Copper City, Michigan Weather Forecast Discussion

676
FXUS63 KMQT 191905
AFDMQT
Area Forecast Discussion
National Weather Service Marquette MI
305 PM EDT Fri Sep 19 2025
.KEY MESSAGES...
- Off and on showers and thunderstorms are expected Saturday through
early next week.
- Seasonable temperatures continue through next week.
&&
.DISCUSSION...
Issued at 304 PM EDT Fri Sep 19 2025
Afternoon water vapor and RAP analysis reveal broad troughing over
the Northern Plains, with an embedded closed midlevel low spinning
over eastern South Dakota and additional shortwaves rotating around
the parent trough. At the surface, low pressure is analyzed over
the eastern Dakotas and western Minnesota, with an associated
stalled front extending out from it into MN and southern WI and
another cold front extending into IA. Closer to home, spotty showers
continue across the western half of the UP courtesy of some weak
shortwave action, but drier midlevel air is moving into northern WI
ahead of the aforementioned stalled front; this will help to bring a
brief pause in shower activity into the evening hours.
Tonight through Sat, the closed low unravels while the parent trough
begins to move towards the Great Lakes, and a somewhat more vigorous
shortwave currently moving into eastern NE swings towards the UP
with the stalled front slowly lifting northward through WI. So,
while dry weather will persist for most through tonight, chances for
scattered showers return for the daytime hours Saturday. Our best
window for showers will be Saturday night as the more vigorous
shortwave ripples through. Another trailing shortwave moves through
Sunday, keeping PoPs in the forecast for the remainder of the
weekend. Some thunder will not be ruled out given some modest
instability (a few to several hundred j/kg of MUCAPE) but weak
forcing and limited shear will preclude any risk for severe storms.
Where we can get any heavier showers or storms, guidance favors the
occasional quarter-inch of QPF. Otherwise, look for temperatures to
continue to come in more or less near normal through the weekend
with highs ranging generally in the mid/upper 60s and lows in the
50s.
Chances for showers and perhaps a non-severe storm linger Monday as
the trough slowly moves through. From there, high pressure builds in
with diminishing cyclonic flow aloft bringing back drier weather for
Tuesday and Wednesday. However, forecast confidence wanes from this
point onwards as synoptic features are poorly resolved by guidance
after Wednesday. The general trend is for a shortwave to move
onshore of the Pacific NW early in the week, drop into the Plains by
midweek. Some of the guidance closes off a midlevel low over the
Midwest or Great Lakes by this point. Then, the trough or midlevel
low finally drops south of the Great Lakes by late Friday. A ridge
looks to build in over the W in the trough`s wake, traversing E
toward the Canadian Prairie into the weekend. How that feature gets
affected by a closed low developing somewhere over the Central U.S.
or several messy shortwaves across the CONUS is not clear. Opted to
leave the NBM as is, favoring drier weather and rather steady temps
with highs in the mid 60s to low 70s and lows in the mid 40s to mid
50s.
&&
.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 205 PM EDT Fri Sep 19 2025
Upper level low over the northern Plains maintains mostly cloudy
skies over the U.P. today, with scattered rain showers ongoing
across the west. This is producing mostly MVFR conditions with some
localized pockets of IFR impacting both KIWD and KCMX as of 18z.
Expect conditions to trend towards VFR through 21z as the current
batch of showers exits the area. Showers will spread back into the
area early Saturday morning, also reaching central and eastern
portions of the U.P. after 08-10z Sat. Expect predominantly VFR
conditions with some intermittent bouts of MVFR in heavier showers
through the end of the period. Winds primarily out of E-SE below 10
kt at most sites, but KCMX could gust to 20-25 kt at times this
afternoon and evening.
&&
.MARINE...
Issued at 304 PM EDT Fri Sep 19 2025
Northeast winds remain elevated across the western arm of the lake
through this evening and into the first half of the night, with 20-
30kt gusts common. There remains around a 20-40% chance of some gale-
force gusts closer to the Duluth harbor. This builds significant
wave heights up to 3-4 ft SW of Stannard Rock and between 4-9 ft
over the W half through this evening. Winds veer ESE tonight into
early Sat with 20-30kt gusts continuing; this time the strongest
winds will be over the eastern half of the lake. This results in
waves of 3-6 ft over the N-Central waters and along the
international border on Sat. Winds gradually settle below 20 kts
from W to E late in the day Sat through Sun morning, likely
remaining below 20 kts through much of next week. Otherwise, expect
on and off showers and thunderstorms this weekend.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
DISCUSSION...LC
AVIATION...CB
MARINE...LC

NWS MQT Office Area Forecast Discussion