457
FXUS63 KMQT 250547
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
147 AM EDT Wed Jun 25 2025

.KEY MESSAGES...

- Wednesday evening through Friday, rain overspreads the UP. 24-hour
rain rates of 1+ inch are 50% likely with rainfall totals up to 2
inches possible (10-20% chance). The WPC Outlook for Excessive
Rainfall is a Slight Risk (category 2 of 4).

- After near-normal temperatures this week, a brief warmup into the
80s is expected this weekend, with showers and thunderstorms
possible (around 50%).

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 139 PM EDT Tue Jun 24 2025

GOES-East visible imagery shows expansive cloud cover over the south
and east while the north and west have cleared out. The clouds are
associated with a stalled boundary that has provided some scattered
remnant low-impact light rain showers for the south-central UP.
Meanwhile, clearing is courtesy of a RAP-analyzed 1024mb high
pressure centered over northern MN. With flow above 700mb mostly
parallel to the boundary, cloudy conditions should prevail over the
south, but the encroaching high should allow for clearing skies
elsewhere. Light north winds associated with the high will allow for
lake breezes to form off Lake Superior and keep high temperatures at
the lakeshores around the 60 degree mark while the interior will be
around 70, a massive decrease in temperatures from the last few
days. Low temperatures falling to around the 50 degree mark tonight
will be a certain relief following the recent heat. Due to lighter
winds and moist conditions lingering at the surface, the HREF
signals a 20 percent chance of visibility falling below 1 mile due
to fog, especially places close to the cool, moist flow off of Lake
Superior.

Wednesday morning remains dry, but chances of rain begin to creep up
from the southwest in the afternoon as weak isentropic ascent ahead
of a subtle disturbance aloft provides forcing for some showers. For
Wednesday and Wednesday evening, the best moisture will still remain
south of the UP as vapor transport plots show some gulf/monsoonal
flow flowing into Wisconsin but having a sharp gradient up to the
UP. As such, PWATs closer to an inch are forecast instead of the
over 1.75 inch PWATs in the Green Bay and south vicinity. Mean LREF
QPF values through 12Z Thursday are around a half inch along
the MI/WI state line, gradually falling to around a tenth of an
inch for the north/eastern UP. With the timing of better shower
coverage expected to be well after peak heating, instability is
not expected to be abundant, so thunderstorms are not forecast,
save for a slight chance (around 15%) for the city of Menominee.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 340 PM EDT Tue Jun 24 2025

By Thursday, the upper air pattern will consist of a decaying 500mb
ridge over the eastern CONUS and a decaying advancing trough moving
from the Rockies into the plains and towards the Great Lakes. At the
surface, a quasi-stationary front will be draped from west to east
across the Lower Midwest and southern Great Lakes basin with a low
pressure system of about 1010mb expected to pass along this boundary
supported by the aforementioned trough. Significant Gulf/monsoonal
moisture advection along this front will be ongoing Thursday morning
bringing heavy rain south and west of the UP, and as stronger
forcing approaches the UP, the UP is in line to get a soaking of
rain. EFI and Shift of Tails are both somewhat elevated along the
MI/WI state line for precipitation, indicating elevated potential
for impactful heavy rainfall. The LREF continues to highlight
10-20 percent chances of daily rainfall totals exceeding 2
inches during the day Thursday, and modest mid-level lapse rates
during the daytime will allow for around 500 J/kg of MUCAPE to
grow, so some thunderstorms will be embedded with the rainfall,
though severe weather is not expected. Flash flooding would be
the main concern with this event, though the WPC outlook for
Excessive Rainfall remains around 15 percent. With forcing
waning through the day Friday, precipitation intensity and
chances also wane from west to east, with weak high pressure
leading to a dry Friday night into Saturday morning.

Into the weekend, with both major synoptic longwave features over
the CONUS this past week having decayed, quasi-zonal flow will
persist over the CONUS through the weekend, with the weather being
highly susceptible to weaker impulse shortwaves. Given the spread of
paths of such shortwaves for forcing, uncertainty in potential for
organized convection this weekend is high (and thus, no severe
thunderstorm outlooks for the UP yet), but ingredients will likely
be present as a warmup to the 80s is expected. With the warmth comes
surface instability with LREF mean surface CAPE growing to around
1500 J/kg in the interior west by 00Z Sunday and around 2000 J/kg by
00Z Monday, both coincident with about 25 kt of bulk shear to
organize convection.

Given the weakly-forced pattern, it is no surprise that the global
deterministics and ensembles rapidly diverge in how the next
pattern establishes itself, however, the most likely pattern for
next week looks to be ridging over the Rockies to Plains with
troughing over eastern North America. This leads to persistent
high pressure over the UP interrupted by clipper shortwaves
riding over the ridge bringing periodic rain chances but
otherwise better chances at warmer than normal conditions, which
the CPC outlooks align with.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 146 AM EDT Wed Jun 25 2025

VFR will be the predominant flight category for the duration of the
TAF period, but there will be a few exceptions. First, will carry
mention of IFR fog formation at CMX early this morning. Also, will
carry PROB30 chances for MVFR conditions at IWD and SAW this
afternoon and evening as rain showers overpsread the area.

&&

.MARINE...
Issued at 459 AM EDT Tue Jun 24 2025

In the wake of a second cold front this morning, high pressure
increasing overhead will keep winds mainly below 20 kts through at
least midweek. On Thu, NE winds briefly increase to ~20 kts across
the W arm of the lake. Winds fall back below 20 kts for Fri as they
back W. Another round of showers and storms will also be possible
Thu into Fri.

&&

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

&&

$$

SHORT TERM...GS
LONG TERM...GS
AVIATION...TDUD
MARINE...Jablonski/LC