The NWS says showers and thunderstorms will increase in coverage from wets to East late Saturday afternoon and continue into Sunday morning.
From the NWS:
SOME OF THE STORMS WILL CONTAIN TORRENTIAL DOWNPOURS, WHICH COULD LEAD TO FLASH FLOODING.
WIDESPREAD RAINFALL AMOUNTS OF ONE TO THREE INCHES CAN BE EXPECTED WITH LOCALLY HIGHER AMOUNTS
RAINFALL RATES OF ONE TO TWO INCHES PER HOUR COULD
OCCUR WITH THE STONGEST THUNDERSTORMS.
HEAVY RAINFALL IN SHORT PERIODS OF TIME MAY CAUSE RAPID RISES ON CREEKS AND STREAMS AS WELL AS FLASH FLOODING IN URBAN AREAS.
A FLASH FLOOD WATCH MEANS THAT CONDITIONS MAY DEVELOP THAT LEAD TO FLASH FLOODING. FLASH FLOODING IS A VERY DANGEROUS SITUATION.
YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION SHOULD FLASH FLOOD WARNINGS BE ISSUED.