Metro Detroit weather: Potential changes to holiday weekend forecast

DETROIT – If you’ve been following my articles all week, you know that I’ve expressed great concern about big disagreements among the computer models as we head into the holiday weekend.

This morning’s models not only do not clarify things, but they actually have taken a step backwards and made things even more challenging. I’ll get to the specifics in a moment -- first, let me get you out the door with today’s forecast.

Thursday weather forecast

It’s been a great night of sleeping weather, and we are waking up to some high level clouds crossing the area. Those will be with us to create a beautiful sunrise, then move out to give us a mostly sunny sky until mid-to-late afternoon, when a cold front approaches.

Some high-resolution computer models keep us completely dry when this front crosses the area, but our in-house RPM model tries to spit out a couple of showers and thunderstorms.

The air mass is pretty dry, so I think that rain will be pretty limited, but it’s a dynamic front, so I have to give it some respect.

Also, something to monitor IF any thunderstorms pop up (especially north of I-69) is that some of the rain falling into that dry air will evaporate, which causes cooling, which then causes a faster down rush of air, which could create some stronger wind gusts here at the surface.

Even if we don’t get any rain, it’ll become windy, with southwest winds increasing to 15 to 25 mph, and we could see gusts between 30 and 40 mph. Those southwest winds will usher in the warmest temps we’ll see for a while -- many of us reaching the mid 80s (29 to 30 degrees Celsius).

Today’s sunrise is at 7:01 a.m., and today’s sunset is at 8:03 p.m.

Becoming mostly clear overnight, with lows in the mid 50s (12 degrees Celsius). Wind will shift to the west behind the cold front, and settle down to 5 to 10 mph.

Friday forecast

Mostly sunny to start on Friday, then fair weather cumulus clouds start developing by late morning and will persist through late afternoon. Cooler highs in the mid 70s (23 to 24 degrees Celsius).

Partly cloudy Friday night, with lows in the mid 50s (12 degrees Celsius).

Weekend update

The computer model challenges I started this article with jump right out of the gate on Saturday. They now suggest that an upper level disturbance (suddenly appearing today in the models) could potentially trigger some showers. There is great disagreement in the models -- I’m seeing everything from no rain, to early rain, to rain late. At this point, I’m going to accept that there’s some rain chance, but I also think that most of the day will be dry, with highs in the mid 70s (25 degrees Celsius).

Saturday evening will hopefully be dry, and I think we’ll be dry for the overnight hours, with lows near 60 degrees (15 to 16 degrees Celsius).

Sunday looks to be dry through the morning into at least the early afternoon, but some models try to pop up some scattered thunderstorms mid-to-late afternoon. Others keep us dry. Highs should warm to near 80 degrees (27 degrees Celsius).

Likewise, the models show tremendous differences in the timing of a front late Sunday night into Monday. At this point, I think the best chance to see some showers and thunderstorms is later Sunday night into first thing Monday morning, with things drying out in the afternoon. Highs should reach the low 80s (28 degrees Celsius) as long as we get some afternoon sun.

I realize that I may not have been much help to your weekend plans, but this is an extremely challenging forecast. We meteorologists always have very low confidence in the forecast details when the computer models change so radically from day to day, and are so different with each other.

Stay with me -- tomorrow’s models should develop a better handle on things, and I’ll straighten this out for you in my Friday morning article. In the meantime, remember that the free Local4Casters weather app has live radar that you can monitor anytime you want to stay ahead of the weather.

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