Iowa’s weather next week may be impacted by what Gustav does, or what moisture from Gustav does. Most models indicate Gustav will make landfall sometime on Monday on the central Louisiana Coast west of New Orleans. They begin to differ as to where it will go after landfall, most models have it moving west northwest into Texas very slowly or some have it going back into the Gulf of Mexico. The GFS model at 18Z (1pm Iowa Time) shows that on Tuesday, Gustav will have made landfall and would be centered near the Toledo Bend Reservoir south of Shreveport. As that occurs a front will be moving into Iowa at the same time.

On Wednesday afternoon the same model run shows the center of Gustav over Shreveport and the heaviest moisture concentrated in northwestern Arkansas and southwestern Missouri. The front will be moving through the eastern part of Iowa at this time with showers and isolated thunderstorms.

Thursday afternoon, the front has passed Iowa and the heaviest moisture is now SE of the state from Pine Bluff Arkansas (where Gustav is centered on this run) to Springfield Illinois. There could be an isolated shower east of Dubuque to Keosauqua line Thursday morning. It’s too early to determine if Gustav’s moisture will entrain into the upcoming storm on Tuesday and Wednesday but it could mean the difference between 1/4 of an inch and widespread 1 inch amounts across the eastern 2/3rds of the state of Iowa.