(Isabella, MN)  —  The wildfire burning in northern Minnesota shows no signs of slowing down.  On Tuesday, the Greenwood Fire exploded to more than 19-thousand acres, prompting firefighters to leave McDougal Lake.  The fire also produced clouds that generated lightning and some rain.  Homes and recreational sites around the area remain in danger.  Officials hope to get full containment around September 1st, adding they believe expected moderate weather could help crews make progress.