Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 250737

Area Forecast Discussion
National Weather Service Marquette MI
337 AM EDT Sun Jun 25 2017

.SHORT TERM...(This evening through Sunday)
Issued at 349 PM EDT SAT JUN 24 2017

Tonight: The shortwave/upper low that has been producing showers and
isolated thunderstorms this afternoon will continue to shift to the
southeast of the area through this evening. At the same time, a weak
surface trough will linger across the area. The combination of the
forcing/moisture associated with the departing low and the trough
will keep isolated to scattered showers across the area through
tonight. The better chance of scattered rain showers will be over
the east half as that area will be closer to the system forcing
associated with the shortwave/upper low as it departs. The west half
will likely see a bit of a break in the precipitation or at best
isolated rain showers as minimal daytime heating decreases. At this
point, the east half looks to gain about a tenth of an inch or less
of QPF tonight with the west half looking at a trace to 5 hundreths
of an inch of additional QPF tonight. Any instability will diminish
quickly after sunset, so the small thunder potential tonight will be
limited to mainly the evening hours south-central and east.

Sunday: The aforementioned surface trough will linger nearby
throughout much of the day, helping to focus showers and
thunderstorms across the Upper Peninsula. At the same time, yet
another shortwave will rotate through the broad troughing across the
Upper Great Lakes. This shortwave is expected to slide directly
overhead during the late afternoon into the evening hours. The
combination of the cooler air aloft associated with the shortwave
along with surface heating during the afternoon, will give steadily
increasing chances for showers and thunderstorms. MUCAPE values
around 800 - 1000 J/kg along with freezing hgts and wet bulb zero
hgts at or around 5kft to 6kft agl will give increased chances for
stronger storms to produce small hail. Similar to Saturday, very
little shear in the 10 to 15 knot range will support only
pulse/unorganized thunderstorm activity. No widespread severe
weather is expected with this, just mainly small hail. Some of the
storms that pulse may cause some heavy downpours, again, the best
timing for this would be the afternoon into the early evening hours
and mainly inland from the Great Lakes.

.LONG TERM...(Monday through Saturday)
Issued at 337 AM EDT SUN JUN 25 2017

Overall, there will be a brief warming and drying trend through the
early part of the week, before another system rolls across the Upper
Mississippi Valley and into the Great Lakes region late Wednesday
and Thursday. Depending on the track of this system moving across
the Great Lakes, we could see heavy rain move across Upper Michigan
that may lead to some hydro concerns. Still a bit early as model
trends continue to fluctuation from run to run, but the medium range
models are in good agreement with the placement of this heavy rain
across Upper Michigan late Wednesday afternoon into Thursday
morning. Towards the end of the week and into the weekend, we will
then see periodic chances for precipitation, with seasonable

On Monday, expect showers to linger across the central and eastern
portions of Upper Michigan as surface low pressure and its
associated upper-level wave are slow to exit the area. The lingering
cloud cover and precipitation should keep temperatures in the 60s yet
again. Locations across the west will see the warmest temperatures,
as they will have the best chance at seeing decreasing cloud cover
in the afternoon hours. Monday night into Tuesday, shortwave energy
will finally dig south across lower Michigan and into southern
Ontario, and surface high pressure will drop south from the northern
Plains. This will allow skies to clear and precipitation to come to
an end from west to east. Heights will rise a bit, but with flow
aloft still progged to be out of the northwest, a few subtle, weak
impulses will dig across the area and allow cloud cover to increase
through the day on Tuesday. Given the amount of dry mid-level air
advecting into the region as surface ridging slides off to our south
on Tuesday, expect much of the area to remain dry.

Wednesday through Thursday, a more potent shortwave will push east
across the Upper Mississippi Valley and Great Lakes regions with
medium range models showing the *potential* for a heavy rain event
across Upper Michigan. Ahead of this system PWATs will increase to
around 1.5 inches as strong warm air advection and 850-700mb
moisture transport lifts northeast towards Upper Michigan. The
medium range models, based off their 00z runs, are in good agreement
with a band of heavy rain developing along the surface warm front as
it lifts north across Wisconsin and into Upper Michigan late
Wednesday afternoon. Wednesday evening and overnight into Thursday,
as a 30-50 knot low-level jet impinges northward, this will sharpen
the mid-level front and allow the sloping baroclinic zone to deepen
to around 500mb. Large scale lift should also increase across the
area as a coupled jet structure develops aloft with shortwave energy
lifting northeast across Wisconsin and another shortwave digging
south across southeast Ontario. Given the antecedent wet conditions
across the area, with many locations over the past week and a half
picking up around 5-8+ inches of rainfall, if this band of heavy
rain does come to fruition across Upper Michigan it could lead to
hydro/flooding concerns. Model trends through this time period will
need to be monitored as a shift either north or south will have a
big impact on how things will play out.

Unfortunately it doesn`t look like this active pattern will release
its grip on the region as additional shortwaves are progged to track
across the area towards the end of the week and through the weekend.
This will bring additional chances for showers and perhaps a few
rumbles of thunder.

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 142 AM EDT SUN JUN 25 2017

Ceilings will be in the IFR/LIFR range at SAW and CMX overnight and
will fall to IFR late tonight at IWD. The next system approaches
this afternoon. Visibility may be restricted at times under
heavier rain showers; however visibility should generally be in
the VFR range. Cigs may be slow to improve today at SAW with
continued moist northerly upslope flow off Lake Superior.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 349 PM EDT SAT JUN 24 2017

Winds of 10 to 15 knots are expected to continue through the first
half of next week as the pressure gradient decreases and high
pressure builds in for the first part of the work week. Towards the
middle of the week, winds will start to increase to around 20 to 25
knots as a system lifts across the Upper Great Lakes. Winds will
then decrease to around or less than 15 knots towards the end of the
week and next weekend as the pressure gradient relaxes again.

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


LONG TERM...Ritzman
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