The sound of rain on windows and roofs this weekend ushered in what could be a wetter than normal July, according to the National Weather Service.
As much as 200 percent of normal precipitation could occur, according to the National Center for Environmental Prediction.
“(The) NCEP’s Climate Forecast System version is calling for precipitation to be plus 200 percent of normal for the Mammoth area for the month of July,” said Howard Sheckter, Mammoth’s local amateur weather forecaster. “That means that we should get some meaningful thunderstorms and rain this month.”
That might sound impressive, but the Eastern Sierra gets the vast majority of its precipitation in the form of snow, not summer rain, so that 200 plus percent of normal translates to only a few inches of rain.
Still, after several drought winters and a bone-dry summer so far, any rain is welcome, especially the monsoon-driven, mostly lightning-free storms that passed through the Eastern Sierra this week.
The storms will mostly subside by the weekend, and temperatures will build again into the low 80s in Mammoth, but the heat could trigger another bout of thunderstorms early next week, again bringing a chance of rain.
“A combination of light flow aloft and daytime heating will result in the typical air mass thunderstorms,” Sheckter said.
This kind of dry-wet pattern is not the same as the monsoon-driven rain this week—which may or may not resume—but it could still bring some much needed rain.
“As a comparison, August precipitation is expected to be near normal,” he said.
The downside to the kind of precipitation common to the Eastern Sierra is it can also come with a significant chance of lightning, hence a greater chance of fires.
It is not an exaggeration to say the Eastern Sierra is bone dry right now—the region is considered to be in an “extreme” drought, only one degree from the worst kind of rating the National Weather Service gives for drought, “exceptional” drought.
Wildfires are thus a strong possibility if lighting ignites a fire and it is not quickly contained.
The forecast for a wetter-than-normal July, however, has nothing to do with the much hoped-for El Niño pattern that has been linked to wetter falls and winters for California, especially Southern California, Shekter said.
Right now, in fact, the numbers don’t look that great for a significant El Niño this winter, although it will be fall before more conclusive forecasts are made, he said.
“The latest numbers for the region are pretty anemic,” he said.
“The latest weekly Niño data shows that during the time period of June 25 through July 2, all Niño regions of the Niño Basin have cooled with the exception of Niño Region Number Three. At this time … it is the opinion of the Dweebs that it is highly unlikely that we will have a “Super Niño.”
“However, even a weak El Niño can bring a normal amount of precipitation to Southern California and a winter that is 80 percent to 90 percent of normal to the Central Sierra Crest. There are a lot of split flow systems in a weak El Niño and so coastal areas of Central and Northern California can get a lot of rain while interior sections can get much less.
“There is no real way to predict with much certainty what the winter will be like until the early fall, as by then, we’ll have a better idea on how the Niño regions are doing heat wise as well as the other teleconnections that will be affecting the weather for the upcoming winter.”