Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 151809

Area Forecast Discussion
National Weather Service Marquette MI
209 PM EDT Sun Oct 15 2017

.SHORT TERM...(Today and tonight)
Issued at 403 AM EDT SUN OCT 15 2017

Shortwave trough will continue to move through the upper Great Lakes
this morning with a kicker shortwave over se Alberta/sw
Saskatchewan. This kicker shortwave kicks out the lead trough and
the kicker moves into the upper Great Lakes this evening and quickly
moves to the lower Great Lakes late tonight. Deeper moisture and
strong 850-500 mb q-vector convergence moves out this morning.
System appears to be moving through faster and weaker than forecast,
so continued the evening shifts trend of lowering wind speeds and
qpf amounts down from previous forecasts. Will continue to speed
things up for exit of the pcpn today. Looking at soundings for
tonight, appears like there will be an inverted-v sounding in the
low levels at IWD and CMX. With Lake Superior being around 12C and
NAM and GFS have 850 mb temperatures of -2C to -4C across the lake.
This is enough lake-850 mb delta-t for lake effect showers, but with
the dry low levels, this will make lake effect clouds instead with
mostly sprinkles or isolated showers even with the kicker shortwave
and its limited moisture moving through. Did put in some slight
chance pops in for tonight in nw lake effect pcpn belts, but the dry
air should eat into the coverage of the showers that form along with
the qpf amounts. Will drop the wind advisory as winds will not be as
strong and only will see 40 mph gusts at best east of Munising. Will
also drop the coastal flood advisory as waves will not be as high as

.LONG TERM...(Monday through Saturday)
Issued at 303 AM EDT SUN OCT 15 2017

Overall, the weather through the extended looks quiet with a warm up
on the way through the middle/end of the week, with the next best
chance for rainfall chances returning later next weekend. Therefore,
the main forecast concern will the magnitude of this warming.

Monday, forecast soundings show just enough lingering cold air and
low-level moisture to foster the development of diurnally driven low
clouds. This cloud cover and lingering cool air aloft will promote
seasonable temperatures. Monday night into Tuesday, a weak shortwave
is progged to dig across the Upper Great Lakes, pushing a weak cold
front across the region. Not expecting any precipitation to develop
along this frontal boundary, but the surface pressure gradient will
become enhanced allowing for breezy winds. These breezy winds should
lessen the impacts of radiational cooling a bit, and allow
temperatures to only drop down into the upper 30s and 40s.

Tuesday through Friday, the weather is expected to remain dry and
with above normal temperatures as warm air advection increase across
the region. Right now it looks like temperatures will climb into the
60s each day, with a few pockets of lower 70s in locations that see
downsloping winds. Overnight low temperatures will remain fairly
mild, generally drop into the 40s and 50s.

The next best chance for precipitation will arrive next weekend as
de-amplifying longwave troughing tracks across the region. There is
some disagreement among the medium range models, with the ECMWF and
GFS bringing the next system across the region Saturday night
through Sunday; whereas, the Canadian is much faster with this
system as it tracks east across Upper Michigan on Saturday.
Depending on the arrival of this system, it will not only impact
precipitation chances, but also how warm temperatures will get.
Ahead of the cold front, if the GFS and ECMWF solutions come to
fruition, temperatures in the current forecast package would need to
be adjusted upwards. Even though mixing to around 850mb may be
challenging this time of year, the potential will still be there for
temperatures to climb nearly 15 to 20 degrees above normal for this
time of year.

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 154 PM EDT SUN OCT 15 2017

Rapid improvement at all sites will occur as the low pressure system
moves away from the area. All 3 terminals will be VFR by evening, if
not sooner.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 403 AM EDT SUN OCT 15 2017

Current system is weaker and moving through quicker and winds are a
bit less than previously forecasted. WIll continue gale warnings
across the east half of Lake Superior into this afternoon. As the
system exits the region, winds will briefly diminish to around 15
knots tonight; however, expect the winds to ramp back up to 20 to 30
knots Monday into Tuesday morning. No gales seen after that as winds
look to remain in the 15 to 25 knot range mostly.

Upper Michigan...
Lake Superior...
  Gale Warning until 2 PM EDT this afternoon for LSZ244-245-

Lake Michigan...
  Gale Warning until 4 PM EDT this afternoon for LMZ221-248-250.



LONG TERM...Ritzman
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