Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 270735

Area Forecast Discussion
National Weather Service Marquette MI
335 AM EDT Sun May 27 2018

.SHORT TERM...(This evening through Sunday)
Issued at 319 PM EDT SAT MAY 26 2018

Into this evening, nw flow shortwave moving across moist and very
unstable environment with MLCAPE values of 1500-2000 j/kg has led to
initiation of numerous thunderstorms into central Upper Mi this
afternoon with isolated severe storms focusing along sfc trough and
enhanced by convergent lake breeze boundaries. One inch hail fell
here at the NWS office and at several other places in the Negaunee
area with one of the severe storms. Training storms across southern
Marquette County from Big Bass Lake through Gwinn to Little Lake
have also prompted the issuance of a flash flood warning until
around 6 pm EDT. As the shortwave and associated trough pushes east
this evening and diurnal instability begins to weaken toward 8-9 pm,
expect convection to quickly begin to dissipate.

Tonight, as sfc high pressure briefly settles in behind the exiting
surface trough, light winds will favor the possibility of patchy or
areas of fog developing especially over areas that saw heavier rain
this afternoon/early evening. Will probably need to watch for the
potential of dense marine fog along the Great Lakes shores given
added moisture from storms.

Sunday, building 5h ridge heights and warmer cap of dry air at 14C
between 850-700 mb should yield dry conditions across the area.
Expect inland high temps to climb into the mid 80s to lower 90s
while light winds will allow prominent lake breezes to bring cooling
along the Great Lakes into the upper 60s and lower 70s. Dewpoints in
the upper 50s and lower 60s will continue the uncomfortably humid

.LONG TERM...(Monday through Saturday)
Issued at 334 AM EDT SUN MAY 27 2018

As we get into a brief blocking pattern across the CONUS with a
cutoff low lingering across the Great Basin and upper-level ridging
building across the Great Lakes, expect the well above normal
temperatures to persist, along with humid conditions at times. It
looks like we`re going to have to deal with the summer-like
temperatures through the middle of the work week, but a cool down
does look to arrive later in the week into next weekend! The active
weather we`ve been seeing as of late will continue as numerous
shortwaves crest the upper-level ridge; however, any convection that
can break through the capping inversion through the middle of the
work week should remain fairly isolated.

Monday - A combination of a shortwave ejecting out of the cutoff low
over the Great Basin and another shortwave tracking along the
US/Canadian border will allow for the potential for overnight
convection upstream of the region to gradually make it`s way into
western portions of Upper Michigan. While surface based convection
this early in the morning, given the strong decoupling expected at
the surface, looks unlikely, enough elevated instability should be
in place to maintain the ongoing convection. Right now it appears
that the west half will have the best chance at seeing these morning
showers and thunderstorms as convection looks to diminish/weaken as
the moisture transport weakens and veers out by mid-morning. We
could see additional thunderstorms develop in the late afternoon
along a thermal trough progged to develop along the WI/MI border,
but coverage should remain isolated at best given the capping
progged to be in place as 850mb temperatures climb upwards of 18-
20C. With this very warm air mass in place, expect afternoon highs
to climb into the upper 80s, perhaps hitting the 90 degree mark in
some spots away from the Great Lakes.

Monday night through Thursday - The warmth will persist through the
middle of the week, with temperatures inland from the Great Lakes
approaching the upper 80s. Cooler temperatures each day will setup
near the Great Lakes. Overnight lows will also remain on the mild
side. A kicker wave moving onshore in the Pacific Northwest Monday
night into Tuesday will allow the above mentioned cutoff low to
finally start to lift across the central Rockies. As this wave
starts to lift northeast, the main stream of moisture transport will
begin to shift towards the Upper Great Lakes through the middle of
the week. Therefore, additional chances for isolated showers and
thunderstorms are expected. Even though ample instability will
linger across the region through the middle of the work week, deep-
layer shear values will remain very week, so expect pulse-type
thunderstorms that do not move very much at all.

By Wednesday night through Thursday, the main upper-level wave will
continue to lift across the northern Plains and Upper Mississippi
Valley. Medium-range guidance are consistent with this transition
towards troughing across the region allowing the remnants of
Tropical Storm Alberto to lift towards the Great Lakes. This favors
increased moisture and more widespread showers and thunderstorms
later in the week. Certainly a time period to keep an eye on.

Friday into next weekend - A brief cool down and a break from the
active weather looks on tap as troughing moves over the eastern
Great Lakes and we get back under the influence of the Hudson Bay
High. Temperatures during this time period may still run above
normal, but will feel much more seasonable for this time of year.

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 124 AM EDT SUN MAY 27 2018

Through the early morning hours, we could see the potential for fog
over areas that saw heavy rain earlier today as winds become light
and skies continue to clear out. As high pressure moves across the
region today, winds will be fairly light. Expect ceilings to remain
VFR, except at KSAW where the marine layer may move inland as flow
becomes onshore this afternoon.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 353 AM EDT SAT MAY 26 2018

This morning, surface troughing has begun to push south across the
Lake. Along the leading edge of this trough, expect a brief increase
in winds to upwards of 20 to 30 knots. Otherwise, winds are expected
to remain less than 20 knots today, and through the middle of next
week. Expect areas of fog to develop and linger at times into the
weekend as multiple rounds of rain are expected over the lake and
the humid airmass lingers. Fog may be dense at times. Thunderstorms
are possible this afternoon into sat night, and then again early
next week.

Upper Michigan...
Lake Superior...
Lake Michigan...
  Dense Fog Advisory until 2 PM EDT this afternoon for LMZ248-250.



LONG TERM...Ritzman
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