Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000 FXUS63 KDTX 182305 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 705 PM EDT Wed Oct 18 2017 .AVIATION... Clear sky will persist through the evening as gusty southwest wind subsides with the loss of surface heating. The boundary layer decoupling will allow a moderate low level jet to develop through the night. Model soundings indicate LLWS averaging around 30 kts which is marginal for inclusion in the forecast. Surface gradient wind will average 5-15 knots before the upstream cold front arrives Thursday morning. Satellite imagery indicates an associated band of mid and high clouds over the western Great Lakes which is expected to move over SE Michigan overnight. Model guidance does indicate some lower clouds will be possible, mainly in the MBS area, as the front moves through the region. Considering the very dry low level conditions, expect any ceiling to remain VFR during the morning and early afternoon while the front weakens with time. //DTW THRESHOLD PROBABILITIES... * None. && .PREV DISCUSSION... Issued at 308 PM EDT Wed Oct 18 2017 DISCUSSION... Southwest gradient and full insolation once again supporting warm temperatures this afternoon. Boundary layer will remain mixed through tonight as the approaching front attendant to the cyclone over central Canada approaches from the west and ensures overnight lows are contained to values no lower than this morning`s obs. Cold fropa early Thursday morning will occur uneventfully given SE Michigan`s removal from dynamic forcing and dry antecedent conditions. Minor suppression of the thermal field will primarily influence the northern half of the CWA, where highs will be a few degrees cooler than today in the mid 60s. Near 70 again across the south. Return flow will quickly get underway Thursday night into Friday as high pressure becomes reestablished over the Appalachians in response to pattern amplification driven by an surging NPAC energy out west. Highs Friday once again near 70 under cloudless skies. The pattern for Saturday and most of Sunday will remain largely unchanged from that of the late half of the week, with surface and upper ridging leading to dry conditions with above normal temperatures in the low 70s. The energy that lead to the digging trough in the western CONUS and amplified ridge for SE Michigan most of this week will begin to impact us late Sunday into Monday. Ample moisture ahead of the surface front will lead to a decent chance for showers overnight Sunday. Cooler air will begin to filter in behind the front; highs Monday into the mid 60s and a lingering chance of showers. Following this front on Tuesday into Wednesday, an upper trough will dig through the Great Lakes and much of the eastern CONUS. This will lead to the coolest temperatures of the season so far, highs falling to the upper 40s and lower 50s by Wednesday, with generally unsettled conditions and a chance for showers through midweek. MARINE... Small craft advisories across the Saginaw Bay will persist this afternoon and likely overnight as southwest winds continue to gust between 20 - 25 kts, isolated 30 kt, across the bay. Winds and wind gusts will start to relax throughout Thursday morning as the pressure gradient weakens, which will hold wind gusts to sub-20 knots through the remainder of the week. Additionally, high pressure will hold steady through Saturday, bringing relaxed waves over the bay and shorelines, along with copious amounts of sunshine. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...Small Craft Advisory until 10 AM EDT Thursday for LHZ421-422-441. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ AVIATION.....BT DISCUSSION...JVC/TF MARINE.......AM You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.

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