055
FXUS63 KMQT 062258
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
658 PM EDT Mon May 6 2024

.KEY MESSAGES...

-Quiet weather through tonight.
-Complex mid-week weather pattern with rain chances increasing
 on Tuesday and multiple passing low pressures keeping rain in
 the forecast through the end of the week.

&&

.SHORT TERM /THROUGH TODAY/...
Issued at 142 PM EDT Mon May 6 2024

Upper air pattern consists of a 500 mb trough in the central Rockies
and a shortwave in the mid Mississippi River Valley. The trough
heads northeast and develops a closed 500 mb low that moves into the
Dakotas by 12z Tue. Weather will be quiet through tonight with very
few changes made to the going forecast.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 344 PM EDT Mon May 6 2024

The extended forecast is largely dominated by a trough currently
approaching the Northern Great Plains and its complex evolution and
influence on the surface lows moving across the CONUS through the
upcoming week, which will keep precipitation chances in the forecast
throughout the forecast period.

For Tuesday, the negatively tilted trough forms a closed off low
over the Northern Plains as the shortwave continues northeast from
Iowa to the Upper Great Lakes. This stacked low will be stalled over
the Dakotas Tuesday through Wednesday morning, but a shortwave
rotating around the base of the low aloft will be the focus for the
weather pattern heading into the midweek. This shortwave will get
jet support as it becomes coincident with a right-entrance region of
a ~125 kt 300mb, giving enough synoptic support for showers over the
UP beginning Tuesday late-morning in the west and overspreading the
UP by the end of the day. This continues a model trend of
precipitation arriving later with each major model run. With bulk
shear low (20-35 kts) and mean 12Z HREF MUCAPE of around 100mb, not
many thunderstorms are expected, but a few rumbles of thunder can`t
be ruled out. With moisture advecting in and cloud cover ahead
limiting mixing potential, minimum RHs barely fall into the 30s
ahead of the approaching showers, so fire weather shouldn`t be a
concern, and with a WPC Marginal Risk of Excessive Rainfall, any
minor fires that may start should be extinguished naturally.

The pressure falls associated with the shower activity Tuesday will
become a discrete surface low pressure by Wednesday morning and
depart the region by the afternoon. As it does, the original closed
low over the Dakotas will weaken from a peak strength of near 980mb
Tuesday morning to near 1000mb by midday Wednesday as it slides
southeast. As it does, it will phase with another weak lee cyclone
off the Rockies, with ensembles tracking this new low generally
around Lake Michigan and Illinois by overnight Wednesday into
Thursday. Precip will be the forecast if the northern clusters
verify, but the UP could be high and dry if a more southern solution
materializes. By Friday, anomalous ridging over coastal British
Columbia will be contrasted with anomalous troughing over the Lower
Great Lakes, putting the UP in a northwesterly flow regime. Some
deterministic and ensemble guidance suggests a clipper-type low late
in the week into the weekend, keep PoPs in the forecast, though
uncertainty is high in any specifics as the complex setup has a lot
of variables to work out first. Confidence is increasing that this
ridge will shift over the Great Lakes by the midweek of next week,
warranting the CPC to favor below normal precipitation for the
second half of May.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 658 PM EDT Mon May 6 2024

VFR conditions continue through tonight as an occluding front
approaches the U.P. from the south, arriving Tuesday. This front
will degrade conditions at KIWD to IFR by the early afternoon and
MVFR at KCMX and KSAW late in the afternoon as rainfall moves into
the area. Some LLWS is expected over KIWD late tonight as the front
approaches. While there is a small chance (20%) for LLWS to develop
around 12z Tuesday over KCMX, given the that the stronger winds will
more than likely not reach KCMX until the late morning to early
afternoon hours (when they will be able to mix down to the surface),
LLWS isn`t expected for KCMX.

&&

.MARINE...
Issued at 344 PM EDT Mon May 6 2024

With high pressure over the Upper Great Lakes, resulting stability
will keep winds mainly below 20 kts through tonight for the vast
majority of Lake Superior. The exception to this would be over the
far western portion of the lake near the Duluth Harbor where some
northeast channeling may yield some gusts up to 25 kts. An
approaching low pressure Tuesday morning will force northeasterly to
east winds to funnel over the western half of Lake Superior to 25
kts by noon Tuesday with a few gusts to 30 kts in the far west and
along the Minnesota shorelines. Winds across the east half of the
lake increase to around 20-25 kts Tuesday afternoon. A brief break
in 20+ kt winds is expected Tuesday night. Periodic chances for
winds in the 20-30 kt range dot the forecast through Thursday as
multiple weak low pressure systems pass through the Upper Great
Lakes region, but uncertainty still remains.

&&

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

&&

$$

SHORT TERM...07
LONG TERM...GS
AVIATION...TAP
MARINE...GS