Slow moving Tropical Storm Isaac finally moved inland across the Louisiana Coast last night as a category 1 hurricane with 80 MPH winds. The storm has moved painfully slow overnight and this morning, producing torrential rainfall across Southeast Louisiana and a high tidal surge along the coast and lakes. The storm will continue to move inland today with some slight acceleration in forward speed and a turn toward the Northwest. As Isaac moves across land the storm will weaken and should drop below hurricane strength later today. Due to the large size of Isaac and the fact it is moving over rather marshy and flat terrain, Isaac will weaken somewhat slower than average for a tropical system over land. Arkansas will stay dry today with the rain bands remaining South, but rain will begin to increase across the State Thursday as the system moves toward Northwest Louisiana. Below is the 2 PM CDT forecast track for Isaac from the National Hurricane Center.
The track has generally been shifting Westward and slowing down over the last 24 hours, bringing the center of Isaac into South Arkansas Thursday evening and through West Central Arkansas Friday morning. It then moves into Missouri by Saturday morning. Note that according to the forecast track, the center of Isaac would remain over Arkansas for over 24 hours. This path and relatively slow movement would bring heavy rains across much of Central Arkansas Thursday into Friday with several inches of rain likely. The Hydro-Meteorological Prediction Center now shows a band of heavy rainfall right through Central Arkansas along and just East of the forecast center.
The forecast shows 3 to as much as 6 inches of rain for Central Arkansas. This forecast is not a lock though, as some of the forecast models show the center of Isaac going much farther West than indicated by the Hurricane Center track.
If the center goes near the Arkansas/Oklahoma border, Central Arkansas would likely still receive some heavy rainfall. Rainfall usually extends out farther from the East of the Center rather than West of the center due to the Gulf moisture drawn Northward on that side. If the center goes very far West, say over Texas and Oklahoma, then the amount of rain we receive would be put into question. Below is a computer model rainfall projection based on Isaac going across Central Oklahoma.
Notice how changing the path of the center just a little drastically changes the amount of rain over Central Arkansas. A track to the West also raises the concern for weak tornadoes, which sometime accompany mainly the Eastern side of tropical systems moving over land. Winds will be a minor concern, as Isaac will be below tropical storm strength as it moves over Arkansas, however, gusty winds to about 30 MPH will be likely, especially near and just to the East of the center.