599
FXUS63 KMQT 261114
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
714 AM EDT Wed Jun 26 2024

.KEY MESSAGES...

- Scattered showers arrive over northwest Upper MI around sunrise.

-Pattern remains active, especially from late week into early next
week, with yet more rounds of showers and storms

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 314 AM EDT Wed Jun 26 2024

GOES-16 water vapor imagery shows a region of unsettled clouds over
northwestern Ontario moving southeast collocated with a RAP-
analyzed 500mb trough. As the surface high pressure ended up
weaker and further south than previous global model runs had
forecast, this has lead to increased chances that the shortwave
can overcome the dry air and cause some light showers over the
UP later this morning. Per the HREF, these showers will mostly
be limited to north of a line from Ontonagon to Marquette. These
showers should end by 18Z, and by the time the dust settles,
HREF mean QPF over the Keweenaw is around 0.1 inch with 0.01
inch to 0.1 inch of rain for the remainder of the areas that see
rainfall.

Skies gradually clear behind the shortwave and winds become
northerly, setting up a north-south gradient for high temperatures
today, with highs in the mid to upper 50s along Lake Superior to
highs in the mid to upper 60s along Lake Michigan and the interior
west. The clear skies overnight should allow temperatures to
underperform relative to most guidance. This forecast will reflect
values close to the NBM 10th percentile, with lows in the upper 30s
for the interior and 40s along the lakeshores.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 252 AM EDT Wed Jun 26 2024

The pattern will remain fairly active and progressive through the
extended fcst period as a couple of Pacific-based shortwave troughs
traverse the northern tier of the CONUS and bring more rounds of
showers and t-storms to the Upper Great Lakes mainly in the Friday-
Saturday night and Monday night into Wednesday time periods.

Starting Thursday, a weak high pressure ridge persists across the
region into much of Thu night as dry weather prevails. Weak pressure
gradient and light winds will result in lake breezes during the day
on Thursday. Expect highs generally in the lower 70s, except a touch
cooler in the mid to upper 60s near the Great Lakes shores. Look for
lows Thu night in the lower to mid 50s, except for some cooler upper
40s readings over the eastern interior.

Friday and Saturday, a mid-level trough/closed low just off the
Pacific Northwest coast as noted on satellite imagery early this
morning will move onshore later this morning. This trough will
support cyclogenesis in the lee of the Northern Rockies Thursday
night with the sfc low ejecting east into the Dakotas and along the
international border/northern MN Friday and into the Upper Great
Lakes on Saturday. WAA/isentropic ascent and theta-e advection ahead
of the low will support showers and thunderstorms spreading into
Upper Mi on Friday. The initial shortwave embedded within the mid-
level trough will move into the region Saturday while pushing a cold
front through the area Friday night into Saturday. Increased
instability noted ahead and along the cold front should increase
chances for thunder as it passes through the area at this time. A
second shortwave moving through the trough axis will send a
secondary cold front across the area late Sat into early Sun perhaps
triggering some isolated to scattered light showers along with a
burst of gustier nw-n winds and colder temps.

High pressure building in quickly behind the front will result in
drier, albeit cooler conditions Sunday afternoon into Monday. Models
then advertise another mid-level trough moving in off the West Coast
which again will promote lee-side cyclogenesis over the Northern
Rockies early next week. The associated sfc low is fcst to lift
northeast through the Northern Rockies into Manitoba and northern
Ontario Mon night into Tuesday as it propels a cold front across the
Upper Great Lakes on Tuesday. Ahead of and along this front another
round of showers/t-storms is expected next Mon night into Tuesday.
The passage of another shortwave and secondary cold front from this
system could bring more light showers into the area on Wednesday.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 714 AM EDT Wed Jun 26 2024

VFR conditions are at all TAF sites at 12Z this morning, though a
passing wave of low clouds will likely (75+%) bring a period of MVFR
to SAW and CMX and temporarily at IWD this morning. Once this
wave moves out, SCT to SKC conditions are expected through the
remainder of the TAF and winds become mainly light and out of
the north and northwest.

&&

.MARINE...
Issued at 252 AM EDT Wed Jun 26 2024

Winds have switched northerly early this morning at 15-20 kts behind
a cold front dropping south across the lake but will taper off below
15 kts during the day today. With high pressure over the lake
through Thursday, winds are expected to mainly remain below 20 kts.
A weakening low pressure tracking through the Upper Great Lakes
early this weekend will allow for s-se gusts 20-25 kt Friday over
mainly the east half ahead of the front and then nw gusts 20-25 kt
behind the cold frontal passage on Saturday before building high
pressure returns Sunday and ushers in lighter winds into Monday.

&&

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

&&

$$

SHORT TERM...GS
LONG TERM...Voss
AVIATION...GS
MARINE...Voss