Metro Detroit weather: Unsettled week ahead

Weather will look, feel like fall


DETROIT – Well, things have changed.

Last week, all three major long-range computer models were projecting a large dome of high pressure over our region for the second half of this week, with some nice fall weather for us. That was until a large cutoff low pressure area, which had been handled poorly by the models all last week, finally materialized.

A cutoff low is a deep area of low pressure at jet stream level that gets cut off from those dominant steering winds aloft. The models notoriously have a rough time not only with timing the development of these cutoffs, but also with their movement. Some of them develop and then just continue drifting away, while others sit around for a while, which now appears to be the case for this week.

Skies should become mostly clear Monday night, although areas north of I-69, after initial clearing, will become partly cloudy sometime between midnight and dawn.  Lows in the upper 40s, or 9 degrees Celsius for our Canadian friends using the metric system. Southwest winds at 8 to 13 mph.

Clouds will gradually increase from north to south on Tuesday as that cutoff develops over northern Michigan and begins drifting south. North of I-69, you’ll start partly cloudy and then become mostly cloudy during the morning, with a scattered light shower possible during the afternoon. Across the central part of our area, we’ll start mostly sunny, then become mostly cloudy by afternoon.

Meanwhile, the south part of our area will be mostly sunny through the morning, then see clouds increase during the afternoon. Highs should reach the mid-60s (19 degrees Celsius), and note that it’ll be a very breezy day, with southwest winds at 15 to 25 mph.

Tuesday’s sunrise is at 7:27 a.m., and Tuesday’s sunset is at 7:21 p.m. Mostly cloudy Tuesday night, with scattered light showers possible. Lows in the low 50s (11 degrees Celsius).

The cutoff low is then going to meander around our area for the rest of the week, giving us shower chances and mostly cloudy skies from Wednesday probably through Saturday (I hope we get a few breaks of sun from time to time as ribbons of drier air wrap around the low). Highs should remain mired in the mid-60s (18-19 degrees Celsius), with overnight lows in the low to mid-50s (11-12 degrees Celsius).

The cutoff low should finally make enough of a move eastward to give us a dry day on Sunday, although it’s going to be a close call. Again, the computer models are notoriously inconsistent with the handling of these things. Highs in the mid-60s (19 degrees Celsius).

Once the cutoff moves out, we should have some pleasant fall weather in its wake, with mostly sunny or partly cloudy skies through the middle of next week, and highs rebounding back to near and above 70 degrees (21-22 degrees Celsius).

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