Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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685 FXUS63 KDTX 090334 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 1134 PM EDT Sat Jun 8 2024 .KEY MESSAGES... - A stray shower is possible on Sunday afternoon as a weak cold front crosses bringing slightly below normal temperatures by Monday. - Cool and mainly dry conditions for the first half of the week are followed by a warming trend back into the mid to upper 80s by latter half of the week. && .AVIATION... The rain will be east of the terminals by TAF issuance as subsidence in the wake of the frontal system and upper level trough take hold. There have been some indications of post frontal low cloud development to the west. There are a few model solutions which do indeed suggest some IFR and/or LIFR conditions in low clouds or fog developing overnight. This is a result of lingering low moisture trapped under a deep inversion with clearing skies offering some cooling atop the moist layer. Any low clouds/fog will mix out around or shortly after daybreak. Cold air advection within an increasing west-northwest gradient and deepening afternoon mixing depths will support an increase in winds by Sunday afternoon. Peak gusts in the 25 to 30 knot range looks reasonable based on model soundings. For DTW/D21 Convection...Thunderstorms are not expected through the TAF period. DTW THRESHOLD PROBABILITIES... * Low in ceilings aob 5000 feet overnight and Sunday morning. && .PREV DISCUSSION... Issued at 304 PM EDT Sat Jun 8 2024 DISCUSSION... Area of showers continues to fill-in from north to south this afternoon as local height falls ensue due to a broad upper low crossing Ontario. The main jet axis aloft supporting the shortwave feature extends across most of the northern tier of CONUS today while a speed max emerges over the Upper Midwest and elongates across southern Lower Michigan. Region of peak ThetaE advection arrives after 22Z this evening along the leading edge of an elevated warm frontal boundary. This boundary makes minimal northward progress, but should offer enhancements to saturation via isentropic ascent along the frontal surface. Overall, expect rather benign rainfall rates with shower activity tonight given prior dryness marked by the 08.12Z KDTX RAOB which sampled a PWAT of 0.75 inches. SPC Mesoanalysis suggests the core of the moisture plume (+1.00 inch PWATs) has already advected into western Lower with HREF supporting an eastward progression/fold this evening. A survey of instability based on several deterministic sources and representative forecast soundings highlight positive CAPE values remaining just south of the IN/OH/MI border, therefore will continue to advertise a thunderless forecast. Made minor adjustments to PoPs to slow the arrival of showers along/south of I-94 and accelerated the phase-out of PoPs upon departure of the wave after midnight. The aforementioned upper low dislodges thanks to the amplification of a ridge axis over north-central Canada which merges with a higher amplitude ridge over The West. This drives additional CVA through the Great Lakes Sunday while an area of surface troughing emerges. Westerly gradient flow strengthens after 16Z while a mixed-layer lifts to 5 kft AGL, intersecting a modest low-level wind field of 30+ knots. Breezy conditions are likely as peak gusts approach 30 mph once a weak cold front drops through and veers winds northwesterly. Can`t completely rule out a few spotty afternoon/evening showers, but moisture quality is rather meager, thus any isolated shower activity should be rather light in character. A cooler airmass settles in Sunday night with lows dipping below 50F for some areas in spite of lingering cloudiness. Also can`t rule out a few sprinkles along the shores of southern Lake Huron given the brief lake-influence setup. Sprawling high pressure spills across the Upper Midwest Monday and Tuesday offering high-confidence in a dry forecast. Air parcel trajectories tracing back into northern Canada maintain cooler-than- normal conditions Monday followed by a shift to a return-flow setup by Tuesday afternoon which marks the initiation of a warming trend through the remainder of the week. Highs break into the 80s by Tuesday with medium-range solutions (GEM/ECMWF) supporting the potential for MaxTs to approach 90F for Metro Detroit by Thursday as 850 mb temps approach 19C. A cold front and the chance for storms increases Thursday night into Friday. MARINE... Widespread showers continue over the region this evening before shifting towards the southern Great Lakes overnight as weak low pressure slides across the region. Drier conditions generally redevelop daytime Sunday with only isolated to scattered showers possible mainly over the northern half of Lake Huron tied to lingering, deepening low pressure over Quebec. This low tightens the local gradient resulting in an uptick of northwesterly winds latter half of the day Sunday into Sunday night. Overall, 20-25kt gusts expected over the region though areas for greater achievement pushing towards 30kts are the Saginaw Bay (due to the warmer waters) as well as northern Lake Huron given the favorable fetch. Lighter winds, at or below 20kts, then arrive daytime Monday as high pressure builds overhead. This high remains in place for the first of half of the work week. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...Small Craft Advisory from noon to 10 PM EDT Sunday for LHZ422. Small Craft Advisory from noon Sunday to 4 PM EDT Monday for LHZ421. Small Craft Advisory from 2 AM to 10 PM EDT Monday for LHZ441>443. Lake St Clair...Small Craft Advisory from noon to 10 PM EDT Sunday for LCZ460. Michigan waters of Lake Erie...Small Craft Advisory from noon to 10 PM EDT Sunday for LEZ444. && $$ AVIATION.....SC DISCUSSION...KGK MARINE.......KDK You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.