Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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188 FXUS63 KDTX 190741 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 341 AM EDT Thu Sep 19 2024 .KEY MESSAGES... - Warm weather continues through this weekend with a slight increase in humidity each day. - Scattered showers and storms are possible Friday afternoon into Friday night. Another round of rain is likely Sunday night into Monday. - Additional chances for rain through next week with temperatures settling to more seasonable values. && .DISCUSSION... Broad troughing over the Mid-Atlantic opens up and slowly drifts northeast today. Meanwhile, a potent upper low tracks from the northern Plains into Manitoba and sends an expanding trough into the western Great Lakes. These features continue to squeeze a shortwave ridge over the central Great Lakes through the day, maintaining the dry and warm streak. Another round of patchy fog this morning, with some areas of dense fog at times, gives way to partly cloudy skies as there should be enough boundary layer moisture for another healthy cu up through the afternoon. High temps again reach the lower to mid 80s. We may start to see some high cloud move in from the west this evening but thinking this will do little to affect the otherwise favorable radiating conditions overnight, and another round of fog looks likely Friday morning. Latest guidance shows the ridge giving way to the inbound height falls associated with the aforementioned trough moving in from the Midwest. The parent low will be displaced over northern Manitoba but a coherent lobe of PV will spread over the northern Lakes within the left exit region of the upper jet and looks to bring a corridor of deep moisture into the region. Daytime Friday will be mostly dry but spotty showers may start to move in from the west by the afternoon and evening as elevated moisture ahead of the front moves in. The front and attendant moisture depth do shows signs of substantial weakening as they encounter the resident ridge and dry air mass, but trends in the latest ensemble guidance continue to support at least a chance of showers in the Friday night to early Saturday time frame. Some thunderstorms will also be possible as mid-level lapse rates should be sufficient for several hundred J/kg of MUCAPE. A weak pressure pattern follows through the weekend with the trough sinking southeast and eventually merging with the Mid-Atlantic trough. This places us under another short lived mid-level ridge which should maintain dry and warm conditions Saturday and most of Sunday. During this period a closed low will release from the 4 Corners region and track northeast into the Mid-Mississippi Valley by late Sunday. This system looks to sweep up the moist Gulf air mass over the southern Plains and direct it toward the Great Lakes. LREF grand ensemble data shows around 50% probability for PWAT to reach 1.50 inches within this moisture plume - the highest we`ve seen locally since late August. Likely PoPs are warranted for Sunday night into Monday as the lead moisture surge works in from the south along the system`s warm advective wing. This will mark the beginning of a substantial pattern shift in which various flavors of troughing are depicted over the Great Lakes and eastern CONUS for the first time in weeks. Additional rain chances will exist Tuesday through the rest of the week in this pattern, with high temperatures likely to be more seasonable in the upper 60s or 70s. && .MARINE... High pressure remains in control through the end of the week which will maintain ligther wind speeds. The next chance for rain showers or a thunderstorm will enter tomorrow afternoon into early Saturday morning as a weak cold front and upper-level disturbance moves over the Great Lakes. Otherwise, dry weather will persist today. && .PREV DISCUSSION... Issued at 1155 PM EDT Wed Sep 18 2024 AVIATION... Mostly clear skies and light winds overnight will bring another round of patchy to locally dense fog early Thursday morning. Will maintain tempo groups for MVFR VSBYs, but it will be possible to see lower VSBYs before fog lifts after sunrise. Winds will remain east- southeast below 10 knots tomorrow with another round of diurnal cumulus with the lake moisture boost. For DTW/D21 Convection...No thunderstorms are forecast through this week. DTW THRESHOLD PROBABILITIES... * None. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ DISCUSSION...TF MARINE.......AM AVIATION.....DG You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.