Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 211917

Area Forecast Discussion
National Weather Service Marquette MI
317 PM EDT Mon Aug 21 2017

.SHORT TERM...(Today and tonight)
Issued at 457 AM EDT MON AUG 21 2017

WV imagery and RAP analysis indicated zonal flow across the nrn
CONUS with a couple of upstream shortwave troughs over the cntrl
Dakotas. At the surface, a cold front extended from James Bay
through ern Upper Michigan to cntrl WI. IR loop indicated mostly
clear skies from nw WI through wrn Upper Michigan with patchy
clouds lingering over the cntrl and east.

Today, expect mid clouds to gradually increase as WAA strengthens
ahead of a trough developing from Nebrasaka into WI. The clouds,
around 600 mb, may thin or broken enough for some viewing of the
partial eclipse early this afternoon. Rain chances will increase
over the west by mid to late afternoon as the effects of the Dakotas
shortwave also arrive. Although MUCAPE values only to around 1k
J/Kg are expected, highest over the south, effective deep shear
values into the 30-40 knot range may support some stronger storms
with small hail.

Tonight, as the mid level trough deepens into the n cntrl CONUS the
models have trended toward a stronger sfc wave of low pressure
lifting into se Upper Michigan late tonight. The combination of
moderate to strong deep layer qvector conv and upper level div
with the right entrance of a 250-300 jet over nrn Ontario along
with strong moisture transport and mid level fgen will support a
large area of showers over the cwa. High res models suggest PWAT
values to around 1.75 inches may also support some narrow bands of
heavy rain of a few inches, especially over the cntrl cwa. With
mainly elevated convection, the main severe risk may again be for
hail over the south half, where the instability is highest.

.LONG TERM...(Tuesday night through Monday)
Issued at 316 PM EDT MON AUG 21 2017

Pretty quiet stretch of weather expected for the second half of he
work week. Cool Canadian high pressure will settle over the Upper
Great Lakes with early fall-like temperatures expected Wednesday
into Thursday. Under clear skies and light winds...ideal radiational
cooling conditions will allow temperatures to fall into the mid and
upper 30s over parts of the interior west Wednesday night.  Some
patchy frost in those normally colder locations is not out of the
question. With warm advection pattern returning for the
weekend...there could be a few showers around but temperatures will
moderate back to normal.

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 738 AM EDT MON AUG 21 2017

VFR conditions are expected through early this evening. Showers
and thunderstorms return late on Monday and into Monday evening,
especially at SAW where MVFR conditions are likely to develop by
late evening and IFR conditions are possible overnight.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 457 AM EDT MON AUG 21 2017

Winds will remain at or below 20 knots through the first half of the
work week as the pressure gradient remains fairly weak across Lake
Superior. The next chance for gusty winds will be Tuesday night into
Wednesday as low pressure slides to the east of Lake Superior.
Northwest winds may gust as high as 30 knots during that time period.

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


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