365
FXUS63 KMQT 181118
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
718 AM EDT Tue Aug 18 2026

.KEY MESSAGES...

- Showers and isolated thunderstorms will be possible along a cold
front early this morning and again this afternoon (mainly east).

- Temperatures will be close to seasonal averages most days through
the 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 359 AM EDT Tue Aug 18 2026

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.

Currently, mainly rain showers are drifting into central Upper
Michigan per latest radar mosaic with any earlier upstream
thunderstorms already done. And, with a lack of forcing/instability,
appreciable rainfall will also be minimal with most amounts under
0.10". 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 this afternoon. 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 do form along with brief heavy
rainfall.

Any lingering showers will exit the far south-central tonight with
cooler and drier air filtering into the area. This will result in a
comfortable airmass with seasonable highs in the 70s for tomorrow
and Thursday. Lows will be mainly in the 40s tonight into tomorrow
with parts of the interior west falling 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 tonight and
tomorrow 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 this 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 /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 717 AM EDT Tue Aug 18 2026

VFR will be the predominant flight category for the duration of the
TAF period. The only exception could be brief MVFR conditions at SAW
later this afternoon in any rain showers that do form. But,
will not include MVFR mention at this time and will only
highlight PROB30 showers with VFR conditions. Meanwhile,
westerly winds will veer to the northwest with frontal passage
later this morning. Strongest gusts will be at CMX in the 20 to
25 kt range through this afternoon.

&&

.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/TDUD
AVIATION...TDUD
MARINE...NL