Detroit/Pontiac, Michigan

• Mild and mostly cloudy through early next week.
• Warmer on Tuesday with an increasing chance of rain mid-week.

Slow progression of governing synoptic features maintains benign weather through the weekend and into early next week. The 12z DTX raob showed stable conditions and the saturation between 700 and 550mb responsible for the mostly cloudy day. Satellite imagery reveals a vast swath of the central CONUS shrouded in mid-level cloud, boosting confidence in a continued mostly cloudy forecast going forward as this cloud is steered around the SE CONUS 700mb ridge. A few sprinkles will be possible at times where transient pockets of forcing emerge within an ill-defined warm frontal structure aloft. The blanket of clouds maintains milder conditions tonight, with evening temperatures in the mid 50s settling into the 40s and lower 50s overnight.

Despite the clouds, positive thickness advection will help boost high temps back into the 60s Sunday and Monday. A 30% chance for light showers arrives Monday evening and overnight as an upstream low sends a more organized arm of theta-e advection across the Great Lakes. The bulk of the moisture transport is forecast to hold upstream. Arrival of the warm sector Tuesday brings high temps some 15 to 20 degrees above normal, near 70 degrees.

Evolution of the upstream low exhibits increasing spread beyond Monday, but in general a pattern shift is looking likely by mid to late week as a Pacific wave eventually makes its way across the Great Lakes. The wave nearly cuts off from the steering flow as it tracks over the Plains Monday, then a northern stream shortwave descends from central Canada on Tuesday. The interaction of these waves opens the door for significant differences to arise wrt timing of precip locally. Later solutions that bring rain in late Wednesday are driven by a much stronger system that occludes sooner over the Plains, delaying arrival of meridional moisture transport. Earlier solutions, which make up a smaller portion of the ensemble membership, appear to result from a slightly stronger system over the Corn Belt that`s capable of producing greater poleward moisture transport, but not so strong that the low completely occludes upstream. Ultimately, most of the sensitivity in the forecast comes from the forward speed of the Pacific trough which will come into focus the next few forecast cycles. Highest confidence in precip at this stage is currently on Wednesday, at around 60 to 70%.

Expansive high pressure centered over the central and eastern Great Lakes this afternoon will slowly exit east this weekend. Light southerly winds will prevail for the second half of the weekend. Southerly winds will increase early next week as low pressure develops over Minnesota and lingers into the midweek. Wind gusts are expected to peak out 25 to 30 knot range, as warm air (lower teens at 850 MB) keeps mixing depths in check. Enough moisture is expected to advect into the Great Lakes region to support increased coverage of showers Tuesday and Wednesday. Showers could potentially linger into Thursday as either the primary cold front or a weaker low pressure system tracks through. Wind speeds and direction remain uncertain for Thursday.

AVIATION

Strong high pressure centered over the eastern Great Lakes today and tonight will sustain light winds and a feed of dry air in the low levels across Se Mi. Despite the continued influx of moisture aloft, this low level dry air will maintain VFR conditions through the TAF period. Intervals of warm air advection aloft have supported a few light rain showers/sprinkles. While isolated showers/sprinkles may persist through the day, the impacts to aviation will be minimal.

DTW/D21 Convection...No convection will occur through the TAF period.

DTW THRESHOLD PROBABILITIES

• None

MI

None.

Lake Huron

None.

Lake St Clair

None.

Michigan waters of Lake Erie

None.