Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 221907

Area Forecast Discussion
National Weather Service Marquette MI
307 PM EDT Tue Aug 22 2017

.SHORT TERM...(Today and tonight)
Issued at 503 AM EDT TUE AUG 22 2017

WV imagery and RAP analysis indicated a mid/upper level trough from
the srn portion of Hudson Bay through nw Ontario to the Upper
Mississippi Valley. A shortwave trough from ne MN into nw WI
supported the lingering band of shra and isold tsra through ern Lake
Superior and cntrl Upper Michigan. At the surface, a cold front
extended through the cntrl U.P. from low pressure over ern Lake

Today, after the shrtwv and associated showers move out early today,
expect dry conditions with decreasing clouds into the early
afternoon. However, another upstream shrtwv over Manitoba along with
daytime heating may support some isold -shra into the wrn cwa by mid
to late afternoon. With gusty nw winds temps will climb into the
upper 60s with some lower 70s over the south. The brisk wnw flow
will also bring high enough waves into Alger county for a high swim

Tonight, a surface trough or secondary cold front moving into the
area with winds veering from wnw to nnw will bring addition
potential for -shra/-dz, especially for locations favored by upslope
flow off of Lake Superior as 850 mb temps drop to around 3C. Even
with lingering clouds and wind, temps over the interior west should
drop off into the mid and upper 40s while readings in the lower to
mid 50s prevail closer to the Great Lakes and over the east.

.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 18Z TAFS through 18Z Wednesday afternoon)
Issued at 151 PM EDT TUE AUG 22 2017

Conditions will continue to improve, but winds will remain gusty
until late this evening. A trough moves through tonight, turning
winds out of the N to NNW, which should bring CIGs down some mainly
at KIWD and KSAW. Any lowered conditions will improve Wed morning.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 503 AM EDT TUE AUG 22 2017

A tight pres gradient between low pressure lifting northeast from
Lake Superior and high pressure building toward the area from the
northern plains will result in wnw winds to 30 knots this afternoon
into this evening and a few gale force gusts over the eastern Lake.
Winds will veer to the nnw tonight behind a trough with winds
remaining in the 20-30 knot range through Wednesday. The winds will
then diminish Wed night as high pressure builds into the area and
remain below 20 knots for the rest of the week.

Upper Michigan...
  Beach Hazards Statement until 9 PM EDT this evening for MIZ006.

Lake Superior...
Lake Michigan...


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