Thunderstorms imminent as smoke persists |

Thunderstorms imminent as smoke persists

Matthew Renda
Staff Writer

Western Nevada County's recent spate of weird weather will continue to scorn normalcy as the week progresses.

A low-pressure system stationed in the atmosphere about 200 miles offshore due west of Los Angeles will impact Northern California throughout the week, bringing thunderstorms and decreasing temperatures in tow as it moves steadily to the northwest, said Drew Peterson, forecaster for the National Weather Service.

Isolated thunderstorms will strike the Sierra foothills, beginning Monday and persisting through Thursday morning.

"We have issued a Red Flag Warning to coincide with the significant lightning threat," Peterson said.

The weather system will drag ample moisture in from the ocean, but as much of it is located in the upper level of the atmosphere, it will generally evaporate before hitting the ground.

"It won't help too much with the fires," Peterson said.

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The warm weather that marched through the region over the weekend will persist, but temperatures will continue to decrease incrementally throughout the week. A high of 92 is predicted for Grass Valley Tuesday with highs hovering in the upper 80s for the remainder of the work week.

Overnight Sunday offered little relief from the hot temperatures that lingered for much of the afternoon, as the overcast cloud layer served as a blanket, trapping the heat in the lower portion of the atmosphere, Peterson said.

"There were several records set as the overnight low temperature was the highest ever recorded for the date," Peterson said. "I know that sounds strange."

Auburn only got down to 79 degrees Sunday night and temperatures settled in the lower 70s for Grass Valley and the surrounding area. Overnight lows will trend toward normal through the week as daytime temperatures dip.

Air quality concerns endure for the region as the American Fire near Foresthill continues to emit voluminous amounts of smoke, some of which is brought to western Nevada County overnight via the downsloping winds that typically occur in the region.

The smoke is trapped in the lower layer of the atmosphere until afternoon warming causes an intermingling between atmospheric layers and releases the heavy concentration of haze.

The enormous plume of smoke emitting from the 14,765-acre American Fire actually had a hand in modifying the fire's behavior Sunday into Monday, according to the latest release by Gwen Ernst-Ulrich, Tahoe National Forest spokesperson.

"Heavy smoke shaded the fire yesterday, moderating fire behavior," she said.

The west side of the fire remains essentially inactive as mop up operations are in effect, while most of the nearly 2,000 firefighters on hand are concentrating efforts on stopping the fire's eastward advancement.

"Along the eastern portion of the fire last night, firefighters conducted a firing operation, meaning they used fire to reduce unburned fuel between the fire line and the main fire," Ernst-Ulrich said. "The center portion of the east flank was still very active during the day, but indirect containment lines remained secure."

Containment is listed at 49 percent, and officials are not offering an estimate for when the fire will be fully contained and extinguished.

Nevada County and surrounding areas have had an air quality advisory in effect for the past week. People with respiratory problems or other health problems potentially exacerbated by exposure to particulate matter should avoid the smoke, if possible.

The steep, rugged terrain featured in the remote section of the Tahoe National Forest about 10 air miles northeast of Foresthill has rendered containment efforts and firefighter accessibility difficult.

To contact Staff Writer Matthew Renda, email or 530-477-4239.

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