570
FXUS63 KMQT 010018
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
818 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 TONIGHT/...
Issued at 410 PM EDT Fri May 31 2024

Only minor forecast updates were needed today with sunnier skies
allowing for slightly warmer temperatures approaching 80F. Deeper
mixing also allowed for somewhat stronger winds, but overall the
fire weather forecast was spot on across the east with RH dipping to
around 25% and SSW winds of 10-15 mph with gusts to 20mph. The only
exception was the Newberry RAWS which is reporting a dew point 11-
17F lower than all surrounding observations raising questions about
how representative the observation is. On the other side of the
Peninsula, an area of rain/rain showers lifted northeast across our
western tier of counties for most of the day. While no thunder has
been reported, CMX reported a brief period of heavy rainfall as it
moved overhead. Coverage is currently waning suggesting a general
lull head of the next wave this evening. As of 355 PM our radar
started picking up the frontal boundary extending southeast from Big
Bay.

Looking ahead through tonight, the frontal boundary is expected to
slow and eventually stall tonight. As the boundary stalls, the
nocturnal LLJ ramps up to around 35 kts as it noses into our area
this evening. This disturbance and the associated area of of showers
and embedded thunderstorms is already showing up on regional radar
in the vicinity of Minneapolis. CAPE is insufficient for severe
concerns, but pwat values >1 inch (approaching the 90th percentile)
and potential for multiple rounds of rain suggests a chance for
locally heavy rainfall and perhaps patchy fog too. 12z HREF PMM
guidance paints a stripe of heavier QPF between Watersmeet and
L`Anse, which is primarily instigated by NAMnest and HRW NSSL
guidance. However, it`s worth noting that most other guidance is
further west roughly between Ironwood and Copper Harbor.
Fortunately, river levels remain low and flooding concerns are
limited to ponding in poor drainage areas.

&&

.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 /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 816 PM EDT Fri May 31 2024

VFR conditions to deteriorate to MVFR/IFR at IWD/CMX early tonight
with onset of showers associated with a cold front. Best chances
for any thunderstorms will remain confined to IWD. Meanwhile,
SAW is expected to remain at VFR levels for the duration of the
TAF period. But, VFR is progged to return to IWD/CMX as well by
tomorrow afternoon when the cold front pushes eastward. Winds
will be light and southerly.

&&

.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...EK
LONG TERM...LC
AVIATION...TDUD
MARINE...LC