Tuesday will be slightly warmer in the upper 80s under partly cloudy to mostly sunny skies. A pop-up storm is possible in central or southern Oklahoma. Showers and storms will develop in northwestern Oklahoma Wednesday morning, along a weak cold front. The front will wash out during the day but widely scattered showers and storms are expected statewide. Rain totals will be low. Highs will climb to the upper 80s and lower 90s. Temperatures continue to climb Thursday and Friday. Showers and storms increase Saturday night through Sunday morning with a stronger front. A few storms could be strong to severe, mainly north.