Metro Detroit weather: What to expect this week

DETROIT – Today, March 1, is the start of meteorological spring, and this confuses people, because it’s different from astronomical spring which, this year, occurs at 5:37 a.m. on March 20.

Astronomical spring occurs every March at the moment that the sun is directly over the equator on its way from the southern hemisphere to the northern hemisphere. This is called the vernal equinox, and it’s an exact point in time when an astronomical event occurs.

So why don’t we meteorologists just use the time from the vernal equinox to the summer solstice to compute our spring weather statistics? Because the equinox and solstice occur at different times and even different days every year.

To keep the statistics consistent over the years, meteorologists and climatologists use the period from March 1 through May 31 as our statistical spring, and that keeps our record-keeping nice and tidy. It really doesn’t matter if you want to throw your Happy Spring party today, or on March 20 -- as long as you understand the difference between the two dates!

Speaking of spring, after enjoying this past weekend’s afternoons with sunshine and mild temperatures, it’s back to reality today as colder air is streaming in.

Monday forecast

We are starting the day with lots of clouds, but should see an increase in sunshine as the day progresses. It’ll be brisk, though, with temperatures not rising much -- perhaps into the mid 30s (1 to 2 degrees Celsius) midday, then falling by mid-afternoon. When will blow from the west at 15 to 20 mph, with gusts over 30 mph possible.

Today’s sunrise is at 7:08 a.m., and today’s sunset is at 6:24 p.m.

Mostly clear Monday night, and it’ll be very cold with lows dropping into the low teens (-11 degrees Celsius). Wind diminishing from the west to 5 to 10 mph.

Tuesday, Wednesday forecast

Mostly sunny Tuesday and Wednesday, with highs near 40° (4 to 5 degrees Celsius) Tuesday, and back into the mid to upper 40s (8 to 9 degrees Celsius) on Wednesday. Lows Tuesday night near 30 degrees (-1 degree Celsius), and lows Wednesday night in the mid 20s (-4 to -3 degrees Celsius).

Thursday, Friday forecast

Partly cloudy on Thursday, as high as drop back into the upper 30s (4 degrees Celsius).

Mostly clear Thursday night, with lows in the low 20s (-5 degrees Celsius).

Mostly sunny on Friday, with highs near 40° (4 to 5 degrees Celsius).

Weekend outlook

Although are some model differences in the Saturday forecast, I’m seeing enough agreement to go with a partly cloudy day, and then a mostly sunny Sunday. And with highs near 40 degrees (4 to 5 degrees Celsius), it’s shaping up to be a splendid weekend ahead!

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