Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 182016

Area Forecast Discussion
National Weather Service Marquette MI
416 PM EDT THU AUG 18 2016

.SHORT TERM...(This evening through Friday)
Issued at 414 PM EDT THU AUG 18 2016

WV imagery and RAP analysis indicated mainly zonal flow through most
of the nrn CONUS between a trough over nrn Manitoba and a ridge
through the southeast CONUS. At the surface, a cold front extended
from nw Ontario through the nw MN into nrn South Dakota with srly
flow ahead of the front over the upper MS valley and nrn Great Lakes.
Vis loop showed Cu over the cwa with a tsra near Whitefish point
where lake breezes converged. Although there were also some isold
shra over nrn WI, stronger capping today compared to the past few
days has reduced chances/coverage of shra over the cwa even with
MLCAPE values in the 500-1000 J/Kg range. An upstream shrtwv over
cntrl MN supported tsra into far wrn WI.

Tonight, radar/satellite trends, short range models, and position of
CAPE gradient, and 850 mb llj/theta-e advection, suggest the most
numerous/heavier shra/tsra will remain to the south of the cwa.
However, sct shra/tsra may still develop farther north as models
hint that a weak shrtwv will slide through the area.

Friday, The cold front is expected to sag into Upper Michigan and
provide the focus for additional shra/tsra development as daytime
heating increases. With considerable clouds and humid conditions
(dewpoints in theupper 60s) temps will climb into the upper 70 and
lower 80s. Resulting modest MLCAPE values to around 1k J/kg and 0-
6km shear of around 30 knots, should only support isold stronger
storms if any. There is less confidence whether additional
shortwaves could move through the area and enhance shra/tsra

.LONG TERM...(Friday night through Thursday)
Issued at 325 PM EDT THU AUG 18 2016

Surface front will be just south of the area by Friday evening.
Expect a lull in precipitation during the evening hours on Friday.
Shortwave moving through Northern Plains trough will allow a wave to
develop along the frontal boundary over eastern Wisconsin Friday
night. Models are now in pretty good agreement with the development
of this feature and its track to the northeast on Saturday.  The
only outlier is the NAM which has a much more Fall-like look to it
with a deepening low pressure system developing over WI and lifting
across the U.P. into Lake Superior. A consensus of the other models
with a weaker wave was used for the forecast.

Overall forecast isn`t that different from previous forecast.
Overall QPF might be a little less during the Friday night through
Saturday time period but still expect a decent soaking rain for all.

Gusty north and northwest winds on the back side of the low will
create dangerous swimming conditions on Lake Superior on Saturday and
Sunday. However...with plenty of clouds/rain and temperatures well
below normal...almost early fall-like...few will be at the beaches
this weekend.

Upper trough will move east of the Great Lakes early next week with
upper heights rising across the plains and Upper Great Lakes.
Temperatures will return to at or a little above normal for much of
next week. Next upper trough will drop out of Canada into the
northern plains by later next week.  As the trough approaches the
Great Lakes late in the week it will bring the next chance of
showers and thunderstorms to the area.

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 144 PM EDT THU AUG 18 2016

VFR conditions are expected through this evening. Showers and a few
thunderstorms associated with a slow moving cold front will move
into IWD and CMX overnight and to SAW toward daybreak. There could
be a period with MVFR vsby with the rain showers. Although VCTS was
mentioned at IWD, closest to the higher instability, only showers
were included at CMX/SAW.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 414 PM EDT THU AUG 18 2016

Despite a slow moving cold front pushing through the region, winds
will remain at or below 15 knots until the weekend. High pressure
building in behind the front will boost the pressure gradient enough
to produce stronger N winds to 25-30 knots Saturday night into
Sunday, mainly over the east half of Lake Superior.

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


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