348 FXUS63 KDTX 111054 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 654 AM EDT Thu Oct 11 2018 .AVIATION... Low level cold air advection will be ongoing through the day. As the depth of the cold air grows, so too will the mixed layer. This will not only sustain the ongoing gusty wsw winds, it will support slightly stronger winds by afternoon with some veering toward the west expected. Wind gusts are likely to peak around or just above 25 knots based on the forecast depth of the mixed layer and the low level wind field. While the loss of daytime heating this evening may lead to a slight reduction in the wind gusts, the persistent cold air advection will sustain some degree of gustiness into late evening. Bases within the widespread strato cu field overspreading Se Mi are largely MVFR. As the depth of the cold air increases, the inversion will lift. Thus bases are expect to lift above 3k ft around or shortly after noon. For DTW...There will be some fluctuation in the wind directions between 240 and 270 degrees this morning. With better mixing depths, winds trend more predominately westerly by early afternoon. .DTW THRESHOLD PROBABILITIES... * High in ceilings below 5000 ft this morning. Moderate this afternoon and evening. && .PREV DISCUSSION... Issued at 310 AM EDT Thu Oct 11 2018 DISCUSSION... NEAR TERM / TODAY THROUGH TONIGHT As of 310 AM EDT...Pattern shift back to full-force Fall is underway across southeast Michigan as a cold front continues to sweep eastward across lower Michigan early this morning. Strong cold air advection accompanying the front will allow for temperatures and moisture to fall from west to east, especially in the 09z-12z timeframe. Drier air working into the region courtesy of the system- relative dry slot of low pressure tracking across the northern Great Lakes will virtually end rain chances through at least mid morning. Main weather impact today will be gusty westerly winds of 20-30 mph, with a few higher gusts possible in the Saginaw Valley and northern Thumb. The strong cold air advection, noted by 850 hPa temps cratering below 0 C by this afternoon, will help sharpen a low-level inversion that will leave a fair amount of cloud cover around, aided by the Lake Michigan aggregate moisture flux. Temperatures falling into the low/mid 50s this morning will rise little by around noontime, before slowly falling into the 40s by this evening. Coupled with the gusty winds, a noticeable Fall chill will be in the air after 3 days of summer-like warmth and humidity. A few spotty sprinkles/light showers will be possible late this morning into the afternoon hours, mainly for areas west of I-75/US 23, although coverage will be very isolated. Towards the latter half of the afternoon, enough dry air working in towards the Ohio border may actually result in periods of more sun than clouds Detroit metro south. Partly cloudy skies tonight as surface ridging builds in from the west. Flow shifting more west/northwest will remain persistent through the night, and actually work to keep temperatures from fully bottoming out as 850 hPa temps of -5 C creep into northwest areas by 12z Friday. Still, a chilly night is in store with lows in the mid 30s interior to upper 30s/lower 40s near the larger bodies of water. Patchy frost will be possible in interior areas, but will likely be inhibited due to the persistent wind and occasional cloud cover. SHORT TERM / FRIDAY THROUGH SATURDAY NIGHT Little change in the synoptic pattern over lower Michigan to start the day for Friday, with mostly cloudy skies, brisk west/northwest winds, and temperatures struggling to reach the upper 40s/lower 50s. Northern stream PV anomaly quickly rotating through a digging longwave trough over the Midwest will bring a slight chance of showers late Friday into Friday night, mainly south of the I-96 corridor. Leaning on a drier solution for this timeframe given the anomaly origin, broad high pressure already in place, and lack of overall moisture with this feature, compared to the overdone Euro. Depending on eventual precip chances and cloud cover Friday night, quite a bit of frost will be possible, especially across northern areas as low temperatures again fall into the mid 30s. Pleasant Fall day Saturday with high pressure moving overhead, with clearing skies and still cool temperatures in the upper 40s to lower 50s with the 850 hPa thermal trough lingering overhead. Another crisp night is in store Saturday night with lows in the 30s. LONG TERM / SUNDAY THROUGH WEDNESDAY Disorganized southern stream energy emerging from the central Plains will attempt to phase with northern stream shortwave energy diving southeast from the northern Great Lakes late Sunday into Monday. The jury is still out with regards to precip potential, but will continue to mention a chance of rain in the forecast for early next week. There are signals in the long range guidance for quite the cold airmass settling in early next week over the Great Lakes, with the potential for highs Monday to not make it out of the 40s with lows Monday night possibly dipping below freezing. Cool conditions continue well into next week as expansive high pressure becomes established across much of the CONUS with the polar jet being displaced well north into Canada. MARINE... A long duration of cold air advection will affect the region today into Friday in the wake of last nights cold frontal passage. The resulting deepening of the over lake mixed layer and southwest gradient associated with the departing surface low lifting northeast of the region will support a high likelihood of wind gusts in the 25 to 30 knot range across the marine areas today. Funneling across Saginaw Bay will support some gale force wind gusts today; from Saginaw Bay out into the open waters of Lake Huron downwind of the bay; also near the straits. There will be some veering of the winds to the west this afternoon. This and a slightly weakening gradient will end the risk of gale force wind gusts by late afternoon. Some degree of thermal troughing over the lakes within the cold air advection will however sustain fairly gusty westerly winds tonight into the day Friday. After some further weakening of the flow Fri night into Saturday with high pressure traversing the Ohio Valley, a cold front is forecast to push across Lake Huron Sunday. This will support a modest uptick in the southwest winds, which will veering west- northwest Sun night into Monday with the passage of this front. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...Gale Warning until 4 PM EDT this afternoon for LHZ361-363-421-422- 441-462. Small Craft Advisory until 4 AM EDT Friday for LHZ442-443. Lake St Clair...Small Craft Advisory from 11 AM this morning to 4 AM EDT Friday for LCZ460. Michigan waters of Lake Erie...Small Craft Advisory from 11 AM this morning to 4 AM EDT Friday for LEZ444. && $$ AVIATION.....SC DISCUSSION...IRL MARINE.......SC You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.