Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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570 FXUS63 KMQT 010018 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 818 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 TONIGHT/... Issued at 410 PM EDT Fri May 31 2024 Only minor forecast updates were needed today with sunnier skies allowing for slightly warmer temperatures approaching 80F. Deeper mixing also allowed for somewhat stronger winds, but overall the fire weather forecast was spot on across the east with RH dipping to around 25% and SSW winds of 10-15 mph with gusts to 20mph. The only exception was the Newberry RAWS which is reporting a dew point 11- 17F lower than all surrounding observations raising questions about how representative the observation is. On the other side of the Peninsula, an area of rain/rain showers lifted northeast across our western tier of counties for most of the day. While no thunder has been reported, CMX reported a brief period of heavy rainfall as it moved overhead. Coverage is currently waning suggesting a general lull head of the next wave this evening. As of 355 PM our radar started picking up the frontal boundary extending southeast from Big Bay. Looking ahead through tonight, the frontal boundary is expected to slow and eventually stall tonight. As the boundary stalls, the nocturnal LLJ ramps up to around 35 kts as it noses into our area this evening. This disturbance and the associated area of of showers and embedded thunderstorms is already showing up on regional radar in the vicinity of Minneapolis. CAPE is insufficient for severe concerns, but pwat values >1 inch (approaching the 90th percentile) and potential for multiple rounds of rain suggests a chance for locally heavy rainfall and perhaps patchy fog too. 12z HREF PMM guidance paints a stripe of heavier QPF between Watersmeet and L`Anse, which is primarily instigated by NAMnest and HRW NSSL guidance. However, it`s worth noting that most other guidance is further west roughly between Ironwood and Copper Harbor. Fortunately, river levels remain low and flooding concerns are limited to ponding in poor drainage areas. && .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 /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 816 PM EDT Fri May 31 2024 VFR conditions to deteriorate to MVFR/IFR at IWD/CMX early tonight with onset of showers associated with a cold front. Best chances for any thunderstorms will remain confined to IWD. Meanwhile, SAW is expected to remain at VFR levels for the duration of the TAF period. But, VFR is progged to return to IWD/CMX as well by tomorrow afternoon when the cold front pushes eastward. Winds will be light and southerly. && .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...EK LONG TERM...LC AVIATION...TDUD MARINE...LC