961
FXUS63 KMQT 241848
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
248 PM EDT Fri May 24 2024

.KEY MESSAGES...

- Another shortwave and low pressure system will bring a round  of
showers and some thunder tonight into Saturday morning.

- There will be more opportunities for rain next week although
  model uncertainty leads to low forecast confidence on
  timing/extent.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 247 PM EDT Fri May 24 2024

Water vapor imagery and afternoon RAP analyses show a negatively
tilting midlevel trough over the Northern Plains, and an associated
994mb surface low centered over the western MN border. A pronounced
dry slot is curling into central MN. Robust warm air advection and
isentropic ascent into the Great Lakes out ahead of the system has
touched off convection across WI, but so far, though high cloud
cover is overspreading the Upper Peninsula, bands of showers/storms
haven`t survived the trek through northern WI given a very dry
airmass (see early afternoon NUCAPS profiles, latest model
soundings, and surface dewpoint depressions on the order of 20
degrees). Weak radar returns moving over the UP so far are not
producing much by any way of accumulations, but have allowed for some
isolated shower activity in the forecast across the western half of
the UP the rest of the afternoon. Some rumbles of thunder will also
be possible over the far west with a few flashes over Superior
already.

Meanwhile, in spite of increasing cloud cover, temperatures have
been able to rise quite nicely across the area with most of the UP
climbing well into the 60s already. Many spots should peak in the
lower 70s today. The exception remains areas along hte lakeshores,
where onshore flow is keeping temperatures from climbing out of the
50s along Superior, and suppressing them into the lower 60s along
Lake Michigan. Winds are turning gusty, particularly across the far
western UP so far where SE gusts up to 20-30mph are becoming more
common. Winds should pick up across the central and possibly eastern
UP into the early evening with a tightening pressure gradient and
increasing winds aloft.

As the increasingly vertically stacked system off to our northwest
moves northward over the Ontario/Manitoba border region, the base of
the midlevel trough swings through the area, eventually dragging a
cold front through the area late tonight. An associated swath of
convection currently over central and southern WI reaches the
southern UP by the early evening, and sweeps through from west to
east overnight before exiting eastward during the pre-dawn hours. So
far, under a capped atmosphere, CAPE remains quite limited, and this
should not improve much heading into the evening hours. Still, a
couple hundred j/kg of elevated CAPE is present off the soundings
this evening, so will not totally rule out some thunder. As far as
rain totals go, guidance continues to favor a widespread 0.20-
0.50in, and some higher embedded totals near (and perhaps in excess)
of 0.75in mainly along the WI border. Rain ends from west to east
the second half of the night as the dry slot moves in, with clearing
skies.

Otherwise, look for breezy conditions to continue into the night,
with SE winds continuing to gust to around 20 mph ahead of the
approaching boundary. Winds turn calmer behind this while shifting
more to the WSW. Temperatures, meanwhile, fall back into the lower
40s in the western UP (behind the boundary) and in the upper 40s to
lower 50s in the east (ahead of the boundary).

&&

.LONG TERM /TONIGHT THROUGH THURSDAY/...
Issued at 333 AM EDT Fri May 24 2024

Upper air pattern consists of a deep 500 mb trough on the west
coast, a negatively tilted shortwave and closed 500 mb low in the
upper Mississippi Valley 00z Sat. This shortwave heads northeast
into the upper Great Lakes 12z Sat and across Ontario on Sat night.
Upper troughing then remains over the area into 12z Mon as more
energy comes out of the west coast trough and keeps troughing over
the area. A wave of pcpn will come in tonight and move out late
tonight into Sat morning with dry weather moving in for most of
Saturday before the next system moves in for Sun. There are some
pops that could make it into the far west by Sat evening and have
slights in there to cover it. Otherwise, did not make too many
changes to the going forecast.

In the extended, the GFS and ECMWF and Canadian all show a 500 mb
trough in the Great Lakes region 12z Mon which moves to the lower
Great Lakes region 12z Tue. Ridging then moves into the northern
plains 12z Wed and into Thu. Upper troughing then moves into the
northern plains 12z Fri. Temperatures look to be near normal for
this forecast period. Only prolonged dry period looks to be Wed for
now. With troughing, does look unsettled.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 127 PM EDT Fri May 24 2024

VFR conditions prevail at all TAF sites so far, but rain showers
working into the area beginning at IWD early this evening will
result in deteriorating ceilings and -SHRA. -SHRA arrive at CMX by
00Z, and at SAW by 03Z. There is around a 25-35% chance for TSRA as
well, so VCTS remains in the forecast at all terminals. With the -
SHRA, IWD is expected to fall to MVFR with a 25% chance of IFR while
SAW and CMX are expected to fall to IFR with 20-25% chances of LIFR.
Current model guidance does not suggest LLWS at any of the TAF
sites, but some LLWS may be more prevalent over Lake Superior where
the LLJ may be stronger tonight. A quick improvement to MVFR and
then VFR is expected from west to east as showers move out after
06Z. Otherwise, expect gusty winds mainly out of the south at IWD
and CMX this afternoon and evening. Winds turn calmer behind the
passing wave tonight, shifting over to the SW.

&&

.MARINE...
Issued at 333 AM EDT Fri May 24 2024

East winds will begin to ramp up to 20 to 30 knots today in advance
of another low pressure lifting from the Northern Plains towards
Lake Winnipeg. Northeast gales to 35 knots will continue across the
far western part of the lake today. Winds over the west half
becoming southwest behind the low and the passage of its cold front
late tonight into Saturday and generally stay in the 15 to 25 knot
range. Winds decrease late Saturday behind the exiting system, then
expect light winds of 20 knots or less across Lake Superior for the
rest of this weekend as a high pressure ridge builds over the area.
Looking ahead to early next week, another system moving out of the
Plains will head towards the Great Lakes.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Gale Warning until 8 PM EDT /7 PM CDT/ this evening for LSZ162.

Lake Michigan...
None.

&&

$$

SHORT TERM...LC
LONG TERM...07
AVIATION...LC
MARINE...07