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Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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469 FXUS63 KMQT 250809 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 409 AM EDT Tue Jun 25 2024 .KEY MESSAGES... - 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. - Pattern remains active, especially from late week into early next week, with yet more rounds of showers and storms && .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 /WEDNESDAY THROUGH MONDAY/... Issued at 408 AM EDT Tue Jun 25 2024 Starting Wednesday, a northwest flow shortwave and associated cold front moves from the Northern Plains across the Upper Great Lakes. Most of the models show an inverted sfc trough inflection associated with the shortwave from northern WI along the U.P. border. Instability is limited at 200 j/kg or less so expect isolated to scattered showers Wednesday, probably focused mainly west and along the WI border where the inverted sfc trough axis is situated. Expect drying and clearing skies from the west and north behind the shortwave trough and cold front in the afternoon into early evening as highs peak mainly in the 60s. However, those near the eastern Lake Superior shores may stay in the 50s throughout the day. Weak high pressure ridging persists across the region from Wed night into at least Thu evening, dry weather prevails. Under clear skies and near calm winds, radiative cooling will drop Wed night lows into the 40s, coolest over the interior. Expect highs Thu generally in the lower to mid 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 at least a couple of shortwaves embedded in it. This will support cyclogenesis in the northern Rockies Thursday night with the low ejecting east into northern Ontario Friday night/Saturday. WAA/isentropic ascent and theta-e advection ahead of the low will support showers and thunderstorms spreading into Upper Mi on Friday. The first of the shortwaves within the mid-level trough moves through Sat which pushes a cold front through the area Fri night into Sat. Increased instability noted along the cold front should increase chances for thunder as it moves through the area at this time. The second shortwave in the trough will send a secondary cold front and another round of showers across the area late Sat into early Sun along with a burst of gustier nw-n winds and colder temps. High pressure building in quickly behind the front will result in drier, albeit cooler conditions Sunday afternoon into Monday. Models advertise another shortwave and associated sfc low lifting off the Northern Rockies and tracking e across the Northern Plains and Canadian Prairies into the Upper Great Lakes for early next week. This feature will bring another round of showers/t-storms into the area for next Mon night into Tuesday. && .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 408 AM EDT Tue Jun 25 2024 Thunderstorms tracking across eastern Lake Superior along a cold frontal passage will bring somewhat gusty winds and lightning to mariners over the eastern lake early this morning. Winds will shift from southerly to westerly winds behind the cold front later this morning while gusting as high as 30 kts. Strongest winds are expected over the central portion of the lake as fcst soundings and model guidance suggest a (20-30%) potential for west gale gusts to 35 knots, especially at higher platform locations like Stannard Rock. This period of longer fetch and stronger winds will help waves build up to 4-6 feet this afternoon and evening north of the Keweenaw. Winds around 20-25 kts veer north tonight 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 s-se gusts near 20 kt Friday and 20-25 kt nw gusts behind a cold frontal passage Saturday before building high pressure returns Sunday and ushers in lighter winds. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JTP LONG TERM...Voss AVIATION...07 MARINE...Voss