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
510 FXUS63 KMQT 201139 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 739 AM EDT Fri Sep 20 2024 .KEY MESSAGES... - Extended stretch of well above normal temperatures continues through at least Saturday with highs mainly in the upper 70s and 80s. - A cold front continues scattered showers and thunderstorms over mainly the east half today and tonight. - Multiple rounds of precipitation possible through the first half of next week. Thunderstorms that do form are not expected to be severe at this time. - Temperatures around normal are expected to return next week. && .SHORT TERM /TODAY/... Issued at 430 AM EDT Fri Sep 20 2024 A well-defined mid-level low can be seen rotating over the Manitoba/Ontario border early this morning on water vapor imagery. Meanwhile, current radar mosaic remains active in vicinity of the associated surface cold front with scattered showers concentrated over the Keweenaw and central UP. Embedded thunder has been waning over the last several hours. Nonetheless, will carry mention of thunder through today mainly over the eastern half of Upper Michigan as the aforementioned cold front continues its eastward propagation into environment with marginal instability. No severe threat, though, is expected. Nonetheless, the eastern third of the forecast area could pick up a couple tenths of an inch of rainfall. Farther west, rapid clearing will follow in the wake of the showers/thunderstorms, and high temperatures will have a chance to climb into the mid to upper 70s over the west and south. The eastern third, however, will not have as much time to rebound from the cloud cover/rain and is only progged to top off in the low 70s. Currently, ground-based obs across the area are reporting widespread 60s for temperatures and no patchy fog formation at this time. && .LONG TERM /TONIGHT THROUGH THURSDAY/... Issued at 337 AM EDT Fri Sep 20 2024 The last of the rain showers and thunderstorms associated with the cool front today ends over the east tonight as high pressure ridging builds in. As this occurs, the clearing skies will allow the temperatures to drop to around 50 in the interior west, whereas the interior east may only get down into the mid 50s due to the cloud cover earlier in the evening and patchy fog late tonight. Speaking of which, expect this fog to form over the central and east tonight given the clearing out and moisture from the recent rainfall; I wouldn`t be surprised if the fog was even dense in a few spots come early Saturday morning. The patchy fog looks to eventually burn off a couple of hours after sunrise Saturday morning. Expect Saturday to be another very warm and mostly sunny day via the weak high pressure ridging scooting over us. With warm air advection moving over us aloft late tonight through Saturday, expect high temperatures to get to around 80 in the east and the lower 80s in the west. Meanwhile, given the abundant sunshine and moisture, we could have some good mixing in the boundary layer by the afternoon hours, bringing min RHs down to possibly as low as the lower 30 percents in the interior west. If the mixing overachieves today, we could see some limited fire weather concerns via min RHs getting down to or below 30%. However, given the ridging overhead, winds are expected to be fairly light from the south across most of the area (the exceptions are the Keweenaw/near Lake Superior where some lake breeze action may come into play). Now as a low pressure over the Canadian Prairies lifts towards Hudson Bay Saturday into Sunday, a cold front associated with the low approaches us from the west by the afternoon hours. This cold front looks to bring additional rain showers and thunderstorms over us from Saturday evening into Sunday from west to east. Overall, don`t expect too much rainfall from this cold front either; most areas are looking to only get a tenth of an inch or less, although some spots may locally see more. That being said, the latest Canadian, NAM, and Euro deterministic runs are more generous with the rainfall; hopefully these newer runs are more accurate as we really need the rainfall, particularly over the south central and east where moderate drought (D1) conditions exist according to the latest drought monitor update. While there is an outside chance (2% or less) of seeing a strong storm or two Saturday night through Sunday along the front, with decreasing MUCAPE and increasing cloud cover ahead of the front with time, severe weather is currently not expected. A shortwave lifting from the Plains through the Great Lakes region Sunday through Sunday night may reinvigorate convection over the central and east, but the front may be too far to our south and east by that point for us to receive anything. Thus, the chance of rain from this shortwave over our central and east looks to be about 25% and 50%, respectively, late Sunday through Sunday night. Additional high pressure ridging is expected to return to our area by next Monday, although the warm temperatures are looking to be replaced by those more normal for this time of year. Expect Monday to be the coolest day of next week, with highs only getting into the low to mid 60s and lows possibly dipping into the upper 30s in the interior west Sunday and Monday nights. Moving to next Tuesday, a low originally from the Southern Rockies looks to move through the Great Lakes basin. While the south central and east could be skirted with some light rainfall from the low`s TROWAL Tuesday, with guidance honing in better on the low`s track moving through southern Lower Michigan, not much, if any, rainfall is expected. While near normal temperatures continue through the rest of next week, we may or may not see additional rainfall as the aforementioned low could retrograde back into the Upper Great Lakes. However, the more recent deterministic runs of the medium range guidance are suggesting that we remain under ridging for the last half of next week, with the low being too far to our south. Nevertheless, I feel that the NBM`s 20% pops for most of the area are pretty on point with the rain chances come late next week, just in case the low`s retrograde does move further north towards the Upper Great Lakes in later model runs. && .AVIATION /12Z TAFS THROUGH 12Z SATURDAY/... Issued at 739 AM EDT Fri Sep 20 2024 Lingering rain showers in association with a mid-level low could result in MVFR flight restrictions at times this morning at SAW. But overall, VFR will be the main flight category for the duration of the TAF period at all TAF sites. Meanwhile, winds will slowly veer from the southwest to the west through the day, but will remain under 10 kts. && .MARINE... Issued at 337 AM EDT Fri Sep 20 2024 The southerly 20 to 25 knot winds ahead of the cool front this morning over the north central lake decrease to 20 knots or less later this morning, but southwest winds of 20 to 25 knots do pick up behind the front over the west half of the lake by this afternoon and continue until this evening. Meanwhile, expect showers and thunderstorms to continue trudging eastward over the lake with the frontal boundary. As weak ridging builds in, expect the winds to die down to 20 knots or less again by around sunset, and the last of the showers and thunderstorms ending over the far eastern lake late tonight. Due to the recent rainfall and lighter winds late tonight, we could see some patchy marine fog develop over the eastern lake; some spots could see visibilities of 1 nautical mile or less, so make sure to have your lights on and to use your radar and compass if you are in a fog bank. The light winds continue until another cold front moves through late Saturday into Sunday. While showers and thunderstorms are expected to travel from west to east late Saturday into Sunday over Lake Superior, expect northwest winds of 20 to 25 knots behind the frontal boundary, mainly over the western half of the lake. As the front leaves our area later Sunday, expect the winds to die down to 20 knots or less again as more ridging moves over. The ridging and light winds look to remain over Lake Superior for the rest of next week. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...TDUD LONG TERM...TAP AVIATION...TDUD MARINE...TAP