Despite a season of abundant spring rainfall and runoff in the Gunnison Valley, the late arrival of monsoon season has set the stage for fire, robbing the basin of the moisture it relies on each year to reduce the chance of starts.
After nearly a month of little-to-no precipitation, the valley started registering drought conditions in mid-July. Lack of monsoon rains and high temperatures have exacerbated and prolonged the drying pattern, bringing drought back to the county and setting the stage for multiple fire starts around the Western Slope. Although a few storms have graced the valley recently, more significant precipitation is not expected for at least a week.
Each year around mid-July, monsoon rains travel north from the Gulf of Mexico, bringing moisture to the region after months of heat and aridity. But this year, the monsoon was delayed and the valley didn’t see any precipitation until the end of July. As fuels continued to heat and dry, several small fires started around the Western Slope, as close as Hotchkiss and further south in Bayfield and Pagosa Springs. Most of the southwest corner of the state is now under a red flag warning.
Lack of monsoon weather means heat can stay around for longer, as late-afternoon thunderstorms usually break up high pressure systems that keep heat in the valley. Heat and lack of cloud cover means the sun’s energy radiates more readily to the ground, heating and drying fuels even more.
“They go hand in hand. The high [pressure system] was over us so it wasn't able to bring moisture into the area, it just kind of sat there, and it also exaggerated the drying,” said National Weather Service Forecaster Kris Sanders.
These lingering high pressure systems have ushered in record-breaking temperatures for both Gunnison and Crested Butte. Cities all over the Western Slope set temperature records this year, Sanders said.
Thunderstorms that follow prolonged periods of drying tend not to bring “deep moisture,” he said. Dry air at ground level prevents moisture in the atmosphere from reaching the ground, causing dry thunderstorms. Fire officials have stated that the Lowline Fire burning north of Gunnison was likely started by a lightning strike, and most fires burning around the state have also been started this way.
The high pressure system finally moved out in late July, bringing some moisture. Even then, rain fell in a few isolated incidents while darker storm clouds hung along the edges of the valley and didn’t quite make it into town.
Far less rain fell in June and July compared to the historical averages; 0.05 inches of rain was recorded in Gunnison in July compared to the average of 1.31 inches and 0.48 inches of rain was recorded in June compared to its average of 0.57 inches.
In the last couple weeks, Arizona has started to see some monsoon rains. But moisture down south doesn’t always mean rain in the Gunnison Valley. If the valley doesn’t receive enough moisture from the weakened monsoon, there’s potential that fire season could carry into early fall, Sanders said.
“When that moisture gets here, it doesn't necessarily mean that it's going to be widespread rainfall for everyone,” Sanders said. “It's still sort of a hit or miss.’
Drought update
The delayed monsoon has also contributed to drought conditions creeping back, after the valley (and most of the state) clocked months of no drought conditions — the first time since 2019.
As of July 18, the southwest corner of the state, including Gunnison County, started registering moderate drought conditions. As of Aug. 8, 87% of Gunnison County was categorized as “abnormally dry,” the lowest level of drought indicator on the monitor.
Reservoir storage in the Gunnison River Basin is currently sitting at 90% of average and Blue Mesa Reservoir is only 10 feet below its fill line, sitting at 89% of full. Taylor Park Reservoir is currently at 91% of full. The Bureau of Reclamation will draw Blue Mesa down to 70% by December, in order to meet their icing target, meant to prevent damage and flooding from ice flows.
According to the U.S Drought Monitor’s long-range forecast, dry conditions are likely to persist through October.
(Abby Harrison can be contacted at 970.641.1414 or abby@gunnisontimes.com.)
Comments
No comments on this item Please log in to comment by clicking here