718
FXUS63 KMQT 202006
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
406 PM EDT Fri Sep 20 2024

.KEY MESSAGES...

- Isolated showers and maybe a thunderstorm possible this evening
east half. Patchy fog forming late tonight/early Saturday mainly
central and east.

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

- Multiple rounds of precipitation possible through the first half
of next week. Thunderstorms that do form are not expected to be
severe at this time.

- Temperatures around normal are expected to return next week.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 356 PM EDT Fri Sep 20 2024

Latest water vapor imagery and RAP analysis shows shortwave trough
slowly progressing east through the east half of Upper Mi with the
visible satellite imagery showing widespread diurnal cu across the
U.P. Subsidence/mid-level drying behind this shortwave feature has
resulted in dry conditions today over western Upper Mi. Central and
eastern sections of the U.P. have seen a few isolated showers pop up
in the vicinity of the mid-level trough axis and focused along
outflow boundaries/lake breezes especially east of MQT in the past
hour. This environment has also been more favorable for convection
as lower to mid 60s dew points have led to MLCAPE values approaching
1000 j/kg central and east. However, build up of convection over the
central and eastern U.P. has been largely inhibited by strong mid-
level drying as noted on fcst soundings. Afternoon temperatures have
been mostly in the 70s although a few lower 80s readings have been
observed over the interior west.

Other than some lingering isolated showers/t-storms over the east
mainly early this evening, expect dry conditions to prevail as
shortwave ridging and associated subsidence builds across the area
from the west. Moist dew points in the upper 50s and lower 60s along
with clearing of diurnal cu and light winds will likely lead again
to patchy fog forming overnight into portions of central and eastern
Upper Mi. Fog could become locally dense over eastern portions.
Expect min temps generally lowering into the 50s with a few upper
40s readings possible over the typical cool spots of the interior
west.

&&

.LONG TERM /TONIGHT THROUGH THURSDAY/...
Issued at 337 AM EDT Fri Sep 20 2024

The last of the rain showers and thunderstorms associated with the
cool front today ends over the east tonight as high pressure ridging
builds in. As this occurs, the clearing skies will allow the
temperatures to drop to around 50 in the interior west, whereas the
interior east may only get down into the mid 50s due to the cloud
cover earlier in the evening and patchy fog late tonight. Speaking
of which, expect this fog to form over the central and east tonight
given the clearing out and moisture from the recent rainfall; I
wouldn`t be surprised if the fog was even dense in a few spots come
early Saturday morning. The patchy fog looks to eventually burn off
a couple of hours after sunrise Saturday morning.

Expect Saturday to be another very warm and mostly sunny day via the
weak high pressure ridging scooting over us. With warm air advection
moving over us aloft late tonight through Saturday, expect high
temperatures to get to around 80 in the east and the lower 80s in
the west. Meanwhile, given the abundant sunshine and moisture, we
could have some good mixing in the boundary layer by the afternoon
hours, bringing min RHs down to possibly as low as the lower 30
percents in the interior west. If the mixing overachieves today, we
could see some limited fire weather concerns via min RHs getting
down to or below 30%. However, given the ridging overhead, winds are
expected to be fairly light from the south across most of the area
(the exceptions are the Keweenaw/near Lake Superior where some lake
breeze action may come into play). Now as a low pressure over the
Canadian Prairies lifts towards Hudson Bay Saturday into Sunday, a
cold front associated with the low approaches us from the west by
the afternoon hours. This cold front looks to bring additional rain
showers and thunderstorms over us from Saturday evening into Sunday
from west to east. Overall, don`t expect too much rainfall from this
cold front either; most areas are looking to only get a tenth of an
inch or less, although some spots may locally see more. That being
said, the latest Canadian, NAM, and Euro deterministic runs are more
generous with the rainfall; hopefully these newer runs are more
accurate as we really need the rainfall, particularly over the south
central and east where moderate drought (D1) conditions exist
according to the latest drought monitor update. While there is an
outside chance (2% or less) of seeing a strong storm or two Saturday
night through Sunday along the front, with decreasing MUCAPE and
increasing cloud cover ahead of the front with time, severe weather
is currently not expected. A shortwave lifting from the Plains
through the Great Lakes region Sunday through Sunday night may
reinvigorate convection over the central and east, but the front may
be too far to our south and east by that point for us to receive
anything. Thus, the chance of rain from this shortwave over our
central and east looks to be about 25% and 50%, respectively, late
Sunday through Sunday night.

Additional high pressure ridging is expected to return to our area
by next Monday, although the warm temperatures are looking to be
replaced by those more normal for this time of year. Expect Monday
to be the coolest day of next week, with highs only getting into the
low to mid 60s and lows possibly dipping into the upper 30s in the
interior west Sunday and Monday nights. Moving to next Tuesday, a
low originally from the Southern Rockies looks to move through the
Great Lakes basin. While the south central and east could be skirted
with some light rainfall from the low`s TROWAL Tuesday, with
guidance honing in better on the low`s track moving through southern
Lower Michigan, not much, if any, rainfall is expected. While near
normal temperatures continue through the rest of next week, we may
or may not see additional rainfall as the aforementioned low could
retrograde back into the Upper Great Lakes. However, the more recent
deterministic runs of the medium range guidance are suggesting that
we remain under ridging for the last half of next week, with the low
being too far to our south. Nevertheless, I feel that the NBM`s 20%
pops for most of the area are pretty on point with the rain chances
come late next week, just in case the low`s retrograde does move
further north towards the Upper Great Lakes in later model runs.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 358 PM EDT Fri Sep 20 2024

MVFR conditions have cleared out this afternoon. Expect VFR to
prevail at most of the terminals through the period with the
exception of some MVFR to IFR fog developing at SAW later
tonight into early Sat morning.

&&

.MARINE...
Issued at 337 AM EDT Fri Sep 20 2024

The southerly 20 to 25 knot winds ahead of the cool front this
morning over the north central lake decrease to 20 knots or less
later this morning, but southwest winds of 20 to 25 knots do pick up
behind the front over the west half of the lake by this afternoon
and continue until this evening. Meanwhile, expect showers and
thunderstorms to continue trudging eastward over the lake with the
frontal boundary. As weak ridging builds in, expect the winds to die
down to 20 knots or less again by around sunset, and the last of the
showers and thunderstorms ending over the far eastern lake late
tonight. Due to the recent rainfall and lighter winds late tonight,
we could see some patchy marine fog develop over the eastern lake;
some spots could see visibilities of 1 nautical mile or less, so
make sure to have your lights on and to use your radar and compass
if you are in a fog bank. The light winds continue until another
cold front moves through late Saturday into Sunday. While showers
and thunderstorms are expected to travel from west to east late
Saturday into Sunday over Lake Superior, expect northwest winds of
20 to 25 knots behind the frontal boundary, mainly over the western
half of the lake. As the front leaves our area later Sunday, expect
the winds to die down to 20 knots or less again as more ridging
moves over. The ridging and light winds look to remain over Lake
Superior for the rest of next week.

&&

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

&&

$$

SHORT TERM...Voss
LONG TERM...TAP
AVIATION...Voss
MARINE...TAP