160 FXUS63 KMQT 110803 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 403 AM EDT Thu Oct 11 2018 .SHORT TERM...(This evening through Thursday) Issued at 417 PM EDT WED OCT 10 2018 Areas of moderate to occasionally heavy rain are lifting northeastward across the central and eastern U.P. this afternoon ahead of a low pressure system currently centered over central Wisconsin, with more scattered coverage farther west. With this rainy period we've been in, with some areas having seen more than 4 inches of rain since Sunday, rivers will continue to run high and thus the Flood Watch continues through this evening. Drier mid and upper-level air wraps into Upper Michigan from the southwest this evening as the low pressure area rides along the warm front across the U.P. As the surface-based saturated layer shallows, precip will convert to more of a lingering drizzle and fog for much of this evening through midnight. Cold advection aloft after about 06z will begin to steepen lapse rates and transport some stronger winds of about 10-15 knots with the occasional 20-knot gust to the surface in the wee hours of Thursday morning and begin mixing out the lingering fog. As the low pressure area lifts off to the northeast into northern Ontario and winds shift to westerly across Upper Michigan, the focus for the day thursday shifts to wrap-around precip and lake-effect rain/snow showers for the western U.P. Have bumped up POPs and QPF for Thursday afternoon to match numerous high-res models depicting multiple LES bands in the afternoon supported by sfc-850 delta T's of 14-16 C. Wet build zero heights look to be around 500 feet at midday and fall through the afternoon for the western U.P. which supports a rain/snow mix if not majority snow in heavier bands/cells. However, surface temps will still be marginal, around 33-35 F in the afternoon, so have limited any snow accumulation to the typical higher elevation spots where an inch to at most two is expected. Farther east, high-res guidance resolves another band oriented WNW-ESE into the Superior shoreline of Alger and Luce Counties that then drops southward through Schoolcraft County late. However, temps to the east should be warm enough to maintain mainly rain with just a few slushy flakes mixing in there. .LONG TERM...(Friday through Wednesday) Issued at 402 AM EDT THU OCT 11 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 are still pointing toward slight progression of the ridge into western Canada during next week. This will force a mean Rockies to central N America trof to shift e to eastern N America as next week progresses, and this will lead to a drier pattern (a trend to blo normal pcpn amounts) taking hold across the Upper Lakes next week under developing nw flow. Although there will still be periodic pcpn episodes associated with a series of shortwaves progressing thru the mean trof during roughly the first half of the week, pcpn amounts associated with each wave will be light. As for temps, solidly blo normal temps will prevail now thru much of next week as mean troffing gradually shifts e, placing the Upper Lakes under chilly nw flow. Over the last few days, medium range models/ensembles have generally suggested that the ridge drifting into western N America will broaden farther downstream, which would allow for some overall warming at the end of the week. Beginning Fri, A weak shortwave is fcst to swing across the Upper Lakes. Despite this, fcst soundings show no real response in inversion/moisture depth on Fri. With inversions around 6kft, 850mb temps of -7/-8C, and Lake Superior water temps roughly 6 to 8C, conditions will be supportive of continued lake effect, and would think the shortwave would provide a slight temporary boost to coverage and perhaps allow showers to spread farther inland than would otherwise occur. On the negative side, curvature of the low- level flow is neutral to slightly anticyclonic. In any event, expect sct -shsn on Fri in the usual areas that see lake effect under wnw winds veering more westerly. In areas exposed to the moderating influence of a long fetch across the lake, ptype will be more of a rain/snow mix. Obviously, it will be a cold day for mid Oct. High temps will only be in the mid 30s w and n central high terrain. Expect upper 30s/lwr 40s elsewhere. Sct lake effect -shsn will linger into Fri night, but drying air mass/lowering inversion/waa ahead of the next shortwave dropping into the Dakotas should spell an end to any pcpn, at least over the w as the night progresses. Shortwave that drops into the Dakotas Fri night will shift to the Upper Lakes by Sat evening. WAA/isentropic ascent and rather vigorous deep layer forcing should support some -shra spreading into western Upper MI during the aftn. Sat will be a warmer day though still blo normal. High temps will be in the 40s. A period of isold to sct -shra will acccompany the shortwave across the area Sat night. A trailing stronger shortwave arrives Sun, but with track of vort max over or just n of Upper MI, main forcing with this wave will pass by to the n. Still, it should provide for some lake enhancement on Sun under 850mb temps of -5 to -7C. If boundary layer is cold enough during the day, some minor wet snow accumulation would occur over the w. LES will then follow into Sun night under 850mb temps falling toward -9C. With a fairly sharp sfc trof sweeping s across the lake with passage of shortwave, there will be an opportunity for a period of somewhat heavier shsn that could provide some minor snow accumulations Sun night. Passage of sfc high pres ridge will bring an end to lingering lake effect from w to e Mon aftn into Mon evening. Medium range models are in quite good agreement with the next shortwave to drop se into the Upper Lakes on Tue, bringing the next round of -shra/-shsn. Sct lake effect will then follow into Wed. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 144 AM EDT THU OCT 11 2018 Lower conditions with the rain and fog will slowly imrpove at all sites through this forecast period. Will be some improvement to MVFR conditions by late Thu morning. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 417 PM EDT WED OCT 10 2018 ENE winds of 25-35 knots persists across all of Lake Superior this afternoon and evening. They will back to northerly after midnight over western Superior as the surface low tracks across Upper Michigan, then become westerly Thursday morning. The lingering pressure gradient will be strong enough to support 20-30 knot west-northwesterlies across the entire lake for all of Thursday with gales of 35-40 knots across the east half of Lake Superior. Winds diminish to 15 to 25 knots into Friday morning then relax below 20 knots Friday evening. The next system approaches Saturday with more stiff southwesterlies of 15-20 knots expected for western Lake Superior midday Saturday, spreading eastward across the rest of the lake by late Saturday evening. Winds back to northwesterly Sunday into Monday and stay up around 20-25 knots before relaxing Monday evening. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Gale Warning from noon today to 11 PM EDT this evening for LSZ250-251-265>267. Lake Michigan... None. && $$ SHORT TERM...RJC LONG TERM...Rolfson AVIATION...07 MARINE...RJC/JLA