740 FXUS63 KMQT 290729 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 329 AM EDT Mon Jun 29 2026 .KEY MESSAGES... - Scattered showers with embedded thunderstorms will overspread Upper Michigan early this morning. Some could become strong at times with gusty winds, small hail, and frequent lightning. - Hot and humid weather is expected through much of the week, with the hottest period today through Wednesday. The heat index will reach the lower 100s over the west and south today and much of the western and central U.P. on tomorrow. The very humid airmass will offer little relief and cooling tonight with the heat index staying at or above 70F. So, a heat advisory remains in effect for the western and southern UP. - There will be the chance for thunderstorms every day this week along with the potential for strong to severe thunderstorms. && .UPDATE... Issued at 327 AM EDT Mon Jun 29 2026 Moisture/warm air advection is surging northward early this morning as a warm front continues to overspread Wisconsin. Surface analysis at this time shows the front bowing into southwest Wisconsin where ground-based obs are already reporting temps and dew points in the low 70s. Subsequently, showers and thunderstorms are becoming more widespread on latest radar mosaic with the strongest line stretching from southern Ontonagon County southeastward into northeast Wisconsin. So far, convection has remained sub-severe, but some have become strong with gusty winds and small hail. Main threat at this time is the especially heavy, frequent lightning with this cluster. Will continue to monitor as they make their track northeastward across the UP early this morning. A weaker, earlier line has since passed through northern portions of the forecast area with just a few rumbles of thunder and light rain here at the National Weather Service in Negaunee Township. && .DISCUSSION... Issued at 225 PM EDT Sun Jun 28 2026 Warm air and moisture advection in the mid levels set off a few light showers and sprinkles this morning but otherwise it was dry today. A large MCS pushed from MN to IA and far western WI bringing a shield of high clouds north over the western half of the UP. A few showers associated with the decaying MCS could move into the west this afternoon but overall activity will be isolated. Temperatures had warmed into the 70s to low 80s with southeasterly flow over the region in response to low pressure over the plains. Upstream, an upper level low was over the northern Rockies and north-central MT, with ridging continuing to build over the Great Lakes. Gulf moisture surges north into the UP overnight under southerly flow. Instability will increase through the night as a warm front pushes north into the area. The front seems to be slowing down from yesterdays guidance which may keep the stronger and isolated severe thunderstorms south of the UP, over north-central WI. HREF updraft helicity tracks are confined mainly over WI but there are a few over the southern UP, particularly Menominee county. Plenty of updrafts are indicated across the UP and likely widespread showers and thunderstorms late tonight into the morning hours on Monday. MUCAPE will be in the 1000-2000 J/kg range with effective shear of 30-40kt. SPC has shifted the marginal risk for severe thunderstorms south, which now overlaps only parts of the UP near the MI/WI border where large hail can not be ruled out with a stronger storm. Heavy rain can also be expected with any thunderstorms that develop with a deep, warm airmass. The upper level low will very slowly make its way from the Northern Rockies to northern Manitoba through Wednesday night. Ridging will continue to build ahead of the low pressure bringing southerly flow and increasing temperatures and moisture. By Tuesday and Wednesday 850mb temps warm up to 22-24C which will translate to highs well into the 80s to mid 90s across much of the UP. Humidity also begins to increase starting Monday with Gulf moisture surging north, bringing dewpoints to near or exceeding 70F at times. Heat impacts are expected this week, especially over the west Monday through Tuesday as lows remain warm (60s to low 70s) and daytime highs approach or break the 90F mark, combining with the humid airmass to bring heat indices into the 90-103F range. Heat advisories have been issued for the south and west and may need to be expanded tomorrow for the heat Tuesday into Wednesday. While the heat index remains borderline with respects to criteria, the extended period of heat and warm nights warrants the hazard and messaging. Those who will be exposed to the heat for prolonged periods and those who are sensitive to the heat should have a plan to stay cool and hydrated. In addition to the heat, thunderstorms will be possible at times through the week. Potential instability will remain moderate to high through the week though the atmosphere will largely will remain capped and large scale ascent will likely be needed to trigger convection. ECMWF cape EFI is high on Monday through Wednesday with shift-of-tails of 1 over the Great Lakes Tue and Wed. Values are a bit lower with combined cape/shear but still notable and a few areas of SOT of 1 is now showing up over the UP. Overall, should convection develop during this period it could be strong to potentially severe but it is too early to pin down details. Should MSC activity occur, outflow boundaries and lingering cloud cover will likely impact the evolution of the proceeding day's convection and high temperatures. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 134 AM EDT Mon Jun 29 2026 VFR conditions will prevail at all sites through the early morning hours, but as chances of TSRA increase this morning, the ceilings will decrease to MVFR and over 50% chances of IFR for some period in the morning, even after the precipitation ends. Skies begin to lift and scatter in the afternoon hours. Winds will be consistent out of the south to southeast, though some gusts to 20+ kt are forecast at times at IWD and SAW. && .MARINE... Issued at 225 PM EDT Sun Jun 28 2026 Low pressure will continue to deepen over the central U.S, ahead of a upper level low pressure that will slowly move from the Northern Rockies to northern Manitoba through Wednesday night. This will result in a tightening pressure gradient over Lake Superior and increasing winds. Easterly winds of 20-30kt can be expected to develop this afternoon over the open water, turning south-southeast on Monday. Winds will remain southerly for Tuesday and Wednesday but generally 20kt or less. There is the potential for thunderstorms starting tonight, with chances each day through the week. Predictability on timing and coverage is too low but there remains a chance for strong to severe thunderstorms at times through the week. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Heat Advisory from noon EDT /11 AM CDT/ today to 8 PM EDT /7 PM CDT/ Tuesday for MIZ002>004-009>011-084. Lake Superior... None. Lake Michigan... None. && $$ UPDATE...TDUD DISCUSSION...NL AVIATION...GS MARINE...NL