West Coast, and here’s why.
Back on Nov. 19, 2016, an Atlas V rocket launch a National Oceanic and Atmospheric Administration’s next-generation weather satellite, GOES (Geostationary Operational Environmental Satellite)-R into geostationary orbit from Cape Canaveral. After it was in place, it was designated GOES-16. It’s also referred to as GOES-East.
The images of storms along the East Coast have been breathtaking. And that’s the problem; GOES-16 is position over the eastern United States and the Atlantic Ocean limiting its effectiveness along the West Coast. However, this is all about to change.
“The new GOES-S (now designated the GOES-17 since its geostationary orbit at 137W longitude) will give us a much better view of California compared to GOES-16 and will give us pictures every minute, both night and day.
“This will be revolutionary for meteorologists to see cloud movement and development, much like a flowing river, to assist in weather predictions and severe weather interpretation.” Eric Boldt, a warning coordination meteorologist with the NWS told me. I can’t wait to see the first images.