Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 270235

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
935 PM CDT Fri May 26 2017


.MARINE...Webcams currently do not show any fog over the nearshore
waters. However a moist atmosphere with very low dewpoint
depressions resides over the lake while skies are clearing. Thus
still expect areas of fog, possibly 1 mile or less to develop
tonight and linger into Sat AM.


.PREV DISCUSSION... (Issued 718 PM CDT Fri May 26 2017)

UPDATE...The rain has exited the area with clearing skies over
much of srn WI. A weak west to east sfc ridge will prevail over
the area tnt-Sat. The clouds and rain has led to low dewpoint
depressions over se WI so may see some fog development by late
evening while it will take longer over the remainder of srn WI.
Any fog should quickly dissipate Sat after sunrise. Otherwise a
mild day is expected with a lake breeze over far ern WI. Middle to
high clouds may increase late in the day.

AVIATION(00Z TAFS)...Expect fog to eventually develop across srn
WI tnt possibly occurring by late evening over se WI where
dewpoint depressions are already low. Fog will develop elsewhere
after midnight with Vsbys dropping anywhere from 1-5SM with
locally lower values. The fog should remain shallow and dissipate
within 2-4 hours after sunrise. VFR conditions the remainder of
the day.

PREV DISCUSSION... (Issued 339 PM CDT Fri May 26 2017)


Tonight and Saturday... Forecast confidence is medium.

Showers associated with a MCV (mesoscale convective vortex) that
is rolling across northern IL and southern WI will exit southeast
WI by early evening. The thunder has remained confined to south of
the WI/IL border today, but can`t rule out a stray rumble across
the southern WI counties. Rain is becoming steadier now and up to
a quarter inch is possible south of I-94.

Clear skies are expected behind this system. This should lead to
some patchy radiational fog overnight. More fog is possible over
Lake Michigan due to high dewpoints over relatively cool water, so
kept the Marine Dense Fog advisory going. This fog could advect
inland a bit early Saturday morning.

We should have quiet and warm weather across southern WI for most
of the day on Saturday. Highs expected in the upper 70s inland and
around 70 near the lakeshore.

Saturday night and Sunday... Forecast confidence is medium.

It`s not until the early evening hours when a weak cold front
becomes the focus for some showers and isolated thunderstorms. Not
all models agree on timing, but the majority suggest that the
front and associated showers shouldn`t make it into south central
WI until the early morning hours on Sunday. This would keep our
instability very low.

Meanwhile, another MCV is expected to roll across northern IL
Saturday night. Southern WI could be on the northern fringe of
those showers and isolated storms once again.

Yet another weak cold front could trigger showers and isolated
storms across mainly northern WI midday Sunday, with a few
trailing showers lingering into the afternoon.

Bottom line is cloud cover with a chance for rain at times and
highs around 70.


Monday through Wednesday... Forecast confidence is medium.

A closed upper low will set up over the Great Lakes for the first
half of next week. This will bring scattered showers and isolated
thunderstorms to much of WI each afternoon. Max temps will be in
the upper 60s.


Upper level disturbance moving out of NE IA will spread SHRAs
across sthrn WI this aftn. Most of the activity should remain
along and S of I-94. System is fcst to pull away this evng
leaving scattered VFR clouds tonight. Winds become lght/vrb
overnight as weak SFC ridge moves thru which will set the stage
for some radiation fog. Best chances will be across SW WI which
should be the first areas for clouds to thin tonight. Another area
of concern is a band of fog that dvlpd this mrng along the
lakeshore. Expect this band to persist into Sat with IFR VSBYs.


Webcams near the lakeshore are showing clear conditions this
afternoon and clouds have overspread the area so we cannot see the
extent of fog over the lake via satellite at this time. Will keep
the marine dense fog advisory going until midday Saturday due to
favorable conditions for areas of dense fog during the overnight


LM...Dense Fog Advisory until 1 PM CDT Saturday for LMZ643>646.



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