ST. LOUIS — The Helene forecast trends and the hurricane’s impacts on the St. Louis area remain very complex but the basic idea is the same. Rain is likely to spread from east to west into the region late tonight into Friday.
In addition to soaking rain, very gusty winds are possible especially for our Illinois counties. Friday into Friday night wind gusts of 30-45 mph will be possible.
The best shot of rain will be along and southeast of I-44 in Missouri and I-70 in Illinois. The metropolitan St. Louis area remains on the edge of the heaviest rainfall. The range across the region is from less than 1/2″ on the northwest side of town to as much as two inches in the southeast. The average rainfall for metro St. Louis should be around 1 to 1.5 inches. Totals further south in our region will be 2-4 inches.
There appears to be two key times for rain. Friday from just after sunrise through about 7 p.m., when steady rain is likely. There may be a break for several hours Saturday evening before another round of rain spins in from the east after midnight Friday night into Saturday morning.
The most widespread and continuous rain will be the first batch Friday. After that, the next waves Saturday morning and possibly Sunday will be much more scattered, patchy, and considerably lighter.
Because of the orientation and location of the rain and duration (spread out over multiple hours) I think most creeks and streams will handle the water well. Some ponding on roads and full ditches will be possible later in the day Friday. I do not currently expect widespread major flooding.
