Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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350 FXUS63 KMQT 231716 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 116 PM EDT Mon Sep 23 2024 .KEY MESSAGES... - 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 /THROUGH TONIGHT/... Issued at 116 PM EDT Mon Sep 23 2024 Apart from some fair weather cumulus developing across the western half of the UP, skies remain sunny with weak ridging in place over the Great Lakes. Temperatures hover in the lower 60s so far, and should be able to climb a little higher into the mid and possibly upper 60s across most of the UP this afternoon. Tonight, our ridge breaks down as a couple features of interest move towards the area. The first is a shortwave currently tracking into the mid-Mississippi valley. This heads into the Lower Great Lakes tonight, while another surface low currently moving into Manitoba tracks through Ontario. None of these are expected to track close enough to the UP to bring in any rain chances tonight, but a resulting shift to southerly flow will help to touch off weak WAA. Expect 850mb temperatures to climb to near 8C by early Tuesday morning. This, in addition to increasing mid/upper level cloud cover should help to keep temperatures a couple of degrees warmer than this morning. Still, much of the interior UP should be able to drop into the upper 30s to lower 40s, while some of the typically cooler spots (throughout the interior-west and north-central UP) fall further into the mid 30s. Will not rule out some patchy frost yet again. Patchy fog will also be possible with light southerly winds over the land tonight. && .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 /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 116 PM EDT Mon Sep 23 2024 VFR conditions for the duration of the TAF period with ridging over the region. Midlevel cloud cover fills in late tonight into Tuesday morning as a shortwave trough moves into the Lower Midwest. && .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...LC LONG TERM...Jablonski AVIATION...LC MARINE...Jablonski