-- Discussion containing changed information from previous version are highlighted. --
903
FXUS63 KMQT 272317
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
717 PM EDT Mon May 27 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 425 PM EDT Mon May 27 2024

Water vapor imagery and RAP analyses reveals two well-defined
shortwaves over the Great Lakes, one moving from the Lower Peninsula
into eastern Ontario with an associated deep surface low heading
towards the Quebec border. Another wave is dropping southeast
through central MN. As this second wave continues to move southward,
it will amplify the broad troughing over the region ahead of yet
another weaker wave that is already moving into Manitoba. Rain
showers continue to pivot into the eastern UP this afternoon as the
first low over eastern Ontario continues its eastward trek, with
plenty of lower-level cloud cover apparent on satellite. However, we
have pretty much dried up west of Hwy 41, and skies have even been
able to clear across the far western UP. This has allowed for some
convection to develop, apparent in agitated cu and weak radar
returns popping across Gogebic and Iron county. There is quite a
range in temperatures from west to east as areas that have cleared
out are climbing well into the 60s and even lower 70s, while most of
the eastern UP is struggling even to reach the mid 50s.

As rain across the eastern UP finally moves out of the area, a brief
window of dry weather is expected overnight. Cloud cover should fill
in across the west with the shortwave currently over MN moving into
central WI, and though precipitation associated with this should
largely stay out of the area, will not rule out some showers
reaching the far western UP later tonight.

Otherwise, expect temperatures to fall back into the mid/upper 40s
overnight. Winds remain elevated particularly across the eastern UP
on the back edge of the exiting system, which should help to limit
the development of fog in spite of plenty of lower level moisture.

&&

.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 /00Z TAFS THROUGH 00Z TUESDAY/...
-- Changed Discussion --
Issued at 717 PM EDT Mon May 27 2024

VFR is likely to prevail thru this fcst period at IWD/CMX/SAW. A
disturbance dropping into the Upper Mississippi Valley may bring a
few -shra into western Upper MI late tonight and early Tue morning.
Only a VCSH mention was included at IWD. Do not expect conditions to
drop out of VFR even if a -shra occurs.
-- End Changed Discussion --

&&

.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...
  Beach Hazards Statement until 10 PM EDT this evening for
     MIZ005-006.

Lake Superior...
None.
Lake Michigan...
None.

&&

$$

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