ESFMSO What: Widespread moderate rainfall over a prolonged period of time. Storm total amounts between 1 to 3 inches for valleys and 2 to 3 inches for the mountains. There is a 10 percent chance of isolated rainfall amounts up to 4 inches along the Continental Divide. Where: Flathead and Lake Counties in northwest Montana, including Glacier National Park. Missoula county in west-central Montana. Timing: Beginning Sunday morning, continuing through Monday night. Heaviest rainfall rates anticipated Monday into Monday night. Significant rainfall totals will bring potential for rapid rises on streams and creeks, rock and debris slides and runoff issues in poor drainage areas. Those recreating in the backcountry should take caution on backcountry roadways for falling debris.