Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 200206 AAB
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
906 PM CDT Mon Jun 19 2017

.UPDATE...

Showers are diminishing as expected this evening. Showers and
thunderstorms will arrive in south central WI Tuesday morning. I
sped up our chances for precip a little based on current radar and
the latest model runs. I also increased the chances for mid to
late morning since it looks pretty certain that most areas will
see rain due to a robust shortwave.

&&

.MARINE...

West winds will gust 15 to 20 knots on Tuesday. Otherwise lighter
winds and low wave heights are expected through Wednesday. It will
be another day with shower and thunderstorm chances. Look for more
widespread precip in the late morning and early afternoon.

&&

.PREV DISCUSSION... (Issued 656 PM CDT Mon Jun 19 2017)

UPDATE...

Another round of showers and thunderstorms is moving through
southeast WI early this evening. They were stronger when they
moved through Madison, although we can`t rule out small hail with
these. Brief heavy rain is expected too. A few more showers with
isolated storms are showing up on radar in south central WI right
now, but expect shower chances to dissipate toward dark when we
lose the instability.

AVIATION(00Z TAFS)...

VFR conditions expected through the TAF period except within
thunderstorms. Scattered showers and thunderstorms will dissipate
toward dark. Skies should be mostly clear overnight with light
winds. An upper level disturbance will roll through southern WI
Tue morning. Expect showers and isolated thunderstorms with this
round. These should be out of the area by early afternoon, but a
few showers could linger through late afternoon.

PREV DISCUSSION... (Issued 325 PM CDT Mon Jun 19 2017)

DISCUSSION...

TONIGHT and TUESDAY...Forecast Confidence is Medium...

Isolated showers and thunderstorms will wind down this evening
with the loss of daytime heating. Weather should be quiet tonight
with the mid level trough moving off to the east and surface high
pressure passing southwest of the state.

Scattered afternoon showers will likely move through the region
during the morning and early afternoon. A shortwave trough will
drop through the state Tuesday morning with a mid level low over
southeast Canada. In addition, the left exit region of an upper
jet will be passing over the region creating good upper
divergence. A 925mb thermal ridge will nudge into the southwest
part of the state with warm air advection across the region. Cape
will build to 500-1000 J/KG so there is a chance for thunder.
Shear is strong, but the better cape isn`t until afternoon when
the better forcing has past through. But some storms could be
strong.

Wednesday...Forecast confidence is high.

High pressure pushes in Tuesday night and passes east of the area
during the day on Wednesday. We should be dry all day with highs
continuing in the 70s.

Wednesday night through Thursday night...Forecast confidence is
high.

This scenario remains largely unchanged. A low pressure system
will drift into the area on Thursday, eventually laying out a
frontal boundary along the WI/IL state line that will be the focus
for a few rounds of showers and storms through Thursday night
into early Friday morning.

We get into some decent warm air advection ahead of the low and
front Wednesday night with an increasing low level jet. Rain and
storms should spread into southern Wisconsin, especially after
midnight. The first low scoots off to the east Thursday morning
with a secondary low riding east northeast along the front
bringing another round of potentially training cells later
Thursday afternoon into Thursday night. Far southern Wisconsin
could get into some decent rainfall during this period.

We are outlooked for a marginal risk of severe storms Wednesday
night with the leading warm air advection associated with the
strengthening low level jet.

Friday and Saturday...Forecast confidence is medium.

A period of calm arrives later Friday morning and continues into
Saturday. But, another low pressure system will approach by
Saturday afternoon, bringing another chance of showers and
possible thunderstorms.

Sunday and Monday...Forecast confidence is medium.

There is plenty of uncertainty going into early next week given
the active pattern. The GFS and the ECMWF are in disagreement, but
both suggest that this will not be overly active or wet as the low
that was moving through on Saturday should be pulling away by
Sunday.

AVIATION(21Z TAFS)...
Isolated showers and thunderstorms will wind down this evening.
VFR conditions are expected, except within any thunderstorms.
There will be scattered mid level clouds tonight then 4kft cumulus
developing on Tuesday. There is a chance for showers and
thunderstorms on Tuesday.

MARINE...
West winds will gust 15 to 20 knots on Tuesday. Otherwise lighter
winds and low wave heights are expected through Wednesday.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&

$$

Update...Cronce
Tonight/Tuesday and Aviation/Marine...Marquardt
Tuesday Night through Monday...Davis



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