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Metro Detroit weather: Two severe threats, big changes ahead

Warm front crosses Metro Detroit on Thursday

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DETROIT – There are lots of changes coming our way, so let’s get straight to the forecast.

First of all, a warm front will cross our area late this afternoon and evening. That’s the front edge of yet another warm, oppressively muggy air mass that will certainly get your attention. Ahead of that front we had quite a solid band of rain and thunderstorms move in this morning, but the thing to keep in mind is that those storms were what we meteorologists call “elevated.”

In-other-words, the bases of those storms were thousands of feet aloft. Once the warm front passes by, however, any random storm that pops up will have much, much lower air inflow into their bases than the morning storms did -- and that allows them to tap into the much more unstable air mass, as well as increasing wind shear (change in wind direction as you go up), which is particularly true close to that warm front.

The bottom line is that, although most of us likely won’t see a storm late this afternoon to early this evening, any storm that does pop could produce severe wind gusts -- or even a tornado given the degree of wind shear. But remember, any developing storms this afternoon should be very sparse.

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If any storms pop, they should diminish pretty quickly this evening, leaving us quiet for the overnight period. It’ll be warm and muggy, though -- yet another tough night for those without air conditioning -- as lows only drop into the low 70s (22 degrees Celsius). At least we’ll have a breeze, if you’re depending upon one, with a south wind at 10 to 20 mph.

Friday (TGIF!) will start off mostly sunny, warm and humid. A strong cold front will then cross the area approximately between 1 p.m. and 6 p.m. A line of thunderstorms will develop ahead of this front, and how severe they become will be directly determined by the front’s timing. The later the timing, the hotter it gets ahead of the front, and that makes the atmosphere more unstable.

So, areas farther east have a better chance for severe storms with the cold front than those of us farther west. But unlike Thursday, the wind field ahead of that cold front will be nearly unidirectional from the surface up aloft. That means very little potential for rotating storms, so the primary severe threat Friday will be damaging wind gusts.

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Temperatures by mid-afternoon will be in the mid 80s (29 to 30 degrees Celsius) ahead of the front, and in the low to mid 70s (22 to 24 degrees Celsius) behind the front.  Get ready for a big change once that front blows through. It’ll be a windy day, too, with a southwest to west wind increasing to 20 to 30 mph.

Friday’s sunrise is at 7:20 a.m., and Friday’s sunset is at 7:32 p.m.

Partly cloudy Friday night, with lows in the low 50s (11 degrees Celsius) in our Urban Heat Island near Detroit, with perhaps some mid to upper 40s (8 to 9 degrees Celsius) in rural locations.

Weekend forecast

Saturday looks mostly sunny to partly cloudy and much cooler, with highs only in the mid 60s (18 degrees Celsius).

Mostly clear Saturday night, with lows in the 40s everywhere (6 to 9 degrees Celsius). By the way, parts of the western Upper Peninsula may get their first frost of the season! 

Mostly sunny on Sunday, with highs in the upper 60s (20 to 21 degrees Celsius).

Next week

Partly cloudy on Monday, with highs in the low to mid 70s (22 to 23 degrees Celsius).

There’s a good chance of showers and thunderstorms at some point on Tuesday as another cold front approaches.  Highs in the mid 70s (24 degrees Celsius).

Partly cloudy Wednesday and Thursday, with highs in the mid to upper 60s (19 to 20 degrees Celsius).

Partly to mostly cloudy on Friday with a scattered shower possible.  Highs in the mid 60s (19 degrees Celsius).


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