Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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174 FXUS63 KMQT 250530 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 130 AM EDT Tue Jun 25 2024 .KEY MESSAGES... - Line of thunderstorms moves through the forecast area tonight, some storms could be strong to severe and produce damaging winds and large hail. - Tuesday will be the warmest day of the week with highs in the mid 70s to mid 80s. Gusty winds to 30 mph are also expected, especially over the Keweenaw. - Next round of precipitation is expected Thursday night into the weekend. && .SHORT TERM /THROUGH TONIGHT/... Issued at 143 PM EDT Mon Jun 24 2024 Current mesoanalysis across the region places an upstream shortwave moving through northern Minnesota and a cold front tied to a surface low moving through Lake Winnipeg not far behind. Precip associated with this is trending down per DLH radar and GOES IR. To the south, mid-level ridging extends across the Plains with subtle shortwaves perturbations embedded atop. At the surface, a surface low was observed moving across eastern South Dakota along with a southeastward draped warm front and several surface troughs tied to the mid-level perturbations. Across our forecast area, surface high has allowed for clear skies to largely dominate; at the time of this publishing though, high clouds streaming eastward into the region associated with the shortwave pressing through Minnesota was observed on GOES Vis imagery. With these mostly clear skies and predominately southerly flow, daytime temps have warmed into the 70s while dewpoints in the 50s have been observed. As we progress through the remainder of the afternoon and overnight tonight, upstream weakening showers in Minnesota will continue to weaken as it presses into Lake Superior/western Upper Michigan. HRRR and other CAMS suggest it may hold together enough to support some showers in our forecast area late this afternoon/early evening. Otherwise, expect temps to continue climbing into the upper 70s to low 80s and increasing cloud cover. Impressive instability will continue building on the south side of the decaying shower activity over Minnesota. As this area of instability grows and southwesterly low level winds strengthen this evening, a line of thunderstorms will develop over central Minnesota. These will grow upscale and evolve into a bowing MCS as they stream southeast along the instability gradient. CAMS appear to be coming into better agreement that the strongest storms will stay south of our forecast area, but storms capable of mostly damaging winds can`t be ruled out early in the event. Some large hail will also be possible. The main risk area will be in the counties bordering Wisconsin. North of this bowing segment, the HRRR and to some degree, the FV3 and NAMNEST resolve a secondary line of showers and thunderstorms across the Arrowhead into Ontario, then press these into Lake Superior and Upper Michigan. Some large hail and maybe strong winds will be possible with these storms if the materialize, but confidence in these developing is low to medium (25- 50%) given their proximity to the main bowing segment and the lack of a consensus among the various CAMS solutions. If this develop, these and the northern fringes of the MCS pressing southeast, will press eastward through Upper Michigan, likely clearing the east just after sunrise. While confidence in the evolution is lacking somewhat, consistent temporal signatures in the various CAMS suggest the main period of thunderstorms to be between 5z and 11z with the most likely period for strong to severe being early in the event. && .LONG TERM /TUESDAY THROUGH MONDAY/... Issued at 446 PM EDT Mon Jun 24 2024 Starting Tuesday morning, the mid level trough will be situated over far northwestern Ontario with the associated sfc low just ahead of it at 988mb near the western shores of James Bay. This low`s cold front will be draped southeast along the west end of Lake Superior and into northwest WI. Lingering convection from tonight will likely be over the far east where the warm front continues shifting east out of the area. With instability dropping off, confidence in severe weather is low for the morning as this moves out. Dry weather returns to all in our CWA by mid morning as the cold front presses east. Stronger mixing begins behind the cold front resulting in some gustier west to northwest winds up to 30 mph and drier RHs down into the 30%, possibly some upper 20s near Iron Mountain. Strongest gusts are expected in the Keweenaw and northwest, coupled with the lower RHs. Tuesday is also expected to be the hottest day this week with highs in the 70s to mid 80s, warmer in the south central UP. That said, there are no wildfire concerns given the recent wet pattern. As the cold front makes it`s way through the area, the ARW and HRRR try to initiate some isolated thunderstorms along the east near Lake Michigan. The 6/24 12Z HREF mean SBCAPE does build up to 1000 J/kg in that region, but with model soundings looking moisture deprived. Left afternoon precip out of the forecast for now. Tuesday night into Wednesday, the mid level trough continues east into Quebec and is quickly followed by a shortwave rotating over the Upper Great Lakes. An additional cold front dropping south will shift winds out of the north by Wednesday morning and keep winds up around 5-15 mph through the night, especially over the east and in the Keweenaw. Lows are expected in the mid 40s to low 50s. Also given the shortwave, added in some slight chance PoPs late Tuesday night into Wednesday. Note: There is low confidence at the moment in location/timing, but nothing impactful is expected. Dry weather and clearing skies then is forecast for Wednesday afternoon as highs peak in the 60s. However, those near the eastern Lake Superior shores may stay in the 50s throughout the day. With weak high pressure ridging continuing over the region into Thursday night, dry weather prevails. Radiative cooling Wednesday night brings lows into the 40s, coolest in the east where the drier airmass is located. With Highs on Thursday only are expected to warm up into the low 70s. Meanwhile, a trough just east of the Pacific northwest will move onshore Wednesday night. This trough progresses east along the international border toward the Upper Great Lakes by Saturday morning with 1 to 2 shortwaves shooting out ahead of it. This will support cyclogenesis in the northern Rockies Thursday night with the low ejecting east-northeast to the northern end of Lake Superior for Friday night/Saturday. Thus, PoPs increase Thursday night into the weekend. With the low weakening as it moves through and little instability, hazardous weather seems unlikely at this point. Drier weather looks to return the rest of the weekend into Monday as high pressure returns, but confidence is growing in another low pressure system pushing off the Rockies and moving northeast into the Upper Great Lakes region for early next week. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 129 AM EDT Tue Jun 25 2024 VFR conditions will prevail early this period, followed by a rapid deterioration as a line of thunderstorms moves into Upper Michigan. Expecting most activity between 06Z and 11Z, with the greatest potential for severe winds, maybe some large hail, at KIWD early on in the event. Expect ceilings to fall to MVFR/IFR after the line moves through with some brief fog/mist developing before the sunrise. Tuesday, gusty winds are expected to develop as ceilings improve. Initial thoughts are KCMX could gust near 30kts from the west. LLWS will occur overnight at IWD and SAW. && .MARINE... Issued at 446 PM EDT Mon Jun 24 2024 Southeast winds increase this evening to around 20-30 kts, backing south tonight ahead of the cold front; strongest winds are expected over the east between the north and eastern Lake Superior buoy`s where there is a 15% chance for gale force gusts to 35 knots tonight. Strong to severe storms are possible tonight into Tuesday morning ahead of the cold front. On Tuesday, gusty westerly winds are expected behind the cold front to 20-30 kts. Strongest winds are expected over the central third of the lake between Isle Royale and the Keweenaw. This will be another period with even higher potential for some gale force gusts to 35 kts. (Chance of gusts exceeding 34 kts ~40%). This period of longer fetch and stronger winds will help waves build up to 4-6 feet Tuesday afternoon and evening north of the Keweenaw. Winds around 20-25 kts veer north Tuesday night behind an additional cold front that drops south across the lake before tapering off below 20 kts Wednesday morning. With high pressure over the lake through Thursday, winds are expected to mainly remain below 20 kts. A weakening low pressure tracking through the Upper Great Lakes early this weekend will allow for gusts near 20 kt Friday and Saturday. High pressure returns Sunday and ushers in light winds. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JTP LONG TERM...Jablonski AVIATION...07 MARINE...Jablonski