455
FXUS63 KMQT 181722
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
122 PM 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 122 PM EDT Wed Sep 18 2024

Another warm and dry day over Upper Michigan has developed. This,
after morning temps in the 40s and 50s, and fog, some dense, across
portions of central and eastern Upper Michigan. So far, temps have
warmed into the 70s to low 80s, with the warmest spots being the
southerly wind downsloping locations near Lake Superior. Effective
mixing into a very dry airmass aloft has enabled dewpoints to fall
into the upper 40s to 50s in the driest interior locations, which
with the heat, is supporting RH values in the 30s and 40s in many
locations. Thankfully, winds have been mostly light, which is
limiting fire weather potential.

As we progress through the remainder of the afternoon and tonight,
expecting some additional warming before the heat wanes. Still
expecting widespread low to mid 80s everywhere away from Lake
Michigan`s influence where 70s will dominate. RH will respond as
well and will support continued near and/or isolated elevated fire
weather concerns into the evening. Overnight lows will again dip
into the 40s and 50s. Also expecting another round of raditional fog
to develop in interior locations of Upper Michigan`s south-central
and eastern locations.

Upstream, vertically stacked low spining over North Dakota will lift
northeast into Canada. An associated cold front will march east into
western Minnesota overnight. Ahead of the front, theta-e ridge with
a plume of robust instability will support showers and thunderstorms
overnight. Its possible that some of these showers/storms may
continue into western Lake Superior by morning.

&&

.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 /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 122 PM EDT Wed Sep 18 2024

VFR conditions will prevail 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...JTP
MARINE...TAP