Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 230819

Area Forecast Discussion
National Weather Service Marquette MI
419 AM EDT Wed Aug 23 2017

.SHORT TERM...(Today and tonight)
Issued at 419 AM EDT WED AUG 23 2017

This morning, Upper Michigan was situated between high pressure over
the Northern Plains and low pressure southeast of the Hudson Bay.
Upstream of the area, a weak shortwave began to dig south across
Lake Superior and usher in better cold air advection southward. With
a lingering enhanced pressure gradient and increasing cold air
advection across the region, quasi-breezy winds lingered across
inland areas and especially near the shores of Lake Superior.

The arrival of better cold air advection and remnant upslope flow
will allow ongoing cloud cover to linger and likely become more
widespread this morning as we start to see diurnal heating pick up.
A few areas of light rain/sprinkles are possible early this morning,
but as dry Canadian air continues to drop south, clouds will begin
to dissipate through the afternoon hours from north to south. As the
above mentioned area of high pressure begins to work it`s way into
Upper Michigan later today, breezy winds will subside through the
afternoon and evening hours from west to east. The strongest wind
gusts are expected to be along the shores of Lake Superior, which
will create a high swim risk today for the beaches of Marquette and
Alger Counties. Temperature wise today, it will be a battle between
increased insolation and cold air advection, and in some locations
downslope warming as well. Overall, afternoon high temperatures
should climb into the 60s, with the warmest temperatures expected
across the south central. Given the increasingly dry air mass this
afternoon, wouldn`t be surprised if a few locations reach the 70
degree mark.

Tonight, the combination of dry air, ample boundary layer
decoupling, and mostly clear skies will result in strong radiational
cooling through the overnight and early morning hours. Right now it
is still looking like patchy to widespread frost will be possible
across the interior west early Thursday morning. There is the
potential for mid-level clouds to slow the rate of cooling overnight
along the Wisconsin border as a shortwave digs south across the
Upper Mississippi Valley, but the majority of the thicker clouds are
expected to remain south of the area.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 306 PM EDT TUE AUG 22 2017

Very quiet weather expected through much of the extended forecast.
The only issue expected will be the frost potential on Wednesday
night and again Thursday night into Friday morning.

At the surface, high pressure will build into the area and linger
through much of the extended forecast. This will keep mainly dry
condtions in place across the Upper Great Lakes region under light
winds. Aloft, much of the east half of the CONUS will be under a
general troughing pattern. While afternoon mixing will be very good,
the potential for any afternoon cu development will be marginal as
the airmass looks to be very dry throughout the thermal profile.
PWAT values actually look to be around 50 percent of normal for this
time of year, again, pointing toward the drier air moving into the
area. This very dry air in place along with light winds will lead to
near to slightly below normal temperatures through the extended. In
fact, overnight lows will likely drop to near 30 degrees over
portions of the inland west Wednesday night into Thursday morning
and again Thursday night into Friday morning. Some of the coldest
model guidance is actually showing lows dropping into the mid and
upper 20s in some of the coldest locations of the inland west.
Definitely not out of the question with maximized radiational
cooling. These much cooler overnight lows will lead to patchy to
potentially widespread frost across the inland west areas of the
U.P. for both Wednesday night and again Thursday night.

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 127 AM EDT WED AUG 23 2017

VFR conditions will give way to MVFR to lower VFR cigs overnight as
secondary trough brings in resurgence of cool/moist air to the
region. May be a few light showers late tonight into Wed morning at
IWD and SAW behind the trough but no reduction to vsby is expected.
After broken to overcast clouds to start the day on Wed, expect
skies to clear out in the afternoon. NW winds will be gusty again at
all the TAF sites, but not as strong as occurred on Tue aftn.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 419 AM EDT WED AUG 23 2017

Today winds will start off gusty, at speeds of 20 to 30 knots across
much of the lake, and then gradually weaken to around 10 to 20 knots
from west to east later this evening and tonight as high pressure
drops into the Upper Great Lakes region. This area of high pressure
is expected to linger across the region through the end of the week
and weekend. Therefore, expect winds to be less than 20 knots.

Upper Michigan...
  Beach Hazards Statement through this evening for MIZ005-006.

Lake Superior...
Lake Michigan...


SHORT TERM...Ritzman
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