948 FXUS63 KDTX 211724 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 124 PM EDT Fri Jun 21 2019 .AVIATION... VFR conditions through this TAF period. Variable to light northerly wind will become more pronounced out of the northeast at around 10 kts or less this afternoon into the evening. Diurnal scattered Cu field has developed at around 5 kft and will continue to be supported through the daylight hours. Winds decrease back to calm and variable tonight as the center of the surface high drifts across central Lake Huron. This will allow for a more light easterly wind by tomorrow morning. For DTW...Some afternoon CIGS around the DTW air space have come in just below 5 kft. Still expect CIGS largely above this threshold at DTW for most of the day. .DTW THRESHOLD PROBABILITIES... * Low for CIGS at or below 5000 feet. && .PREV DISCUSSION... Issued at 230 AM EDT Fri Jun 21 2019 DISCUSSION... Surface ridge will build into the region in the wake of passing low pressure which has jumped quickly to the New England states early this morning. This will bring quiet weather both today and Saturday with relatively cool temperatures for the official start of summer. Highs will mainly range in the 70s both days with cooler readings along the immediate Lake Huron shoreline where northeast flow will pull modified air from over the cool lake waters onshore. Meanwhile, 40s/50s can be expected for low temperatures into the weekend. Warming will occur late in the weekend on into Monday as upper heights build as transitory upper ridge translates east through the region in advance of upper trough lifting from the Rockies through the plains (and eventually the Great Lakes by early next week). By that time frame, lower 80s should become more common for highs. This will also mark the next period of increased rain chances. Initially, a weak disturbance will eject east/northeast into the area Sunday in advance of the main upper troughing to the west. This main upper level feature and related surface low pressure will then make inroads into the area on Monday and bring a significant uptick in rain chances Sunday night into Monday with an increased chance of thunderstorms during the day Monday as increased south/southwest flow brings one of the first humid air masses of the season north into the area. A more summer-like pattern then sets up for the balance of the forecast period as an upper ridge extends from Mexico/Texas into or just south of the region with mean upper troughing remains positioned over the Pacific Northeast northeast into Canada. This will allow the temperatures to more consistently climb into the 80s while periodic isolated to scattered showers to thunderstorms impact the area as shortwave energy brushes the area around the periphery of the building upper ridge. Confidence in timing/coverage of this activity is very low at this juncture. MARINE... Surface high pressure reinforced by the lake aggregate will maintain light to moderate wind typical of the season into early next week. Significant wave heights 2 feet or less through this time. Thunderstorms will be possible over the waters beginning Sunday evening as high pressure exits east and land-based instability builds across the region. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ AVIATION.....AA DISCUSSION...DG MARINE.......JVC You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.