972
FXUS63 KMQT 171156
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
756 AM EDT Sat Aug 17 2024

.KEY MESSAGES...

- Patchy fog this morning, becoming locally dense across
  portions of the UP.

- Showers this morning with increasing thunderstorm activity by this
  afternoon. Main threats will be brief, heavy downpours and
  small hail. Below normal highs in the upper 60s to low 70s
  today.

- Isolated showers are possible tonight through Sunday morning.

- Mostly dry forecast through mid next week. Cooler
  temperatures continue through early next week, becoming more
  seasonable late in the week.

- Chances for showers/storms develop late next week.

&&

.SHORT TERM /TODAY/...
Issued at 449 AM EDT Sat Aug 17 2024

As low pressure continues to rotate over northern Lake Michigan
early this morning per water vapor imagery/surface analysis, there
has been an uptick in scattered showers over the last few hours.
Rain showers on current radar mosaics are concentrated over central
portions of the U.P. in the wraparound flow around the
aforementioned low.  Meanwhile, with plenty of lingering low level
moisture and light winds, ground-based obs across the forecast area
have been reporting widespread patchy fog. And, pockets of 1/4-3/4
mile visibilities have been more prevalent over areas that received
the heaviest rainfall yesterday.  And, with the blanket of cloud
cover, temperatures early this morning have been holding steady in
the 60s.

With limited instability this morning, there has been little
thunderstorm activity.  As diurnal instability increases throughout
the day, however, look for more embedded thunder in these rain
showers. Again, severe weather is not anticipated. But, PWAT values
continue to trend toward 1.50 inches again today, so brief, heavy
downpours accompanied by small hail cannot be ruled out until the
trough exits the area.  As far as temps, daytime highs will be below
normal, only topping off in the upper 60s to mid 70s.

&&

.LONG TERM /TONIGHT THROUGH FRIDAY/...
Issued at 447 AM EDT Sat Aug 17 2024

Once this low pressure system`s rain diminishes, a generally drier
pattern is expected for the extended forecast as the pattern often
consists of ridging and high pressure. That said, there are two main
chances for showers during the period: Wednesday into Wednesday
night and Friday/Saturday. Otherwise, temperatures hold near to just
below normal through Tuesday night with a warming trend toward the
following weekend.

Starting tonight, the mid level closed low will have opened up into
a deep trough, centered over lower MI with the sfc low situated just
out ahead of it over Lake Huron. These two features shift east with
ridging and high pressure building in behind it resulting in gradual
drying. Isolated showers supported by upslope flow will continue
through Sunday morning. Lows slowly settle into the mid 50s to low
60s, coldest interior west where the least cloud cover is expected.

While the deep moist profile diminishes on Sunday as high pressure
continues to build in, low level cloud cover may be stubborn to
clear out over the east half where 850 mb temps drop to 8-10C over
an area of water temps ~14-17C. With that in mind, cooler than
normal temps are expected in the upper 60s to mid 70s, coolest near
Lake Superior over the north central and east where the cloud cover
lingers. With mixing, north winds gusting to 20-25 mph are expected,
strongest over the east. Lows Sunday night fall into the upper 40s
to upper 50s, coldest interior west.

Monday and Tuesday stay dry with plenty of sunshine as high pressure
extending south from Hudson Bay into the Midwest shifts east-
southeast toward the Atlantic. Also during this period, mid level
ridging builds in from the west. Cooler to near normal temps
continue with highs in the upper 60s to mid 70s. The drier airmass
descending south into the region will also help radiative cooling
bring cool temps overnight with 40s in the interior and upper 40s to
mid 50s by the lakeshores. Some places may even dip into the 30s!

The next chances for showers return with a shortwave riding atop the
mid level ridging on Wednesday; this is already a delayed onset from
the guidance 12 hours ago. Late next week, guidance begins to
spread, but the best chances for more showers and storms accompany a
shortwave on Friday that brings a cold front across the region. With
uncertainty in following shortwaves into the weekend, left NBM PoPs
mainly as is, but limited it to slight chance only (15-24%).

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 755 AM EDT Sat Aug 17 2024

LIFR conditions to persist at IWD and SAW into this afternoon before
slight improvement to IFR and eventually MVFR late in the afternoon.
 Elsewhere, CMX could see IFR/MVFR conditions by late morning/early
afternoon, but low level moisture is abundant over the area.  And,
it will take awhile for drier air to filter in behind the departing
trough.  In addition, scattered showers with possible embedded
thunder are expected through this evening.

&&

.MARINE...
Issued at 447 AM EDT Sat Aug 17 2024

North winds of 20 kts or less continue through tonight as the low
pressure system meanders east to southern Ontario. Winds over the
east half of the lake increase to around 15-25 kts on Sunday before
diminishing below 20 kts across the entire lake Sunday evening. With
high pressure building in over the lake Sunday night, maintaining
overhead into Wednesday, winds are generally expected to remain
below 20 kts on Monday. East winds on Tuesday veer southerly by
Wednesday morning, mainly holding below 15 kts. The next chances for
winds to exceed 20 kts hold off until late next week/the following
weekend.

Otherwise, thunderstorm chances continue into tonight and some
patchy fog is expected through this morning.

&&

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

&&

$$

SHORT TERM...TDUD
LONG TERM...Jablonski
AVIATION...TDUD
MARINE...Jablonski