556 FXUS63 KAPX 201340 AFDAPX Area Forecast Discussion National Weather Service Gaylord MI 940 AM EDT Tue Oct 20 2020 .UPDATE... Issued at 939 AM EDT Tue Oct 20 2020 High pressure has moved to Lk Superior. Our 1000-850mb winds have remained quite light, but have veered from nw to ne. Further veering to e or ese will occur by late afternoon, as the high moves ne. Those winds will also pick up a bit, aided by low pressure pushing into the central/northern plains. Ongoing lake effect was stalling out just off the Leelanau Co coastline earlier this morning (just before maint was resumed on the APX radar). Further veering of our winds should push lingering lake effect showers out toward the Manitous and Fox Islands. There could also be a few showers hovering near the Sault for another couple of hours. Warm advection wing of precip ahead of the next low will try to advance out of WI late today. Chances for rain arrive in Leelanau Co/Beaver Isl/Ltl Trav Bay region after 4-5 pm. Rain will become more widespread tonight. Max temps mainly mid 40s. && .NEAR TERM...(Today through Tonight) Issued at 243 AM EDT Tue Oct 20 2020 Impactful weather: Minimal. Better rainfall developing tonight. Pattern synopsis and forecast: Large and broad scale upper troughing continues to engulf much of the central and nrn portions of the country early this morning, with one shortwave pushing through nrn Michigan. Only some spotty light synoptic rain/sprinkles/flurries ongoing, as forcing is weak, coming only from some soon to be departing DPVA. We still have more than cold enough air in the lower levels of the atmosphere to produce additional spotty lake effect mixed precipitation in W/NW flow regimes. Although inversion heights are a decent 5-7kft, there's still a slight inverted-V look to the BL, suggesting drier air in the lowest levels. Observations continue to support this, with cloud bases largely in the 3500-6000 feet range. This has led to just nuisance light mixed precipitation with little to no impact. Further upstream, the next more defined shortwave trough and associated sfc low pressure were dropping through the nrn Rockies, with a much better precipitation field working across MT and into the Dakotas. The shortwave currently moving through nrn Michigan will depart by daybreak, with only some continued residual spotty lake effect rain (early morning light snow/flurries) in the W/NW flow regimes for this morning. The upstream shortwave and associated sfc low pressure will push into the mid Mississippi and Upper Midwest today, allowing skies to increase in moisture/clouds in the mid and upper levels. Also, low level winds will start turning more out of the east with time, and that will push any spotty lake effect out over Lake Michigan (maybe a few spits could fall across portions of NE lower, although low level temperatures will be warming, killing much of the overlake instability. So as skies thicken in clouds through the second half of the day, fcst soundings show quite dry dry wedge of air between 3-10kft that has to be overcome. Doubt the incoming more significant forcing involving DPVA, theta-e advection and even some upper divergence, will be able to overcome this dry air until this evening. So, most areas will remain cool and rain-free. The initial forcing however will help to eventually overcome the drier lower level air this evening. Expect rain (mixed with snow initially in inland eastern upper), to become fairly widespread heading through the evening and overnight hours. Temperatures continue to warm in the low levels, with freezing levels climbing well above 1200 feet, to result in just rain eventually for eastern upper. Little to no accumulations expected in eastern upper under this scenario. By daybreak, there is still some low level convergence draped across nrn Lake Huron to Lake Superior, but for all intents and purposes, the main forcing and resultant precipitation is expected to have ended by daybreak. Highs today will mostly be in the mid to upper 40s again, with lows tonight in the low to mid 30s in eastern upper, and in the mid to upper 30s for most of nrn lower. && .SHORT TERM...(Wednesday through Thursday) Issued at 243 AM EDT Tue Oct 20 2020 High impact weather potential: Minimal. Pattern synopsis and forecast: Some wrap around moisture from a departing low pressure system to the northeast of the forecast period may linger some rain showers over eastern upper and the Tip of the Mitt during the morning hours Wednesday, but will diminish as the low pressure system continues it's northeastward movement into Ontario by the early afternoon hours. Behind the departing system, high pressure once again builds in and heights increase...850mb temperatures appear to be too warm for any lake precipitation to form over northern lower, but could see some clouds sticking around. 850 mb temperatures however actually decrease over Lake Superior (-2 to -4C)...producing some delta t/s of nearly 16C with lake temps of 12-13C, which would be enough to have more lake effect rain showers during the late afternoon and may mix with or change over to all snow during the overnight hours as the aforementioned high pressure moves off to the northeast into Ontario. Another low pressure system will bring more widespread shower chances as it moves towards the Great Lakes region from the Central Great Plains area. The associated warm front will begin impacting the forecast area late Wednesday night into Thursday morning with rain showers over northern lower and a mix of snow and rain over eastern upper. This warm front and associated moisture will continue to produce rain showers throughout the rest of this forecast period and into the next. Winds will begin the forecast period southwesterly with gusts up to around 15 mph and veer to more westerly Wednesday afternoon behind the cold front, with gusts of 15-20 mph...and once again become light during the overnight hours as the aforementioned high pressure center moves over the forecast area. Winds will then again ramp up by Thursday morning from the southeast ahead of the approaching warm front and then veer to more southerly during the late afternoon/early evening hours with gusts once again in the 15-20 mph range with some locally higher gusts possible. Daytime highs will reach near normal Wednesday afternoon as high pressure and partly cloudy skies move in behind the weak cold front...reaching near 50 to the mid 50s (warmest in the southeast forecast area). Thursday will finally see above normal temperatures, but will be breezy...temperatures will reach in the mid 50s to low 60s. Lows Thursday will be in the low 30s to near 40...once again with the warmer temperatures over northeast lower. .LONG TERM...(Thursday night through Monday) Issued at 243 AM EDT Tue Oct 20 2020 ...Temperatures remain above normal Friday, then back to below normal... High impact weather potential: Thunderstorms possible Thursday night through Friday night. Another low pressure system over the western Great Lakes will move through the eastern upper peninsula. This system will renew rain chances during mid-week with a warm front and continue producing chances of precipitation with the cold frontal passage through Saturday. Lake effect rain and then a mix or changeover to lake effect snow during the overnight hours may occur behind aforementioned cold front with 850 mb temps of -6 to -8C on northwesterly to north-northwesterly winds. We remain in a progressive weather pattern and remain cool and wet with cold 850 mb temperatures still cold enough to produce lake effect precipitation and the long term models hint at another system Sunday into the beginning of the next work week. Daytime highs finally reach to above normal Thursday and Friday with the warmer temperatures being advecting in on strong southerly flow...reaching into the mid 50s to low 60s. Highs will be colder Saturday and Sunday behind the cold front...only reaching into the low 40s to near 50. && .AVIATION...(For the 12Z TAFS through 12Z Wednesday morning) Issued at 540 AM EDT Tue Oct 20 2020 High pressure over the nrn Great Lakes will drift into Quebec tonight, making way for low pressure to cross late tonight into Wednesday morning. Primarily VFR conditions expected today, with spotty light rain and snow over nrn Michigan ending fairly early this morning. More widespread rain and MVFR/IFR conditions develops tonight ahead of the low pressure. NW/N fairly light winds today, will swing around out of the E/SE and increase tonight, with possible low end LLWS. Winds will turn out of the WSW very late tonight behind the departing low pressure. && .MARINE... Issued at 243 AM EDT Tue Oct 20 2020 High pressure over the nrn Great Lakes will drift into Quebec tonight, making way for low pressure to cross late tonight into Wednesday morning. Higher pressure returns later Wednesday into Wednesday night. Spits of light rain will end this morning, before better rainfall (mixed with some snow around Whitefish Bay) moves in tonight ahead of the low pressure. Most all of the precipitation will end by Wednesday daybreak. General light NW/N winds will turn out of the east/SE later today into much of tonight, before going more WSW behind the departure of the low pressure. Speeds will reach solid advisory levels tonight and Wednesday, with localized gales certainly possible. Speeds fall off through Wednesday night. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...SMALL CRAFT ADVISORY from 8 PM this evening to 8 PM EDT Wednesday for LHZ345>349. LM...SMALL CRAFT ADVISORY from 8 PM this evening to 8 PM EDT Wednesday for LMZ341-342. LS...SMALL CRAFT ADVISORY from 8 PM this evening to 8 PM EDT Wednesday for LSZ321. && $$ UPDATE...JZ NEAR TERM...SMD SHORT TERM...TL LONG TERM...TL AVIATION...SMD MARINE...SMD