THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL OREGON...NORTH CENTRAL OREGON...NORTHEAST OREGON...CENTRAL WASHINGTON...SOUTH WASHINGTON...SOUTH CENTRAL WASHINGTON AND SOUTHEAST WASHINGTON. .DAY ONE...TODAY AND TONIGHT A LARGE UPPER LOW PRESSURE SYSTEM WITH COLD TEMPERATURES ALOFT WILL CREATE AN UNSTABLE ATMOSPHERE THIS AFTERNOON AND EVENING OVER THE FORECAST AREA. THIS WILL ALLOW SHOWERS AND ISOLATED THUNDERSTORMS TO DEVELOP DURING THE AFTERNOON AND CONTINUE UNTIL SUNSET. SOME OF THE STRONGER THUNDERSTORMS MAY PRODUCE SMALL HAIL...GUSTY WINDS AND BRIEF HEAVY RAIN. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY THE ATMOSPHERE WILL REMAIN UNSETTLED AS THE UPPER LOW PRESSURE SYSTEM LINGERS OVER THE AREA THROUGH FRIDAY WITH MORE POSSIBLE AFTERNOON AND EVENING THUNDERSTORMS. ANOTHER LOW PRESSURE SYSTEM WILL MOVE INTO THE REGION ON SUNDAY AND AGAIN ON WEDNESDAY WHICH MAY PRODUCE ISOLATED AFTERNOON AND EVENING THUNDERSTORMS AGAIN.