Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 171934

Area Forecast Discussion
National Weather Service Marquette MI
334 PM EDT Sun Sep 17 2017

.SHORT TERM...(Today and tonight)
Issued at 543 AM EDT SUN SEP 17 2017

Water vapor imagery and RAP analysis show a vigorous shortwave
lifting thru se Manitoba and adjacent MN/northern Ontario.
Associated cold front cuts across far western Upper MI with sct to
nmrs shra and some thunder along/ahead of it. After an unseasonably
warm and humid day yesterday, conditions continue to be unseasonably
warm across Upper MI early this morning with temps in the 60s to
around 70F and dwpts in the 60s, much more typical of mid summer.

Cold front will continue to sweep eastward today, exiting the
eastern fcst area early this aftn. Will generally carry sct shra and
some thunder eastward with the front. With arrival of drier air
after fropa, clouds will begin to clear out with skies becoming
sunny across at least the w half of Upper MI by 18z. Given the very
warm start to the day for this time of year, max temps will still be
above normal today over the central and eastern fcst area despite
fropa. Max temps should range from low 60s far w to the mid 70s s
central. However, temps over the eastern fcst area, especially
closer to Lake Superior, should fall into the lower 60s rather
abruptly this aftn as winds shift to the nw off Lake Superior. Will
be a breezy day on the Keweenaw under favorable post-frontal
westerly winds and decent mixing. Expect gusts to 30-35mph there.
Finally, waves are sufficently high from ongoing southerly flow to
lead to a mdt swim risk for the Lake Michigan beaches of Schoolcraft
County today, though that risk will diminish this aftn as winds
shift w to nw and waves subside. To the n, a high swim risk will
develop for the Lake Superior beaches of Alger County this aftn as
brisk nw winds build waves.

Sfc high pres will build over the Upper Lakes tonight, leading to a
quiet/cool night. With precipitable water down toward 0.35 inches
for at least for the first half of the night, favored some of the
lower guidance for mins in the interior, especially w half where
winds will diminish quickest to light/calm during the evening.
Should see some frost in the interior w half as temps fall into the
mid 30s for at least the traditional cold spots.

.LONG TERM...(Monday night through Sunday)
Issued at 332 PM EDT SUN SEP 17 2017

Nothing too concerning in the long term at this point. The only
thing to not hazard wise is that there could be some stronger storms
on Wednesday.

A shortwave will bring some rain showers Mon night, leaving partly
to mostly cloudy skies and near normal temperatures for Tuesday.

A shortwave moving NW of the CWA will bring a cold front across the
area late Tue night possibly into Wed night. Could have enough
instability (1,000-1,500 J/kg) and shear (around 30kts) for some
stronger storms, depending on timing.

Wed starts the return of above normal temps that will last through
the weekend. Temps will be 5-15 degrees above normal with the
warmest day being Fri with highs in the mid 70s to mid 80s.

Plenty of uncertainty with precip over the weekend as models
disagree on the position of stalled frontal boundary.

Did not make any changes to blended initialization.

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 207 PM EDT SUN SEP 17 2017

Conditions continue to improve with just an hour or two of MVFR cigs
left at CMX and SAW. Expect VFR conditions with a few high clouds
through rest of the TAF period. WNW winds will gust over 25 kts at
CMX this aftn but should gust to 20 kts or less at the other TAF

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 543 AM EDT SUN SEP 17 2017

With the passage of a cold front this morning into early aftn,
westerly winds will increase quickly to 20-30kt for much of Lake
Superior. Winds will then diminish to under 20kt from w to e tonight
as sfc high pres builds into the Upper Great Lakes. With high pres
lingering on Mon, winds should be mostly under 15kt. Winds should be
under 20kt on Tue, then stronger southerly winds of 20-25kt, even up
to 30kt over eastern Lake Superior, are possible on Wed as sfc trof
moves toward the Upper Lakes. Winds will drop off to under 20kt on

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

Lake Superior...
Lake Michigan...


SHORT TERM...Rolfson
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