Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000 FXUS63 KDTX 290408 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 1208 AM EDT MON AUG 29 2016 .AVIATION...
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Clear sky other than some thin cirrus debris will contribute to favorable conditions for continued fog and stratus development during the night. High pressure shifting from northern lower Michigan to Lake Huron will line up to direct some marine moisture inland. Surface moisture conditions are already be favorable for borderline LIFR/IFR fog and the marine moisture will enhance both the fog and LIFR/IFR stratus potential through morning. While prospects are good for restrictions, observational trends will be required to refine timing and coverage at each terminal location. Conditions will then follow a standard improving trend through late morning and lead to clear sky and light wind through afternoon into Monday evening. For DTW... Borderline LIFR/IFR restriction in fog and stratus or obscuration remains likely late tonight through mid morning with improvement to VFR by late morning/early afternoon. Clear sky and light wind will then persist into Monday evening. //DTW Threshold Probabilities... * High ceiling aob 5000 feet late tonight through mid morning. * Low for ceiling/visibility below 200 ft or 1/2 sm late tonight into early morning.
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Issued at 950 PM EDT Sun AUG 28 2016 UPDATE... Mid evening surface analysis indicates a healthy gradient of dewpoint from north to south over SE Michigan, from the mid 60s in the north to lower 70s Detroit to the Ohio border. This marks where the surface trough has stalled and will now wash out during the night in favor of high pressure over the northern Great Lakes, and even that process will be weak and slow. A combination of fog and low clouds remain likely at all locations overnight as surface wind continues to drop off and the sky remains otherwise clear for good radiational cooling. No headlines will be issued at this point but locations to the south will be monitored closely for trends in that direction. PREV DISCUSSION... Issued at 259 PM EDT Sun AUG 28 2016 DISCUSSION... High pressure will settle across the Great Lakes tonight beneath a building shortwave ridge aloft. Light northeast gradient off of Lake Huron will result in a shallow inversion that will support inland development/advection of fog and/or stratus late tonight. Diurnal deepening of the boundary layer will mix out low cloud during Monday morning. Very dry column within flat/confluent upper level flow aloft will support mostly clear skies on Monday and mixing to perhaps 850mb where temperatures will reside in the mid teens around the northern periphery of the expansive mid-level high parked over the eastern 2/3 of the US. Highs will hover just above average values for the date in the low 80s. Little change in the local environment through Tuesday. SE Michigan will still reside safely east of the instability corridor that will be drawn north over the Northern and Western Great Lakes in response to height falls associated with a weak cyclone over northern Ontario. Depression of heights locally will allow for slightly deeper mixing than observed on Monday, so inherited high temps in the mid 80s still look good. Theta-e ridge will fold into the area from the northwest on Tuesday night in advance of a weak cold front. Nothing more than a chc pop warranted Tuesday night given weak dynamic forcing and unfavorable nocturnal timing. Surface cold front will move through the area on Tuesday and Wednesday. A fairly moist airmass ahead of the front will allow for scattered showers and thunderstorms to develop over portions of southeast Michigan. As the cold front passes through on Wednesday, high pressure builds over the region with cooler/drier conditions to follow. High temperatures are expected to be in the low to mid 70`s through Saturday with low to mid 80`s returning for Sunday/Monday. MARINE... High pressure building into the central Great Lakes will bring veering and weakening flow to region overnight into Monday. Northwest winds will become northeasterly Monday morning and though winds will be in the 10 to 15 knot range through most of the night, they will quickly drop off in the morning to less than 10 knots. Modest southwest winds expected on Tuesday ahead of a weak cold front tracking through the region.
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&& .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ AVIATION.....BT UPDATE.......BT DISCUSSION...JVC/DE MARINE.......DRK You can obtain your latest National Weather Service forecasts online at is the U.S. government's official web portal to all federal, state and local government web resources and services.