Between 17 UTC and 18 UTC time (Which is 11a and 12p, LittleRock, AR Time) a Cold Front passed through Little Rock, Arkansas. This is evident as at this time the tempature dropped from 71F to 56F in less than an hour and eventually to 40F. The winds also shifted from S/SSW winds to NW/NNW winds. The precipitation increased in the same time frame, the pressure starts to rise, and the clouds were very low.
The pictures below supports and illustrates my reasoning.
This shows dramatic changes in conditions between 17 and 18 UTC Time
And this was recorded at 1800Z or 18 UTC, in which the Cold Front has just passed Little Rock