Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 201759 AAB
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
1259 PM CDT Tue Jun 20 2017

.UPDATE...


&&

.AVIATION(18Z TAFS)...

Area of showers and isolated thunderstorms will move east
southeast through the area early this afternoon. This will exit to
the southeast by 21Z to 22Z this afternoon. Conditions should
remain VFR category during this time. Lake breeze with southeast
winds should reach Milwaukee and Kenosha by 21Z this afternoon.

Skies should gradually clear out this evening. Light winds
overnight with clear skies may lead to light fog between 09Z and
13Z Wednesday morning. Light east winds Wednesday morning will
become southeast Wednesday afternoon.

Wood

&&

.PREV DISCUSSION... (Issued 950 AM CDT Tue Jun 20 2017)

UPDATE...

Passing shortwave trough in the 700 mb to 500 mb layer will
combine with 850 mb to 700 mb frontogenesis response fields to
push the current area of showers and isolated storms southeast
through the area this morning into early this afternoon. This
activity should gradually wind down later this afternoon and
early this evening, as downward motion in the wake of the
shortwave trough develops.

Area of clouds will push through the area as well into early this
afternoon, before mixing out later this afternoon into this
evening. This will keep temperatures cool for a time into early
this afternoon. Adjusted temperature trends to account for the
showers and clouds. Temperatures should rise into the lower 70s in
south central Wisconsin, with upper 60s to around 70 elsewhere.

Wood

MARINE...

Area of showers with isolated storms will move southeast through
the waters this morning into early this afternoon. There may be
some lingering showers later this afternoon before they dissipate.

West winds gusting to 20 knots this morning will weaken this
afternoon. Southeast winds up to 10 knots with lake breeze should
develop around and south of Milwaukee by middle afternoon. Waves
will remain low.

Gusty southwest to west winds may develop Thursday, and approach
Small Craft Advisory levels. Waves will remain highest over the
open waters.

Showers and thunderstorms are likely Wednesday night into
Thursday, with strong to severe storms possible later Wednesday
night into Thursday.

Wood

PREV DISCUSSION... (Issued 319 AM CDT Tue Jun 20 2017)

SHORT TERM...

Today and Tonight...Forecast confidence is medium:

A low amplitude mid/upper level shortwave trough will move across
Wisconsin this morning, as the left exit region of a 110 knot
250 mb upper jet moves across the area. This results in moderate
upper divergence and 700 mb upward motion.

As a result showers will likely move through the region during
the morning and early afternoon.

A 925mb thermal ridge will nudge into the southwest part of the
state with weak warm air advection across the region. Surface
based Cape will build to 500 J/KG so there is a chance for
thunder. Shear is moderate. Surface based CAPE increases again to
600 joules/kg late afternoon but the better forcing is off to the
east. So only isolated showers/thunderstorms then.

Skies clear and winds diminish tonight with some ground fog
expected, especially in the river valleys late.

LONG TERM...

Wednesday and Thursday...Forecast confidence is medium:

The flow will turn more zonal mid-week, allowing a return of
deeper moisture and warmer temps. Shower/storm chances will also
increase during this time as moisture/instability and forcing
increase with low pressure moving into the region.

Models have slowed a tad more with the arrival of the deeper
moisture and better warm air advection, so Wednesday now looks
mainly dry into early evening. Showers/storms are then likely
later Wed evening and overnight. Storms could be strong to severe
as they arrive into the area given increasing instability and
decent shear as the low level jet pushes into the area.

Still looks like the low level boundary could get hung up in the
area, allowing further rounds of showers/storms on Thursday and
Thursday night. Storms could be severe Thursday too.

Friday through Monday...Forecast confidence is medium:

It looks dry Friday as high pressure builds toward the area.
Surface high pressure will continue to build in slowly from the
west over the weekend into early next week. Meanwhile, weak waves
are expected to move through broad troughing, bringing precip
chances at times. The main issue during this period is that model
timing of the individual waves isn`t great, so not a ton of
confidence in pops. Models do agree that near normal temps Friday
should drop to below normal values for Sat-Mon.

AVIATION(06Z TAFS)...

VFR conditions expected through the TAF period except within
thunderstorms. Skies will be mostly clear overnight with light
winds. An upper level disturbance will roll through southern WI
this 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.

MARINE...

West winds will gust to around 20 knots by afternoon. Otherwise
lighter winds and low wave heights are expected through
Wednesday. Look for mainly offshore winds today and onshore on
Wednesday.

It will be another day with shower and thunderstorm chances. Look
for best potential of precipitation late this morning and early
afternoon.

&&

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

$$

Update...Wood
Today/Tonight and Aviation/Marine...Hentz
Wednesday THROUGH Monday...DDV



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