Rain will continue across the area until around 2 or 3am. Cold air is also spilling into the back side of the low pressure and changing some of the rain over to sleet and snow.
The best chance for snow in NW Arkansas will be from 10pm to 12am with the back edge of the system.
A Winter Weather Advisory is in effect for many counties with higher terrain. Snow and sleet have already been reported above 2,000ft in the Ozarks.
Be aware that I49 near the Hopper Tunnel does approach 1,600ft in elevation and some snow and sleet may make it to the surface. It is possible that Benton & Washington County could be added to the advisory due to precipitation in the higher terrain.
The Winter Weather Advisory is in effect for the higher terrain in these counties. This includes the highest points in the Ouachitas and the Ozarks as well as places like Mt Magazine and Blue Mountain. Snow in these areas could accumulate to as much as 4 inches.
The band on the back edge of the low pressure system is our best chance for accumulating snow in our area.
The cold air will be mixing and the precipitation rates will be higher which leads to cooling within the atmosphere enhancing the snow potential.
This band/back edge moves across NW Arkansas and Fort Smith a few hours on either side of midnight.
The reason the snow will have a hard time sticking to the ground is because the soil temperatures are in the mid 40s.
Should any snow accumulate in bursts it would likely be confined to grassy surfaces or on elevated objects.
12AM WEDNESDAY SNOW/RAIN: From 10pm to midnight snow will be possible across NW Arkansas and also in the Ouachitas.
The limiting factor is going to be both the soil temperatures mentioned above, as well as air temperatures at the surface.
12AM WEDNESDAY TEMPERATURES: Temperatures will remain above freezing tonight so while accumulating snow is possible it will have a difficult time sticking to surfaces. Temperatures at midnight are expected to be in the low to mid 30s; typically temperatures in the mid to upper 20s are necessary for snow to accumulate on paved roads.
Here's a map with the most likely area for snow accumulation. Notice how the higher terrain really becomes the focal point.
The latest data also indicates that up to 1" is possible in NW Arkansas.
Low temperatures across the NW Arkansas cities will be near 33º in the River Valley expect around 36º