Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 272000

Area Forecast Discussion
National Weather Service Marquette MI
400 PM EDT SAT AUG 27 2016

.SHORT TERM...(This evening through Sunday)
Issued at 359 PM EDT SAT AUG 27 2016

Radar imagery shows area of showers over the southeast portion of
Upper Mi generally dissipating and moving east under weakening waa
pattern. Focus now into tonight will shift to area of showers over
the western U.P. which is being supported by increasing q-vector
convergence ahead of mid-level trough and associated shortwave
lifting ene through the Northern Plains toward the Upper Great

With the track of shortwave trough expected to lift more over
western and north central Superior and Ontario tonight models
indicate the strongest q-vector convergence will also stay generally
over the western and northern part of lake and points to the north.
Radar trends and models suggest best chance for sct showers to
numerous shra will likely be confined to far wrn counties of Upper
Mi through this evening into early overnight on edge of best
forcing/dynamics. As shortwave trough lifts well north of area late
tonight, strong q-vector divergence and resulting subsidence is fcst
to spread in fm west and will end showers after midnight for all
areas. There is a concern of some fog forming later tonight as low-
level moisture remains trapped near the sfc under increasing
subsidence...especially with potential for partial clearing.
Southeast upslope flow may also aid fog formation this evening over
central and eastern fcst area where ground will still be moist from
today`s rainfall.

Rising 5h heights and increasing mid-lvl subsidence should result in
dry conditions across the CWA on Sunday. Expect highs mainly in the
70s under mostly sunny/partly sunny skies.

.LONG TERM...(Sunday through Friday)
Issued at 349 AM EDT SAT AUG 27 2016

Sunday through Sunday night: Another shortwave will slide through
the Upper Great Lakes Region Sunday afternoon into Sunday evening,
which may bring some isolated showers and thunderstorms. MUCAPE
values are progged to be around 400 to 700 J/kg across the area
during the afternoon and evening hours. The main forcing mechanism
will be an approaching warm front during the late afternoon and
evening hours. Otherwise, winds will be fairly light across the area
with a trend toward above normal temperatures as the warm front
passes through overnight. Highs will be in the mid to upper 70s with
overnight lows in the mid to upper 50s.

Monday through Tuesday: A surface low, over northern Ontario Monday
morning, will slide to near James Bay by Tuesday afternoon. As this
happens, the low will drag and associated cold front across the
Upper Great Lakes region. The best timing for the frontal passage
looks to be Monday night over the west and central U.P. and the
eastern U.P. Tuesday morning. Along and ahead of the cold front,
warm moist air will slide northward into the Upper Great Lakes
Region. The warm, moist air will create unstable conditions across
the area allowing showers and thunderstorms to form with the forcing
associated with the cold front. MUCAPE values are progged to be
around 1000 to 1500 J/kg ahead of the front. Deep layer shear values
are not overly impressive at or around 20 to 25 knots, with the
stronger shear expected behind the front. There may be a couple
stronger thunderstorms if the higher CAPE values are realized;
however, the lack of shear would lean against organized/widespread
strong to severe thunderstorms. The increase WAA ahead of the cold
front will allow temperatures to warm well above normal Monday with
many locations warming into the low 80s. Normal highs this time of
year are in the low 70s for comparison. High pressure will build
across the U.P. from the west by Tuesday afternoon allowing
conditions to dry out once again and skies to clear from west to

Wednesday through Thursday: High pressure will continue to build
across the Upper Great Lakes region through this time period,
keeping conditions mainly dry under partly cloudy skies. Aloft, flow
will be under slight troughing to near zonal flow through this time
period which will keep temperatures near normal.

Friday through the Extended: Models begin to vary quite a bit during
this time period ranging from nearly zonal flow to a fairly good
ridge axis sliding across the Plains. At this point have decided to
stick with a consensus of the models until the models merge toward a
similar solution from run to run and model to model.

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 137 PM EDT SAT AUG 27 2016

Weak low moving across the region could keep some isolated showers
around the taf sites through this evening. Best chances of rain will
occur at SAW and IWD. Increasing low-level moisture will cause VFR
conditions to lower later on this afternoon at SAW and tonight at
IWD and CMX. Other than some local fog at CMX early on, flight
conditions will be VFR. Expect conditions to lower to LIFR at SAW
late tonight in continued upslope se flow and to MVFR possibly IFR
at IWD and CMX. Conditions will improve again to VFR late Sunday

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 359 PM EDT SAT AUG 27 2016

Winds into next week should remain at 20 kts or less as the pressure
gradient remains weak.

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


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