Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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186 FXUS63 KMQT 311951 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 351 PM EDT Fri May 31 2024 .KEY MESSAGES... - Scattered showers continue across the west through tonight with a few embedded thunderstorms. Locally heavy rainfall >1" possible, especially with thunderstorms. - Frequent opportunities for showers and thunderstorms over the next 7 days. - Above normal temperatures through the first half of next week, then turning cooler. && .SHORT TERM /THROUGH TODAY/... Issued at 355 AM EDT Fri May 31 2024 Southerly flow with increasing moisture, in addition to high clouds building into western Upper Michigan has produced a mild night across the forecast area, except interior portions of the east where dry air and light winds have supported effective radiational cooling. So far interior temps have fallen into the upper 30s while the lakeshores have remain in the 40s or 50s. Across the west, min temps in the 50s and even some low 60s have been observed so far. Upstream, a line of showers with some preceding isolated showers has been observed moving through northern Minnesota, pressing northeast as a weakening cold front advances. Some lighting has been observed, but activity has waned in the past couple of hours. As we move through the remainder of the morning hours and into today, showers and storms across central Minnesota will lift northeast as the boundary presses eastward into the Arrowhead and western Lake Superior. Some rumbles of thunder can`t be ruled out. The weak boundary will continue pressing east while upper level support shifts northeast, bringing with it increasing pops for the west. Onset is a little tricky given the anticipated dwindling line as it approaches, but the overall consensus is for light rain to move into the west by late morning. While the boundary inches across the Arrowhead, continued convergence with growing weak instability out in front will result in continued shower chances through the afternoon for the west half. Thunderstorms can`t be ruled out, but severe weather is not expected. In the east, dry air will win out, likely resulting in clear to partly cloudy skies. This, coupled with dinural heating, will support mixing and enable drier air aloft to mix down to the surface. Model soundings suggest mixing only to around 2k feet, which would support RH percentages dipping down into the mid 20s. If we are able to warm more and mix higher then expected though, lower RH near 20% will be possible. Daytime highs across the region should climb into the 70s, except remain in the 60s by Lake Michigan. && .LONG TERM /SATURDAY THROUGH FRIDAY/... Issued at 350 PM EDT Fri May 31 2024 A deep midlevel low remains situated over northern Manitoba and Saskatchewan into the weekend. Chances for light rain showers continue across the western UP into early Saturday morning with a diffuse frontal boundary stalled out somewhere over western Lake Superior or the western UP. However, a subtle midlevel wave moving northeast from IA and WI into the area by early Saturday afternoon will allow chances for some scattered showers to spread more eastward into the afternoon. A better-defined shortwave then swings around the midlevel low during the afternoon, heading into northern Ontario by early Saturday evening. This second wave will drag the surface boundary eastward, allowing for a broken line of showers to track through central Upper Michigan through the afternoon and evening hours. Simulated reflectivity shows this largely falling apart before reaching hwy 41, with just some spotty activity across the eastern UP that should taper off by 06Z Sunday. Weak forcing will work against our potential for any strong to severe convection, but soundings showing potentially several hundred j/kg of CAPE over the area during the afternoon, some thunder will not be ruled out. Given several rounds of scattered showers across the western UP tonight through Saturday, HREF ensemble mean QPF indicates a good half to 0.75in of rain by Saturday evening across the western UP, but there is still a slight chance (20-30%) for some higher embedded totals nearer an inch. Expect lighter amounts across the rest of the UP before rain wraps up later Saturday evening. Otherwise, look for somewhat breezy conditions through the eastern UP into the afternoon as mixing deepens. Under partly to mostly cloudy skies area-wide, temperatures peak in the 60s to lower 70s. High pressure over the area Sunday will allow for a brief dry window to finish out the weekend. With light winds and clearing skies, we may start off with some patchy fog early Sunday morning. Then, expect temperatures (starting in the upper 40s and lower 50s) to recover nicely with most of the area climbing into the 70s. Some spots may even make a run towards the 80 degree mark. Meanwhile, along Lake Michigan and our western Superior shorelines, SW winds may keep temperatures a few degrees cooler, perhaps struggling to crack into the lower 70s. The next shortwave moving onshore over the Pacific NW on Saturday will reach the Upper Mississippi Valley late Sunday night and the western Great Lakes by Monday afternoon. Showers and storms developing along/ahead of the associated cold front will move across MN during the day Sunday, reaching the western UP late Sunday night. The late arrival time into the western UP will help to work against a strong/severe storm risk as instability diminishes with time and eastward extent, but with a 40-45kt low-level jet translating over western Upper MI by 12z Monday, our thunderstorm potential will be worth watching into MOnday morning. If overnight convection can persist into Monday morning, and skies stay cloudy, perhaps we don`t destabilize enough for stronger storms to fire along the passing front Monday afternoon/evening. If we do clear out ahead of the front in the central and eastern UP, there is the potential for some stronger convection. Expect another brief dry window for most of Tuesday as high pressure slides over the area behind the exiting system. Then, a negatively- tilted trough swings through the Canadian Prairies and Northern Plains, deepening into the middle of the week while anchoring somewhere near Lake Winnipeg. Robust WAA ahead of this will touch off our next chance for rain and thunder late Tuesday night into Wednesday, then expect hit and miss chances for rain the rest of the work week with a highly amplified pattern developing as a ridge builds over the western CONUS and the midlevel low potentially stalls out over the Great Lakes. Otherwise, look for much warmer temperatures by Tuesday, then temperatures fall below normal late week as a cooler airmass works in. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 225 PM EDT Fri May 31 2024 A slow-moving cold front is over far western Upper Michigan this afternoon and may move over the central UP before stalling this evening. This will result in VFR conditions prevailing at SAW and deteriorating conditions at IWD/CMX where scattered showers are occurring. Additional showers including potential for a few rumbles of thunder are expected to develop around CMX/IWD this evening as the nocturnal low level jet increases convergence along the frontal surface. Repeated rain chances eventually lower cigs to MVFR/IFR late in the TAF period until the front begins to push east again on Saturday. This results in improving conditions at IWD/CMX and deterioration at SAW Saturday evening. South-southwesterly winds gusting to around 20-25 mph are expected at SAW ahead of the front this afternoon, but generally light south winds prevail at all terminals. && .MARINE... Issued at 350 PM EDT Fri May 31 2024 Under a relatively weak pres gradient and stable conditions over the lake, expect winds mostly under 20kt today thru Sun. An approaching cold front Sun night will bring an increase in southerly winds, especially across the e half of Lake Superior which is typically favored for stronger winds this type of situation. By sunrise Mon, S to SE winds up to 25kt are expected, though given the stability over the cold lake waters, these winds up to around 25kt will mostly be observed at high obs platforms. That said, 25kt winds may observed locally in the nearshore waters where flow off of the terrain affects the wind. Cold front will pass later Mon/Mon night with winds under 20kt following on Tue. Winds pick up again midweek ahead of another approaching trough/frontal system. Expect winds primarily out of the SW at around 20 knots, mainly across western Lake Superior. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JTP LONG TERM...LC AVIATION...EK MARINE...LC