Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 170830

Area Forecast Discussion
National Weather Service Marquette MI
430 AM EDT Tue Jul 17 2018

.SHORT TERM...(Today and tonight)
Issued at 429 AM EDT TUE JUL 17 2018

WV imagery and RAP analysis indicated a mid/upper level low just
east of Hudson Bay resulting in cyclonic northwesterly flow through
the Upper Great Lakes. At the surface overnight, gusty northwest
winds of 10-20 knots prevailed between 1022 mb high pressure into
the Northern Plains and a 1001 mb low east of James Bay. Latest 08Z
IR satellite imagery indicates mass of stratus clouds north of Lake
Superior which some of the models (RAP and NAM) suggest will move
into at least of the east half of Upper MI later this morning.

Today, Most models indicate any morning clouds should dissipate by
midday. Sunshine/mixing with 850 mb temps into the 8C-10C range will
support highs in the mid and upper 60s north to low and mid 70s
south. North to northwest winds will gust to 20 mph especially over
the east half of the U.P.

Tonight has the potential to be a rather chilly night inland from
the Great Lakes due to strong radiational cooling and light winds.
Some bias-corrected data are hinting at some locations possibly
dropping into the upper 30s in a few spots, but generally showing a
range from the lower 40s inland to the lower 50s near the Great
Lakes shorelines.

.LONG TERM...(Wednesday through Monday)
Issued at 336 AM EDT TUE JUL 17 2018

Upper level troughing that brings cooler conditions to Upper Lakes
today moves east on Wed allowing upper ridge and return flow to
bring warmer conditions to Upper Michigan. Have highs reaching back
into lower 80s away from lake breezes which will be strongest off
Lake Michigan, but humidity values should still be on the low side.
Based on the chilly night tonight and sunshine/mixing on Wed,
continued to lower Td compared to model blends. Will be the driest
in the interior east closer to departing high pressure ridge.
Stronger south winds on Wed night into Thu should result in much
warmer conditions on Wed night than what will occur tonight. Temps
will warm into at least low 80s all areas away from Lk Michigan on
Thu. Should stay dry until Thu night when shortwave trough and
associated wrapped up sfc low pressure system approaches the Upper
Great Lakes from the west.

Models continue to waffle back and forth as to how far north the
late week system will track. A farther north system tracking over
Upper Michigan would lead to better chances for thunder while there
would be less thunder if the system tracks more over southern
Wisconsin. In either case there should still be a good chance of
scattered showers across much of Upper Michigan Fri into Sat. Temps
on Fri likely warmest over far east with later arrival of rain
chances. Farther west on Fri with better chances of rain and thicker
clouds, readings will stay in the low to mid 70s. Highs on Sat
should be in the 70s across the board and with better chance of
north winds behind the low pressure system, it could stay in the 60s
near Lk Superior. System begins to lose its influence of the weather
over Upper Michigan on Sun, but will still see similar temps to Sat
with stiff north winds expected. Model consensus still yields slight
chances for rain on Sun. ECMWF remains slowest in departing the
upper system where the GFS and GEM are moving it out of the area by
that time. Given the upper trough will be sandwiched btwn ridging
over northern plains and ridging along east coast, the slower idea
may end up correct. Strongest jet digging into the trailing side
of upper trough would also slow it down. Quite possible that Sun
will end up cooler and with more showers than this forecast
indicates. Stay tuned on that though.

By early next week, stronger shortwave trough kicks into the
northern Plains from western Canada. This should push the pattern
along and allow weak ridging/dry weather to cross the Upper Great
Lakes on Mon.

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 138 AM EDT TUE JUL 17 2018

Expect VFR conditions through the forecast period.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 429 AM EDT TUE JUL 17 2018

Today, high pressure will build across western Lake Superior, so
expect the gustier nw winds to around 20 knots to be confined
across eastern Lake Superior. Later in the week, high pressure
will move across the region bringing light winds on
Wednesday/Thursday. South to southeast winds will increase again
late Thu into Fri to possibly as high as 25 knots over eastern
Lake Superior ahead of an approaching low pressure system over the
Plains. &&

Upper Michigan...
  Beach Hazards Statement from 8 AM EDT this morning through this
     afternoon for MIZ005-006.

Lake Superior...
Lake Michigan...


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