826
FXUS63 KMQT 011751
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
151 PM EDT Tue Oct 1 2024

.KEY MESSAGES...

- Gusty NW winds die-down this afternoon and evening.

- Abnormally dry and moderate drought conditions have been expanding
across Upper MI over the last several weeks. The upcoming pattern
for the next 1 to 2 weeks shows no signs of a transition to a more
typical fall pattern that brings frequent precipitation to Upper MI.
Drought likely to expand.

- Fire weather concerns will become an increasing issue, especially
as we experience more frequent breezy conditions typical of fall. In
the near term, Wednesday is a day of particular concern.

- Low end gales with southwest winds across western Lake Superior on
Wednesday.

- Some frost potential in the interior tonight, Thursday night and
Friday night.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 150 PM EDT Tue Oct 1 2024

Outside of some scattered cu at around 4 to 5 thousand ft up, most
of the U.P. is remaining sunny and cooler today behind the cold
front that passed through early this morning. In addition to the
partly cloudy skies, winds have remained breezy from the northwest
early this afternoon. With min RHs still expected to dip below 30
percent in the interior west and south central later this afternoon,
some short-lived elevated fire weather conditions are expected.
However, as we head into the evening hours (5 PM EDT onwards), the
surface should moisten once again as the sun sets. Therefore, with
the limited to elevated conditions only lasting an hour or two, no
SPS for fire weather was issued today. Looking at current
observations, most of the area has only gotten into the mid 50s to
lower 60s. While the partly cloudy skies this afternoon will allow
the surface to heat-up a few more degrees, expect the high
temperatures to max out to around 60 over the west and north central
and the mid 60s in the south central and east.

Expect fairly clear skies early this evening as the last of the lake-
effect cloud cover vanishes. However, some mid to upper level clouds
associated with a developing shortwave low over northern Ontario
look to move into our area late. While this will prevent us from
seeing the stars tonight, with the mid to upper level clouds only
providing a little bit of insulation, we could see temperatures
plummet down into the lower 30s across the interior. While light
southwesterly winds are expected through late tonight, there could
be some patches of frost that develop, mainly over the south central
and east. Therefore, if you live in the interior areas, it may be
prudent to cover any vulnerable plants this evening, as any frost
could damage plant life.

&&

.LONG TERM /TONIGHT THROUGH MONDAY/...
Issued at 508 AM EDT Tue Oct 1 2024

Increasing dryness has been the rule across Upper MI during the
month of Sept, and the drought monitor shows that abnormally dry and
moderate drought conditions have been expanding. Moderate drought is
noted over s central into much of eastern Upper MI. Over the last 30
days, pcpn has been less than 50pct of normal, except across the
Keweenaw. Less than 25 percent of normal pcpn has occurred from far
western Upper MI across much of southern Upper MI. Although we are
transitioning out of the pattern that brought persistently warm
weather to the area, medium range models show that we are not
entering a pattern that favors frequent pcpn events more typical of
this time of year. The upcoming pattern thru this weekend will be
more progressive with a series of waves tracking eastward in the
vcnty of the U.S./Canada border. The first is crossing the area
today, at least 2 weaker waves pass in the Wed night-Fri time frame,
and the last wave of this fcst cycle reaches the Great Lakes region
on Sun. The more frequent shortwave passages would typically lead to
more frequent pcpn. However, with low pres dominating the Gulf of
Mexico into the weekend, the cyclonic flow around that feature will
prevent any transport of gulf moisture northward to reach the waves
moving along the vcnty of the International Border, diminishing the
potential of meaningful pcpn. Of the upcoming waves to pass
over/near Upper MI, the last wave arriving on Sun provides really
the only opportunity of rainfall. Looking farther out thru next
week, medium range models suggest positive mid-level height
anomalies expanding from the western U.S. and sw Canada eastward
across the Northern Plains to the Great Lakes as low amplitude
ridging shifts eastward. This is certainly suggestive of an overall
dry pattern continuing for Upper MI during the week of Oct 6. As for
temps, with the progressive nature of the flow and with the jet
stream mostly n of Upper MI, temps will be on the warm side of early
Oct normals on most days, but certainly not as warm as the recent
weather has been. Coolest weather will probably occur Sun/Mon as
wave reaching the Great Lakes should amplify a bit. Above normal
temps will then return as positive height anomalies spread to the
Great Lakes during next week.

Beginning tonight, sfc high pres center will be drifting e into the
Mid-Mississippi Valley. Ridging will extend from the high into Upper
MI this evening, but will shift e thru the night, allowing winds to
start stirring. In addition, strong waa regime spreading out across
the Northern Plains toward Upper MI will result in considerable high
and mid clouds spreading into the area during the night. As a
result, conditions will be far from ideal for good radiational
cooling tonight. The early start to the increasing clouds will work
against frost development. For now, fcst still reflects lows down
into the mid 30s F in the interior along with a mention of frost.
Temps will range up into the 40s F along Lake Superior.

On Wed, a couple of waves will be tracking eastward in the vcnty of
the International Border toward Lake Superior/northern Ontario.
Associated cold front will sweep e, reaching western Lake Superior
Wed evening. Tightening pres gradient btwn the approaching trof and
the departing high pres ridge will lead to breezy s to sw winds
developing. Considerable high and mid-level cloudiness will start
the day per fcst soundings, and then those clouds will gradually
thin out from w to e in the aftn. The cloud cover complicates
heating potential/mixing height, affecting winds/temps. Based on
fcst soundings, gusts to around 30mph should be common on Wed with
potential to gust up to 40mph if there is more sun and mixing
heights build higher. As for dwpts, the HRRR is the worst case
scenario showing dwpts in the low/mid 20s F, resulting in RH of 15-
20pct. The HRRR has frequently been a low outlier with dwpts in
recent weeks. However, current sfc obs show 20s and 30s F dwpts
spreading out across the Plains, including some lwr 20s F across
western portions of the Plains. This dry air will advect to Upper MI
on Wed under the sw winds. With the growing season winding down
(diminishing evapotranspiration) and lots of abnormally dry
conditions upstream, little modification of the air should occur.
So, could the HRRR low dwpts be correct? Possibly. For now, leaned
on the lower side of the rest of the model guidance. Expect dwpts
down to the upper 20s F at the low end across the w half of Upper MI
on Wed. With high temps 65-70F, RH will fall to as low as around
25pct across much of the w half. Combined with the gusty winds and
the abnormally dry to moderate drought conditions, it will be a day
of elevated wildfire conditions across the w half of Upper MI on
Wed. Downwind of Lake MI under s to sw winds, dwpts will be higher
with temps lwr, working to ease fire wx conditions there somewhat
compared to the w.

Cold front will pass without any pcpn Wed night. A cooler day
follows on Thu, at least w and n. Expect highs from the low/mid 60s
w and n to around 70F s central. RH will fall to around 30pct s
central, but winds will be lighter, only gusting to around 10mph,
limiting fire wx concerns. Expect considerable high and mid-level
clouds to overspread the area on Thu due to upper diffluence from
right entrance of a 120kt jet extending ene from northern MN. This
upper diffluence may eventually lead to the development of some
-shra/sprinkles during Thu night, but since there will be
considerable antecedent low-level dry air to overcome, no mention of
pcpn appears warranted attm.

High pres nosing into the area Thu night may support some frost
potential interior w if clouds clear out. Sfc high pres moves over
the area on Fri. Under mostly sunny skies, expect highs in the 60s
F. Departing high pres will still be close by Fri night to support a
good radiational cooling night and probably a better potential of at
least some frost across much of the interior central and east.

Over the weekend, shortwave moving across the Dakotas/Canadian
Prairies on Sat will reach the western Great Lakes on Sun. With
modest building of upstream ridge over western N America, this trof
will amplify some as it moves over the Great Lakes during Sun/Sun
night. Although gulf moisture inflow is blocked, height
falls/amplification should support at least some shra development.
With EPS/GEPS/GEFS then showing median 850mb temps falling toward 0C
on the backside of the system, expect some lake enhanced shra Sun
night into at least Mon morning under cyclonic nw flow across Lake
Superior. Warming/dry weather will follow on Tue.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 104 PM EDT Tue Oct 1 2024

VFR conditions continue across the TAF period as lake-effect cloud
cover gives way to clear skies this evening, before mid to upper
level cloud cover moves overhead late tonight and remains through
Wednesday morning. The gusty NW winds continue until this evening,
then calm down as winds back SW`rly. Expect winds to pick back-up
again from the SW Wednesday as a low-level jet moves overhead. While
this may bring some low-level turbulence over KIWD early Wednesday
morning, the gusty winds may reach the surface before LLWS criteria
is hit. Given that this is low-level turbulence, I will not be
including LLWS in the KIWD for late tonight/early Wednesday morning.

&&

.MARINE...
Issued at 508 AM EDT Tue Oct 1 2024

Cold front has been sweeping across Lake Superior during the night
and will exit the eastern lake in the next few hrs. NW winds have
been gusting 35 to ~40kt immediately after frontal passage. Winds
will fall blo gale force across the w half of Lake Superior in the
next hr or two and then across the e half around 12z. Expect nw to w
winds in the 20-30kt range across the lake thru the day, but winds
will settle back to 15-25kt from w to e late aftn and tonight as sfc
high pres ridge slides across the western Great Lakes. As the ridge
exits to the e on Wed and the next low pres trof approaches, sw
winds will ramp up. Warmer air moving over the lake increases
uncertainty in mixing depth and thus how much of the stronger winds
aloft will mix down. For now, fcst soundings suggest gusts to 35-
40kt will occur across the w half of Lake Superior on Wed, which is
favored for stronger winds when the wind direction is sw.
Probabilistic guidance indicates about a 20-30pct chance of gusts
exceeding 40kt. Across the e half of Lake Superior, expect winds to
30kt on Wed with some gale gusts to around 35kt. Will need to
reevaluate whether a gale warning will be warranted across the e on
Wed after next round of model guidance arrives. With passage of cold
front Wed night, winds will fall back to around 20kt as they shift
to the nw. Westerly winds will tick back up to gusting to around
25kt across western Lake Superior on Thu. Winds generally around
20kt should then prevail Thu night and Fri. Next system will reach
the western Great Lakes over the weekend, resulting in increasing
winds. Current guidance points to gale potential late Sat/Sun.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Gale Warning from 8 AM EDT /7 AM CDT/ to 5 PM EDT /4 PM CDT/
     Wednesday for LSZ162-240>244-263-264.

Lake Michigan...
None.

&&

$$

SHORT TERM...TAP
LONG TERM...Rolfson
AVIATION...TAP
MARINE...Rolfson