526 FXUS63 KDTX 100740 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 340 AM EDT Sat Oct 10 2020 .DISCUSSION... Low pressure in northern Ontario continues its rapid eastward progression moving into Quebec this morning. The LLJ that has persisted over the region since yesterday will begin weakening this morning as the pressure gradient weakens with the low pushing further east away from the Great Lakes. Despite this, WAA will continue through the first part of the day with h850 temps remaining around 12-14C and combined with the mild night, highs will reach back into the mid to upper 70's. The exception to this will be the Thumb and Tri-Cities area who will see the cold front earlier in the day slightly limiting highs to the low 70's. This cold front reaches northern SE MI this afternoon and pushes to the Ohio border by evening. Cloud cover increases as the day progresses with increasing moisture (PWATs 1+") folding into the region in advance of the front. This moisture brings with it a narrow band of instability though capping will likely limit shower potential. As mentioned in the prior discussion, a warm layer in the 850-650mb range still is looking substantial enough to cap any surface instability leaving only weak (<600 J/kg) elevated CAPE available. While forcing in general will be weak, some lake influence/enhancement could be enough to generate showers along the eastern counties of the CWA. Inherited PoPs still look reasonable given the current model solution space so have kept them going. More seasonable highs return Sunday behind the front as CAA develops under northerly flow from Canadian high pressure. Progressive pattern continues as the surface high quickly slides east into Quebec and the upper ridge axis crosses MI late Sunday ahead of an upper level trough over the northern Plains/Canadian Plains. An expansive surface low develops as a result over Saskatchewan strengthening as it tracks into Manitoba. Its associated cold front stretches south all the way down to the Midwest and tracks into the Great Lakes late Monday into Tuesday. Strong southerly flow aloft develops ahead of the front Monday leading to another day of above average highs in the 70s. Long range models have this longwave trough remaining over the central part of the continent into next weekend allowing an additional series of shortwave troughs to shoot across the Midwest and Great Lakes this week. Each shortwave brings with it a reinforcing shot of cold air with highs looking to drop below average by the second half of the week. && .MARINE... A cold front will cross the region today with the passage largely dry, although a few showers will be possible mainly over the southern Lake Huron basin. Winds will flip northerly behind the cold front and remain moderate as high pressure quickly builds in across the northern and central Great Lakes. The persistent onshore northerly winds will lead to elevated wave action tonight and hazardous small craft conditions along the Thumb. As the area of high pressure slides further east Sunday into Monday, winds will turn more easterly and remain at least moderate in strength before veering more southeasterly Monday ahead of the next approaching frontal boundary and associated chances for rain. && .PREV DISCUSSION... Issued at 1153 PM EDT Fri Oct 9 2020 AVIATION... A few SW wind gusts near 20 knots lingered after sunset as gradient flow remained elevated in very mild air over the region. Boundary layer stabilization strengthens during the late night which supports the low level jet and LLWS for the late night period as the front moves into the MBS area by early morning. Cloud trends are an additional factor as patches of mid to high coverage thicken and lower as the front approaches. Higher surface dewpoint moving in from the Illinois area appears to be the key to activating lower clouds along and ahead of the front during the morning with an additional boost from Lake Michigan. This results in expansion of stratus on the borderline of VFR/MVFR along and ahead of the front as the boundary moves north to south across the region during the day. The improved moisture supply during peak daytime heating produces a chance of showers but with coverage on the low side into Saturday evening. For DTW... Low level wind shear leads to SW surface wind maintaining or renewing gusts around 20 knots during the morning as a cold front approaches from the north. Boundary layer mixing leads to lower probability of MVFR ceiling however bases below 5000 ft are expected through afternoon. A few VFR showers are possible right along the frontal passage 20-22Z. DTW THRESHOLD PROBABILITIES... * Low for ceiling 5000 ft or less mainly after 14Z. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...Small Craft Advisory from 8 PM this evening to 10 AM EDT Sunday for LHZ442-443. Small Craft Advisory from 8 PM this evening to 4 PM EDT Sunday for LHZ421-441. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ DISCUSSION...KDK MARINE.......IRL AVIATION.....BT You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.