Sidnaw, Michigan Weather Forecast Discussion

504
FXUS63 KMQT 131842
AFDMQT
Area Forecast Discussion
National Weather Service Marquette MI
242 PM EDT Sat Sep 13 2025
.KEY MESSAGES...
- Warm and humid weather through early next week.
- Fog is expected to develop tonight, dense fog is possible.
- Cooler air moves back in for the late week.
&&
.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 242 PM EDT Sat Sep 13 2025
An omega block is in place with an upper level ridge extending from
southern U.S north threw the midwest into Canada (Manitoba) while
upper level lows were in place upstream and downstream of the ridge.
Shortwave energy ahead of the upper level low over western Montana
had resulted in multiple MSCs in the northern Plains overnight into
this morning. One of these shortwaves undercut the ridge and moved
through the upper Midwest overnight into the early morning hours
bringing scattered showers to much of the area along with a few
rumbles of thunder in the west. Most of the organized convection
stayed well south of the area, tracking from west-central WI to
northern IL during the early morning hours. Overall rainfall amounts
were light, up to a quarter inch fell over parts of the west and
amounts trickled off and become spotty over the central and east. It
was a relatively warm and humid start to the day with morning
temperatures in the upper 50s to low 60s. This afternoon was
pleasant with temperatures warming into the 70s across much of the
area through it was a bit cooler near Lake Superior due to an
afternoon lake breeze. With ample low level moisture we haven`t been
able to get rid of all the clouds, skies were mainly partly cloudy
through there were still areas of overcast from the Keweenaw to the
central U.P.
Through the weekend the upper level ridge axis will
shift slowly east, centered over the western Great Lakes up to the
Hudson Bay by Sunday as the cutoff low over MT merges with a trough
approaching the Pacific Northwest. The highly amplified ridge will
steer any shortwaves north from the central Rockies to the Northern
Plains, keeping things dry over the U.P. This will make for another
warm and humid day on Sunday with temperatures warming well into the
70s. With a humid airmass in place and favorable conditions for
radiation cooling expect areas of dense fog to develop late tonight
into early Sunday morning.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 242 PM EDT Sat Sep 13 2025
For the early part of the week the upper level ridge will begin to
shift east and break down. While warm conditions will continue
expect the chance for showers and thunderstorms to come back into
the forecast with multiple shortwaves ejecting from the central
Rockies northward through the plains ahead of the western trough.
These systems will just skirt the area with shower/thunderstorm
chances confined to the very far west on Tuesday. As the trough
progresses east the chance for showers/thunderstorms will return to
the rest of the area for mid to late week. Deterministic model
guidance diverges quite a bit with the evolution of the western
trough as it pushes east mid to late week. The GFS has had a deeper
low moving through the Great Lakes for Friday and Saturday and most
recently the 00Z ECMWF shows a similar solution. The last few runs
of the GFS seems to have backed away from this solution. The deeper
trough solutions appear to be outliers compared to the distributaion
from ensemble guidance. Ensemble cluster analysis shows most of the
ensembles (90%) favoring a solution with weak upper level troughing
over the Great Lakes as it undercuts the ridge, deeper troughing
remains over eastern Canada. A small set (10%) of ensembles favor a
deeper upper level trough developing over the Great Lakes. The
latest NBM has backed off on the strength of the cold front for late
this week, with 60s on Friday rather the previously progged 50s.
&&
.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 141 PM EDT Sat Sep 13 2025
Save for some intermittent low-level clouds at CMX, VFR conditions
persist at all TAF sites. With light winds and temperatures
falling to their dew points tonight, confidence is high in fog
development over the UP tonight, though the timing and intensity
details are still somewhat spread out between the models. IWD
carries the lowest chances of FG among the TAF sites at only
25-40 percent, though should FG develop, it would be at least
IFR or lower. CMX is over 50% likely to have periods of VFR this
afternoon before chances of at least LIFR exceed 50% overnight.
SAW is most likely to hit airport minimums tonight at around
70%, though there is some uncertainty at the onset time of FG
tonight. Despite the uncertainty in the morning recovery at all
sites, by 18Z, all 3 sites are expected to be VFR once again.
Winds will begin to pick up in the early afternoon out of the
east to southeast with CMX gusting up to 15 kt.
&&
.MARINE...
Issued at 242 PM EDT Sat Sep 13 2025
Light winds under 20 knots are expected over much of Lake Superior
through mid-week. An upper level ridge of high pressure will result
in dry weather through Sunday. Models are really trying to crank out
the fog tonight over the lake but I`m a bit skeptical and current
model analysis is greatly overdoing the extent of the fog. Unlike
last night we will not have any precipitation to act as a trigger.
While dense fog is possible opted to keep it out of the forecast at
this time due to uncertainty. Early next week the ridge begins to
break down and shift east as troughing approaches. This will bring
the chance for showers and thunderstorms back into the forecast for
the far western part of the lake Monday and Tuesday and lake-wide
Wednesday through Friday. There is little in the way in agreement
among the guidance with the evolution of the mid-week trough,
currently gale probabilities remain low with the system, 25% chance
for gales Thursday night and Friday over the western half of the
lake.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...NL
LONG TERM...NL
AVIATION...CB/GS
MARINE...NL

NWS MQT Office Area Forecast Discussion