Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 211955

Area Forecast Discussion
National Weather Service Marquette MI
355 PM EDT Fri Jul 21 2017

.SHORT TERM...(Today and tonight)
Issued at 408 AM EDT FRI JUL 21 2017

This morning, IR satellite imagery shows multiple complexes of
ongoing convection from the northern Plains down across the Corn
Belt. A rather complex surface field was present across the Plains
as two areas of low pressure have tried to organize, one coming out
of the northern Rockies and the other the central Rockies. At the
upper-levels, broad ridging was observed across the central CONUS
with a progressive upper-level low beginning to work its way east
across the Canadian Rockies. Ahead of this upper-level low, a
shortwave began digging south-southeast this morning and will play a
role in how things evolve later today/tonight. Across Upper Michigan
we`ve remained under surface ridging with mostly clear skies and
light winds. This has allowed for patchy ground fog to develop
across much of the area with surface observations coming in and out
of the shallow fog. Expect the fog to diminish as mid- and upper-
level clouds stream in from the west.

The shortwave digging south into the northern Plains this morning
will allow the northern most area of low pressure to eject out
across the northern Plains and into portions of the Great Lakes
later tonight. The warm front is progged to near portions of Upper
Michigan later this afternoon, but the better low-level moisture
looks like it will only make it into northern portions of Wisconsin
at best. Therefore, things will become more humid as the day
progresses, but expect the oppressive dew points to remain south of
the area. Convection is expected to develop along the warm front and
eventually grow upscale into a MCS as low pressure rolls across
Wisconsin late this afternoon and through the overnight hours. Right
now it looks like the best warm, moist air advection will arrive
after convection has begun to grow upscale in Wisconsin, so this
should keep the threat of any severe storms and heavy rains off to
our south. However, cannot rule out a few areas of showers and
perhaps a rumble of thunder along converging lake breezes this
afternoon and as the main shortwave moves across the area tonight.
The SPC has included far southern portions of Upper Michigan within
a marginal risk for severe storms; however, with convection expected
to develop across the warm sector and grow upscale south of the area
think that the main threat for severe storms should remain south of
the Wisconsin/Michigan border.

.LONG TERM...(Saturday night through Friday)
Issued at 355 PM EDT FRI JUL 21 2017

Not expecting any high impact weather in the long term. There is
some potential for some lingering stronger storms over the far south-
central Lake Saturday, but the strength of any convection will be
diminishing pretty quickly.

As the shortwave passes, convection will exit E early Sunday, with
upslope drizzle/showers Sun morning and afternoon in NW-N favored

A shortwave and weak cold front may bring some convection late Tue
into Tue night, but after that high pressure dominates with no
precip expected.

Did not need to make any changes from the blended initialization.

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 137 PM EDT FRI JUL 21 2017

Ceilings are expected to remain VFR trough the afternoon into this
evening; however, low-level moisture will steadily increase late
this evening through the overnight hours, allowing ceilings to drop
to at least the MVFR category, with the best chance being at the
KIWD TAF site. Showers and thunderstorms are expected to remain
south of the area through tonight; however there could be a few pop
up showers and maybe a stray thunderstorm this afternoon near the
KSAW TAF site. The better chance of showers and thunderstorms will
perhaps push into the far western TAF sites toward the very end of
this issuance. At this point did not include mention in the TAF as
the chances increase even further after 18Z/22. Some fog is possible
late tonight as the low level moisture increases, with the best
chance again being over the KIWD TAF site will moisture increase
more rapidly.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 408 AM EDT FRI JUL 21 2017

Winds will start off less than 15 knots across the lake today, then
towards the end of the day and into the overnight hours winds across
the western half of the lake will increase to around 20 to 25 knots.
By Saturday morning, expect winds of 15 to 20 knots to spread across
much of the lake before diminishing to around 15 knots by the
evening hours. Sunday afternoon expect the winds to increase across
the lake to around 20 to 25 knots. These winds will diminish to
under 15 knots by mid-morning on Monday. Through the rest of the
week, winds will remain under 20 knots.

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


SHORT TERM...Ritzman
MARINE...Ritzman is the U.S. government's official web portal to all federal, state and local government web resources and services.