Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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728 FXUS63 KMQT 232224 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 624 PM EDT Sun Jun 23 2024 .KEY MESSAGES... - Showers and thunderstorms possible this afternoon and evening. Severe weather is not expected. - A slight risk (~15%) of damaging wind and hail in the far west associated with thunderstorms Monday night into Tuesday morning. - Tuesday will be the warmest day of the week with highs in the mid 70s to mid 80s. - Next round of precipitation expected Thursday night into the weekend. && .SHORT TERM /THROUGH TONIGHT/... Issued at 104 PM EDT Sun Jun 23 2024 Clear skies with pockets of mostly cloudy skies have been present over Upper Michigan today. This has yielded a mix of temperatures, but overall most areas have climbed into the mid-60s, with a few low 70s here and there. DLH radar returns this morning showed scattered showers across the northern fringes of the Arrowhead and some light rain or sprinkles over western Lake Superior. These are associated with a closed mid-level low and preceding shortwave moving through western Ontario/northern Minnesota. Some of these have started showing up in Upper Michigan, but its uncertain if anything is reaching the ground at this point. As we progress through the remainder of the afternoon/evening, the wave aloft opens up as it moves through Upper Michigan. Some very modest instability may support additional showers and some thunderstorms this afternoon. Any convective development should progress southeast and weaken into the late afternoon and evening hours. High pressure builds in tonight, supporting a mostly clear night with lows dipping into the high 40s to mid 50s, warmest lake- side. The combination of cooler conditions, recent rainfall, and a low level inversion may support fog development across portions of western Upper Michigan tonight. && .LONG TERM /MONDAY THROUGH SUNDAY/... Issued at 433 PM EDT Sun Jun 23 2024 Starting Monday, Upper MI will be underneath mid level ridging with a trough over New England and another more broad trough over the Canadian Prairie Provinces. With the northern end of a 1015 mb high pressure ridge shifting southeast through the Great Lakes, we stay quiet and dry. Meanwhile, the western trough progresses east toward Saskatchewan/Manitoba throughout the day and its associated sfc low deepens to around 990mb just north of Lake Winnipeg. This set up increases southerly flow, increasing warm air and moisture advection; PWATs increase to around 1.7" by Tuesday evening. Some lake breezes are possible in the afternoon, but may struggle against the southerly flow. Otherwise no noteworthy weather is expected. Highs are expected in the 70s to low 80s. Monday night through Tuesday the mid level trough over Manitoba moves east, becoming centered just east of James Bay. The associated sfc low moves east with it, moving through far northern Ontario, reaching James Bay Tuesday afternoon, and then continuing east into Quebec Tuesday evening. This sfc low well to the north drapes a cold front south into the midwest that moves into the far western UP around 6Z Tuesday, supporting showers and storms aided by isentropic ascent. The significant uncertainty yet with how the convection along the front plays out is well represented by the wide range of solutions among the CAMs. Model soundings show a decent cap and the 6/23 12Z HREF mean CIN is ~100 J/kg Monday evening across much of the western UP. Also, stronger large-scale ascent with the tough will remain north of the international border. That said, a small region of MUCAPE (HREF mean of 1000-2000 J/kg) builds up over Gogebic/Ontonagon/S Houghton/Iron counties Monday night; values as high as 2500-3000 J/kg are not out of the question. Mid level lapse rates will increase to ~7 C/km with bulk shear between 35-40 kts. If we are able to break the cap with the frontal boundary passing through as well as a strengthening LLJ, the environment will be supportive of strong to severe storms with damaging hail and winds being the main threats. This event will depend on how upstream convection earlier in the day plays out. Some solutions including the 12z runs of the NAM Nest/ARW/FV3 depict a more pronounced MCS developing over northern MN, progressing through the region. The MCS tracks are spread as well with some only clipping the WI/MI border while the FV3 tracks right across our CWA. The HRRR and RAP are not as organized or strong. Given the potential environment, the SPC slight risk (15%) for the far west seems appropriate. This event will continue warrant monitoring as uncertainty remains high. Showers and storms continue east across the UP through the rest of the day Tuesday as the front continues out. As the trough presses south in the later part of the day, PVA supports additional shower and storm chances, mainly over the east half of the UP. Otherwise, Tuesday is expected to be the warmest day of the week with highs in the mid 70s to mid 80s. Mixing behind the front late morning/early afternoon will help alleviate any early muggy conditions in the morning. A dry period then is expected Wednesday into Thursday night as high pressure descends southeast through the Great Lakes from the Canadian Prairie Provinces. Confidence is growing in the weekend forecast for a trough over the Pacific NW to make landfall Wednesday night, then continue east along the U.S./Canada border, and reaching the Upper Great Lakes by Saturday. This will support cyclogenesis in the northern Rockies Thursday night/Friday with the low ejecting east-northeast to just north of Lake Superior for Friday night/Saturday. Drier weather looks to return the rest of the weekend as high pressure returns. && .AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 624 PM EDT Sun Jun 23 2024 VFR conditions will continue through the period. && .MARINE... Issued at 433 PM EDT Sun Jun 23 2024 West to northwest winds will diminish through this evening, then remain below 20 kts through Monday as high pressure ridging passes over Lake Superior. South winds increase to around 20 kts Monday night ahead of a passing cold front. Southwest winds behind the front are expected around 20-25 kts, though a few gusts may be in the 25-30 kt range between Isle Royale and the Keweenaw Peninsula Tuesday afternoon. Winds taper off Tuesday night into Wednesday as they veer north, remaining below 20 kts through the late part of the week. Strong to severe storms are possible in the west Monday night into Tuesday with the passing cold front. Waves will be strongest between Isle Royale and the Keweenaw Peninsula Tuesday afternoon and evening (4-6 feet). && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JTP LONG TERM...Jablonski AVIATION...07 MARINE...Jablonski