Small Craft Advisory 3, NWS Milwaukee, WI

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
1112 AM CST Thu Jan 5 2017

.UPDATE...

Updated forecast to add light snow showers across most of the
area into the middle afternoon hours. Observations at office and
reduced visibilities at some airport sites indicating that what is
falling is more than just flurries. Not expecting any
accumulations with the west northwest winds blowing it around.

Main 500 mb vorticity maximum exiting the area and there should be
downward vertical motion to gradually end this activity from north
to south this afternoon. Some mid level frontogenesis response may
be helping these light snow showers/flurries along.

Some uncertainty with the cloud trends for this afternoon into
Friday. It looks like the drier air from the northwest will move
into the area during the late afternoon and evening, which should
bring clearing skies. There are some areas of clouds upstream, and
these may move through the area at times into Friday. Will trend
downward with cloud cover, and may have lower clouds more if
models remain too moist in the low levels.

Cold temperatures and bitter cold wind chills are anticipated into
Friday. Most areas should drop into the single digits below zero
tonight, with the coldest 850 mb/925 mb temperatures overhead.
Single digits above zero look on track for Friday.

Wind chills should drop to between 15 below and 23 below zero
tonight into Friday morning. The coldest readings will be north of
Madison and Milwaukee. Another Wind Chill Advisory will likely be
needed for the northern portions of the area.

&&

.AVIATION/18Z TAFS/...

Area of light snow showers with some flurries are expected to
linger across most of the area into the middle afternoon hours. No
accumulations are expected on runways, with the west northwest
winds blowing it around. There may be reduced visibilities to 3
miles or so at times, though may not mention in TAFs due to short
duration of any light snow showers.

West northwest winds will linger this afternoon, tonight and
Friday across the area. Gusts to around 15 knots are expected this
afternoon, and perhaps again on Friday.

Some uncertainty with cloud trends this afternoon into Friday.
Current cloud deck with 2000 to 3000 foot ceilings should linger
into the middle to late afternoon hours, before moving southeast
of the area. May see a period of partly cloudy to mostly clear
skies tonight into Friday, as there are some cloud patches
upstream of the area. These clouds may have ceilings in the 2000
to 3000 foot range as well.

&&

.MARINE...

Small Craft Advisory will be allowed to expire at noon CST, as
pressure gradient continues to relax. Any west northwest wind
gusts should remain around 20 knots this afternoon into Friday.
High waves and any freezing spray will remain over the open waters
of Lake Michigan.

Winds and waves may reach Small Craft Advisory levels Saturday
into Saturday night, and again at times Monday into Tuesday.

&&

.PREV DISCUSSION... /Issued 236 AM CST Thu Jan 5 2017/

TODAY AND TONIGHT...Forecast confidence is high.

Temperatures are mostly on track from the previous forecast...maybe
a tad "warmer" than expected early this morning. Highs will
generally stay in the single digits today.  Wind chills this morning
range from near 20 below across Sheboygan to Marquette county to
around 10 below along the Illinois line.  I'll leave the wind chill
advisory in place across the north.

One new forecast issue is an area of clouds moving southeast out of
Minnesota associated with a mid level trough swinging through. These
clouds are making steady progress and low level rh progs suggest it
will move across southern Wisconsin this morning, eroding this
afternoon.  There are some light snow/flurries with it, so will
carry scattered flurries at this point.  No accumulation.

Temps tonight will be a few degrees colder, ranging from around zero
in Milwaukee to 4-6 below from Madison on west and north.  Wind
chill values toward sunrise will be colder than this morning. Around
20 below across the northern half of the CWA to 15 to 18 below south
half.  We'll probably have another wind chill advisory issued later
today, once the current one expires.

FRIDAY THROUGH SUNDAY...Forecast confidence is High.

Arctic high pressure will dominate through the weekend. Low
temperatures will be at or below zero Friday night and Saturday
night. There will be little relief during the day with highs in the
single digits to lower teens. West winds will be on the lighter
side during most of this time but will still be enough to create a
wind chill. Wind chill values of 15 to 20 below zero are expected
through Friday morning and again Saturday night into Sunday morning.
Wind chill values will be at at or close advisory levels across the
northern 2 tiers of counties during these times. They will be
somewhat "milder" at 5 to 15 below Friday night into Saturday
morning. With the current advisory in place will hold off with
another advisory for now.

MONDAY THROUGH WEDNESDAY...Forecast confidence is Moderate.

A trough moves through on Sunday night or Monday bringing a chance
for light snow.

Temperatures moderate on Monday as an upper ridge moves into the
region with southwest flow at the low levels. There is good agreement
on a stronger system moving through Tuesday and Wednesday. It is
pretty early to nail down the details on precipitation type now since
there is variability with how warm it will get. It could start
as snow or mixed precip Tuesday morning. Rain is possible in the
afternoon and evening, especially in the southeast. The ECMWF and
Canadian are the warmest showing temps in the upper 30s Tuesday
afternoon and evening. Snow is possible on the backside Tuesday night
or Wednesday morning as temps cool down.

The variability with temperatures continues for later in the week.
The unsettled pattern looks to continue with chances for precip
at times for the later part of the week into the weekend.

AVIATION/12Z TAFS/...

VFR conditions are expected through the TAF period.  A new concern
for this forecast is a rather large area of clouds based between
3500-4500ft moving southeast out of Minnesota.  These clouds are
expected to move across southern Wisconsin this morning.  They
should reach KMSN by around 11z and Milwaukee between 13-14z.  There
is some uncertainty about whether they'll make it all the way to
Milwaukee, but will assume that for now.  There are flurries falling
out of these clouds, but no accumulation is expected.  Will carry
scattered flurries this morning.  Look for the westerly winds to
be fairly steady today, diminishing tonight.

MARINE...

 Will stretch the small craft advisory through 18z north of Port
Washington and let it expire at 12z south of Port Washington.
Westerly winds will remain elevated today, diminishing steadily
tonight.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...SMALL CRAFT ADVISORY until noon CST today for LMZ643.

&&

UPDATE...Wood
TODAY/TONIGHT AND AVIATION/MARINE...Davis
Friday THROUGH Wednesday...Marquardt

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1006 AM CST THU JAN 5 2017

WIZ046-047-051-052-056>060-062>072-061615-
MARQUETTE-GREEN LAKE-FOND DU LAC-SHEBOYGAN-SAUK-COLUMBIA-DODGE-
WASHINGTON-OZAUKEE-IOWA-DANE-JEFFERSON-WAUKESHA-MILWAUKEE-
LAFAYETTE-GREEN-ROCK-WALWORTH-RACINE-KENOSHA-
1006 AM CST THU JAN 5 2017

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EAST CENTRAL
WISCONSIN...SOUTH CENTRAL WISCONSIN AND SOUTHEAST WISCONSIN.

.DAY ONE...TODAY AND TONIGHT

LOOK FOR WIND CHILLS TO RANGE FROM 5 BELOW TO 15 BELOW ZERO
TODAY...COLDEST NORTH OF THE MADISON AND MILWAUKEE AREAS.

WIND CHILLS TONIGHT WILL BE A FEW DEGREES COLDER...RANGING FROM
15 TO 23 BELOW ZERO ACROSS SOUTHERN WISCONSIN. THE COLDEST VALUES
WILL AGAIN BE NORTH OF MADISON AND MILWAUKEE. A WIND CHILL
ADVISORY MAY BE NEEDED AGAIN FOR THIS AREA LATER TONIGHT INTO
FRIDAY MORNING.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

COLD TEMPERATURES WILL PERSIST THROUGH THE WEEKEND. WIND CHILL
TEMPERATURES WILL GENERALLY RANGE FROM 10 TO 20 BELOW ZERO EACH
MORNING THROUGH SUNDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED.

LMZ643>646-061615-
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-
1006 AM CST THU JAN 5 2017

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF LAKE MICHIGAN.

.DAY ONE...TODAY AND TONIGHT

A SMALL CRAFT ADVISORY REMAINS IN EFFECT THROUGH NOON NORTH OF
PORT WASHINGTON...DUE TO BRISK WEST NORTHWEST WINDS.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

WINDS AND WAVES WILL APPROACH SMALL CRAFT ADVISORY LEVELS
SATURDAY INTO SATURDAY NIGHT...AND AGAIN AT TIMES MONDAY INTO
TUESDAY.

WOOD
WWW.WEATHER.GOV/MKX