Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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961 FXUS63 KDTX 090250 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 1050 PM EDT Wed May 8 2024 .KEY MESSAGES... - Much cooler on Thursday with rain expected south of M-59 and a chance north. - Next chance of showers and thunderstorms comes Saturday. && .AVIATION... VFR conditions hold through the night as mid-cloud lifts north from OH/IN tied to developing low pressure over the Ohio Valley. Model guidance has been trending further south with its track Thursday shifting its precip coverage likewise further south. Detroit terminals still have the greatest chances to see light, to perhaps briefly, moderate showers Thursday afternoon with chances decreasing further north you go. With lesser moisture advection in SE MI due to this track, MVFR ceilings are more uncertain with low VFR being favored in current forecast for the southern TAF sites. MBS has increasing potential to remain completely dry so have taken out precip mention with FNT reduced to a Prob30 group owing to the decreasing confidence in precip extending that far north. DTW THRESHOLD PROBABILITIES... * Low for ceilings at or below 5000ft tonight into Thursday morning. High by Thursday afternoon. && .PREV DISCUSSION... Issued at 354 PM EDT Wed May 8 2024 DISCUSSION... A flattening shortwave ridge sliding over southern MI today in the wake of Wednesday`s low has lead to a mostly sunny and mild day with temps well into the 70s. A lingering trough axis draped across northern lower this afternoon has lead to an enhance cloud field which will impact locations as far south as the northern Thumb, otherwise diurnal cu shouldn`t last too long across the rest of the area. As temps attempt to drop off tonight, elevated clouds start filling in north of the stalled cold front just south of the state which will limit the mins to around 45-50 degrees. Tonight marks the beginning of a bigger shift in the weather pattern as a very positively tilted trough drops out of eastern Canada while digging westward and phasing with the orphaned upper low over the northern Plains. Remnant mid level wave will then advance along the trough with a weak surface low tracking east along the front on Thursday. Moisture advection up the elevated portions of the front lingering over southern MI will result in a period of rainfall for most of the CWA. Two main questions will be when does the rain move in and how far north will it extend? Most guidance suggests the lead edge of the deeper moisture will push north across the Ohio border after 06Z tonight with northerly flow feeding dry air in the lower levels beneath the stout low level inversion which will take some time to saturate. A narrow corridor of higher theta e air will advance north to around I94 while fgen flares up after about 15Z which should lead to more moderate showers. Fgen higher on the front makes it up to Saginaw but with a good deal of dry air still in the soundings up to 10kft. Even so, hires suite offers a good duration of light rain through the day so will hedge forecast a little to keep a slight chance or chance pop going up there for now. Rain will taper off after dark with the deformation pulling east away from the area. QPF up to around a third of an inch is expected. Friday should be dry with another short wave ridge sliding SE through lower MI. Northerly flow will keep cool air filtering into the area keeping highs muted in the lower 60s. The next chance of rain comes Saturday as a narrow trough slides SE through the Great Lakes out of Canada. There will be a brief flip around to SW flow ahead of this system which may be able to bring a bit of moisture into the area, but PWATs are only expected to get just above a half inch. Light flow keeps shear minimal, less than 20 knots but there is some potential for a couple hundred joules of MUCAPE so can`t rule out some thunderstorms. The progressive pattern brings ridging back for Sunday. MARINE... Weakening surface low has drifted well to our east, with its attendant cold front washing out overhead. For the Great Lakes, this has corresponded to winds veering to the north while stable open waters have kept gusts below 25 knots. Closer to the shoreline where land influence comes into play, winds may gust to around 30 knots before subsiding later this evening in which Small Craft Advisories are in effect. Elevated portions of the frontal boundary remain orphaned overhead to reactivate shower activity by Thursday morning across western Lake Erie/Lake St. Clair, with a slightly cooler airmass overhead once again introducing wind gusts to 25 knots Thursday afternoon. Weekend weather remains unsettled precipitation- wise owing to broad troughing aloft, but the overall wind field remains light. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ AVIATION.....KDK DISCUSSION...DRK MARINE.......MV You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.