531 FXUS63 KMQT 110549 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 149 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...(Thursday night through Wednesday) Issued at 417 PM EDT WED OCT 10 2018 ...Cool and unsettled weather to continue into extended forecast... Mean ridging will remain over the Gulf of AK, extending n thru AK and far nw Canada at times from late this week through the middle of next week. This will induce a broad trough across the northern Rockies into central North America including the Upper Great Lakes region. Under this pattern and a prevailing nw flow, temps will remain blo normal as a series of clipper systems move through the region bringing periodic light pcpn. Deeper moisture doesn't begin to depart until later Thu night/Fri morning. With 850mb temps of -6 to -8C and Lake Superior water temps running mostly 6-8C and locally up to 10C or so, wnw/nw flow sct lake effect showers will continue Thu night, and ptype will transition to just snow as wetbulb zero heights fall blo 700ft, except in areas exposed to the moderating influence of a long fetch across the lake. In those locations, expect a mix. Some light accumulations of snow (inch or less) will probably occur, mainly over the higher terrain. A weak shortwave passes on Fri, but fcst soundings show no real response in moisture depth. Nonetheless, the weak forcing overtop adequate instability over the lake (850mb temps around -8C) should continue to support some light w to nw flow lake effect showers on Fri. Will be another chilly day with w and n central not getting out of the 30s. Low to mid 40s expected elsewhere. A few lake effect showers may linger into Fri night, but drying air mass and the start of waa ahead of the next shortwave dropping into the Dakotas should end any remaining pcpn. A slightly faster trend is noted with the next clipper shortwave arriving this weekend. While most of the area should still remain dry on Sat, waa/isentropic ascent ahead of the first wave may bring some light showers into the western fcst area in the afternoon. Sat will be a warmer day though still blo normal. High temps will be in the 40s. Isold to scattered showers will acccompany the shortwave across the area Sat night with a trailing stronger shortwave arriving Sun. Given 850mb temps of -4C or lower, could see a short period of decent lake enhanced pcpn as this wave passes. If boundary layer stays cold enough during the day which GFS soundings seem to suggest, some minor wet snow accumulation would occur over the w on Sun. LES with a mix closer to shore will then follow into Sun night as 850mb temps fall toward -8C or colder. At least one more shortwave will move across the area in the Mon-Wed time frame, probably on Tue into Wed based on model consensus, bringing an increase in sct showers. Otherwise, air mass will likely be cold enough for much of this time to support some isold/scattered lake effect -shra/-shsn. && .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 LSZ250-251-266-267. Lake Michigan... None. && $$ SHORT TERM...RJC LONG TERM...Voss AVIATION...07 MARINE...RJC/JLA