555
FXUS63 KMQT 230110
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
910 PM EDT Fri Aug 22 2025

.KEY MESSAGES...

- This afternoon and evening, showers and thunderstorms push
  across the UP from the west. A few may be strong to severe,
  with damaging winds being the primary threat, resulting in a
  SPC Marginal Risk (category 1 of 5).

- A seasonably strong system moving north of the Great Lakes
  will bring hazardous marine conditions to Lake Superior this
  weekend; gales up to 35 knots are possible (20 to 40% chance).

- Cooler than normal temperatures and lake enhanced to lake
  effect rain showers are projected to return this weekend.

&&

.UPDATE...
Issued at 909 PM EDT Fri Aug 22 2025

Showers and thunderstorms are quickly working through the eastern UP
this evening, with just some spotty, light showers lingering more
westward across the remainder of the UP. Upstream, ahead of the
secondary cold front draped over MN, another batch of showers and
tumbles of thunder are working towards the Arrowhead. This begins to
move over the western arm of Lake Superior over the next few hours,
possibly scraping the far western UP closer to midnight if it can
hold together. Otherwise, some patchy fog/low stratus lingers in the
immediate wake of rain this evening, but clouds are lifting from
west to east with satellite indicating midlevel cloud cover already
moving out of the far western UP. Minor adjustments to PoPs have
been made with this latest forecast update to account for a quicker
end to rain/storms this evening.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 415 PM EDT Fri Aug 22 2025

Today will be the last near to slightly warmer than normal day for
the remainder of the fcst through next week as 850 mb temps this
afternoon hover near 14C and sfc temps range the 70s; a few spots
have reached into the low 80s in the E. A round of TSRA currently
over the W flank of the UP will track from W to E across the area
this afternoon and evening with a passing shortwave and cold front.
Given Tds in the mid 60s to low 70s, instability is sufficient with
the SPC mesoanalysis indicating the 1500-2000 j/kg range accompanied
by mid level lapse rates ~7C/km. Low level lapse rates at 6C/km or
less are not impressive, but model soundings do indicate decent
mixing possible near the sfc with DCAPE between 800-1000 j/kg over
much of the UP. TSRA that tap into the ~30 kts of effective wind
shear primarily bring a damaging wind threat with gusts up to 40-60
mph, but the secondary threat of hail up to 1" can`t be ruled out.
This matches well with the SPC Marginal Risk. TSRA should weaken
into tonight as we loose daytime heating with scattering skies in
the wake of the passing cold front. That said, some lingering SHRA
and weak TSRA are possible yet early on Sat over the E and Keweenaw.
QPF ranges between 0.25" to 0.5" with higher amounts in stronger
storms dropping 0.75 to 1.5". Otherwise expect lows in the 50s to
low 60s.

A sfc low tracking E over N Ontario sends a secondary cold front
across the UP early on Sat, bringing a cool airmass and resulting in
breezy fall like conditions. NW winds are expected around 10 mph
with gusts up to 20 mph for most, gusts up to 30-35 mph are expected
in the Keweenaw. 850 mb temps falling to around 7-8C will limit sfc
temps in the mid 60s to low 70s; some marginally sufficient delta-ts
from this looks to yield lake enhanced cloud cover to the UP and
possibly some transient -DZ. As the mid level trough continues to
pivot over N Ontario, the airmass cools further and lake enhanced
cloud cover and PoPs increase Sat night into Sun. Temps Sat night
settle into the mid 40s to mid 50s.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 415 PM EDT Fri Aug 22 2025

The mid level trough will be positioned over N Ontario and James Bay
with a embedded shortwave pivoting directly overhead starting Sun
morning. A high pressure resides well to the SW over the four
corners, extending a mid level ridge into the PAC NW. A 994mb low
will have made it to James Bay at this point with high pressure over
the Canadian Prairie extending into the Plains. As a result, cold NW
flow will be parked over the UP with 850mb temps settling to ~3C by
the end of the day; Lake Superior waters currently are averaging
~17C, yielding delta-Ts of 13-15C. Given the strong lift, buoyancy
present and ample low level moisture noted in model soundings up to
10 kft, lake effect SHRA are expected across the NW wind belts. As
high pressure and an associated drier airmass continues to creep
over the CWA and lift weakens, coverage of SHRA should lessen, but
supportive delta-ts for lake effect -SHRA should continue through
Mon. This seasonably cold airmass yields below normal temps with
highs in the mid 50s to mid 60s and lows in the 40s to low 50s. If
cloud cover/SHRA are able to clear out better, temps dipping into
the 30s are possible. Meanwhile, breezy NW winds of 10-20 mph are
expected on Sun, particularly in the Keweenaw where gusts up to 30-
35 mph are likely. These tapper down slightly overnight, but return
elevated in the 10-25 mph range for Mon.

After the start of the work week, a drier pattern is favored as
cyclonic flow continues to weaken and sfc high pressure shifts to
the Mid MS Valley. Temps warm slightly into the 60s for Tue and
upper 60s to mid 70s for Wed. A much weaker mid level trough quickly
descends over Manitoba and Ontario on Wed and over the Great Lakes
Wed night. An associated sfc trough and cold front look to accompany
this, bringing back a around of SHRA to the region Wed night/Thu.
Confidence in the fcst quickly breaks down into the weekend as the
mid level ridge to the W falls apart. Left the NBM dry PoPs after
Mon given the uncertainty, but some PoPs could be added with future
fcst packages as time progresses and better model agreement is
achieved.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 747 PM EDT Fri Aug 22 2025

Showers and thunderstorms are moving eastward out of the area this
evening, with a return to VFR conditions under lingering midlevel
cloud cover that is expected to largely clear out from west to east
the next several hours. VFR prevails for most of the forecast
period, though a brief period of MVFR ceilings is possible between
14-18Z Saturday (20% chance) behind a secondary cold front.

Otherwise W to SW winds continue into tonight, shifting NW and
increasing to 10-15 kts behind a secondary cold front early on Sat.
Gusts on Sat are expected up to 20 kts at IWD/SAW and 30 kts at CMX.

&&

.MARINE...
Issued at 415 PM EDT Fri Aug 22 2025

Southwest winds across the lake, up to 20 kts over the west half,
continue through this evening as a cold front approaches. A
disturbance moving over the Upper Great lakes will continue to bring
showers and storms across the lake, with some of the storms
potentially bringing gusty, erratic winds and small hail to the sfc.
Winds shift west-northwest tonight into Sat as the cold front
crosses the lake, increasing to 20-30 kts for Sat. A few gale force
gusts up to 35 kts are possible (20-40% chance).

Continued cold air advection behind the cold front through the
weekend keep the northwest winds elevated across the lake around 15-
30 kts through Sun night and between 15-25 kts on Mon. Low chances
for gales briefly return on Sun (10-30% chance over the east). Winds
fall below 20 kts by Tue as ridging builds in over the region.

&&

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

&&

$$

UPDATE...LC
SHORT TERM...Jablonski
LONG TERM...Jablonski
AVIATION...LC
MARINE...Jablonski