243 FXUS63 KDTX 190938 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 538 AM EDT Fri Oct 19 2018 .AVIATION... Mainly VFR conditions will take us through the taf period with a chance of MVFR CIGS at times as scattered rain showers work across the area later this afternoon along a cold front. Southwest flow will gust just over 20 knots this afternoon before veering more westerly tonight behind the exiting front. Winds will stay elevated near 12 knots tonight before veering to the northwest and becoming gusty again Saturday afternoon. Best chance to see showers today will be from 20-06Z but coverage is questionable with a lack of moisture. A few showers may linger overnight. For DTW...Ceilings at or below 5,000 feet will accompany the next system moving through the Great Lakes, which should arrive after 20Z and last through the evening hours. Rain chances exist both this evening with the first front and Saturday afternoon with a secondary cold front. Winds will be out of the 270-290 degrees tonight into Saturday before veering northwesterly but should remain below crosswind threshold. .DTW THRESHOLD PROBABILITIES... * Medium for ceilings at or below 5,000 feet beginning after 20Z. * Low for crosswinds to exceed 25 knots out of the 270-290 degrees Saturday morning. && .PREV DISCUSSION... Issued at 255 AM EDT Fri Oct 19 2018 DISCUSSION... Southwesterly flow will increase significantly today in advance of an approaching cold front. While overall moisture content in the atmosphere to the southwest of the forecast area is rather scant, expect clouds to thicken steadily today with isentropic lift/fgen forcing sufficient to eventually lead to light showers across the area late today into tonight (peaking between 22z-06z). While this precipitation will be fairly widespread, amounts will be very much on the light side (more than likely aob 0.05" in most cases). This strong southwest flow will also bring milder air back into the area if only temporarily with high temperatures well into the 50s by afternoon (with spotty readings likely reaching 60). The aforementioned cold front then pushes southeast through the area late Saturday night, bringing any lingering rain shower activity to an end overnight. A strong upper level PV anomaly, now dropping through the Canadian Prairie Provinces, will then descend quickly into the area on Saturday and deliver a strong shot of cold air right on the heels of the first cold front. So, after rising back well into the 40s by early/mid afternoon, temperatures will drop off quickly later in the day on their way back into the upper 20s/lower 30s for minimum temperatures early Sunday morning. It still appears there will be enough instability in advance of this front to support scattered to numerous rain showers with the more vigorous cells likely producing graupel as well as temperatures cool substantially throughout the day (H85 temperatures nearing -5C). Gusty winds can be expected in/around this convective activity. In fact, the pressure gradient strengthens sufficient to produce wind gusts on the order of 30+ mph without the help of showers dragging higher wind gusts to the surface. Temperatures cool enough into Saturday night to support snow showers. However, subsidence in the wake of the passing system will bring a quick end to any notable convective showers after 00z with Lake Effect activity focusing mainly offshore over Lake Huron on north-northwest flow. This trajectory will at least allow a few rain and/or snow showers to brush the Thumb region before activity winds down into Sunday as high pressure builds into the region. The next several shortwaves to drop southeast through mean upper trough over eastern NOAM largely bypass the area to the northeast as several large areas of high pressure maintain generally dry weather for a bulk of next week. Temperatures will generally top out in the lower/mid 50s as upper trough shifts gradually east and upper heights build. The largely clear/dry airmass associated with the high pressure systems will also support cool nights in the 30s. MARINE... A deepening low pressure system tracking across Ontario into Quebec today will pull a strong cold front through the Great Lakes tonight. Winds across central Lake Huron will gust to gale force even within the more stable southwesterly flow this afternoon. There may be a brief lull in wind speeds just below gales for a few hours late tonight into Saturday as they veer northwesterly behind the first front, but a secondary cold front with reinforcing cold air advection will bring gales back across most of the Huron basin Saturday. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...Gale Warning from 2 PM this afternoon to 1 AM EDT Sunday for LHZ362- 363-421-462-463. Gale Warning from 2 PM Saturday to 1 AM EDT Sunday for LHZ464. Small Craft Advisory until 1 AM EDT Sunday for LHZ422-441>443. Gale Warning from 8 AM to 10 PM EDT Saturday for LHZ361. Small Craft Advisory until 2 PM EDT this afternoon for LHZ421. Lake St Clair...Small Craft Advisory from 4 PM this afternoon to 1 AM EDT Sunday for LCZ460. Michigan waters of Lake Erie...Small Craft Advisory from 4 PM this afternoon to 1 AM EDT Sunday for LEZ444. && $$ AVIATION.....DRK DISCUSSION...DG MARINE.......DRK You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.