An extended period of heavy rain expected in New Jersey on Wednesday has led forecasters to issue a flood watch for 12 counties with up to 2 inches of rainfall possible between early afternoon and late this evening.

Dry conditions this morning will give way to rain by early afternoon with precipitation pushing in from south to north, according to the National Weather Service.

The flood watch begins at 1 p.m. for Bergen, Burlington, Essex, Hudson, Mercer, Middlesex, Monmouth, Morris, Ocean, Passaic, Somerset and Union counties. Expect creeks and streams to spill over their banks and for flooding to occur in urban areas and places with poor drainage. The watch expires at 6 a.m. Thursday.

Eastern parts of the state will wind up with the most rain — from 1.5 to 2 inches — before the steadiest and heaviest rain winds down before midnight. Northwestern parts of the state will receive about a half-inch to 1 inch of rain while a wide area stretching from Morristown to Trenton to Vineland collect 1 to 1.5 inches of precipitation.

Highs on Wednesday will be in the mid 50s before dropping into the 40s overnight.

A dense fog advisory has also been issued for 16 counties for Wednesday morning through 10 a.m. The advisory includes Atlantic, Burlington, Camden, Cape May, Cumberland, Gloucester, Hunterdon, Mercer, Middlesex, Monmouth, Morris, Ocean, Salem, Somerset, Sussex and Warren counties.

Though the bulk of the rain will be gone by Thursday, drizzle could linger, the weather service said. Thursday will be a cloudy day with temps again in the 50s.

Sunshine returns on Friday with highs in the 50s, but the weekend is expected to bring more rain.

Forecasters haven’t nailed down the timing of the weekend storm, but a good estimate is that precipitation will roll in during the second half of Saturday and stick around into the first half of Sunday.

There won’t be nearly as much rain as on Wednesday. The weather service says a half-inch to 1.5 inches of rain is likely. Flooding could be the bigger issue with the ground still saturated from two previous rounds of rain this week.

“More rain this weekend could push certain rivers in our region into flood stage or cause rivers coming down from flood stage to rise once again,” the weather service said Wednesday.

The second half of Sunday looks better with partly sunny skies. Highs on both days will be mainly in the 50s.

Our journalism needs your support. Please subscribe today to NJ.com.

Jeff Goldman may be reached at jeff_goldman@njadvancemedia.com