Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 200150
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
850 PM CDT Fri May 19 2017

.UPDATE...
Our brief lull in the rain has arrived and will continue through
tonight. There was enough dry air and subsidence to bring some
breaks in the overcast this evening. Those breaks will fill in
over the next few hours as more clouds begin to stream in from the
south. As the previous discussion explained, moisture will stream
back into the area very quickly Saturday morning ahead of another
advancing low pressure system. Our easterly flow will be dry and
cool coming in off Lake Michigan. This will help to evaporate some
of the initial advancing rain, but eventually it will overspread
the entire area. The latest HRRR has the rain reaching Madison by
about 10-11 am and Milwaukee closer to noon. Some of the guidance
shows this initial band moving through in a few hours, then a
break, then more rain arriving by late afternoon or evening. The
chance for thunder is diminished due to our cooler conditions
under dominating easterly low level flow.

&&

.MARINE...

Easterly winds and waves will remain elevated through Saturday
resulting in small craft advisory conditions through Saturday.

&&

.PREV DISCUSSION... (Issued 547 PM CDT Fri May 19 2017)

AVIATION (00Z TAFS)...

VFR conditions have returned to most of southern Wisconsin and
will remain in place through about 12z Saturday. After 12z,
another surge of moisture arrives from the south ahead of another
large area of low pressure that will track from southwest Iowa to
northern Wisconsin between Saturday afternoon and Sunday
afternoon. MVFR CIGS/VSBYS will return quickly by mid morning on
Saturday with IFR CIGS expected by early afternoon. Those lower
conditions will persist through at least Saturday night. Winds
will remain easterly, turning southeast Saturday evening.

PREV DISCUSSION... (Issued 329 PM CDT Fri May 19 2017)

SHORT TERM...

Tonight through Monday...Forecast confidence medium.

The showers will continue to dissipate through the late afternoon
as an upper wave moves away to the north and the nose of the LLJ
that was over ne IL shifts ewd. A mostly dry night is expected
until well after midnight over south central WI when rain will
return from the south. A sly LLJ will return as low pressure over
the srn Great Plains moves to nrn MO. The low will reach ern IA by
00z Sun and occlude Sat nt into Sun over nw WI and the LS region.
The sly LLJ and low to mid level warm, moist advection will bring
the largest surge of rainfall on Sat. The occluded front will then
pass Sat nt with continued chances of showers and storms mainly in
the evening. CAPE will be very minimal so little to no chance of
SVR storms. A dry slot will then overspread srn WI late Sat nt and
Sun. Low level instability will probably lead to broken sky cover
at times on Sun.

A surge of warm advection on wly winds will then boost temps to
near 70F for Mon. However the warm advection and an approaching
shortwave trough will bring chances of rain for Mon aft into Mon
nt.

LONG TERM...Tuesday through Friday...Forecast confidence medium.

An upper trough will approach from the nw and become a closed low
over the region. Cyclogenesis may occur at the sfc with the low
slowly moving ewd. Thus good chances for rain on Tue and lingering
into Wed. A warm advection pattern will then maintain small
chances of rain for Thu-Thu nt. The warm advection may boost temps
to near 70F once again for Fri.

AVIATION(21Z TAFS)...The light rain and low stratus will end
across far srn WI by late afternoon. However the rain and low
stratus from 1-3 kft will return Sat AM when a warm front slowly
approaches from the south. For Sat afternoon, the showers and
chances of tstorms will continue while Cigs fall below 1 kft. MVFR
Vsbys can be expected for much of Sat due to the rain and
possibly light fog.

MARINE...A Small Craft Advisory continues through Sat due to
brisk nely winds turning ely late tnt and Sat. Waves will remain
from 3 to 6 feet.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory until 7 PM CDT Saturday for LMZ643>646.

&&

$$

Update...Davis
Tonight/Saturday and Aviation/Marine...Gehring
Saturday Night through Friday...Gehring



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