625 FXUS63 KDTX 042310 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 710 PM EDT Sun Apr 4 2021 .AVIATION... Low pressure over MN this evening ripples along a stationary front and into southern Lower MI tonight. As it does, a pattern of showers with a few thunderstorms spread out ahead of the system. This activity takes until closer to sunrise before reaching the terminal corridor and then is projected to affect the PTK to DTW areas most. The latest timing is for a mid morning to mid afternoon time window for any flight restrictions firmly into MVFR ceiling and visibility. The moisture from rainfall only brushes the FNT to MBS region but supplies clouds into the frontal zone which affect all terminals with intervals of MVFR during the afternoon into Monday evening. For DTW... The late afternoon lake breeze influence blends into the background pressure gradient maintaining a light SE wind tonight. VFR conditions consist of clear sky into a steady increase of high clouds tonight before a pattern of rain showers arrives Monday morning. Moderate rainfall intensity brings MVFR conditions with a rumble of thunder possible by late morning into early Monday afternoon. .DTW THRESHOLD PROBABILITIES... * Moderate for ceiling 5000 ft or less Monday. * Moderate for thunderstorms late Monday morning and early afternoon. && .PREV DISCUSSION... Issued at 338 PM EDT Sun Apr 4 2021 DISCUSSION... Lower amplitude upper ridge axis featured along the front range of the rockies late this afternoon, with the outer expanse of the associated elevated upper height field encroaching upon the great lakes within the existing mid level northwest flow. Net result remains a pervasive window for above temperatures - as noted today with late day readings well into the 60s outside of those locations impacted by onshore flow off the cold lake waters. Stationary frontal boundary fixated within the mean flow now anchored just to the south and west. A gradual veering of the wind responding to the slowly building upper height field will result in the slow northeastward advancement of the elevated frontal slope back into southeast Michigan tonight. The ensuing increase in mid level warm/moist air advection affords a thickening high based cloud overnight, but little if any potential for precipitation prior to daybreak absent of meaningful forced ascent or lower level saturation. Slightly elevated portion of the warm frontal zone maintains residence Monday and Monday night, as the surface front hangs just to the southwest. Intervals of higher theta-e advection, likely enhanced by the passage of shortwave energy, will provide a chance for showers throughout this time. A more widespread response certainly in play should greater mid level dynamics effectively engage the frontal zone, but otherwise development likely remains more chaotic. The decline in mid level stability maintains a low potential for some rumbles of thunder as well. A larger temperature gradient will again exist from southwest to northeast - highs ranging from mid/upper 60s to mid 50s. Upper ridging will take an increasing hold on conditions during the Tuesday-Wednesday periods. Recent model guidance suggests perhaps a lingering window for convective development Tuesday /particularly the thumb/, depending on the northeast pace of the surface warm front. Otherwise, emergence of a well-mixed diurnal warm sector boundary layer lacking of meaningful forcing to overcome shallow moisture depth favors dry conditions. This period will continue to feature temperatures near 15 degrees above average as low level south-southwest flow strengthens and mean thicknesses climb. A deep closed mid level circulation will settle over the midwest during the Thursday-Friday periods. An increasingly moist cyclonic flow within the sprawling lower height field downstream points to a potentially unsettled period locally with periodic rain chances during this time. Temperatures perhaps trending downward relative to early week conditions owing to the possibility for compromised heating potential given uptick in clouds/precip, but still mild as the main height falls and subsequent cold air advection fails to materialize until next weekend. MARINE... Observations this afternoon show high pressure across Lake Huron with a stalled frontal boundary draped across southern Lake Michigan eastward through western Lake Erie. This is resulting in mostly sunny skies, light winds, and low waves for all marine zones today. Upper ridge axis slides towards the central Great Lakes on Monday carrying shortwave energy that will generate some scattered rain chances on Monday afternoon and evening along the lingering frontal boundary. The Monday wind direction will be from the east-southeast with most marine zones experiencing gusts of less than 15 knots. The exception will be far northern Lake Huron where some gusts to around 20 knots will be possible given the favorable wind direction. Similar story from Tuesday to Friday with winds out of the east- southeast and gusts. Excluding the lighter winds for Wednesday, each day during the mid to late week stretch will have gusts topping out in the 20-25 knot range. Good moisture advection will bring more chances for rain showers on Tuesday with the best chances coming Thursday into Friday with a strong low pressure develops across the Central Plains and moves into the Great Lakes. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ AVIATION.....BT DISCUSSION...MR MARINE.......AA You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.