Severe weather threat Saturday

Moisture from Hurricane Patricia will affect us next week


DETROIT – We have a pretty complicated weather scenario today, so pay attention, because it's important.

First of all, a warm front crossing the area early this morning is spreading showers across the area. Once the front passes by, I think we'll see a lull in the rain activity, perhaps only a few scattered showers from mid-morning through mid-afternoon.

Then, a cold front approaches after 4 p.m. with a line of showers and scattered thunderstorms.

Here's where situation gets iffy: During a typical summer-time severe weather situation with great instability that extends high up into the sky, we get towering thunderstorms reaching perhaps 50,000 feet. On Saturday, we'll have low-level instability develop, but not as much farther aloft.

So, instead of those enormous cumulonimbus clouds, we'll have lower topped showers and storms which, normally, wouldn't bring severe weather. However, we'll also have a strengthening wind field aloft, with wind at 20,000 feet approaching 80 m.p.h. and we'll also have good wind shear (change in wind speed and direction as you go up).

The bottom line is that if we can warm up enough, then it might be possible for a few of those storms to tap into that impressive wind field aloft and generate severe wind gusts, and, possibly, even an isolated, brief tornado. We'll have cloud cover most of the day, but I do have one model suggesting that a few breaks of sun might develop this afternoon ahead of the front.

If that happens, highs would approach 70 degrees (21 degrees Celsius for our Canadian neighbors), although most of us, particularly north of 8 Mile Road, will be in the mid to upper 60s (19 degrees Celsius). Southeast winds early Saturday morning will shift to the south following the warm front's passage and increase to 15 to 25 m.p.h.

If you haven't done so already, I strongly suggest that you download the FREE Local4Casters app and monitor the radar if you have outdoor plans today. Also, if you have a weather radio, make sure it's plugged in, has a fresh battery, and is properly set to alert you if any warnings are issued.

Saturday's sunrise is at 7:56 a.m. and sunset is at 6:38 p.m.

Late afternoon showers and thunderstorms should move out by 8 p.m. (9 p.m. for those of you across the river in Ontario), and clouds will gradually break up overnight. Lows will be in the mid 40s (7 degrees Celsius). Northwest wind develops behind the cold front, at 10 to 15 m.p.h. overnight.

Skies will be mostly sunny on Sunday and the back half of our weekend looks like a splendid fall day, with highs in the mid to upper 50s (14 degrees Celsius). No weather issues for Lions tailgaters. Go Lions!

It will be mostly clear Sunday night with lows in the mid to upper 30s (3 degrees Celsius) outside of the Detroit Urban Heat Island, and near 40 degrees (5 degrees Celsius) in the heat island.

Mostly sunny on Monday with highs mid to upper 50s (14 degrees Celsius). Partly cloudy Monday night, with lows generally near 40 degrees (5 degrees Celsius).

Increasing clouds on Tuesday, with highs in the low 60s (16 degrees Celsius). Rain develops Tuesday night, with lows in the low 50s (11 degrees Celsius).

Rain and thunderstorms are likely on Wednesday as moisture from former Hurricane Patricia is drawn northward into the Great Lakes region. Highs near 60 degrees (15 degrees Celsius). It will also become breezy on Wednesday.

Rain diminishes Wednesday night, and winds increase. Lows will drop near 45 degrees (7 degrees Celsius).

Mostly cloudy, very windy and colder on Thursday, with scattered light rain and/or snow showers. Highs briefly near 50 degrees (10 degrees Celsius), but most of the day will be in the 40s and the wind will make it feel even colder.

Still breezy Thursday night, but becoming mostly clear. Lows in the mid 30s (2 degrees Celsius).

Mostly sunny on Friday, with highs in the low to mid 50s (11 degrees Celsius).

There's still no change to my Halloween outlook. Saturday looks to be a mostly sunny day, with dry conditions for the Trick or Treaters! Even the wind doesn't look like anything to worry about. Temperatures will fall from highs in the mid 50s into the 40s by the time the kids head out to gather the pounds of candy they'll feast on for the next few weeks.

Follow me on Twitter at @PGLocal4

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