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Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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500 FXUS63 KMQT 300706 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 306 AM EDT Sun Jun 30 2024 .KEY MESSAGES... - Rip currents and dangerous swimming conditions at Lake Superior beaches of Alger and Marquette counties through this evening. - Dry weather Sunday morning through Monday evening under high pressure. - Next rounds of showers and thunderstorms arrive Monday night, continuing into Wednesday. - Warm and wet pattern expected to continue well into July. && .SHORT TERM /THROUGH SUNDAY NIGHT/... Issued at 418 PM EDT Sat Jun 29 2024 Thunderstorms continue across the far eastern UP this afternoon, with a cold front not far behind in the central UP. These storms have a history of producing large hail, and with MUCAPE still up to 2000 j/kg and sufficient shear to sustain updrafts, will not rule out additional strong convection from eastern Luce county southwest through Green Bay. Meanwhile, outflow from earlier storms in northern Marquette and Alger counties is quite apparent on radar, and has touched off additional weak showers. That said, most convection apart from clusters currently working through Luce, southern Schoolcraft, and Mackinac counties have struggled to climb high enough even to produce lightning - not surprising, given modest capping indicated in model soundings and the afternoon NUCAPs profiles. Upstream, additional spotty shower activity has become apparent. Given cooler post-frontal flow as winds turn over to the NNW, moist lower levels, and another shortwave dropping from northern MN through the UP tonight, expect spotty shower activity to continue at least through the first half of the night. This would be most likely across portions of the UP where NNW flow is upsloping (so, much of the higher terrain of the western UP, portions of the north-central UP, and across Alger and northern Luce counties). Skies gradually clear out the rest of the night, with temperatures largely bottoming out in the lower to mid 40s. However, some cooler spots in the western and north-central UP may fall even further into the upper 30s. Strong post frontal northwesterly winds are expected to create dangerous swimming conditions for Marquette and Alger counties through this evening. A Beach Hazards statement is in effect. && .LONG TERM /MONDAY THROUGH SATURDAY/... Issued at 305 AM EDT Sun Jun 30 2024 Long term period, beginning Monday, kicks off with a 1027mb surface high overhead while mid-upper level ridging extends from the Gulf of Mexico northward through the region. This will support a dry day, but the next system moving closer will support increasing cloudiness in the west by afternoon. Daytime highs should climb into the 70s. Upstream on Monday, broad troughing will exit the northern Rockies, moving into the northern Plains and lifting a shortwave through the region by Monday night into early Tuesday. Increasing isentropic ascent will support rain lifting into the west overnight. Some thunderstorms can`t be ruled out given the elevated instability characterized by 200-500 j/kg MUCAPE. As Tuesday progresses, ridge of theta-e advection moves through the region enabling the initial swath of rain to shift east. This while a stout 35-45kt 925mb LLJ moves through as well. Similarly to Monday night, thunderstorms can`t be ruled out given the elevated instability, but severe weather is not expected. The LLJ will likely support a breezy day, particiarly on the downslope spots near Lake Superior. EFI and SOT highlight the abnormality of this wind as it relates to the climate record and the EC ensemble system suggests a 50+% chance of 34kt gusts in the high terrain and downslope spots in Alger, Marquette, and Baraga counties. Additionally, the same suggests the higher wind potential in Gogebic County. Expect a break in the rain by afternoon from west to east. The last slug of moisture and the system`s cold front presses through overnight Tuesday and Wednesday, finally clearing eastern Upper Michigan sometime Wednesday afternoon. Over the course of the entire event, deterministic EC suggests 0.5-1.5 inches of rain may fall while the GFS appears to be more tampered. With this being said, both their ensemble systems suggest the south-central and east would be most favored (20-50% chance) for these higher rain amounts. High pressure and a dry start 4th of July follow, but afternoon showers and thunderstorms may develop by afternoon in the west ahead of hte next system moving in. This system looks to press into the Upper Great Lakes Thursday night through Friday. There`s enough differences in the timing of this system to make me uncertain on when the rain will end Friday and its possible it may persist into the evening hours. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 108 AM EDT Sun Jun 30 2024 High pres over the Northern Plains will settle over the western Great Lakes later today and tonight. Very dry air mass associated with the high will result in clearing skies overnight with clear skies then persisting into Mon morning. VFR will prevail at IWD/CMX thru this fcst period. MVFR cigs at SAW will scatter out to VFR before sunrise with VFR persisting for the rest of the fcst period. && .MARINE... Issued at 305 AM EDT Sun Jun 30 2024 Pressure rises and cold air advection should gradually weaken early this morning, enabling winds to begin settling across Lake Superior. Expecting winds below 20kts to return lake-wide by mid-late morning. High pressure begins sliding in from the west through the day, maintaining these light winds through at least Monday. Another system presses in from the west Monday night, bringing with it waves of rain and maybe some thunderstorms, into Wednesday. These rain showers may support fog developing and periods of low visibility on the lake. A stout 925mb low level jet of 35-45 kts will also come with this sytem. This will support increasing southerly winds Monday night into Tuesday. Internal probabilistic tools suggest a low probability (<25%) that these stronger winds will mix down to the surface, and there`s some validity to this given the increasingly warm airmass and stability over the lake at the time. With this being said though, localized terrain driven influences should support small pockets of mixing down low end gales, particularly downwind of the lakeshores east of Marquette and along the northern shores of the Keweenaw. Latest EC ensemble system suggests a 10-30 percent chance of low end gales north and east of the Keweenaw over the open waters. Given the setup and the consensus of the strength of the low level jet, I suspect these percentages will increase as we approach the event. Another slug of moisture will lift through Tuesday night into Wednesday while winds settle down. The cold front presses through west to east through the day Wednesday, allowing winds to become westerly/southwesterly through the day Wednesday. Another period of stronger winds, upwards of 25- 30kts, looks possible between the Keweenaw and Isle Royale Wednesday in this southwesterly flow. High pressure and light winds return Wednesday night into Thursday. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...LC LONG TERM...JTP AVIATION...Rolfson MARINE...JTP