283
FXUS63 KMQT 141654
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
1254 PM EDT Sun Jul 14 2024

.KEY MESSAGES...

- Seasonably warm again this afternoon with scattered showers and
thunderstorms over the central and east this afternoon and evening.
One or two strong to severe storms possible with gusty winds and
hail.

- Marginal risk (category 1 out of 5) of severe thunderstorms on
Monday, main threat is damaging winds.

- Cooling and drying trend into the midweek portion of next week
with the arrival of high pressure.

&&

.SHORT TERM /THROUGH TODAY/...
Issued at 1234 PM EDT Sun Jul 14 2024

Upper air pattern continues to consist of 598 dam 500 mb anticyclone
centered over the Four Corners and a cutoff low just west of Hudson
Bay. Baggy low-amplitude troughing exists over the local area in a
slightly diffluent area downstream of the best 500 mb height
gradient. Weak impulse seen crossing into western Lake Superior
responsible for an isolated storm near Isle Royale. Though the
midlevel forcing for ascent will be weak, a good low-level
convective trigger will be in place this afternoon in the form of a
composite lake breeze/wind shift boundary. The Superior lake breeze
runs from Negaunee to Chatham as of 1225 EDT, and a north-south
oriented wind-shift boundary is inferred separating the Lake
Michigan-induced moist boundary layer with a slightly deeper/drier
boundary layer over the interior west. This wind shift boundary goes
across eastern Marquette County to the Delta/Menominee County line.
CAMs continue to depict scattered convective cells along these
boundaries this afternoon, with highest probability south of the
Superior boundary and east of the N/S boundary (roughly Alter/Delta
eastward, although a few cells cannot be ruled out further west as
well). Forecast soundings do suggest capping in this area, but the
low-level forcing can likely overcome it. With MLCAPE forecast to
reach 1000-2000 J/kg and 25-30 kt deep-layer shear, a couple of
these storms could be strong to severe with multicell or even
transient supercell mode. Gusty winds and hail will be the main
threat. These should diminish rather quickly around/after sunset,
with weak high pressure building in in its wake. Decent radiational
cooling setup with lows in the upper 50s interior to low/mid 60s
shorelines. Patchy fog possible especially in areas that receive
rainfall today.

&&

.LONG TERM /TONIGHT THROUGH SATURDAY/...
Issued at 456 AM EDT Sun Jul 14 2024

Moving onto Monday, our next shortwave trough over MN and
Manitoba swings through the region. A sfc low develops off the
Rockies into the northern Plains Sunday night. This low moves
east toward Upper MI and Lake Superior for late in the day
monday, continuing into Quebec by Tuesday afternoon. This brings
another round of showers and storms across the UP ahead of a
cold front. Bulk shear significantly increases to 40-45 kts
(7/14 0Z LREF mean) with the passing shortwave supporting
organized convection. Monday will be another warm day as well
with highs in the upper 70s to mid 80s and ample moisture as dew
points hang around the mid 60s and PWATs increase to around
1.5"(~90th percentile of the GRB sounding climatology). This
should allow for some instability, yielding weakly capped SBCAPE
~500-1000 J/kg; mid level lapse rates struggle to reach 6C/km.
Although the instability is not impressive, the forcing is good,
so thunderstorms are expected with a few being potentially
strong to severe, consistent with the SPC Marginal Risk
(category 1 of 5). Given the orientation of the shear with the
cold front, a more linear mode is expected leaving the main
threat with any severe storms to be damaging winds.

A drier airmass moves in Monday night into Tuesday behind the cold
front, diminishing precip and cloud cover. Lows are expected in the
mid 50s to low 60s.

Tuesday and Wednesday, the positively tilted mid level trough over
northern Ontario becomes more vertically oriented as it pivots over
the UP before swinging east toward Quebec and New England for late
next week. This should support some light northwest winds gusting up
to 20 mph, increased cloud cover accompanied by some light showers
and maybe a rumble of thunder on Wednesday, and cooler temps. Highs
on Tuesday stay in the 70s while Wednesday cools off even more with
highs only in the mid 60s to low 70s. Lows Tuesday and Wednesday
night dip into the 40s in the interior with 50s near the lakeshores.

High pressure then builds in from the west Wednesday, continuing to
shift over the Great Lakes through the rest of the week and next
weekend. This results in a gradual warming pattern late next week
into the weekend with dry weather. Model guidance begins to diverge
next weekend, specifically regarding when precip returns. Likely,
any precip will be supported by a shortwave dropping southeast
through the region. However, deterministic solutions of the
Canadian/ECMWF/GFS all show additional high pressures shifting back
into the region again next week with mid level ridging finally
moving east toward the midwest. So, the dry pattern may only be
briefly interrupted as it continues into the following week.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 747 AM EDT Sun Jul 14 2024

Generally VFR conditions for the duration of the TAF period with the
exception of some MVFR flight visibility restrictions at SAW due to
elevated smoke.  Other impacts include westerly wind gusts up to 22
kts at CMX this afternoon as well as possible thunderstorm
development at SAW along lake breezes (mid/late afternoon).
Confidence in timing and placement is too low, however, at this
time to mention thunder in SAW TAF.

&&

.MARINE...
Issued at 456 AM EDT Sun Jul 14 2024

Very light southerly winds below 15 kts this morning become west to
southwest by the afternoon as a cold front progresses across the
lake. Winds are generally expected to remain below 20 kts during
this period, however the strongest winds up to 20 kts are expected
between Isle Royale and the Keweenaw. Winds turn very light again
tonight through Monday morning. A round of storms is expected Monday
into Monday night as a low pressure system moves through the area.
Patchy dense fog is a possibility in the wake of any precipitation.
Following the low pressure system`s cold front, northwest to west
winds increase to around 15-20 kts across much of the lake Monday
night and Tuesday. After another period of 15-20 kt northwest winds
on Wednesday, high pressure begins to build in from the west
resulting in winds to remain below 20 kts through the remainder of
the forecast period.

&&

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

&&

$$

SHORT TERM...Thompson
LONG TERM...Jablonski
AVIATION...Thompson
MARINE...Jablonski