The National Weather Service (NWS) in Little Rock says strong southerly winds will blow in before a cold front that's expected to trigger showers and thunderstorms across much of the western and northern parts of the state.
The stormy weather is expected to move in during the afternoon and early evening hours.
NWS forecasters say the front may stall for a time, which could lead to a narrow band of heavy to excessive rain.
While the location could change when the system moves in, the NWS says at this time it appears the band could set up along and just north of the Interstate 30 and Highway 67/167 corridors, or from Murfreesboro to Conway and Hardy.
Two to four inches of rain is possible in that area.
Moving on to overnight and predawn hours of Wednesday, the NWS says the front should gain momentum toward the Mississippi River, with precipitation building into southern and eastern sections of the state. Widespread one to two inch rainfall amounts are in the forecast.
Other than the concern for heavy rain, some severe weather is anticipated. Thunderstorms should form into a line upon entering the region Wednesday afternoon and then will leave the state as a line later that night.
Along the line, strong to damaging winds will be possible. Winds surrounding the front will turn somewhat with height, so an isolated tornado or two cannot be ruled out, but the threat is low.
The amount of severe weather that occurs will depend on how unstable the atmosphere becomes. While it will be warm and humid near the ground, there will be a lack of cooling aloft because the main system associated with the front will lag to the west. The NWS says given marginal instability, an outbreak of severe storms is unlikely.
That may put the storms in LR right around the 4-7pm period. A later arrival MAY also allow for extra warming ahead of the storms and maybe increase the threat for severe storms.
The maps above show 3 parameters from the NAM model. The left panes show the situation around midday (10am-2pm) and the ones on the right show the same parameters in the evening 4-8pm.
The top panes (green color) indicate accumulated rainfall. Heavier amounts are shown in darker green. This is NOT a radar image. B/c the map shows what rain has accumulated, the actual rainfall is always located on the eastern (right) edge of the area of green. You will notice above how much the darker greens increase from afternoon to evening indicating a significant increase in rainfall coverage and likely intensity (usually associated with increasing storms).
The middle set of panes shows energy available for storms. Just like radar, yellows are lower values than oranges and reds. You'll notice that in the afternoon plot, there's a lot more yellow than orange. By even the orange has expanded well north into eastern Arkansas. Energy for storms comes from daytime heating. It would make sense then that the later you get into the day the more energy is available for storms. The energy only exists in areas ahead of the rain and storms. Once storms move through, the energy is used up and the threat is done. A later arrival of the storms would mean more energy available for them across central and east Arkansas.
The bottom pair of panes shows something that I've called "Tornado Energy." The real name for this is EHI or Energy Helicity Index. Basically is a plot of where areas of high t-storm energy and high spin at the surface coincide. Areas where the two occur together have a higher probability of seeing a tornado. Areas in blue are typically not enough to worry about. It's the regions in yellow or higher (oranges and reds, if available) that warrant watching. You'll notice there isn't much yellow in the state during the middle of the day. It's really during the evening that the threat conditions for tornadoes increase. This is why timing is important. If you get the storms early in the day, your tornado threat with them will be lower versus those that, let's say, get them after 4pm. So, you want the storms to move through as early as possible if you don't like severe weather. It's an unfortunate fact, but some folks will get the storms later in the day in Arkansas when the threat for tornadoes will be higher. If the system continues to slow down, like this NAM model wants to suggest, then more Arkansans will see a higher severe threat.
Of course I cannot predict when exactly the storms will be in your town/county. I also do not know how bad they will be. We are all under a threat of severe storms. Wind, hail & tornadoes are all threats and you should take each seriously. Don't downplay a t-storm warnings b/c it's not a tornado warnings. T-storm winds will destroy a house just like a tornado if they get high enough, whether it be through the wind itself of a fallen tree. You can be sure I'll keep an eye on things and will update you through the rest of today and of course tomorrow.