785
FXUS63 KMQT 180725
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
325 AM EDT Wed Sep 18 2024

.KEY MESSAGES...

- Extended stretch of well above normal temperatures continues
through at least Saturday with highs mainly in the upper 70s and 80s.

- A cold front brings scattered showers and a few thunderstorms late
Thursday into Friday.

&&

.SHORT TERM /THROUGH TODAY/...
Issued at 121 PM EDT Tue Sep 17 2024

Dry and warm airmass continued to sit over the Upper Great Lakes
today. Outside of some mid-high clouds here and there, and some
recently developing diurnal cumulus in the west, the forecast area
has been mostly clear which enabled many to easily break into the
70s before noon. In fact, many locations were beating hard on the 80
degree door at that point. As of publishing this discussion, most
surface observations were in the upper 70s to low 80s, which is
approximately 10 to 15 degrees above normal for mid-September. Under
mostly light southerly flow, daytime mixing has supported dewpoints
in the mid 50s to low 60s. This is yielding RH values mostly in 50s
and 40s in areas removed from Lake Michigan`s influence. Some drier
locations have fallen into the 30s as well. As we progress through
the remainder of the afternoon, I expect temps to climb a little
more and RH values in the 40s to be more widespread with some 30s
here and there before recovering with the waning heat. Expecting
clear skies to continue through tonight, which will yield overnight
lows in the 50s and 60s, save the interior portions of south-central
and east, which could slip into the 40s. Patchy overnight fog will
be possible as well, particularly in the interior spots of central
and eastern Upper Michigan.

&&

.LONG TERM /TONIGHT THROUGH TUESDAY/...
Issued at 325 AM EDT Wed Sep 18 2024

We get one more mostly dry, late summer-like day on Thursday before
the high pressure ridging over us gives way to a cool front moving
in from the west late Thursday through Friday. Afterwards, expect
temperatures to decrease closer to normal, with a low pressure over
the Canadian Prairies lifting towards Hudson Bay and another low
lifting from the Desert Southwest/Southern Rockies into the Upper
Midwest possibly bringing back rainfall over us as well next week.

Another mostly clear night is in store tonight as the ridging
persists but slowly weakens over us with time. As temperatures cool
during the overnight hours, we could see some patchy fog develop in
the south central and near Lake Michigan late as the temperatures
reach the dewpoint. Overall, thinking low temperatures tonight will
get into the 50s, with a few spots in the interior central possibly
getting into the upper 40s via the help of the radiational cooling.
Moving into Thursday, expect another very warm day and mostly sunny
skies. While we won`t be as warm as the past few days, we can still
expect high temperatures to get into the low to possibly mid 80s in
the interior areas. Fire weather concerns should be lessened
Thursday too, as min RHs aren`t looking to get below the upper 30
percents. In addition, rainfall looks to finally make its way into
our area come Thursday as troughing from the Plains begins to push
into our far west. As this happens, we could see some isolated
showers and maybe a stray storm or two during the morning hours near
Ironwood, in addition to partly cloudy skies over the rest of the
western U.P. throughout a significant portion of the day. While CAMs
are generally showing the showers and storms dying out and avoiding
the Upper Peninsula by the early afternoon hours, there looks to be
another line of convection that develops over Minnesota late in the
day that makes its way into the U.P. after sunset. This line of
convection looks to follow a cool front moving from west to east
across the area late Thursday into Friday as the parent low lifts
from the Canadian Prairies towards western Hudson Bay. While not
much rainfall is expected with this cool front, we could see some
heavier downpours in the stronger showers and storms that produce
some locally soaking rainfall over the U.P. as guidance shows PWATs
around 1.50 inches along the frontal boundary. While the European
ensemble shows us that we do have enough instability to get
thunderstorms and showers going, with bulk shear remaining fairly
modest (25 knots or less) across the area, no severe weather is
expected at this time along the cool front. With the thicker cloud
cover overhead, we could see some record high minimum temperature
records broken Thursday night (and possibly Friday night too across
the eastern U.P.). The cool front looks to leave our area by Friday
night as weak ridging fills in behind it.

Model guidance begins to significantly diverge past this Saturday as
each medium range suite has different strengths and locations for
two vertically-stacked lows over the CONUS that could impact our
weather. The first of which is one over the Canadian Prairies
Saturday that lifts towards Hudson Bay for the latter half of the
weekend. This low looks to bring another cold front over us Saturday
night into Sunday. This front may bring us some additional showers
and thunderstorms across our area during that time period, but with
the lifting mechanisms weakening as it moves over us, some guidance
looks to keep us dry but cloudy through the latter half of the
weekend. However, once this front passes, expect to see temperatures
closer to normal with highs only getting into the lower 70s post
cold front on Sunday to the mid to maybe (?) upper 60s come Monday.
A second vertically-stacked low looks to lift from the Desert
Southwest and the Southern Rockies towards the Upper Midwest early
next week. Depending on how the cold front of the first low phases
with the developing warm front of the second low, as well as where
the second low tracks, we may or may not receive rainfall during the
first half of next week; while the GFS and Canadian suites are
generous with the rainfall over us early into mid next week, the
Euro is suggesting that we will remain dry through the remainder of
the period. Hopefully, the former two will occur, as we really need
some meaningful rainfall across our area.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 239 AM EDT Wed Sep 18 2024

Dry airmass over the region will continue VFR conditions in this TAF
period.

&&

.MARINE...
Issued at 325 AM EDT Wed Sep 18 2024

Light winds of generally 20 knots or less continue today into
Thursday before southeast to southerly winds pick up to 20 to 25
knots over the north central lake late Thursday ahead of an
approaching cool front from the west. As the front weakens while
traveling eastward across Lake Superior Thursday night into Friday,
expect the winds to die down to 20 knots or less again by Friday
morning. The light winds continue through Saturday as weak ridging
moves through the Upper Great Lakes, before possibly another cold
front from the west increases winds to greater than 20 knots
Saturday night/Sunday.

As for thunderstorm chances over Lake Superior the next several
days, outside of a stray thunderstorm or two near Isle Royale early
this morning, expect the lake to remain storm-free until the cool
front reaches the far western lake near Duluth Thursday morning.
Shower and storm chances continue over the far western lake Thursday
before a line of convection moves from west to east across the lake
along the cool front late Thursday through Friday. There is a
marginal risk (2+% chance) for some strong, erratic winds and
damaging hail over the far western lake Thursday. As the showers and
storms move eastward into a less favorable environment, the severe
weather threat diminishes. The last of the showers and storms looks
to leave eastern lake Superior by Friday night.

&&

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

&&

$$

SHORT TERM...JTP
LONG TERM...TAP
AVIATION...07
MARINE...TAP