575
FXUS63 KMQT 181932
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
332 PM EDT Fri Apr 18 2025

.KEY MESSAGES...

- Accumulating snow is possible over the interior western and north-
central U.P. late Sunday night into Monday. Probability of exceeding
3 inches is 20-50%.

- Rain and snowmelt will continue to lead to rises on area rivers
and possible minor flooding on typically flood-prone rivers.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 232 PM EDT Fri Apr 18 2025

Upper air pattern consists of a 500 mb ridge across the ern half of
the U.S. with a deep trough down into the western half of the U.S.
and a shortwave in the northern plains. The shortwave over the
northern plains moves into the upper Great Lakes 12z Sat while
troughing remains over the central and southern Rockies. A sfc cold
front bisects the U.P. this afternoon with also a lake breeze
component kicking in out ahead of the cold front as what happened at
SAW and the NWS office here. When that happened, thick upslope fog
with the northeast wind and low clouds came in and this will
continue into this afternoon until the cold front passes through the
eastern and southern cwa. Expect a resurgence in development of
showers along the cold front later this afternoon and have been
seeing a drizzle area growing across the central U.P. this
afternoon. This is covered well in the going forecast and will not
make many changes to the going forecast.

&&

.LONG TERM /SATURDAY THROUGH FRIDAY/...
Issued at 331 PM EDT Fri Apr 18 2025

Deep moisture plume will have shifted east of the local area by
Saturday morning, with positively tilted trough sweeping through.
Forecast soundings show enough low-level moisture to squeeze out
some upslope-enhanced rain/snow showers over the western UP early
Saturday; otherwise, expect a dry weekend. Temps moderate with highs
in the low 40s to low 50s Sat increasing to mid-40s to mid-50s Sun.

As the northern part of the full-latitude positively tilted trough
shifts east over the weekend, it will leave behind a cutoff low over
the Southwest/southern Plains. This low will eject NEwd, opening up
and going negatively tilted Sunday night into Monday as it enters
the upper Great Lakes. Ensembles have started to hone in on the
track of the attendant surface low from near Kansas City across
northern lower MI into Lake Huron, but ensemble spread increases
toward 00Z Tuesday. Cluster analysis shows the two most likely
outcomes (which are about equally likely) are different in the
pressures within and to the NW of the low track. Resultant QPF
differences with these scenarios are such that a slightly
weaker/eastward low track shifts heavier QPF over the
eastern/southern UP (amounts ranging from 0.25 in the west to 0.75
in the east), while a stronger/westward track puts us squarely in
the heavier QPF (a more widespread 0.75-1.25"). The latter scenario
also brings accumulating snow into the equation due to evaporative
and dynamically forced cooling, mainly over the interior north-
central and west. Probs of > 3" from the EPS/GEFS range from about
20-50%, with > 6" snow 20% or less. Given the time of year and time
of day, with some of this potential snow occurring during the
daylight hours Monday, it would be likely be low impact due to warm
surface temps, but something to monitor nonetheless. River responses
can also be expected on the warm side of this system, which will be
have to monitored where significant snowpack still exists over the
eastern UP.

Following this system, midlevel heights will tend to rise as flow
evolves toward quasi-zonal. As this occurs, a couple of waves will
bring additional rainfall chances for the middle part of the week.
Tendency toward flat ridging will support a warming trend,
especially toward the end of the week.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1233 PM EDT Fri Apr 18 2025

A prolonged IFR period will continue at IWD until late Sat morning
when MVFR conditions occur. CMX will be plagued with upslope fog and
low ceilings and will stay LIFR/VLIFR through tonight and then
improve to VFR by late Sat morning. SAW will continue with upslope
fog and low clouds and be LIFR/VLIFR through the period. SAW could
also see some rain late this afternoon and tonight.

&&

.MARINE...
Issued at 331 PM EDT Fri Apr 18 2025

Areas of fog will continue at times through tonight. Northwesterly
winds will increase modestly to 20-25 kt over the east half tonight
into Saturday. Winds will be 20 kt or less Saturday night into Sunday
night before increasing as a low pressure system approaches from the
south. Winds will back from easterly to northerly Monday while
increasing to around 25 kt.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.

&&

$$

SHORT TERM...07
LONG TERM...Thompson
AVIATION...07
MARINE...Thompson