A frontal system begins to move through the state today.  This large-scale weather feature will be responsible for thickening clouds and isolated thunderstorms for northern, central and eastern Wyoming.  The greatest weather threat today will exist across far southeast Wyoming, as severe thunderstorms will likely develop after 2 PM and last through 9-10 PM.  Downbursts, damaging wind, and damaging hail will be the main concerns.  Storms will move slowly, so hazardous conditions may linger in localized areas.  Severe storms will diminish after 10PM tonight, but scattered rain showers may linger through the night.  Tomorrow, expect some fog, lingering clouds and rain showers.  Saturday's temperatures will be much cooler (mostly in the 50s) with "gloomy" conditions for southeast Wyoming.  Elsewhere across the state, sunshine develops on Saturday and temperatures will be mild to warm.