Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 290812

Area Forecast Discussion
National Weather Service Marquette MI
412 AM EDT Thu Jun 29 2017

.SHORT TERM...(Today and tonight)
Issued at 411 AM EDT THU JUN 29 2017

Water vapor imagery this morning showers shortwave activity lifting
northeast towards the area, allowing the surface low to lift into
western portions of Lake Superior. Two main areas of rainfall were
observed across the area this morning, one associated with lingering
warm air advection and moisture transport across the east, and then
more rain shower activity back across the west around the main
surface low. Areas of fog have developed ahead of the surface low
pressure where dew points remain in the low 60s. With drizzle
accompanying the fog in some locations this morning, visibilities
have been flucuating a bit this morning so think the dense fog
should remain rather patchy through the early morning hours.

Today, expect the cloudy conditions to linger across much of the
area. As the surface low tracks across the area today, southerly
winds will eventually become westerly with a bit drier air mass.
This westerly flow should allow cloud cover to gradually diminish
across the south central portions of the area, where downsloping
will increase. As a result, temperature are expected to be warmest
across the south central, around 70 degrees, and then in the 60s
elsewhere. As the main upper-level trough moves overhead and surface
low tracks east through the day, a transient band of light rain
should move across the area; elsewhere drizzle will be possible
especially through the morning and early afternoon hours.

Through the first part of the evening and overnight hours, weak
ridging is progged to move into the area and should allow any
lingering precipitation over land to weaken/diminish. However, into
the early morning hours on Friday another shortwave is expected to
lift across the area bringing back chances for rain showers,
especially across the east.

.LONG TERM...(Thursday night through Wednesday)
Issued at 440 PM EDT WED JUN 28 2017

Models suggest that a slowly progressive pattern will prevail
with zonal flow giving way to troughing through the north central
CONUS this weekend as a mid level low moves from northern Manitoba
to near the northern Great Lakes. A ridge will then build from
the Northern Plains into the Upper Great Lakes for the first half
of next week. Temperatures will remain below normal with
moderation closer to seasonal averages early next week.

Thursday night into Friday, as the larger scale mid level trough
deepens from the Northern Plains into the Upper Great Lakes, a
shortwave trough and associated sfc low is expected to lift from the
Central Plains into the western Great Lakes. Although the
stronger convection Thursday night should remain well to the south
over srn WI, and fcst 700-300mb qvector conv by Friday with this
feature is relatively weak, diurnal heating should be strong
enough to support sct/isold shra and a few tsra.

Saturday-Sunday, with the mid-level trough deepening into the
northern Great Lakes, rain chances will increase Saturday,
especially inland during peak heating. Isolated t-storms will also
be possible cntrl as MLCAPE values approach 500-1000 J/Kg. Enough
moisture/instability will linger into Sunday as the mid level low
or shrtwv drops through nrn Ontario or even to Lake Superior to
support low chc pops for mainly afternoon isold to scattered

Monday-Wednesday, Models and ensembles were in good agreement
with the drying trend expected at least for the first half of next
week as mid-level and sfc ridging build into the area. With a
gradual warming trend, sunshine should push temps well into the
70s Mon/Tue to around 80 by Wed. Lake breezes should keep readings
mainly in the 60s to around 70 along the Great Lakes.

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 123 AM EDT THU JUN 29 2017

Abundant low-level moisture settling over the area combined with an
upslope wind will lead to LIFR conditions overnight at KCMX/KSAW.
At KIWD, MVFR conditions should trend down to LIFR overnight as
veering winds develop an upslope component. Expect -shra at times
overnight into the morning hrs. As sfc low pres exits to the e
today, cool upslope northwesterly flow off Lake Superior will
probably lead to LIFR or IFR cigs persisting thru the day at
KIWD/KCMX. Downslope nature of the flow at KSAW will allow
improvement to MVFR.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 411 AM EDT THU JUN 29 2017

As low pressure tracks across Upper Michigan today, winds across the
lake will remain a bit enhanced at around 15 to 25 knots. Patchy to
areas of fog are possible this morning, and into tomorrow. In some
locations fog may be locally dense, in fact on ship north of the
Keweenaw Peninsula this morning reported reduced visibilities due to
fog. As this point, no plans for issuing a dense fog advisory over
the lake, but is something that will need to be monitored this

Into Friday morning, winds will relax to around 10 to 15 knots as
the surface pressure gradient weakens with low pressure exiting the
region. Winds through the weekend and much of next week are expected
to remain 15 knots or less.

Upper Michigan...
Lake Superior...
Lake Michigan...


SHORT TERM...Ritzman
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