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
080 FXUS63 KMQT 220838 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 438 AM EDT Sun Sep 22 2024 .KEY MESSAGES... - Showers end from west to east through today as the cold front exits the UP. Gusty NW winds behind the front, with the highest gusts along the eastern shores of Lake Superior up to 30 mph. - Other than a low chance (15-25%) of showers Tuesday afternoon through Tuesday night associated with a low pressure passing through Lower Michigan, dry weather is expected this week. - Patchy frost is possible (~20%) for typical cold spots of interior western Upper Michigan both Monday and Tuesday mornings. - Supportive setup for patchy fog (~25%) each morning next week. && .SHORT TERM /THROUGH SUNDAY NIGHT/... Issued at 321 PM EDT Sat Sep 21 2024 Latest water vapor imagery shows a well-defined shortwave trough lifting northeast into northern Ontario and northern MN this afternoon. This shortwave trough will move into the Upper Great Lakes later tonight and Sunday, sending a sfc cold front across Upper Mi tonight into Sunday morning. WAA and a 40+ kt LLJ max ahead of the cold front have already supported showers and scattered t- storms early this afternoon into north central WI and portions of western Lake Superior. A few showers may have made it into far western Upper Mi but showers have generally dissipated moving into into ridging and the associated dry and stable air mass across Upper Mi. While it`s been more cloudy into western Upper Mi due the convection drifting into that area, ridging has supported more sunshine into central and eastern areas of the U.P. this afternoon. Afternoon temperatures have generally been in the 70s to lower 80s, warmest inland east and coolest west under the clouds. Heading into this evening and tonight, the vort max/shortwave will continue to lift northeast through northern Ontario which will send the mid-level trough axis across Upper Mi later tonight into Sunday. As the system`s associated cold front moves across Upper Mi tonight into Sunday morning, showers along the cold front will most likely move into far western Upper Mi early this evening and then spread into central Upper Mi late evening and eastern Upper Mi overnight. Instability along the front is not particularly impressive, generally 500 j/kg MUCAPE, with the best of that south along the WI border. Effective shear along the front when showers will be occurring also generally looks like it will be 30 knots or less, so not really expecting any severe storms, but maybe a stronger storm with some dime-sized hail could develop south central along the WI border where marginal instability and shear appear to be maximized. Look for min temps lowering into the 50s behind the cold front tonight. Northwest winds behind the front could gust near 30 mph late tonight/early Sunday along the tip of the Keweenaw. && .LONG TERM /TONIGHT THROUGH SATURDAY/... Issued at 437 AM EDT Sun Sep 22 2024 Tonight through Monday, the mid level trough over Lake Superior and northern Ontario lifts northeast toward Hudson Bay while another trough to the west moves southeast to the Dakotas. This allows for weak high pressure to shift northeast from MN to northern Ontario/Quebec. The associated cold front and showers are expected to already have exited the CWA by tonight, leaving clearing skies tonight save for a scattered low level deck over north-central Upper MI. This low level cloud deck looks to clear out Monday morning leaving mostly Sunny skies the rest of the day. A drier airmass behind the cold front and subsidence from the weak high pressure will help yield a cooler night. Lows tonight are expected in the mid 30s to upper 40s, warmer by the Great Lakes, especially beneath scattered low cloud deck in north-central UP. Some patchy frost may develop in the interior west and also some patchy fog may develop in the far west late tonight. Highs on Monday will peak in the 60s. Monday night through the mid portion of next week, the trough over the Dakotas dives southeast toward the Lower Mississippi Valley while a shortwave over the Mid Mississippi Valley moves northeast over Lower MI and the Lower Great Lakes. Meanwhile ridging is building over the western CONUS. This sends a low pressure system over southern IL on Tuesday to lower MI. Then the low takes a slower and more northerly track Tuesday night through Wednesday night to Quebec. While some light showers may scrape the south and eastern portions of the UP Tuesday afternoon and Tuesday night, not much of any accumulations are expected as the better forcing remains outside the CWA. Otherwise, highs on Tuesday and Wednesday will be just above normal in the mid 60s to mid 70s. Monday night could be another cool night with lows in the upper 30s to upper 40s. Patchy frost is possible again in the interior west. Model soundings show a more impressive inversion Monday night compared to tonight, so more patchy fog is possible Monday night across the entire UP. The mid level ridge positioned over the Rockies Wednesday morning shifts east toward the Great Lakes for next weekend. There are some discrepancies how the trough that dives southeast to the Lower Mississippi Valley mid next week interacts with potential tropical system. That said, the stronger ridging moving over the Great Lakes region favors drier weather with warmer than normal temps in the 70s. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 130 AM EDT Sun Sep 22 2024 Cold front moving through Upper Michigan tonight and Sunday will support cloud bases lowering and ceilings developing, mainly at KSAW, although KIWD and KCMX may experience MVFR ceilings this morning before scattering out. Expect conditions to improve through the day Sunday. Models continue to suggest that showers, perhaps mixed with some thunderstorms, will develop later tonight and impact KSAW. These same models have, notably, struggled all night with upstream convection moving into the U.P., so confidence is low. Post frontal airmass will also support some gusts of 20-25kts, mainly at KSAW and KCMX. && .MARINE... Issued at 437 AM EDT Sun Sep 22 2024 A cold front currently over central Lake Superior will continue east across the rest of the lake this morning. South-southwest winds ahead of the cold front quickly veer northwest as the front passes, gusting up to 20-30 kts. Some thunderstorms are possible over the east half of the lake this morning with the passing cold front, although no strong to severe weather is anticipated. Waves behind the front will peak between 4 and 5 feet along the western UP shores this morning and over the east half of the lake between 6 and 7 feet later this morning through this evening; waves fall below 4 feet lakewide by Monday morning. Northwest winds gradually fall below 20 kts from west to east across the lake this afternoon through this evening, veering north tonight. Although a low pressure system tracks through Lower MI Tuesday night and Wednesday, winds are expected to remain below 20 kts the remainder of the forecast. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Voss LONG TERM...Jablonski AVIATION...JTP MARINE...Jablonski