Wetter year for Boulder County driven by ‘unusual’ weather patterns …

Amid bouts of soggy weather over the past few months that have brought several inches of rainfall to Boulder County, 2023 is shaping up to be a wetter-than-normal year for the area.

Meteorologists say the wet conditions lately have been driven by some “unusual” weather patterns.

In terms of precipitation, several locations in Boulder County — Boulder, Longmont and Gross Reservoir in the foothills near Nederland — have exceeded their normal year-to-date totals, and Longmont has already surpassed the amount of precipitation it normally gets in a full year.

“We’ve just been seeing a somewhat unusual pattern,” said meteorologist Jim Kalina with the National Weather Service in Boulder. “In May, we had a blocking high over Canada. And that produced a deep southeast flow over our area. And that brought a lot of moisture into the Front Range, including Boulder (and) Denver. And there were some low pressure systems com(ing) across, and those brought a lot of precipitation.”

A blocking high is a large, high-pressure area that lingers over an area for a period of time. Kalina said last month a trough, a long region of lower pressure, over the western U.S. brought more moisture and cold fronts to the Front Range.

Jennifer Stark, meteorologist-in-charge at NWS Boulder, said this summer has also been an especially active thunderstorm season. She attributed the weather partly to El Niño conditions, but also said it’s a product of the unique storm track in the area in recent months.

“We’re staying fairly active, fairly cool. Not a big, warm summer really so far,” Stark said. “We’re in a different setup this year than we have been in the past couple of years.”

As of Friday, the most recent date for which data is available, Boulder has received 15.77 inches of precipitation this year. Normally, by July 7, the city has seen a total accumulation of 12.39 inches. In total, Boulder usually gets 21.23 inches of precipitation each year.

Boulder’s wettest year ever was 2013, a year of disastrous flooding for parts of the Front Range. The city saw a whopping 34.15 inches of rain that year, so Kalina doesn’t believe Boulder is likely to break its record this year, but precipitation has still been higher recently than is typical.

For Longmont, this year has been further out of the ordinary: Normally, by this date, the city has only received 8.38 inches of precipitation, and this year it’s gotten almost twice that amount with 15.46 inches.

Longmont normally only gets 15.21 inches of rain in a year, and its record high rainfall was 22.73 inches in 1915. Kalina said there’s a chance Longmont could set a new record in 2023.

At Gross Reservoir, the precipitation patterns are more similar to Boulder. The area has seen a total of 15.6 inches this year, and normally receives 11.4 by this time in July and 20.28 inches by the end of the year.

For those who have had enough of the rain, Kalina has some good news: the next few weeks and months look as if they could bring warmer, drier weather.

“Tomorrow might be our last day of wet weather. And then we have upper level high pressure building into the area starting Sunday into next week,” he said. “(It’s) looking like temperatures are going to warm, probably into the low 90s, and mostly dry conditions, probably to mid-week and maybe through the end of the work week.”

Kalina also said he expects “more of a normal pattern” through the rest of the summer with closer-to-normal temperatures and drier weather than the past couple of months.

Stark anticipates the traditional Southwest monsoon pattern will arrive in the area in late July, possibly bringing afternoon and evening thunderstorms with heavy rain, but said if that doesn’t happen, the wildfire risk could be heightened.

“I think we’ll still see that traditional monsoon season and hopefully (can) keep the precipitation going,” Stark said. “If we don’t get the monsoon, there is concern that we could end up having an active wildfire season in the late summer and fall because we’ve grown a lot of fuel.”