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Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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028 FXUS63 KDTX 151755 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 155 PM EDT Thu Aug 15 2024 .KEY MESSAGES... * Increasing cloud cover today with periods of showers this evening through Sunday. * Chance of strong thunderstorms Friday and Friday night. && .AVIATION... VFR conditions will prevail as coverage of high clouds increase into the evening. The increasing mid level moisture will also bring increasing rain chances this evening and tonight while some degree of low level dry air holds. Expecting conditions to remain predominately VFR with FEW-SCT cloud bases below 5,000 feet, though any heavier shower may bring a brief period below VFR. Covered the more likely time frames for pockets of rainfall with TEMPO groups between 00Z and 09Z with potential for a break in activity early tomorrow morning before an uptick in shower activity occurs again around 12Z and beyond. Isolated thunderstorms will be possible, but low probability precludes mention at this time. For DTW/D21 Convection...Low probability for an isolated thunderstorm late tonight and Friday morning. Friday afternoon will hold a slightly better chance for thunder. DTW THRESHOLD PROBABILITIES... * Low for thunderstorms late tonight and Friday. && .PREV DISCUSSION... Issued at 300 AM EDT Thu Aug 15 2024 DISCUSSION... Upper level storm system organizing over Minnesota/Midwest this morning, with the closed 500 MB low on track to move through Lower Michigan on Saturday. Lead spoke of energy/upper level PV filament moves through this evening, with good moisture advection bringing the likelihood of high based showers. Looking at the 850-700 MB Theta-E ridge fully entrenched Friday morning, with PW Values around 1.5 inches. Weakening 500 MB height fall center to move through during early Friday afternoon, out of sync with peak heating of the day. A second round of height falls then arrives Friday night. Still could be enough destabilization on Friday (MUcapes 1000-2000 J/kg) with 0-6 KM bulk shear around 30 knots to support a marginal risk of severe thunderstorms. This also includes the late evening- early morning activity/second round of height falls. Continued occasional showers and possible thunderstorms on Saturday as the nearly stacked lows (sfc-700-500 MB) slowly track through the State. Wrap around moisture on the backside will also lead to more showers into Sunday as well. A very strong northern stream upper level wave tracking through Central Canada then progged to merge/phase with our departing 500 MB low early next week and lead to an unusually amplified (for summer standards) eastern North American trough. Southeast Michigan looks to be on the western fringe of the cold air, with expansive high pressure in control through at least mid week. MARINE... Benign marine conditions this morning transition toward a more unsettled pattern throughout the day as an upper low and leading thunderstorm complex accelerate toward the Great Lakes. Most of the day remains dry with flow organizing out of the southeast as the gradient tightens. Rain chances to then ramp up late this evening with coverage increasing overnight as elevated portions of the warm front lift into the area. Gusty winds approaching 25-30 knots are possible until the warm front passes through Friday morning. Small Craft Advisories may therefore be necessary late tonight through Friday morning. Attention Friday afternoon-evening turns to organized thunderstorm potential, though there is uncertainty in timing, coverage, and intensity as several waves of convection will be plausible. Governing upper low will slowly drift across the Great Lakes through the weekend, extending shower and thunderstorm potential through most of the weekend. HYDROLOGY... Periods of showers this evening right through Sunday, with embedded thunderstorms from time to time to enhance rainfall. Total Rainfall over the 3 day stretch is expected to be near 1 inch, but any strong thunderstorms will lead to enhanced totals of 2+ inches. Localized minor flooding of urban, low-lying, and otherwise flood prone areas remains possible in the strong thunderstorms, but the off and on nature of the rainfall is not expected to cause significant flooding. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ AVIATION.....AA DISCUSSION...SF MARINE.......MV HYDROLOGY....SF You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.