Special Weather Statement, NWS Milwaukee, WI

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
556 PM CDT Sun Aug 5 2018

.UPDATE...At least scattered thunderstorms are expected to
increase across the area overnight as low level jet pivots
northeast and low to mid-level theta-e advection increases.
Keeping close eye on far northeast IA convection. Showing signs of
becoming more surface-based despite CAP.

&&

.AVIATION(00Z TAFS)...Scattered thunderstorms are expected to
increase across the area overnight as low level jet pivots
northeast toward the tri-state area.

&&

.PREV DISCUSSION... (Issued 216 PM CDT Sun Aug 5 2018)

SHORT TERM...

Tonight and Monday...Forecast Confidence is medium to high:

It will likely remain dry into the early evening hours today.
Multiple rounds of showers and storms are then likely late evening
into Monday. Moisture and instability will be plenty and remain in
place through tomorrow. In addition, the low level jet will stay
parked across the area, with waves in the flow kicking off the
rounds of storms. The threat for this activity will persist until
the main trough passes and the instability/moisture decreases
later tomorrow. Given persistent decent deep layer shear, a few
storms could reach severe levels through Monday. Given the warm
and moist airmass, strong winds are probably a bigger threat than
large hail. Heavy rain is a concern too given precipitable water
values around 2 inches and the possibility of rounds of storms
impacting the same places.

Somewhat less confidence in timing and placement of individual
rounds of storms. Model trends have been generally later, holding
off widespread storms entering the west until late evening, though
a couple models continue to insist on earlier in the evening.
The storms tomorrow will depend on where the effective boundary
gets shoved and how quickly the first round moves out, impacting
the amount of available heating. Right now, it looks like the best
chance tomorrow afternoon will be across the southeast half of the
forecast area.

It will be a mild night again tonight, with lows around 70. Highs
tomorrow will be largely dependent on the timing of clouds/precip.
Overall, it looks like temps around normal, but forecast highs
could vary a few degrees in either direction given more or less
sunshine.

LONG TERM...

Monday Night and Tuesday...Low to Moderate Confidence.

Thunderstorms should be pushing south of the area Monday
evening/night, though a few showers may linger across the area.
Another wave will wiggle through the area Tuesday, which may
result in a few additional showers and thunderstorms during the
day Tuesday. Confidence remains fairly low in exact timing and
extent of showers/thunderstorms.

With a fair amount of cloud cover across the area and
the rain chances, highs on Tuesday will only top out in the upper
70s to around 80.

Tuesday night through Friday...Moderate Confidence.

There is general agreement among model guidance that a slightly
cooler airmass will (briefly) build into the area Tuesday night
into Wednesday, with Wednesday generally looking dry. Highs
Wednesday are expected to be in the low 80s. Warmer temperatures
are expected to return for Thursday, as highs reach the mid to
upper 80s. There is expected to be a weak boundary across the
northern portion of the forecast area Thursday, which may serve as
a focus for thunderstorm development Thursday afternoon into
early Thursday evening. Additional scattered showers and
thunderstorms will be possible on Friday.

Saturday and Sunday...Forecast confidence is low.

Model to model and run to run consistency remains very low for
next weekend. Generally speaking, there is broad support for
temperatures at or just above normal, with at least scattered
thunderstorm chances. Any specifics in terms of timing and
coverage will need to be fined tuned over the coming days.

AVIATION(21Z TAFS)...

Mainly dry conditions are expected through the afternoon hours.
Storms are then likely by later this evening, persisting into
overnight. Models are in decent agreement that the activity will
wind down early Monday morning, with more storms then possible
during the afternoon, especially from Madison southeastward. The
remains a chance that some for the storms could reach severe
limits tonight and tomorrow, with strong winds the main threat.

VFR conditions will remain in place for much of the time through
Monday, aside from lower visibilities possible within heavy
rainfall.

MARINE...

The Small Craft Advisory timing still looks good, with southwest
gusts to 25 knots until early evening. Offshore winds will keep
the waves on the lower end, with the highest waves north toward
Port Washington and Sheboygan...and toward open waters.

&&

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

&&

Update...MBK
Tonight/Monday and Aviation/Marine...MBK
Monday Night through Sunday...99

Hazardous Weather Outlook
National Weather Service Milwaukee/Sullivan WI
252 PM CDT Sun Aug 5 2018

WIZ046-047-051-052-056>060-062>072-062000-
Marquette-Green Lake-Fond Du Lac-Sheboygan-Sauk-Columbia-Dodge-
Washington-Ozaukee-Iowa-Dane-Jefferson-Waukesha-Milwaukee-
Lafayette-Green-Rock-Walworth-Racine-Kenosha-
252 PM CDT Sun Aug 5 2018

This Hazardous Weather Outlook is for portions of east central
Wisconsin, south central Wisconsin and southeast Wisconsin.

.DAY ONE...Tonight

Thunderstorms are expected this evening through the overnight
hours. A few strong to severe thunderstorms will be possible, with
a risk for gusty winds and large hail. There will also be a risk
for locally heavy rain.

.DAYS TWO THROUGH SEVEN...Monday through Sunday

Thunderstorms are likely through the day on Monday, and a few
strong to severe thunderstorms will again be possible. Additional
thunderstorms are expected on Tuesday, and again from Thursday
into next weekend.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed tonight. The NWS Milwaukee radar
will be down from Tuesday through Saturday, so any additional
ground reports will be appreciated with any storms over that
period.

LMZ643>646-062000-
Sheboygan to Port Washington WI-
Port Washington to North Point Light WI-
North Point Light to Wind Point WI-
Wind Point WI to Winthrop Harbor IL-
252 PM CDT Sun Aug 5 2018

This Hazardous Weather Outlook is for portions of Lake Michigan.

.DAY ONE...Tonight

Breezy southwest winds with gusts to around 25 knots are expected
into early evening. A Small Craft Advisory is in effect.

Thunderstorms are expected late this evening through the overnight
hours.  A few strong to severe thunderstorms will be possible.

.DAYS TWO THROUGH SEVEN...Monday through Sunday

Thunderstorms are likely at times on Monday, with a chance of
thunderstorms continuing on Tuesday. Thunderstorm chances return
on Thursday.

www.weather.gov/mkx