CHICAGO (CBS) — Chicago area gas prices have shot back above $4 per gallon — just barely.

That would have seemed extraordinarily high a few days ago, but Chicago-area gasoline prices are spiking again, and an analyst said they are likely to remain well above the current $4.01 average for one to three weeks.

“I expect a majority of gas stations to have increased prices at least 10 to 35 cents per gallon by Friday evening with most stations starting to raise prices as early as Thursday morning when compared to today’s prices. Some areas in Michigan and Indiana may flirt with $4 a gallon,” said Patrick DeHaan, Senior Petroleum Analyst.

He said prices in the Chicago area have increased an average of 35 cents a gallon in the past month, and said the spot price that stations pay before taxes, rose nearly 21 cents a gallon Wednesday morning alone.

LISTEN: WBBM Newsradio’s Bob Roberts reports

DeHaan said a series of events led to the spike, beginning with problems at three regional refineries over the weekend, including a fire in the BP Whiting, Ind., facility. He said it was further fueled Tuesday when leakage in Wisconsin forced the pipeline firm Enbridge to shut a pipeline that delivers crude from Canada to Chicago, putting further dampers on a tight market.

“While this situation will be temporary in nature, prices will remain high as long as these problems continue,” DeHaan said.

DeHaan said at $4.01 a gallon, prices are actually 7 cents a gallon less than they were at this time a year ago, but he said that difference could be wiped out overnight.

He said Chicago-area gas prices are second highest in the nation, lower only than those in Hawai’i.