October was a dismally dry month for Utah.
The state as a whole averaged just 20 percent of the precipitation it usually gets for the month, and most of that fell in isolated mountainous areas. The valley floors, according to this month’s Utah Climate and Water Report from the federal Natural Resources Conservation Service, averaged zero inches of rainfall.
Utahns might not expect to see much rain, say, in June. But historically, October is supposed to mark the start of the state’s rainy season, or snowy season for those further north. So experts say the dearth of moisture is notable.
“We got blanked,” said Randy Julander, Utah Snow Survey supervisor for the NRCS. The absence of valley rain in October was so unusual, he said, that he “can’t remember it ever happening. I’m sure there probably are [times it happened before], but not in my memory.”
Salt Lake City received just .18 inches of rain last month, well short of the October normal of about 1.52 inches, according to Brian McInernery, a hydrologist for the National Weather Service in Salt Lake City. Generally speaking, higher elevations on the north end of the state got more rain, while lower areas to the south got less.
Similarly dry conditions prevailed over most of the western U.S., with the southwest in particular seeing a near-complete absence of October precipitation, McInernery said.
“It was quite dry, no matter how you wrap your head around this,” he said. “We should be getting more precipitation during this time.”
As remarkable as such an absence of rain may be, one month without low-elevation precipitation doesn’t mean much for Utah’s water supply. The bigger question is whether October was an exception, or a signal of a longer-term dry trend.
Think of Utah’s water year, which technically begins on Oct. 1, as having three stages, McInerney said. The first stage is the wet fall months, followed by accumulating snows over the winter, then runoff in the spring.
“Right now,” McInerney said, “we had an OK September, and a really bad October, but if we can start raining hard or start snowing any time soon, this won’t matter. We won’t even remember this. The key is you want to have snow at the end of November.”
It’s unclear whether rain and snow will materialize next month, McInerney said. While the western U.S. is stuck in a dry weather spell, the pattern is unsettled and could change at any moment.
“It’s one of those things,” Julander said. “It’s Utah and, like, get used to it, because if we recall last year, it was exceptionally dry all the way through to December.”
Last year’s snowpack effectively ended a five-year drought in Utah in two months. That pattern — bursts of intense precipitation, followed by long dry spells — is becoming a norm, McInerney said.
In September, for example, Utah received significantly more rain than normal — about 160 percent, on average. But nearly all of that fell in just four days.
“We are seeing more extreme precipitation events,” McInerney said. “That’s our future, that’s where we’re headed. Weather is more of that scenario, more than average conditions.”
Julander said he has observed that since the 1980s, large quantities snow and rain seem to arrive in bursts every 5-8 years, followed by extended dry periods.
“When we look at temperatures at the higher elevations, one trend stands out — and that is fall,” he said. “Fall over the past 15 years has been much, much warmer than it has been. So snow is coming a little bit later.”