Weather Lookup

Key Messages

- showers and slight chance thunderstorms into thursday morning

- heavy rain possible saturday

Discussion

Issued at 244 PM EDT wed sep 16 2026

- showers and slight chance thunderstorms into thursday morning

The chance for occasional showers and perhaps a thunderstorm continues into thursday morning, though the potential for heavy rain should likely be contained south of southwest michigan tonight. Low and midlevel cloud cover and patches of light rain stretch from southern michigan into iowa. A train of midlevel mesoscale vorticity centers has been evident on radar and satellite among these clouds along the effective midlevel front, and will be the primary impetus for showers this afternoon. 850 mb air parcels are modeled to be weakly unstable, though convective tops may struggle to reach -10 c, which supports showers but with a limited chance of lightning.

Tonight into thursday morning, a southwesterly low-level jet noses into iowa and becomes more of a westerly llj over northern illinois and indiana. Thunderstorm development will be focused over this region along the effective midlevel front, as the convection-allowing models have been suggesting. A few showers may still develop over lower michigan from weakly unstable cloud layers between 850 and 700 mb under a slight uptick in more favorable upper- level jet dynamics. The ECMWF ensemble has been most aggressive in providing a soaking rain to lower michigan (the 00 Z ensemble even gave grr a median QPF of 1 inch, though the 06 Z run did back off some). However, the GEFS and cmc ensemble system along with the cams have been keeping the soaking rains south of michigan, which i AM more inclined to believe.

- heavy rain possible saturday

Late thursday into friday is favored to be dry as the front moves farther south while surface high pressure scoots across northern ontario. Rain chances then become highly likely from late friday night into a portion of saturday. The front well to our south and southwest will surge back northeast as a warm front, approaching southwest michigan, with a 35 knot low level jet ascending up the frontal surface. PWAT values around 2 inches and weak instability will also be present.

The global ensemble systems have generally been producing median QPF around 1 inch, with about 20 percent reaching 2 inches, indicating a widespread soaking rain is likely along with swaths of locally more than 2 inches where thunderstorms persist. There will remain some question for now regarding where the axis of heavier rain will fall, whether it be more so in central michigan or in southern michigan, as it will depend on the latitude of the low pressure development and its associated warm frontal surge, and whether the thunderstorm complexes may preferentially propagate farther south into the better instability compared to where the global models place them.

Aviation — 18Z Tafs Through 18Z Thursday

Issued at 116 PM EDT wed sep 16 2026

Conditions this afternoon range from IFR across southern lower michigan to MVFR across central lower michigan. We expect a trend towards IFR overnight as low clouds and some showers expand northward. This is followed by slow improvement thursday morning as the bulk of the rain and low clouds moves off to the east.

Marine

Issued at 244 PM EDT wed sep 16 2026

Relatively light and generally northeast winds expected through friday will keep nearshore waves low. There is a slight chance of a thunderstorm cell or two developing over the lake tonight. Small craft advisory conditions are possible friday night into sunday as winds strengthen with gusts to 25 knots. These winds would most likely have an easterly directional component, keeping the larger waves away from shore. There may also be thunderstorms over a portion of the lake on saturday, lightning being the primary hazard.