816
FXUS63 KMQT 171817
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
217 PM EDT Mon Aug 17 2026

.KEY MESSAGES...

- Showers and thunderstorms will be possible (up to a 50% chance)
along a cold front tonight into Tuesday.

- Temperatures will be close to seasonal averages most days through
next week, with highs in the 70s and lows in the 40s and 50s.

- Showers and thunderstorms are possible (up to a 75% chance)
Thursday night into Friday as another front moves through the area.

&&

.DISCUSSION...
Issued at 217 PM EDT Mon Aug 17 2026

It was a pleasant afternoon across the UP with sfc observations
showing temperatures generally in the low to mid 70s along with
dewpoints in the 50s to near 60. Satellite imagery showed fair
weather cumulus had formed with diurnally driven instability
resulting in partly cloudy skies. Model height analysis and water
vapor imagery showed an upper level low over the Hudson Bay with
broad troughing over much of Canada, extending south across the
northern tier of the U.S. Multiple subtle shortwaves were evident in
the flow with a few thunderstorms over northwest MN.

Overall the UP will remain under northwest flow aloft through next
weekend bringing seasonal temperatures along with a few passing cold
fronts. The upper level low pressure over Hudson Bay will slowly
move east, reaching eastern Quebec Friday night as yet another upper
level low pressure moves toward the Hudson Bay to take its place.

Thunderstorms are expected to develop and increase in coverage this
afternoon to the west, over the central plains into MN as a cold
front pushes southeast through the region. Thunderstorms are
expected to move east through tonight and diminish as the approach
the UP will loss of diurnally driven instability and an overall lack
of forcing to sustain elevated convection. This will result in
rather meager chances for appreciable rainfall, only about a 10-25%
chance for a wetting rain (0.10" or more). As the morning progresses
the front will sag south across the UP, reaching the far south-
central late in the day. Additional showers and thunderstorms are
expected to form along and immediately behind the front during the
afternoon hours. HREF joint probabilities for mucape>500J/kg and
shear(0-6km)>30kt are around 60% close to Lake Michigan and over the
south-central in the early afternoon, rapidly decreasing over the
east but higher probs lingering over the south-central into the late
afternoon. Despite the higher shear thermodynamic profiles do not
support hail growth but couldn`t rule out gusty winds with any
storms that due develop along with brief heavy rainfall.

Any lingering showers will exit the far south-central tomorrow night
with cooler and drier air filtering into the area. This will result
in a comfortable airmass with seasonable highs in the 70s for
Wednesday and Thursday. Lows will be mainly in the 40s Tuesday night
into Wednesday with parts of the interior west could fall as low as
the mid-30s. The blended guidance mean has been running several
degrees too warm during recent cool nights, thus have opted for the
lower end of the distribution, 10th percentile for low temperatures
Tuesday night and Wednesday night.

The next chance for rain will be Thursday night into Friday. Warm
air advection ahead of a deepening trough will bring increasing
chances for showers on Thursday night. A shortwave and trailing cold
front will continue precipitation chances into Friday. At time it
appears the strongest instability will stay south of the UP with
only about a 30% chance for enough cape/shear to support stronger
thunderstorms. As far as rainfall amounts, NBM probabilities for
0.25" or more are in the 25-45% range. These probabilities quickly
drop off though with only about a 10-25% chance for 0.34" or more.
While any thunderstorms that do form could put down locally heavy
rainfall a widespread heavy rainfall is not expected. Thus not
expecting appreciable improvements to the ongoing drought conditions
over the south and west.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 116 PM EDT Mon Aug 17 2026

VFR conditions will prevail at all sites throughout the period.
Generally westerly to northerly winds 5-10 kt will becoming
southerly to southwesterly this evening ahead of a cold front that
will bring some showers to the UP overnight, though chances of rain
are only up to 60% at IWD, and up to 30% for any given hour at CMX
and SAW. Chances of thunder are only above 15% at IWD and with the
peak chance of thunder at only 20%, will leave TSRA out of the TAF
at this time.

&&

.MARINE...
Issued at 217 PM EDT Mon Aug 17 2026

Lake Superior - Southwesterly winds 20-25kt are expected through the
early evening between Isle Royale and the Canadian shore where winds
are being funneled. Over the rest of the lake southwest winds of 15-
20kt can be expected. Winds will shift northwest wind and
increase to 25kt near/east of the Keweenaw late tonight into
Tuesday. Thereafter winds will generally be less than 20kt
through the remainder of the week. A few thunderstorms will be
possible tonight and again on Thursday night and Friday but
strong thunderstorms are not expected. Another period of
northwest winds are expected on Saturday, 20-30kt, mainly along
and east of the Keweenaw.

Northern Bay of Green Bay and northern Lake Michigan - Overall
expect winds less than 20kt trough Thursday. Showers and
thunderstorms are possible tonight into Tuesday (50% chance) as a
cold front pushes through the area. Isolated thunderstorms Tuesday
afternoon could produce gusty winds. Another front is expected to
bring showers and thunderstorms into the area Friday night into
Saturday. Southwest winds to 25kt are expected ahead of the front on
Friday near and east of Manistique. Winds diminish Friday night,
then shift northwest on Saturday increasing to 25kt.

&&

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

&&

$$

DISCUSSION...NL
AVIATION...LC
MARINE...NL