186
FXUS63 KMQT 311951
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
351 PM EDT Fri May 31 2024

.KEY MESSAGES...

- Scattered showers continue across the west through tonight with a
few embedded thunderstorms. Locally heavy rainfall >1" possible,
especially with thunderstorms.

- Frequent opportunities for showers and thunderstorms over the next
7 days.

- Above normal temperatures through the first half of next week,
then turning cooler.

&&

.SHORT TERM /THROUGH TODAY/...
Issued at 355 AM EDT Fri May 31 2024

Southerly flow with increasing moisture, in addition to high clouds
building into western Upper Michigan has produced a mild night
across the forecast area, except interior portions of the east where
dry air and light winds have supported effective radiational cooling.
So far interior temps have fallen into the upper 30s while the
lakeshores have remain in the 40s or 50s. Across the west, min temps
in the 50s and even some low 60s have been observed so far.
Upstream, a line of showers with some preceding isolated showers has
been observed moving through northern Minnesota, pressing northeast
as a weakening cold front advances. Some lighting has been observed,
but activity has waned in the past couple of hours.

As we move through the remainder of the morning hours and into
today, showers and storms across central Minnesota will lift
northeast as the boundary presses eastward into the Arrowhead and
western Lake Superior. Some rumbles of thunder can`t be ruled out.
The weak boundary will continue pressing east while upper level
support shifts northeast, bringing with it increasing pops for the
west. Onset is a little tricky given the anticipated dwindling line
as it approaches, but the overall consensus is for light rain to
move into the west by late morning. While the boundary inches across
the Arrowhead, continued convergence with growing weak instability
out in front will result in continued shower chances through the
afternoon for the west half. Thunderstorms can`t be ruled out, but
severe weather is not expected. In the east, dry air will win out,
likely resulting in clear to partly cloudy skies. This, coupled with
dinural heating, will support mixing and enable drier air aloft to
mix down to the surface. Model soundings suggest mixing only to
around 2k feet, which would support RH percentages dipping down into
the mid 20s. If we are able to warm more and mix higher then
expected though, lower RH near 20% will be possible. Daytime highs
across the region should climb into the 70s, except remain in the
60s by Lake Michigan.

&&

.LONG TERM /SATURDAY THROUGH FRIDAY/...
Issued at 350 PM EDT Fri May 31 2024

A deep midlevel low remains situated over northern Manitoba and
Saskatchewan into the weekend. Chances for light rain showers
continue across the western UP into early Saturday morning with a
diffuse frontal boundary stalled out somewhere over western Lake
Superior or the western UP. However, a subtle midlevel wave moving
northeast from IA and WI into the area by early Saturday afternoon
will allow chances for some scattered showers to spread more
eastward into the afternoon. A better-defined shortwave then swings
around the midlevel low during the afternoon, heading into northern
Ontario by early Saturday evening. This second wave will drag the
surface boundary eastward, allowing for a broken line of showers to
track through central Upper Michigan through the afternoon and
evening hours. Simulated reflectivity shows this largely falling
apart before reaching hwy 41, with just some spotty activity across
the eastern UP that should taper off by 06Z Sunday. Weak forcing
will work against our potential for any strong to severe convection,
but soundings showing potentially several hundred j/kg of CAPE over
the area during the afternoon, some thunder will not be ruled out.
Given several rounds of scattered showers across the western UP
tonight through Saturday, HREF ensemble mean QPF indicates a good
half to 0.75in of rain by Saturday evening across the western UP,
but there is still a slight chance (20-30%) for some higher embedded
totals nearer an inch. Expect lighter amounts across the rest of the
UP before rain wraps up later Saturday evening.

Otherwise, look for somewhat breezy conditions through the eastern
UP into the afternoon as mixing deepens. Under partly to mostly
cloudy skies area-wide, temperatures peak in the 60s to lower 70s.

High pressure over the area Sunday will allow for a brief dry window
to finish out the weekend. With light winds and clearing skies, we
may start off with some patchy fog early Sunday morning. Then,
expect temperatures (starting in the upper 40s and lower 50s) to
recover nicely with most of the area climbing into the 70s. Some
spots may even make a run towards the 80 degree mark. Meanwhile,
along Lake Michigan and our western Superior shorelines, SW winds
may keep temperatures a few degrees cooler, perhaps struggling to
crack into the lower 70s.

The next shortwave moving onshore over the Pacific NW on Saturday
will reach the Upper Mississippi Valley late Sunday night and the
western Great Lakes by Monday afternoon. Showers and storms
developing along/ahead of the associated cold front will move across
MN during the day Sunday, reaching the western UP late Sunday night.
 The late arrival time into the western UP will help to work against
a strong/severe storm risk as instability diminishes with time and
eastward extent, but with a 40-45kt low-level jet translating over
western Upper MI by 12z Monday, our thunderstorm potential will be
worth watching into MOnday morning. If overnight convection can
persist into Monday morning, and skies stay cloudy, perhaps we don`t
destabilize enough for stronger storms to fire along the passing
front Monday afternoon/evening. If we do clear out ahead of the
front in the central and eastern UP, there is the potential for some
stronger convection.

Expect another brief dry window for most of Tuesday as high pressure
slides over the area behind the exiting system. Then, a negatively-
tilted trough swings through the Canadian Prairies and Northern
Plains, deepening into the middle of the week while anchoring
somewhere near Lake Winnipeg. Robust WAA ahead of this will touch
off our next chance for rain and thunder late Tuesday night into
Wednesday, then expect hit and miss chances for rain the rest of the
work week with a highly amplified pattern developing as a ridge
builds over the western CONUS and the midlevel low potentially
stalls out over the Great Lakes. Otherwise, look for much warmer
temperatures by Tuesday, then temperatures fall below normal late
week as a cooler airmass works in.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 225 PM EDT Fri May 31 2024

A slow-moving cold front is over far western Upper Michigan this
afternoon and may move over the central UP before stalling this
evening. This will result in VFR conditions prevailing at SAW and
deteriorating conditions at IWD/CMX where scattered showers are
occurring. Additional showers including potential for a few rumbles
of thunder are expected to develop around CMX/IWD this evening as
the nocturnal low level jet increases convergence along the frontal
surface. Repeated rain chances eventually lower cigs to MVFR/IFR
late in the TAF period until the front begins to push east again on
Saturday. This results in improving conditions at IWD/CMX and
deterioration at SAW Saturday evening. South-southwesterly
winds gusting to around 20-25 mph are expected at SAW ahead of
the front this afternoon, but generally light south winds
prevail at all terminals.

&&

.MARINE...
Issued at 350 PM EDT Fri May 31 2024

Under a relatively weak pres gradient and stable conditions over the
lake, expect winds mostly under 20kt today thru Sun. An approaching
cold front Sun night will bring an increase in southerly winds,
especially across the e half of Lake Superior which is typically
favored for stronger winds this type of situation. By sunrise Mon, S
to SE winds up to 25kt are expected, though given the stability over
the cold lake waters, these winds up to around 25kt will mostly be
observed at high obs platforms. That said, 25kt winds may observed
locally in the nearshore waters where flow off of the terrain
affects the wind. Cold front will pass later Mon/Mon night with
winds under 20kt following on Tue. Winds pick up again midweek ahead
of another approaching trough/frontal system. Expect winds primarily
out of the SW at around 20 knots, mainly across western Lake
Superior.

&&

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

&&

$$

SHORT TERM...JTP
LONG TERM...LC
AVIATION...EK
MARINE...LC