Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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578 FXUS63 KDTX 220754 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 354 AM EDT Wed May 22 2024 .KEY MESSAGES... - There will be a low chance (30-35%) for isolated to scattered showers and thunderstorms late this morning into the afternoon. An isolated strong thunderstorm cannot be ruled out. - Brief warm-up Friday with some additional chances for showers and storms Friday into Saturday. && .DISCUSSION... A strong low pressure system now located over southwest Ontario will occlude through the morning hours, taking on a more northeast trajectory as it paths into the James Bay by this afternoon. This will result in a cold front that is on track to traverse across Michigan from west to east between the hours of 12Z to around 22Z. Prior to the arrival of this frontal boundary, strong southwest flow characterized by h850 wind speeds between 45-50 knots have sustained overnight lows in the low to mid 70s, supported by the large positive flux of warm air advection. It is safe to say these overnight temperatures will easily break record high low temperature values (see the climatology section). An isolated shower or storm will be possible through the late morning and into the afternoon along the instability gradient, but a building cap around 7kft and inflow of drier air in the mid-levels will have a hampering effect on greater convective potential. While the hi-res output is less than impressive in regards to CI, the thermodynamic and kinematic profiles do support a marginally severe environment with MLCAPEs hitting 1,500 J/kg and bulk shear values around 20-25 knots. In this low probability setup (30-35 PoPs, favored along or east of a line from Bad Axe to Adrian), there will be the low chance of a storm becoming strong, with highly localized gusts to 50 mph and/or hail to an inch as the main threats. The best window for this will be between 15Z-19Z. Otherwise the improved mixing depths fueled by diurnal heating will interact with the stronger winds aloft, bringing breezy conditions through the day. Expect sustained 20 mph winds from the southwest with gusts 30-35 mph. Clouds will clear in the wake of the front, where a notable difference in humidity will be felt. Highs return into the mid-70s (Tri-Cities) to lower 80s. There will be a low chance for a shower late tonight as an upper- level wave quickly moves over the state, but otherwise clear skies and the early day passage of the cold front will work to drop temperatures into the 50s. The Great Lakes will then be wedged in the northern periphery of a high pressure system under increasingly zonal mid-level flow through early Friday. Dry weather will persist through Friday, with building temperatures back into the 80s on Fri as an upper-level wave carves into the northern Plains, which will reinforce ridging across the Great Lakes. An extension of this wave will bring the chance for showers and storms on Saturday. High pressure will quickly fill in behind this wave, where a second chance of showers/storms then moves in Sunday/Monday. An upper-level wave crossing near the Panhandle of Texas will strengthen low pressure, which will then drive it northeast into the Midwest/Great Lakes, becoming the source for the early week precipitation chances. && .MARINE... A strengthening low pressure system will reach western Lake Superior this morning before lifting and stalling over Ontario. Meanwhile it will force a cold front through the Great Lakes this afternoon. There may be some scattered showers and thunderstorms ahead of the front this morning with additional chances later this afternoon with the front. Winds increase out of the south to around 20-25 knots ahead of the front this morning, then veer to the west Wednesday night into Thursday but settling back down to 15 knots. A small craft advisory is in effect for Saginaw Bay this morning through this evening as the winds funneling out of the bay have a higher chance to exceed 25 knots. && .CLIMATE... Here are the record high temperatures for May 22: May 22nd: Detroit 90 (set in 1994) Flint 91 (set in 1934) Saginaw/Tri-Cities 89 (set in 1992) Here are the record high low temperatures for May 21-22: May 22nd: Detroit 67 (set in 1941) Flint 65 (set in 1977) Saginaw/Tri-Cities 68 (set in 1977) && .PREV DISCUSSION... Issued at 1211 AM EDT Wed May 22 2024 AVIATION... A very strong anticyclonic vorticity dipole coupled to the strong low pressure system will pass directly through much of Lower Michigan tonight. Active downward vertical motion in addition to warming in the 5.0 to 10.0 kft agl layer will yield VFR conditions throughout tonight. Old convective remnant showers are expected to approach the northern taf sites 11-14Z and the Detroit tafs 13-16Z. Very low confidence in coverage and have included the mention as a Prob30. Non convective low level wind shear in the lowest 2.0 kft agl tonight and southwest winds Tuesday of 15 to 25 knots. For DTW/D21 Convection... No thunder anticipated tonight. Low confidence in showers impacting DTW between 13-16Z 5/22. Questionable coverage. DTW THRESHOLD PROBABILITIES... * Low for thunderstorms 13-16Z Wednesday morning. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...Small Craft Advisory from 8 AM this morning to 10 PM EDT this evening for LHZ421-422-441. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ DISCUSSION...AM MARINE.......AM CLIMATE......AM AVIATION.....CB You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.