-- Discussion containing changed information from previous version are highlighted. --
849
FXUS63 KMQT 271029
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
629 AM EDT Mon May 27 2024

.KEY MESSAGES...

- Below normal temperatures for the first half of the week, followed
by a drying trend midweek. Areas of frost expected Thursday morning.

&&

.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 234 AM EDT Mon May 27 2024

Upper air pattern consists of a 500 mb closed low in eastern
Manitoba with a shortwave over the upper Great Lakes with another
shortwave over the northern plains. The northern plains shortwave
heads east and helps the trough amplify over the Great Lakes region
00z Tue. 850-500 mb q-vector convergence and deeper moisture remain
over the eastern half of the cwa today while the west is drier. This
will continue to be where the highest pops will be while the west
remains mostly dry. Overall, did not make too many changes to the
going forecast.

&&

.LONG TERM /TONIGHT THROUGH SUNDAY/...
Issued at 316 AM 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.

In terms of sensible weather, weak ridging will sit atop the
shortwave moving south of the region today, supporting a dry evening
across the west. After midnight though, the leading edge of the next
shortwave moves in, potentially supporting showers in the west by
early Tuesday morning. Rain showers in the east should continue
their slow diminishing trend as the surface low to the northeast
pulls away to night into Tuesday. A cooler airmass will build into
the region tonight and Tuesday alongside the closed mid-level low.
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, possibly a thunderstorm as well.

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 continue Tuesday`s 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, I suspect a freeze may even be on the table. 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
increasing rain chances Saturday with the passage of a cold front.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
-- Changed Discussion --
Issued at 628 AM EDT Mon May 27 2024

Low pressure over Lake Michigan will track east today, bringing shra
to the east half of Upper MI. At IWD, VFR will prevail thru this
fcst period, but there will be some VLIFR fog coming off Lake
Superior early this morning. At CMX, either lower clouds wrapping
back to the terminal or upsloping of fog/stratus over the lake
should result in MVFR cigs developing this morning briefly. VFR will
return later this afternoon. SAW will be on the nw edge of the pcpn
shield. That should lead to IFR cigs setting in this morning under
upslope nne winds of around 15kt. These low clouds are likely to
persist until this evening when VFR should return.
-- End Changed Discussion --

&&

.MARINE...
Issued at 316 AM EDT Mon May 27 2024

A surface low will track northeast across Lake Michigan and northern
Lower Michigan today. As the low transits, expect primarily
northeast winds to become northerly this morning, and then
northwesterly by evening. Winds are mostly expected to be 20 to 30
knots across the east half while the west remains below 20 knots.
Wave heights of 4 to 7 feet should be expected across the east half.
The low will pull away tonight with these elevated northwest winds
continuing into Tuesday night across the east. 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.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
Upper Michigan...
  Beach Hazards Statement through this evening for MIZ005-006.

Lake Superior...
None.
Lake Michigan...
None.
-- End Changed Discussion --

&&

$$

SHORT TERM...07
LONG TERM...JTP
AVIATION...07
MARINE...JTP