091
FXUS63 KMQT 280618
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
218 AM EDT Tue May 28 2024

.KEY MESSAGES...

- Rain continues in the far eastern UP this evening, then additional
rain showers move across the UP later tonight through Tuesday.
- Below normal temperatures for the first half of the week, with dry
weather returning midweek.
-Areas of frost expected Thursday morning.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 217 AM EDT Tue May 28 2024

GOES 16 IR base and derived products and surface observations
highlight a mix of clouds across the region with overnight
temperatures in the 40s and 50s. Upstream, radar returns from the
DLH radar show light rain showers exiting the Arrowhead and pressing
southeast into western Lake Superior, the Apostles, and northwest
Wisconsin. A little further west, another patch of showers is moving
through northern Minnesota. GOES 16 Water Vapor and RAP height
analysis suggest both of these patches appear to be associated with
two weak shortwaves rotating through the base of a closed upper
level low. As we progress through the remainder of the overnight
period, both will inch closer to the western U.P. The forward most
patch may support some sprinkles or light rain here and there
beginning in the next hour or so, and then continuing past sunrise.

Today, the closed mid-level low in western Ontario will press south
into Lake Superior, pushing these shortwaves through the Upper
Midwest/Great Lakes. Guidance suggests both will press southeast,
with the forward most one supporting showers along the stateline
counties. The second shortwave looks to press further south and
avoid our region. Further upstream in Minnesota and western Ontario,
vort max rotating through the mid-level low, aided with some dinural
instability, may kick off showers and maybe some thunderstorms.
These may drop into western Lake Superior/Isle Royale this afternoon
and evening, but the stable lake and decreasing heating into the
evening should limit how far these press south over the lake. A
cooler airmass will also rotate into the region through the day.
Under northerly and northwesterly flow, this should support highs in
the 50s by Lake Superior and low-mid 60s elsewhere.

&&

.LONG TERM /TUESDAY THROUGH MONDAY/...
Issued at 425 PM EDT Mon May 27 2024

Recent deterministic and ensemble guidance packages are continuing
to handle the up coming pattern consistently for Upper Michigan. The
long term pattern for Upper Michigan will start off with broad mid-
level troughing overhead as today`s surface low pulls away through
Ontario into Quebec. Within this flow, a shortwave will press east
through MN/WI into this evening followed by a weakening closed low
pressing through the Upper Great Lakes Tuesday. Afterwards, ridging
builds into the region for the latter half of the week followed by a
cold front for the weekend.

After a brief, mainly dry period overnight, the next shortwave
(currently over Manitoba) begins to drop through, ushering in a
cooler airmass as well as our next batch of rain showers. While the
better synoptic forcing appears to be south and west, increasing
instability through the day, coupled with the possible morning
shortwave, could support increasing coverage of showers through the
day in the west, and possibly a thunderstorm as well. Meanwhile,
look for temperatures to range in the 50s and 60s, coolest along
Superior amid onshore flow. Winds may turn breezy during the
afternoon, gusting up to around 20mph especially across the eastern
half of the UP.

Ridging and an increasingly dry airmass will build into the region
late Tuesday night and then persist through at least Friday. This,
alongside the cooler airmass will keep daytime highs of 50s and 60s
into Wednesday. Frost may be a concern for portions of the interior
west Tuesday night and will be for most interior locations Wednesday
night. Confidence is high (>75%) for patchy to areas of frost
Wednesday night. While our internal model certainty tool and NBM
probabilities suggest a 50% chance of falling below 35F for interior
portions of Upper Michigan, both EC and GEFS ensemble suggest PWATS
of 20-30% of normal. Given this, subsidence overhead, and the weak
winds, a freeze is also a possibility. Will note NBM guidance shows
around a 20% chance for lows below freezing. At this point, a Frost
Advisory seems likely (>75% chance) Wednesday night but will
continue to monitor model trends. While frost is also possible
Tuesday night, the timing of the drier air and potential for
continued winds above 5 mph suggest radiating out may be more
difficult.

Guidance also continues to suggest the dry and well-mixed boundary
layer will support plummeting dewpoints and RH falling below 30%
away from the lakeshores Wednesday and Thursday. A mitigating factor
for the fire weather risk, in addition to fairly light winds, will
be the widespread rain in the preceding days. Ridge axis builds into
the region Thursday night while another trough presses out of the
Rockies. Guidance consensus continues to suggest the surface high
and dry conditions will win out through at least Friday night, with
rain chances returning Saturday as a cold front moves through. June
may start off wet with a troughy-looking pattern setting up over the
Great Lakes.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 123 AM EDT Tue May 28 2024

VFR will prevail thru this fcst period at IWD/CMX/SAW. A disturbance
dropping into the Upper Mississippi Valley may bring a few
-shra/sprinkles overnight into early this morning across western
Upper MI, possible affecting IWD. Do not expect conditions to drop
out of VFR even if a -shra occurs.

&&

.MARINE...
Issued at 425 PM EDT Mon May 27 2024

Behind an exiting surface low, winds continue to back to the NW over
eastern lake Superior and over to the west across the western half
of the lake. 20-25 kt gusts continue across the eastern half of the
lake through the evening hours, but should fall back to around 20
knots later tonight while winds remain below 20 knots to the west.
Wave heights of 4 to 7 feet should be expected across the east half.
The low will pull away tonight, but NW winds continue to gust to
around 20 kts through Tuesday before falling back Tuesday night.
High pressure builds across the lake on Wednesday supporting light
and variable winds and decreasing waves until Thursday midday, when
light easterly to southeasterly flow at 5-15 kt re-establishes
itself across the western lake, along with waves 1-3 ft. Winds then
veer to the south for Friday and into the weekend, but continue to
come in at around 5-15kts with waves around 1-3ft across the lake.

&&

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

&&

$$

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