Small Craft Advisory 88, NWS Milwaukee, WI

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
902 PM CDT Tue Oct 24 2017

.UPDATE...

I increased the pops for the morning event. The bulk of the
guidance supports at least likely pops at this point and these
could go higher if trends continue to support it. There is quite a
bit of dry air that has to be overcome, but the dynamics are so
strong that this shouldn't be a huge issue. Of course, temps are
at the threshold for rain vs snow. It should initially start as
rain, but then wet bulb cooling should cause a quick changeover
to snow or at least a mix of rain/snow. Local temperature
variations at the diurnal min of the day will add more complexity
to the thermal profile. The main axis for the precip should run
from Sauk to Rock/Green counties. Little or no accumulations are
expected due to the warm ground. If any area sees accums on grassy
areas, it will most likely be northwest of Madison.

Skies are clearing out quickly from west to east and if temps can
radiate out quick enough before the next batch of clouds moves in
from the northwest, we could see some patchy frost in low lying
areas. Those clouds are moving in quickly, so frost isn't a major
concern.

&&

.MARINE...

Winds have come down, so converted the Gale Warning to a small
craft advisory and will expire it at 4 am. The highest waves
remain out toward open water.

&&

.PREV DISCUSSION... (Issued 549 PM CDT Tue Oct 24 2017)

UPDATE...

Clearing is starting to work into the western CWA at the start of
the evening and this should progress quickly east. Temps will
tumble into the 30s, before next round of clouds moves in toward
3-4 am tonight.  The current forecast is on track.

AVIATION(00Z TAFS)...

VFR conditions are returning to the area, with most places VFR by
00z this evening. Skies will clear briefly, before more mid and
high level clouds spill in between 08-10z Wednesday. A fast moving
mid level short wave will bring a narrow band of precipitation to
south central Wisconsin between 11-16z Wednesday. The temperature
profile supports light snow at the beginning, then transitioning
over to a mix of rain/snow then all rain before it ends by mid to
late morning on Wednesday. The axis of this band should stretch
from Sauk county southeast into Rock county. It looks like it
should stay just west of KMKE/KENW, but possibly clipping KUES. No
accumulations are expected due to warm pavement temperatures.
Grassy areas could see a light accum. This band of precip could
bring a brief period of MVFR CIGS Wednesday morning, otherwise
look for VFR conditions to dominate through the period.

PREV DISCUSSION... (Issued 347 PM CDT Tue Oct 24 2017)

SHORT TERM...

Tonight and Wednesday...Forecast Confidence is Medium.

Wind gusts are not meeting the wind advisory criteria (39 knot/45
mph gusts or greater) this afternoon, nor are they expected to.
Highest gusts so far are 39 mph at Fond du Lac Airport and 38 mph
at Mitchell Airport, along with higher wind gusts over Lake
Michigan. Therefore, the wind advisory was cancelled. Winds will
diminish through late evening.

The main area of rain moved out of southeast WI, but there are
areas of light rain and drizzle traversing southward through
southeast WI due to small impulses in that upper low sitting over
the eastern U.P. of Michigan. This will move out by late evening.

There should be a period of clear skies and much lighter winds
overnight before mid level clouds spread in from the west. The
clearing is expected to be centered over Madison between midnight
and 3 am. This window should be enough to allow temps to drop
into the 33 to 35 degree range for a short period of time.
Therefore, frost is possible tonight, but not certain. At this
time, we are not planning on issuing a frost advisory headline.

A mid level shortwave trough will slide southeast into western WI
late tonight. The left exit region of a strong upper jet will be
moving in at this time as well. Upward motion with this forcing,
along with theta-e advection should bring in a band of deeper
moisture. The deep saturated layer with sufficient forcing will
be squarely within the dendritic growth zone which can support
light snow.

The 12Z models came in with much drier low levels than previous
runs, but an area from the Dells to Janesville, including Madison,
seems fairly likely to see snow falling from the sky. Surface
temperatures will be too warm and precip amounts will be too light
for any snow accumulation.

Wednesday night through Friday...Forecast confidence medium.

Strong low pressure will track across the nrn Great Plains to ne
MN through Thu with upper ridging over srn WI. A weak ridge of
high pressure will prevail Wed nt with low temps near freezing.
Thus a Frost Advisory will likely be needed for Wed nt into Thu
AM. Afterward, ssely winds and warm advection will develop for Thu
with temps rebounding into the middle 50s.

The upper trough associated with the low over ne MN will dig swd
to srn MN and IA for Thu nt-Fri with the sfc low occluding over
srn or central WI. Low to mid level warm, moist advection and
frontogenesis will increase across the region with increasing
DCVA. A consensus of models do saturate over the nrn CWA so went
with rain likely Thu nt there, with chances of rain in the south.
The chances of rain will then linger into Fri but a dry slot will
reduce the rain chances by the afternoon. The cold front will also
pass Fri AM on swly winds.

LONG TERM...Saturday through Tuesday...Forecast confidence
medium.

The occluded system will then slowly move across WI during the
weekend with light rain and light snow expected at times. Another
upper trough will follow the occlusion into the Great Lakes,
thereby bringing another cold front to srn WI late on Mon. Thus
cool temps in the 40s during the day and lower to middle 30s at
night will continue.

AVIATION(21Z TAFS)...

Gusty winds will diminish this evening, along with the periods of
rain and drizzle. Skies are expected to clear for a time
overnight. Mid- level clouds and eventually VFR ceilings around
3500 ft will spread into south central WI late tonight and
southeast WI Wednesday morning. There could be some light snow
falling out of these clouds, but the light precip amounts and
warmer ground/pavement temps should inhibit any accumulation. Best
chance for light snow is over south central WI, as the low level
air in southeast WI is expected to be too dry for precip reaching
the ground.

MARINE...

Gale force northwest winds will diminish this evening. The gale
warning may need to be cancelled early. A small craft advisory
will be needed after the Gale expires. Highest waves will be
toward open waters due to the offshore nature of the winds.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory until 4 AM CDT Wednesday for LMZ643>646.

&&

Update...Davis
Tonight/Wednesday and Aviation/Marine...Cronce
Wednesday Night through Tuesday...Gehring

Hazardous Weather Outlook
National Weather Service Milwaukee/Sullivan WI
337 PM CDT Tue Oct 24 2017

WIZ046-047-051-052-056>060-062>072-252045-
Marquette-Green Lake-Fond Du Lac-Sheboygan-Sauk-Columbia-Dodge-
Washington-Ozaukee-Iowa-Dane-Jefferson-Waukesha-Milwaukee-
Lafayette-Green-Rock-Walworth-Racine-Kenosha-
337 PM CDT Tue Oct 24 2017

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

.DAY ONE...Tonight

Frost may form after midnight as temperatures fall into the lower
to middle 30s.

.DAYS TWO THROUGH SEVEN...Wednesday through Tuesday

Near or below freezing temperatures are likely Wednesday night and
each night from Friday night into next week.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

LMZ643>646-252045-
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-
337 PM CDT Tue Oct 24 2017

This Hazardous Weather Outlook is for portions of Lake Michigan.

.DAY ONE...Tonight

A Gale Warning is in effect until 4 am for infrequent wind gusts
to 34 knots or greater.

.DAYS TWO THROUGH SEVEN...Wednesday through Tuesday

Breezy south winds and high waves are likely Thursday night into
Friday. Brisk westerly winds may then develop for Monday and
Monday night with the passage of a cold front. Small Craft
Advisories may be needed during these times.

www.weather.gov/mkx

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
421 PM CDT TUE OCT 24 2017

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

0101 PM     NON-TSTM WND GST 2 NE MILWAUKEE          43.06N 87.89W
10/24/2017  M42 MPH          MILWAUKEE          WI   MESONET

            PEAK WIND GUST AT MESONET STATION E0512, 1
            NE MILWAUKEE.

&&

SPM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
422 PM CDT TUE OCT 24 2017

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

0107 PM     NON-TSTM WND GST 2 WSW FOND DU LAC       43.77N 88.49W
10/24/2017  M39 MPH          FOND DU LAC        WI   ASOS

            PEAK WIND GUST AT ASOS STATION FLD, FOND DU
            LAC AIRPORT.

&&

SPM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
455 PM CDT TUE OCT 24 2017

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

0300 PM     NON-TSTM WND DMG 2 NE KOHLER             43.75N 87.76W
10/24/2017                   SHEBOYGAN          WI   NEWSPAPER

            SEMI-TRUCK EXITING HWY 23 ONTO I-43 SOUTH
            RAMP OVERTURNED INTO MEDIAN DUE TO HIGH WIND
            GUST. TIME ESTIMATED.

&&

SPM