Why have we gotten so much rain for so long this week?

Posted at 11:13 AM, Oct 01, 2016
and last updated 2016-10-01 12:46:38-04

What's the deal with this drenching we've been getting?

Most of the greater metro Detroit area has had to absorb two to five inches of rain since it started raining on Wednesday. Downtown Detroit has gotten some of the heaviest amounts with over five inches of rain.

Flooded basements, horrific traffic jams and canceled baseball games have been some of the impacts.

It's all because of a very slow moving low pressure area, both on the ground and up in the atmosphere, that has pumped moisture into the area from the warm waters of the Gulf Stream and the Atlantic Ocean.

Sometimes in September and October, as the atmosphere starts to transition from summer to winter, the steering currents in the upper levels allow low pressure areas like this to move very slowly, or even remain stationary for days at a time. This one has moved very little for the last two days.

Unusually warm sea surface temperatures off our east coast probably added a little juice to the equation. Parts of the mid-Atlantic have also gotten flooding rains from this same system.

September is not an unusual time to get flooding around here, as some of the worst flooding in the last century hit almost exactly thirty years ago, centered a bit to the north of metro Detroit in the Thumb and Saginaw Valley. 

The system as of Saturday has finally started to move north and weaken, meaning less rain and lighter amounts this weekend.

Though rainfall the rest of the weekend will be lighter, we still will likely add a bit to our rainfall totals.

This low pressure area impacted our weather in two different months and reminded some of us of that house guest that was politely greeted (we started the day Wednesday with below average rainfall for the month) but overstayed the welcome by at least two days.

We ended September more than three inches above average rainfall for the month.