789 FXUS63 KDTX 300702 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 302 AM EDT Thu Jul 30 2020 .DISCUSSION... Upper level trough axis will swing south over the Central Great Lakes today and gradually wash out tonight/tomorrow, as 500 MB low center reaches the St Lawrence River. The good sfc-850 MB moisture axis has finally shifted south of the state, with drier air bleeding in from the anti-cyclone to the northwest. As of 6z, dew pts have dropped into the mid to upper 50s across the Tri-Cities region. None- the-less, still enough residual low level moisture to draw concern for an isolated pop up shower today, as some moisture pooling noted in the RAP along far eastern areas late today. Still, looks to be enough of a speed bump around 10000 feet per soundings to just carry a silent 14 pop/no shower mention. Best shot of a stray shower this afternoon is actually probably near Saginaw Bay with some semblance of positive upper level PV advection, along with the drought stricken Thumb region as northeast winds off Lake Huron actually contributes to the low level moisture with the noted water temperatures in the 70s across southern Lake Huron. High temperatures expected to reside mostly in the lower 80s for the majority of southeast Michigan today and tomorrow based on 850 MB temps around 14 C. Ridging at all levels in control Friday night and Saturday, with max temps likely climbing into the mid 80s with slightly modified airmass. Could see some patchy fog tonight and Friday night, mainly across the Thumb region, similar to this morning. Digging longwave trough then forecasted to take hold Sunday-Monday along and east of the Mississippi River Valley, with GFS ensemble members (12z vs 00z run) continuing to flip/flop with the potential surface low track through southeast Michigan, potentially lingering into Tuesday if the amplified Euro solution (one-two punch) verifies. None-the-less, GFS ensemble members and Canadian are mostly weaker, with a wide variation in the exact location of the upper low center by Tuesday, anywhere from the western Ohio valley to James Bay. Tropical Storm Isaias will also be somewhat of a player as it becomes absorbed by the trough and tracks up the East coast. Confidence in the forecast for Sunday into early next week is low, as there is just too many moving parts at this moment. && .MARINE... High pressure will build into the region today and remain in place through the end of the week. Light northwesterly winds are expected to become more northerly throughout the day, and persist into the weekend. The chance for rain then returns on Sunday as a low pressure system moves in from the Ohio Valley. && .PREV DISCUSSION... Issued at 1158 PM EDT Wed Jul 29 2020 AVIATION... Mid and high level cloud debris make up VFR conditions over the terminal corridor to start the late night forecast. The surface cold front settled south of the Ohio border during the evening and any remaining shower activity is expected south of DTW through sunrise. Light north wind ahead of incoming high pressure does not look very capable in observations leading up to midnight which could lead to some MVFR fog development at FNT and PTK in addition to the DTW area. At the same time, shoreline observations suggest enough flow from Lake Huron to maintain a watch for MVFR stratus through mid morning. A measured approach to clouds and fog remains preferred while monitoring observational trends, especially for the clouds that have yet to develop. High pressure gains some traction during the day resulting in a more persistent 5-10 knot northerly wind and some standard fair weather cumulus lasting through afternoon. For DTW... A short period of MVFR fog remains possible around sunrise in calm to light northerly wind along with some stray patches of MVFR stratus until about mid morning. North to northeast wind reaches near 10 knots before shifting toward the east in weak lake breeze influence toward Thursday evening. DTW THRESHOLD PROBABILITIES... * Low for ceiling 5000 ft or less during the morning. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ DISCUSSION...SF MARINE.......MV AVIATION.....BT You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.