Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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892 FXUS63 KMQT 170933 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 533 AM EDT Mon Jun 17 2024 .KEY MESSAGES... -Possible strong to severe thunderstorms late today/this evening. In addition, heavy rainfall will be a threat today with the south- central counties possibly receiving 1-2 inches. - Strong to severe storms possible Tuesday night into Wednesday. - Very warm to start the work week, then temperatures trend towards normal from midweek onward. - Frequent chances for rainfall continue the rest of the week. && .SHORT TERM /THROUGH TONIGHT/... Issued at 530 AM EDT Mon Jun 17 2024 The cap has just been too much for showers and thunderstorms to develop tonight with current showers even quickly diminishing as they enter Upper Michigan. It has, though, been a warm and muggy night so far with temperatures holding steady in the 60s across much of the forecast area. After this lull in activity, the HRRR does become more active from the west/southwest after Mon 12Z as a cool front drops into the area. It will be tough for this first round of thunderstorms to become strong to severe, however, with cloud cover still lingering over the area. Better chances will come later today as a surface low continues its track from northeast Nebraska toward southeast North Dakota. Meanwhile, its associated warm front will push northward across the Upper Midwest providing an area for additional convective development along and north of it through the peak heating of the day. The best chances for any warm sector storms will remain behind the front, concentrated over southern MN/central WI. Nonetheless, sufficient bulk shear could be enough to support isolated strong to severe thunderstorms crossing into the UP late today into tonight. The higher threat tonight, though, could be the heavy rainfall with western and central portions of the forecast area under a Slight Risk for excessive rainfall and WPC guidance pinpointing 1-2 inches across the south- central counties. As far as temperatures, trended a bit higher across the far southern counties due to the surge of WAA, putting that quadrant in the low 80s. Elsewhere across the UP, widespread mid to upper 70s are expected except across the far west and along the spine of the Keweenaw. Those areas will trend more toward low 70s. Tonight, another warm and muggy night is expected as overnight lows hold steady in the 60s across the interior with 50s near the lakeshores. && .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 /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 122 AM EDT Mon Jun 17 2024 Expect maybe some isolated showers across the area tonight with showers affecting mainly IWD and CMX. The moist conditions could still lead to MVFR conditions overnight in patchy fog or stratus. Around round of convection is expected to move in from the west after sunrise as ceilings will likely go to MVFR during the day on Monday. Showers will be most prevalent at IWD and SAW with SAW having the best chance of getting a thunderstorm. A break in the showers in the afternoon could be followed by more scattered showers Monday evening. Look for MVFR ceilings to lower to IFR Mon evening and fog formation possible again. && .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...TDUD LONG TERM...LC AVIATION...Voss MARINE...LC