South San Francisco, CA

Weather Underground Forecast for Wednesday, June 19, 2013.

Wet and active weather will spread across the Northwest with threats of severe weather development on Wednesday. An upper low along the Pacific Northwest Coast will begin to shift inland on Wednesday, ushering ample moisture and energy inland across the Pacific Northwest, Northern Intermountain West and Northern Rockies. Expect scattered showers and thunderstorm activity to spread across these regions through the day, with areas of severe weather becoming possible in central and eastern Montana into northwestern North Dakota. The Storm Prediction Center has issued a slight risk of severe thunderstorm development for this area on Wednesday with primary threats of large hail and damaging wind gusts. In addition to severe storms, these areas will also see increased chance of flooding due to the slow moving nature of this system.

Elsewhere in the West, fire danger will run high across the Four Corners as gusty winds sweep across the region and a warm and dry airmass remains overhead. Red Flag Warnings are expected for this region as this weather setup will increase chances of wildfire development.

In the Plains, generally isolated showers and thunderstorms in the Southern High Plains will advance northeastward across the Central Plains, spanning into the Northern Plains and the Mid-Mississippi Valley by the evening.

In the East, showers will gradually taper off in the Northeast and upper Mid-Atlantic as cold fronts impacting the regions move offshore and high pressure moves overhead. The southern portion of a cold front extending across the Southeast will become nearly stationary as it nears the Gulf Coast. Expect showers and thunderstorm to continue in the southeastern corner of the nation and along the Gulf Coast.