Oregon wildfires: Threat of abundant lightning, strong winds lead to red-flag warnings Friday through Wednesday
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on August 08, 2014 at 12:05 PM, updated August 08, 2014 at 12:27 PM
Gusty, west winds that led to the blowup Wednesday of the Rowena fire between Mosier and The Dalles will continue Friday, said forecaster Jeremiah Pyle of the National Weather Service in Portland.
"Friday will have the gustiest winds, with gusts of 30- to 35 mph around The Dalles,''Pyle said.
"Saturday will be breezy, but not as windy and by Sunday we will begin transitioning to an east wind."
Pyle said the east winds will not be particularly strong, but that wind shift marks the beginning of another round of thunderstorms caused by an upper-level low weather system moving off the northern California coast. Pyle called it a "textbook setup for thunderstorms over our region."
"The position of the low is ideal for thunderstorm development, as that moisture and instability spread into Oregon from the south,'' Pyle explained.
The primary threat will be Sunday over the southern half of the state, and by Monday and Tuesday the threat expands into the northern half. Due to the position of the low, Pyle said, any storm that form over the Cascades will tend to drift to the west into the Willamette Valley.
In Portland, high temperatures will tend toward normal Friday (79 degrees) and Saturday (83 degrees), before rising to 90 degrees on Sunday and Monday, and then dropping into Tuesday and Wednesday to the low- to mid-80s.
Abundant lightning, combined with critically dry forest fuels and strong winds is expected to spark new, large wildfires and add to the growth of existing fires, officials said.
To that end, a red-flag warning remains in effect for the Columbia River Gorge through 11 p.m. Friday; the warning means weather conditions—wind, heat and low humidity—combined with critically dry fuels make it ideal for fires to grow.
In southern Oregon, fire weather forecasters in a fire weather watch alert, say multiple lighting strikes on dry, drought-stressed vegetation "have the potential to overwhelm initial attack resources."
The storms on Sunday afternoon and evening, they said, will be mostly dry, with little or no rain. By Monday, the storms could be wetter, producing "significant rainfall in some areas, but little in others."
-- Stuart Tomlinson