Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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044 FXUS63 KMQT 171759 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 159 PM EDT Mon Jun 17 2024 .KEY MESSAGES... - Continued showers and thunderstorms this afternoon with some potential for isoalted strong or severe storms. - Multiple rounds of showers and thunderstorms expected this week. Strong to severe storms possible Tuesday night into Wednesday. - Hot and humid Tuesday, followed by very muggy rest of the week. - Potential heavy rain event this weekend. && .SHORT TERM /THROUGH TONIGHT/... Issued at 159 PM EDT Mon Jun 17 2024 A line of showers and thunderstorms moved through Upper Michigan today along of a warm frontal boundary, with what appeared to be a mix of strong to severe storms embedded within the complex. As of now, some pea sized hail has been reported and a wind gust at KIMT measured 53 mph. Ahead of the line, dewpoints surged into the upper 60s to near 70F. Behind the line, temps in the 60s were observed ahead of another line of showers draped northeast from northwest WI and western Upper Michigan into western Lake Superior. At the time of this writing, no lightning was being observed with this second line. To the south, isolated thunderstorms are developing across northeast WI within an environment characterized by 2000-2500 j/kg MLCAPE, per SPC mesoanalysis just south of or along the warm frontal boundary. Effective bulk shear from the same source generally ranges from 40-50 kts. As we progress through the remainder of the afternoon, ongoing thunderstorms currently across the central will continue its eastward progression. Additional shower and thunderstorm development will be possible as the warm front begins lifting north. Main focus area will be across central and eastern Upper Michigan given the mean flow and proximity to the warm front as it continues lifting north. There is some potential for strong to severe thunderstorms within this. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Issued at 418 AM EDT Mon Jun 17 2024 The active weather pattern doesn`t look like it will relent over the rest of this week as troughing deepens over the western U.S. and ridging amplifies over the Eastern Seaboard early this week. This keeps us on tap for very warm and moist conditions Monday through Tuesday, before the troughing pattern moves east and brings cooler temperatures across our area Wednesday into Thursday; be careful if working outside Tuesday, as the hot and humid weather could cause heat exhaustion and heat stroke! Meanwhile, expect showers and thunderstorms chances to continue across Upper Michigan throughout the rest of this week into next weekend, with a few strong to severe storms being possible Monday and Tuesday night/Wednesday. The severe weather threat, should any occur, would be hail, winds, and repeated heavy rainfall causing ponding. Additional details follow below. The frontal boundary lifts north of the area Tuesday, and should stall out across northern Lake Superior and northern MN. Skies turn sunny, then expect muggy and even warmer weather Tuesday as we sit directly underneath the warm sector of a low lifting through the Lake Winnipeg area. A tight pressure gradient and a 30-40kt LLJ over the area all point to a potential for a breezy day (will also note the EFI continuing to highlighting unusually strong winds for Tuesday). However, with a low-level cap in place, it may be difficult to get the winds to gust much more than 30 mph, save for the downslope areas near Lake Superior where mixing could be locally enhanced. Expect temperatures to get into the high 80s to low 90s during the afternoon hours, with dewpoints reaching up into the low 70s. This will cause the heat index to get into the 90s across much of the area, with a spot or two possibly flirting with the 100 degree mark. Breezy conditions may help to keep things from feeling so oppressive, but be mindful of the heat and take precautions regardless. Stay hydrated! Moving into Tuesday night, the aforementioned low near Lake Winnipeg will continue to move through Ontario while weakening, then the cold front off to our west slowly swings through overnight into Wednesday. Showers and storms begin to move back into the western UP as early as Tuesday evening along the front, which would be favorable timing for strong to severe convection. MUCAPE across the western UP could exceed 1000 J/kg and 0-6 km bulk shears approach 40 to 50 knots. Our main threat would be hail, with damaging wind a secondary concern. In addition, expect heavy rainfall, with ensembles showing PWATs near the max of climatology/around 2 inches! With storms possibly training ahead of the frontal boundary, ponding of water in poor drainage would be a concern. However, as episodes of rain in the preceding days have chipped away at hourly flash flood guidance, some flash flooding is not out of the question (around 5% chance) in smaller streams and even in somewhat better- draining areas. The central and eastern UP may miss out on severe convection Tuesday night as we`ll have long since run out of daylight by the time the front moves in. Meanwhile, nighttime won`t do much to alleviate heat concerns as temperatures only fall back as far as the mid/upper 60s for a large portion of the area. Wednesday, the front finally begins to settle just to our south. Weak waves rippling through will provide some additional lift to keep chances for convection to fire along the boundary Wednesday through Friday. Will note that PoPs are concentrated mainly across the southern half of the UP given the potential for weak high pressure over Ontario to further suppress the frontal boundary southward. Going into next weekend, a low pressure lifting off of the Colorado Rockies and an upper level Clipper low look to phase with each other over the Upper Midwest. This will bring additional showers and thunderstorms across our area via warm frontogenesis through at least the first half of next weekend, then the cold front moves through late in the weekend with lingering PoPs. Ensembles continue to favor PWATs as high as 2in, well above normal, highlighting another couple of days worth monitoring for the heavy rainfall potential. && .AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 122 PM EDT Mon Jun 17 2024 Showers and thunderstorms moving through Upper Michigan will continue pressing east, trailed by periods of light rain. Some additional thunderstorms may develop near KSAW this afternoon, but overall, thunderstorm activity is expected to be minimal for the remainder of the afternoon. Another wave of showers, potentially mixed with some thunderstorms, moves in to mainly western Upper Michigan this evening and tonight, impacting KIWD and KCMX. By morning, rain showers and thunderstorm activity activity is expected to be over. With the increased moisture from rain, ceilings should trend to MVFR this afternoon/evening at all sites and then to IFR at KCMX/KSAW. Additionally, fog/mist should develop overnight after the showers/storms end. Expect fog to lift in Tuesday morning, followed by gusty winds developing. && .MARINE... Issued at 418 AM EDT Mon Jun 17 2024 Light winds around 5-10kts start off mainly from the west this morning, but shift over to the east this afternoon. The light winds continue through tonight before increasing from the south to 20 to 25 knots over the eastern half of the lake Tuesday. In addition, expect some downsloping winds near the southern shoreline to gust up to 20 to 30 knots, with a few gale force gusts up to 35 knots possible (10% chance or lower), particularly in the nearshores from Marquette to just west of Whitefish Point. The winds fall back down to 20 knots or less again by early Wednesday morning as the frontal boundary just west of the area finally begins moving across the lake. Winds stay light through the rest of the week as weak high pressure ridging settles over northern Ontario. Several rounds of showers and storms are expected across the lake from this afternoon through Wednesday. Some strong to severe storms are possible during this time, with hail and wind being the main threats. Areas of fog, dense at times, are possible following rounds of rainfall. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JTP LONG TERM...LC AVIATION...JTP MARINE...LC