Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
009 FXUS63 KMQT 240812 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 412 AM EDT Mon Jun 24 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 far west associated with thunderstorms Monday night into Tuesday morning. - Tuesday will be the warmest day of the week with highs in the mid 70s to mid 80s. Gusty winds to 30 mph also expected, especially over the Keweenaw. - Next round of precipitation expected Thursday night 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 /TUESDAY THROUGH SUNDAY/... Issued at 411 AM EDT Mon Jun 24 2024 Tuesday morning, a cold front draped from a 989mb low over far northern Ontario and its parent 500mb trough will push through the UP. While some thunderstorms will likely remain over some portions of the UP, the extent that thundershowers remain is uncertain. Among the 00Z HREF run, only the HRRR shows widespread thunderstorms present by 12Z Tuesday with the other members showing only isolated to scattered showers remaining. Attempted to somewhat split the gap in these solutions with this forecast, but confidence is somewhat low given the spread in the ensemble solutions. Any lingering storms are unlikely to be severe as the better instability will be to the south while better forcing will be to the north with probably less than 1,000 J/kg of MUCAPE to work with over the UP. MOS guidance suggests high temperatures in the central UP climbing to the mid 80s with the 75th percentile of the NBM still hinting that 90s could be possible in some typical warm spots in the south. Mixing behind the front will allow for dew points to not be as high as originally forecast. The other thing that mixing will do is create some gusty conditions especially in the west and over the Keweenaw. This forecast will reflect gusts in the 30-35 mph range, but the ceiling for gusts over the Keweenaw could be higher as the HREF suggests locally over 50% chances for 40 mph gusts Tuesday evening. A dry period then is expected into Thursday night as a ~1015 mb high pressure descends southeast through the Great Lakes from the Canadian Prairie Provinces. While a shortwave trough will pass over the UP Wednesday morning and both the Euro ensemble and GEFS show a 20-30% chance of precipitation, this forecast will reflect dry weather with the subsidence associated with the dry weather. Cool northerly surface flow on Wednesday will cause highs to only reach the 60s, and potentially only the high 50s along the eastern Lake Superior shores. Attention then turns upstream as a trough over the Pacific NW makes landfall Wednesday night, then continues east along the U.S./Canada border and reaches the Upper Great Lakes by Saturday. This will support cyclogenesis in the northern Rockies Thursday night/Friday with the low ejecting east-northeast to just north of Lake Superior for Friday night/Saturday. While spread is still high on the details of this system, the general trend is for this low pressure to weaken as it approaches the Upper Great Lakes, so hazardous weather seems unlikely at this forecast issuance. Drier weather looks to return the rest of the weekend as a stronger high pressure near 1025 mb settles over the UP by Sunday evening. As the high shifts east to start next week, PoPs increase as another low is expected somewhere in the Plains, but spread is high on the track of said low. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 204 AM EDT Mon Jun 24 2024 Lingering relatively moist dew points will result in some patchy fog overnight which could impact the terminals. The best chance of visibility restriction will be at IWD where conditions could bounce between MVFR and IFR. Otherwise, VFR conditions are expected during the day on Monday under high pressure. The approach of a cold front from the west will bring in a threat of showers/t-storms into the western U.P. this evening. While there is considerable model uncertainty at this time on the evolution of these showers and possible storms tonight, I did include showers with a vicinity TS for IWD by late evening/overnight into Tue. A tightening pressure gradient ahead of the front will also result in LLWS at all the terminals Monday evening. && .MARINE... Issued at 411 AM EDT Mon Jun 24 2024 Expect winds below 20 kts through the day as high pressure ridging passes over Lake Superior. South winds increase to around 20 kts tonight ahead of a passing cold front. Tuesday, gusty westerly to northwesterly winds will increase to around 25 knots over the western and central portions of the lake and to near 30 knots between Isle Royale and the Keweenaw, with a 10% chance of a few gale force gusts. Winds taper off Wednesday morning as they veer north, remaining below 20 kts under high pressure through Thursday. A weakening low pressure approaching the region will allow for gusts near 20 kt, but given the uncertainty in the track of the low, the timing and direction of these gusts is difficult to determine with this forecast package. High pressure returns Sunday and ushers in light winds. Strong to severe storms are possible in the west tonight into Tuesday with the passing cold front. Waves will be strongest north of 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...07 MARINE...GS