821 FXUS63 KMQT 091907 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 307 PM EDT Tue Oct 9 2018 .SHORT TERM...(Today and tonight) Issued at 522 AM EDT TUE OCT 9 2018 ...Periods of heavy rain could result in flooding... SW flow between broad trough over western CONUS and strong high just off east coast is pumping the unusually high moisture into the Upper Great Lakes. PWAT at GRB 00z was 1.73 or a whopping 279 pct of normal for this time of year. Deep moisture advection and low-level warm air advection along and ahead of sfc-H925 trough (now as far north as scntrl Upper Michigan) continues to drive the show thus far with multiple clusters of showers/t-storms extending from Upper Michigan sw all the way to the Big Bend area of TX. The extensive coverage of the moderate to heavy rain across the central CONUS is rather impressive. Initial wave of heavier rain moved across central Upper Michigan last night and dropped rainfall amounts up to 1.00 inch, heaviest near Lake Michigan. Next batch of showers/t-storms over central Upper Michigan through about daybreak is riding along and north of strongest H925 warm advection and edge of MLCAPE gradient. Decent rainfall with 0.61 inch/1 hour at IMT as convection moved through. Since this heavy rain will affect areas that saw heavier rain on Mon evening (northern Menominee, Delta and Alger counties) expanded flood watch into those areas earlier this morning. May be a bit of a lull behind this activity but regional radar indicates another batch of at least moderate showers already pushing into central WI. Looks to be quite a soggy morning for central Upper Michigan. Attn later today is on area of showers/t-storms currently lifting across western MO extending down into OK/TX. These showers are more along stronger sfc wave of low pressure over TX that will be lifting across Neb/IA this evening and reaches southeast MN by 12z Wed. Strong large scale lift is expected to spread across the Upper Great Lakes this evening and overnight ahead of negative tilted upper level trough lifting across the central Plains. Large scale q-vector convergence will combine with stronger sfc-H85 convergence ahead of the low/warm front to bring a period of showers/t-storms with very heavy rain. Expect widespread heavy rain as this background forcing will be supplemented by another surge of H925 warm air advection and strong low-level moisture transport into the Upper Great Lakes. PWATS tonight forecast to be at least if not higher than values seen currently, so probably above 300 pct of normal. Wow! Rainfall rates may be intense as area will also be on northern edge of MUCAPE leading to larger areas of convection. Overall, type of regime that is occurring in TX and OK this morning could very well be ongoing over Upper Great Lakes tonight. Preferred to lean on heavier qpf from GEM as it is initializing upstream activity better this morning. Some locations over especially the west half of Upper Michigan may see rainfall totals just tonight of 1 to 2 inches. This will boost event totals to near 3 inches with more rain to come on Wed. No need to change the going flood watch as it covers this situation appropriately. Other issue tonight will be strong/gusty east winds on the Keweenaw. May see gusts to around 30 mph. Temps today and tonight will stay mainly in the low-mid 40s northwest and north central as they remain on cool side of sfc boundary. Fog at times for these areas as well. Temps over the far south and east currently in the 50s to near 60F should stay steady much of the day before falling off late as northerly winds increase to the north of the approaching sfc low. .LONG TERM...(Wednesday through Monday) Issued at 411 AM EDT TUE OCT 9 2018 Thru the upcoming weekend, a mean ridge will remain over the Gulf of AK, extending n thru AK and far nw Canada at times. Operational medium range guidance and ensemble means point toward broadening and slight progression of the ridge during next week. This will force a mean Rockies to central N America trof to drift e to eastern N America next week. In the end, this will lead to a drier pattern taking hold across the Upper Lakes later next week under wnw flow. This drier regime may show some persistence as well. In the meantime, the pattern will continue to provide frequent opportunities of pcpn. Current amplified western CONUS trof/eastern CONUS ridge configuration will support hvy pcpn amounts for the next couple of days until the main shortwave currently over the southern Rockies lifts thru the Upper Lakes Wed night/Thu. Thereafter, future pcpn events will be much lighter for the remainder of this 7 day fcst. Blo normal temps w and near to above normal temps se for the next couple of days will fall solidly blo normal late week thru the first half of next week as mean troffing gradually shifts e, placing the Upper Lakes under chilly nw flow. Then, if the upstream ridge evolves as currently depicted in medium range guidance, a somewhat warmer regime will be in the offing, beginning late next week. Beginning Wed/Thu, main shortwave will be ejecting from the Rockies trof out across the Plains Wed. Associated, organizing sfc low should be over IA at 12z. This low will deepen as it lifts ne, passing across central Upper MI/eastern Lake Superior Wed night. With precipitable water of 1.5 to 1.75+ inches, nearing 300pct of normal, approaching shortwave and healthy upper diffluence will support periods of hvy shra on Wed. With a few hundred j/kg of mucape, also expect isold to perhaps sct tsra which will be efficient hvy rain producers. Hvy rain shuts down quickly Wed night as negative tilt shortwave trough and associated deepening sfc low lift northeast of the area. Will turn blustery/colder behind the front thru Thu as 850mb temps fall to -4 to -6C by late aftn. Under cyclonic flow, caa and deepening moisture toward 10kft, lake enhanced showers will develop from w to e off Lake Superior later Wed night thru Thu under w becoming nw low-level flow. With wetbulb zero heights falling blo 700ft, expect some shsn along with the shra. May see some graupel as well, typical of earlier season lake effect. Incoming pres rises are not particularly notable, so not expecting much of an isallobaric enhancement to the post-frontal winds Wed night into Thu. Given potential mixed layer winds, may see some gusts approach 45mph, but at this point, not anticipating that a wind advy will be needed as we move closer to Thu. Will be a cold day Thu with higher terrain of the w and n central not getting out of the 30s during the daylight hrs. Deeper moisture exits Thu night, leading to decreasing coverage of lake effect pcpn, but with 850mb temps down around -7C, isold/sct lake effect shra/shsn should continue under wnw winds thru the night. That said, water temps are blo avg for this time of year with the 3 mid lake buoys showing 8C, 6C, 6C from w to e. This will put conditions a little more on the marginal side for lake effect pcpn once enhancement factors of deep moisture exits/cyclonic flow relaxes. There are hints of a shortwave swinging across the area late Thu night/Fri morning, so that may provide some support. While some lake effect shra/shsn may persist into Fri morning, developing well-mixed boundary layer and negative impact of early fall daytime heating will likely spell an end to the lake effect pcpn. Will be another cold day with highs in the 30s and 40s. At least a couple of shortwaves are fcst to swing thru the area over the weekend and early next week. Models are not showing good agreement or run-to-run continuity on these features, both in timing and amplitude. Might be able to slip in a dry day across the board on Sat, but after that, expect pcpn at times Sun thru Tue with a lake component to that pcpn. Air mass will be cold enough to support shsn at times as well, especially high terrain. Given the amplitude of the flow, not out of the question that a se diving shortwave could provide a pcpn event early next week that includes a little accumulating snowfall. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 111 PM EDT TUE OCT 9 2018 Poor aviation conditions will persist over the next 24 hours as a system lifts northeast across the Upper Great Lakes tonight through Wednesday. IFR to LIFR ceilings are expected to persist with visibilities likely varying between MVFR during light rain to LIFR as heavier rain moves in tonight through the early to mid morning hours. Right now it appears the longest period of lower visibilities is expected across KIWD/KCMX, due to a persistent moderate to heavy band of rain. Very slim thunder chances are possible at KSAW Wednesday morning, but were not high enough to include mentions within the TAFs at this time. Outside of the poor ceiling and visibilities, northeast winds will increases and become gusty across all TAF sites tonight through Wednesday morning. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 305 PM EDT TUE OCT 9 2018 Winds will pick up substantially tonight into tomorrow, with the western half of Lake Superior seeing the highest winds tonight, followed by the east half on Thursday. This is due to the approach and passage of a deepening low pressure system that will be crossing the Upper Great Lakes. These periods of increased winds through tomorrow evening have been highlighted in a Gale Warning, with an additional warning possible for the east half on Thursday. Sustained winds out of the NE tonight will start out in the 20-30 knot range, then increase to near/above 34 knots for the western half tomorrow. Gusts will approach 45 knots, with brief, localized gusts exceeding storm force possible. Greater than gale force gusts will persist into tomorrow night, with the focus shifting to the eastern half by Thursday, as mentioned. As the low passes across, expect the winds to swing around to out of the NW by Thursday. Winds will likely remain elevated into early Friday, before the pressure gradient slackens over the region. Look for less than 20 knot winds to prevail through the weekend. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Flood Watch through Wednesday evening for MIZ001>006-009>013-084. Lake Superior... Gale Warning from 5 AM to 5 PM EDT Wednesday for LSZ266. Gale Warning from 8 PM EDT /7 PM CDT/ this evening to 1 AM EDT /midnight CDT/ Thursday for LSZ162-263-264. Lake Michigan... None. && $$ SHORT TERM...JLA LONG TERM...Rolfson AVIATION...Ritzman MARINE...lg