Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 190523

Area Forecast Discussion
National Weather Service Marquette MI
123 AM EDT FRI AUG 19 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 06Z TAFS through 06Z Friday night)
Issued at 122 AM EDT FRI AUG 19 2016

VFR conditions are expected into Fri aftn. There will be potential
for shra and possible tsra, especially late tonight through Fri at
IWD and SAW. A front sliding through the area will settle south of
all terminals by late Fri aftn and evening. As this occurs, expect
flight conditions to deteriorate to MVFR or lower through the rest
of Fri evening as cooler and moist northerly flow develops off Lk
Superior. Some showers may continue at times.

.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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