Rain chances increase by Friday

(TULSA, Okla.) Dry weather is expected across eastern Oklahoma and western Arkansas until late in the week. Two mid-level systems, a southern stream system centered over southwestern Arkansas and a northern system centered over east-central Illinois, will merge to the east of the area resulting in a north-northwesterly flow aloft through Tuesday. An upper ridge will build over the area Wednesday and persist into Thursday. During this time, a gradual warming trend is expected with temperatures above normal for this time of year. The next chance of showers and a few thunderstorms will come Thursday night through Friday as a southern stream mid-level shortwave moves out of the Southwest and across the plains. Monday Sunny, with a high near 60. Calm wind becoming west around 5 mph in the morning. Monday Night Clear, with a low around 34. Northwest wind around 5 mph. Tuesday Sunny, with a high near 62. Northwest wind around 5 mph. Tuesday Night Clear, with a low around 35. Calm wind becoming southwest around 5 mph. Wednesday Sunny, with a high near 69. Southwest wind around 5 mph. Wednesday Night Mostly clear, with a low around 40. South wind around 5 mph. Thursday Mostly sunny, with a high near 68. South wind 5 to 10 mph. Thursday Night A slight chance of showers, then a chance of showers and thunderstorms after midnight. Mostly cloudy, with a low around 47. South wind 5 to 10 mph. Chance of precipitation is 40%. Friday A 40 percent chance of showers. Mostly cloudy, with a high near 56. South wind 5 to 10 mph becoming northwest in the afternoon. Friday Night A 20 percent chance of showers. Mostly cloudy, with a low around 36. Northwest wind 5 to 10 mph. Saturday Partly sunny, with a high near 47. Northwest wind around 10 mph. Saturday Night Partly cloudy, with a low around 32. Northwest wind around 5 mph. Sunday Mostly sunny, with a high near 47. Northwest wind 5 to 10 mph.