Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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299 FXUS63 KMQT 231704 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 104 PM EDT Sun Jun 23 2024 .KEY MESSAGES... - Showers and thunderstorms possible this afternoon and evening. Severe weather is not expected. - A slight risk (~15%) of damaging wind and hail in the west associated with thunderstorms Monday night into Tuesday morning. - Tuesday will be the warmest day of the week with highs in the mid 80s, with dew points in the 60s making it a hot and muggy day. - Next round of precipitation expected late Thursday into the weekend. && .SHORT TERM /THROUGH TONIGHT/... Issued at 104 PM EDT Sun Jun 23 2024 Clear skies with pockets of mostly cloudy skies have been present over Upper Michigan today. This has yielded a mix of temperatures, but overall most areas have climbed into the mid-60s, with a few low 70s here and there. DLH radar returns this morning showed scattered showers across the northern fringes of the Arrowhead and some light rain or sprinkles over western Lake Superior. These are associated with a closed mid-level low and preceding shortwave moving through western Ontario/northern Minnesota. Some of these have started showing up in Upper Michigan, but its uncertain if anything is reaching the ground at this point. As we progress through the remainder of the afternoon/evening, the wave aloft opens up as it moves through Upper Michigan. Some very modest instability may support additional showers and some thunderstorms this afternoon. Any convective development should progress southeast and weaken into the late afternoon and evening hours. High pressure builds in tonight, supporting a mostly clear night with lows dipping into the high 40s to mid 50s, warmest lake- side. The combination of cooler conditions, recent rainfall, and a low level inversion may support fog development across portions of western Upper Michigan tonight. && .LONG TERM /MONDAY THROUGH SATURDAY/... Issued at 442 AM EDT Sun Jun 23 2024 Beginning this coming week, persistent 500mb ridging over the southwest to south-central US with longwave troughing over the eastern coasts of North America leaves the Upper Great Lakes in the main path of shortwaves riding above the ridge and into the larger trough. The resulting surface features will result in multiple distinct rounds of rainfall in this period, first Monday night through Tuesday and then again late Thursday into the weekend. The best chances (~15%) for strong thunderstorms will be with the precipitation Monday night into Tuesday. Without long-duration southerly flow, temperatures generally remain near-seasonal, with the exception of Tuesday when temperatures look to climb to around 80 with dew points in the 60s. Once the remaining fog burns off in the early morning hours, Monday looks to be a mainly quiet day as the region is on the north side of a 1015mb high pressure. CAMs resolve a lake breeze along Lake Superior, but otherwise, southerly to southwesterly winds begin to build in response to a deepening low pressure near 990mb transiting central Saskatchewan and Manitoba. The warmer, moisture-rich air will allow instability to build late, with both GEFS and Euro ensemble CAPE probabilities of over 1k J/kg well over 50% for much of the interior western and central UP by Monday night and 30-40% chance of 2k J/kg. The mainly southerly surface flow contrasted with the mainly westerly flow aloft will create a supportive shear profile for the maintenance of storms, as surface-500mb shear values will be near 40 kt in the west Monday night. The forcing will come from the cold front draped from the low as it passes into far northern Ontario. With the past 24 hours of model guidance, confidence has increased in the cold front arriving in the western UP around 06Z Tuesday. The current run of the HREF shows virtually no precipitation potential prior to 00Z over the UP, however, it does show convective initiation further upstream, and given the present forcing and ingredients present, the SPC Slight Risk for dual 15% risks of severe wind and hail is warranted. The biggest source of uncertainty seems to be in storm mode, whether it will maintain a (super)cellular structure or if a MCS will form upstream. Southerly winds at the surface persist into the daytime hours Tuesday, which the warm advection combined with radiational heating will allow Tuesday to be the warmest day of the week, with the most likely high temperatures for Tuesday being in the low to mid 80s, though the 75th percentile shows some isolated spots of 90s. It could also be a muggy day as forecast dew points approach 70. Eventually, winds will veer westerly behind the front draped from the long-away low pressure and temperatures will moderate somewhat. Lingering thunderstorms are possible, especially if the lifting from the front is on the stronger end of guidance, but PoPs are generally expected to be around 30% Tuesday afternoon to evening. Ensemble guidance has increased in certainty over the past 24 hours in a high pressure following behind the cold front, transiting the Upper Midwest and through the Great Lakes Wednesday through Thursday morning. This will lead to the most prolonged dry period of the forecast period with generally clear skies and light winds forecast. Meanwhile, a deep 500mb trough will make landfall in the Seattle/Vancouver region, setting up another northern Rockies low pressure forming by Thursday evening. PoPs over the UP gradually climb as this low will most likely eject towards and north of the Great Lakes by Friday and the weekend. Exact timing, location, and intensity of showers is still hard to pin down given the growing range of possibilities, but there is a surprising amount of certainty in the next high pressure bringing dry weather to the region by next Sunday. Overall, nothing in the ensembles shows any major shift in the pattern, which lines up with the CPC continuing to outlook the UP with best chances for above average temperature and precipitation even into the first portions of July. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 104 PM EDT Sun Jun 23 2024 A weak shortwave moving through the Upper Great Lakes this afternoon and evening may support showers at KCMX and KSAW this afternoon, but otherwise, VFR ceilings are expected to prevail. With clear skies expected at KIWD/KSAW tonight, fog/mist should develop, bringing the terminals down to at MVFR/IFR until fog mixes out after sunrise. && .MARINE... Issued at 442 AM EDT Sun Jun 23 2024 A low pressure system will exit into Ontario this morning. Today, west to northwest winds will mainly remain below 20 kts. High pressure ridging then passes over Lake Superior tonight and Monday, keeping light winds in the forecast until Monday night. South winds increase to around 20 kts Monday night ahead of a passing cold front. Southwest winds behind the front are expected around 20-25 kts, though a few gusts may be in the 25-30 kt range between Isle Royale and the Keweenaw Peninsula Tuesday afternoon. Winds taper off Tuesday night into Wednesday, remaining below 20 kts through the late part of the week. Some isolated thunderstorms are possible this afternoon and evening across the west. Strong to severe storms are possible in the west Monday night into Tuesday with the passing cold front. Waves will be strongest between Isle Royale and the Keweenaw Peninsula Tuesday afternoon and evening (4-6 feet). && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JTP LONG TERM...GS AVIATION...JTP MARINE...GS