Metro Detroit weather forecast: Changes to Sunday's Marathon forecast

By Paul Gross - Meteorologist

The weekend weather pattern is coming into a little better focus, and that focus is now forcing a change to the weather expectation for the Free Press – Chemical Bank Marathon forecast…more on that in a moment.

Tonight will feature a continuation of the clouds, with some fog and drizzle also possible at any time.  Lows in the low to mid 50s (12 degrees Celsius).  Very light south wind.

Mostly cloudy to start on Friday, with at least partial sunshine developing during the afternoon.  As long as we get that sunshine, expect highs near 70 degrees (21 degrees Celsius).  South wind at 5 to 10 mph.

Increasing clouds Friday night, with rain developing likely north of M-59.  This line of demarcation could change, but this is how it looks as of this afternoon’s computer models.  Lows in the upper 50s (14 degrees Celsius).

How nice of a day your Saturday is will be highly dependent upon how far north and south you are in our area.  The Friday night line I discussed above may not change much during the day on Saturday.  Those of us south of 8 Mile have only a slight shower chance, whereas those rain chances increase as you head north…especially north of M-59.  Again, there could be changes to where the south end of the rain pattern is, but this is how it looks right now.  Highs in rain-free areas to the south will likely reach the mid 70s to near 80 degrees (24-27 degrees Celsius), with high temps naturally dropping the farther north you go as clouds thicken and you head into the rain…perhaps only in the low to mid 60s (16-18 degrees Celsius) in our North Zone.

Although shower chances continue in the same areas Saturday night, coverage should diminish.  Lows near 60 degrees (15-16 degrees Celsius).

The weekend cold front that the Local4Casters have been talking about is still coming through on Sunday, but today’s computer models have accelerated the time table:  it now appears that the front will come through during the marathon!  It’s possible that we’ll be dry before the race and at the start, and then have to deal with scattered showers during the race as the front arrives.  Once the front moves east of us, the rain will end for the remainder of the day.  The front will also impact our race wind:  ahead of the front, it will blow from the south to southwest at 10 to 20 mph with higher gusts, while after the front crosses the area it will blow from the southwest to west at 20 to 30 mph with higher gusts.  Temperatures at the start will be in the low 60s (16-17 degrees Celsius), and rise into the upper 60s to near 70 degrees (20-21 degrees Celsius) by 11:00 a.m.  The weather will certainly be a factor this year, and those of you with the Local4Casters app will certainly reap the benefits of our FREE app.

Here’s how the weekend weather pattern is being projected by our in-house high-resolution RPM model:

Sunday afternoon should become partly cloudy, but it’ll be continued windy, with highs probably edging into the low 70s (21-22 degrees Celsius).

Next week:

Now that we’ve had our good soaking rain, we can go back to wishing for spectacular fall weather without feeling guilty about it!  And Mother Nature will deliver big time.  Skies should be mostly sunny for the entire week ahead, with highs starting off near 60 degrees (15-16 degrees Celsius) on Monday, and warming steadily each day until we reach the mid 70s (23-24 degrees Celsius) by Friday / Saturday.  What a week!  Might be a good idea to get the car washed on Monday…you’ll get your money’s worth.

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