Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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717 FXUS63 KMQT 230841 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 441 AM EDT Mon Sep 23 2024 .KEY MESSAGES... - Moderate swim risk through this morning for the Lake Superior beaches of Alger County. - Other than a low chance (15-40%) of showers Tuesday into Wednesday in the southeast and eastern U.P., dry weather is expected this upcoming week with a trend toward much above normal temps again late in the week. - Patchy frost is possible (~20%) for typical cold spots of interior western Upper Michigan both this morning and Tuesday morning. - Supportive setup for typical fall radiative patchy fog (~25%) each morning this week. && .SHORT TERM /TODAY/... Issued at 441 AM EDT Mon Sep 23 2024 Water vapor imagery/surface analysis early this morning show Upper Michigan under the influence of shortwave ridging as yesterday`s trough pushes out of the region. This has meant quiet weather all night across the forecast area, but the drawback has been the cold temperatures with ground-based obs reporting widespread mid 30s across the interior west and the usual cold prone areas of Baraga Plains and Yellow Dog, which are reporting 30 and 29 degrees, respectively. As a result, it would not be unlikely to see some patchy frost this morning across those areas. For the remainder of today, expect plenty of sunshine and dry weather. But, the ENEerly onshore flow will prevent high temperatures from topping off above the 60s. && .LONG TERM /TONIGHT THROUGH SUNDAY/... Issued at 434 AM EDT Mon Sep 23 2024 Tonight remains quiet as a sfc high pressure over Quebec extends weak ridging into the Upper Great Lakes. Meanwhile, a mid-level shortwave over IA lifts northeast to the Great Lakes and a trough over the Dakotas digs southeast. The antecedent dry airmass will help keep the UP dry, but cloud cover will increase overnight from the south ahead of the shortwave which could be a limiting factor in radiational cooling. Given the strong inversion, areas where skies remain clear longer should dip into the mid 30s to low 40s, particularly cooler in the interior west. This leaves potential for some patchy fog and frost development in the interior west. Lows by the lakeshores will be in the mid to upper 40s. The trough continues to dig southeast toward the Lower Mississippi Valley through Tuesday night while the shortwave tracks northeast over the Great Lakes. This takes a weak ~1008mb low pressure over IL on Tuesday northeast to Lower MI by Tuesday evening, then over Lake Huron Tuesday night. While some light showers may scrape along the UP shores of Lake Michigan during the day Tuesday and lift over the east Tuesday night, the better forcing and moisture will remain to our south and east. Thus most will remain dry and accumulations will remain low below 0.1". Highs peak just above normal in the mid 60s to low 70s. Lows Tuesday night settle into the upper 30s to low 50s, colder in the interior west where skies remain clear. By Wednesday, strong mid level ridging will be positioned over the Rockies. The troughing over the Great Lakes will progress eastward through the end of the work week as the mid level east pushes east to the Great Lakes. Also, the southeast diving trough forms a closed low over the Lower Mississippi Valley. This supports dry weather the rest of the work week with one low confidence exception. The Canadian and NAM have the trough over northern Ontario extending further southeast into the Great Lakes Wednesday and Wednesday night as it propagates east. Also, both models note better available moisture so that PVA forces some scattered showers on Wednesday. Given the strong ridging building in from the west, opted to keep the forecast dry for now, but will monitor future model trends. Southerly flow brings temps back above normal temps with highs in the 70s and lows in the 40s to mid 50s. MOS guidance has toggled back and forth between some spots maybe hitting 80 late in the week. While the dry and warm pattern likely will persist much of the weekend, uncertainty begins to grow as a tropical system develops in the Gulf of Mexico. The exact details on how this low interacts with the closed low already in the south are murky, but low chances (<25%) for showers return Sunday onward as tropical moisture surges north from the Gulf. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 126 AM EDT Mon Sep 23 2024 Dry air over the region will support VFR conditions in this TAF period. Some patchy fog will be possible at KIWD overnight but given low confidence, was left out of the TAF. && .MARINE... Issued at 434 AM EDT Mon Sep 23 2024 With high pressure moving northeast over the Upper Great Lakes today, variable winds remain mainly below 15 kts. East winds increase this evening with some gusts up to 20 kts, gradually veering south tonight as the high pressure moves to Quebec; strongest winds are expected over the west half of the lake. Southerly winds taper down below 15 kts Tuesday morning. Although a low pressure system tracks through Lower MI and the Central Great Lakes late Tuesday into Wednesday, winds are expected to remain below 20 kts through the remainder of the forecast as stability increases mid week and high pressure returns late this week. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...TDUD LONG TERM...Jablonski AVIATION...JTP MARINE...Jablonski