River Flood Warning 58, NWS Milwaukee, WI

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
620 AM CDT Mon Aug 27 2018

.UPDATE...Expect scattered showers and a few storms to spread back
into south central WI next several hours associated with upstream
short wave over central IA. Will need to watch those temperatures
closely in the far south. May get into the lower 90s, increasing
the liklihood of Heat Index values higher than 100 for several
hours.

&&

.AVIATION(12Z TAFS)...Mainly VFR conditions with scattered showers
and a few storms redeveloping this morning. Briefly lower
ceilings and visibilities with any showers and storms.

&&

.PREV DISCUSSION... (Issued 332 AM CDT Mon Aug 27 2018)

SHORT TERM...

TODAY AND TONIGHT - Confidence...Medium.

Expect deeper convection over northeast CWA to continue to diminish
as strongest push of moisture convergence associated with low level
jet pivots to the northeast.  However upstream short wave over IA
and weaker warm air and moisture convection along with lingering
MUCape above 2K joules, should continue to generate scattered
convection across the area through the morning. See below hydrology
section for heavy rainfall discussion. Warm front over central CWA
is expected to shift northward this morning, resulting in a warm and
humid day. The majority of the precipitation is expected to end
later this morning with dry conditions expected most of the
afternoon.  Low level jet re-energizes late this afternoon and
tonight over WI with the strongest low level convergence well north
of the area.   All the short term guidance focuses the heavy
rainfall across central WI tonight, but NAM is showing stronger
frontogenetical forcing and Q-vector convergence spreading south
into southern WI during the night. Also, Corfidi Vectors and MBE
Velocity/track would carry activity into southern WI overnight.  As
mentioned below, due to considerable uncertainty of heavy rainfall
location, held off on Flash Flood Watch in CWA.  Did keep likely
pops and higher across northern CWA for tonight.

LONG TERM...

Tuesday and Wednesday...Forecast confidence is medium to high:

A warm, unstable, and very moist airmass will remain in place
across southern Wisconsin through Tuesday. Precipitable water
values are forecast to be around 2 inches, which is twice the
average for late August.

High confidence for widespread storms later Tuesday into Tuesday
night as the trough and associated cold front move through.
Severe thunderstorms and heavy rainfall will be possible once
again.

Could see a wave move through early Wednesday, with a few more
showers/storms possible before high pressure moves into the area.
There should be some sunshine by afternoon. It will be
considerably cooler Wednesday, with highs struggling to around 70
degrees.

Thursday through Sunday...Forecast confidence is medium to
high:

High pressure is expected to be in place for Thursday into Friday,
bringing dry weather, lower humidity, plenty of sunshine, and
pleasant temperatures in the 70s.

Moisture is expected to return later Friday into Saturday as
southerly low level flow develops on the back side of departing
high pressure. This will allow for a return of shower/storm
chances for this period.

High pressure will then return for Sunday, with plenty of sunshine
and near normal temperatures likely.

AVIATION (09Z TAFS)...Mostly VFR conditions are expected, but may
be patchy lower clouds around for a time this morning associated
with scattered convection.  Mixiness in boundary layer winds should
prevent fog development.

MARINE...Warm front over southern Lake Michigan extending into
southern WI is expected to lift northward into northern Lake MI this
morning as scattered convection diminishes.  This will result in
surface winds becoming more southerly.  A low level temperature
inversion should continue to prevent strongest winds from mixing
down to the lake surface away from the shore.  However gusty
southwest winds over the shore areas will affect western parts of
the near shore waters.  Gusts up to 25 knots are expected, so wl be
posting a Small Craft Advisory in effect from mid-morning through
Tuesday.  Early morning convection may yet produce strong winds up
to 40 kts at the lake surface, especially closer to shore.  Areas of
fog will continue in the northern zone for a time this morning until
winds turn to the south to southwest.

HYDROLOGY...Heaviest rainfall since Sunday afternoon has been
focused over Columbia County east to northern Milwaukee and Ozaukee
county including Washington and Dodge counties.  Radar estimated,
confirmed by surface observations show 2 to 4 inches has fallen so
far, as of 08Z.  Areas of flooding recently reported in parts of
Ozaukee county.  The convection is waning over this area as low
level jet pivots to the southwest, pushing better convergence over
Lake Michigan.  However upstream mid-level short wave and weaker
moisture convergence will keep scattered activity around this
morning.  Differences in short term guidance in potential for heavy
rainfall location across central and southern WI tonight. GFS/ECMWF
focuses north of CWA.  NAM also shows QPF axis to the north, but yet
has stronger synoptic lift spreading into northern CWA tonight. Due
to differences, will hold off on issuing Flash Flood Watch for
tonight into Tuesday.

BEACHES...Gusty southwest surface winds are expected to
develop this morning along the shore, while more south winds are
expected offshore.  Wind gusts up to 25 knots will be possible,
however due to the offshore component, the swim risk will remain low
to moderate with 1 to 4 foot waves at the beach today.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory from 10 AM this morning to 7 PM CDT Tuesday
     for LMZ643>646.

&&

Update...MBK
Today/Tonight and Aviation/Marine...MBK
Tuesday THROUGH Sunday...MBK

Hazardous Weather Outlook...UPDATED
National Weather Service Milwaukee/Sullivan WI
632 AM CDT Mon Aug 27 2018

WIZ046-047-051-052-056>060-062>072-281145-
Marquette-Green Lake-Fond Du Lac-Sheboygan-Sauk-Columbia-Dodge-
Washington-Ozaukee-Iowa-Dane-Jefferson-Waukesha-Milwaukee-
Lafayette-Green-Rock-Walworth-Racine-Kenosha-
632 AM CDT Mon Aug 27 2018

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

.DAY ONE...Today and Tonight

Scattered thunderstorms are expected this morning over south
central Wisconsin.  No severe weather is expected.

Thunderstorms will develop in the area again later today into
tonight. There remains some uncertainty if these storms will
effect southern Wisconsin. If they do, severe storms and heavy
rainfall will be possible tonight.

Heat index values will reach the middle to upper 90s today,
possibly hitting 100 in southeast Wisconsin.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

Additional rounds of thunderstorms are likely later Tuesday into
Wednesday morning. There will be a threat for severe thunderstorms
and heavy rainfall once again. The possible heavy rain will
result in a risk for flooding, especially for areas that have seen
very heavy rain over the last week.

Heat index values may reach the middle 90s on Tuesday.

A chance for thunderstorms will return for Friday night and
Saturday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed tonight.

LMZ643>646-281145-
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-
632 AM CDT Mon Aug 27 2018

This Hazardous Weather Outlook is for portions of Lake Michigan.

.DAY ONE...Today and Tonight

Areas of dense fog will reduce the visibility to one mile or less
for a time this morning from Port Washington to Sheboygan. A Dense
Fog Advisory is in effect until 10 am this morning for this area.

A Small Craft Advisory goes into effect at 10 am for gusty
southwest winds.

Thunderstorms are likely through early morning. Storms will then
develop in the area again later today into tonight. There remains
some uncertainty if these storms will effect the nearshore waters
of southern Wisconsin. If they do, severe thunderstorms will be
possible tonight.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

The Small Craft Advisory will be in effect through early Tuesday
evening due to persistent gusty southwest winds.

Additional rounds of thunderstorms are likely later Tuesday into
Wednesday morning. There will be a threat for severe thunderstorms
once again.

A chance for thunderstorms will return for Friday night and
Saturday.

www.weather.gov/mkx

MBK

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
742 AM CDT MON AUG 27 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0742 AM     HEAVY RAIN       2 WSW GERMANTOWN        43.23N 88.15W
08/27/2018  M3.02 INCH       WASHINGTON         WI   CO-OP OBSERVER

            WWTP.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
745 AM CDT MON AUG 27 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0700 AM     HEAVY RAIN       1 NE KEWASKUM           43.53N 88.22W
08/27/2018  M7.50 INCH       WASHINGTON         WI   PUBLIC

            RELAYED FROM BROADCAST MEDIA.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
753 AM CDT MON AUG 27 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0600 AM     HEAVY RAIN       3 E ALLENTON            43.42N 88.28W
08/27/2018  M4.75 INCH       WASHINGTON         WI   TRAINED SPOTTER

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
832 AM CDT MON AUG 27 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0732 AM     HEAVY RAIN       1 W ALLENTON            43.42N 88.35W
08/27/2018  M5.52 INCH       WASHINGTON         WI   CO-OP OBSERVER

            WWTP.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
833 AM CDT MON AUG 27 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0800 AM     HEAVY RAIN       1 E BEAVER DAM          43.46N 88.81W
08/27/2018  M3.60 INCH       DODGE              WI   CO-OP OBSERVER

            WWTP.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
851 AM CDT MON AUG 27 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0720 AM     HEAVY RAIN       4 W RICHFIELD           43.23N 88.32W
08/27/2018  M5.00 INCH       WASHINGTON         WI   PUBLIC

&&