Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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000
FXUS63 KMKX 111604
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1004 AM CST Wed Jan 11 2017

.AVIATION/18Z TAFS/...Main focus continues to be on the timing of
precip this afternoon and types. 12z upper air shows evidence of the
warm layer with KDVN 850 temp at 5c and even warmer to the southwest
and lingering colder airmass of -4c at KGRB. Meso models show the
gradual increase in precip potential as the afternoon wears on with
plenty of dry air to overcome in the interim. No real change to
forecast or precip types at this time, however latest RAP soundings
show that if anything there could be a delay to precip onset
with drier column holding on a bit longer. Initially warm temps in
the southeast should allow for some rain before progressively colder
airmass intrudes from the northwest leading to the period of mixed
precip/icing potential before changing to light snow. Expecting cigs
to lower as the day and evening wears on.

PC

&&

.MARINE...A cold front will slowly from nw to se across srn WI and
Lake MI. The winds will veer nly 10-20 kts from late afternoon into
the early evening. Waves of 2-4 feet are expected. No Small Craft
Advisory is planned at this time. Winds will gust into the 20 knot
range at times.

PC

&&

.PREV DISCUSSION... /Issued 955 AM CST Wed Jan 11 2017/

UPDATE...
Forecast is looking good at this point with little to nothing to
update at this time. Warm air advection ahead of the developing
low over eastern Kansas is pushing temps towards the upper 20s and
lower 30s in the next few hours. As the system slides east the
chances for a full mixed bag of wintry mix will be very likely
from the afternoon into the evening hours. Currently watching this
expected precipitation develop over extreme northern Missouri and
southern Iowa...all slowly drifting northeast towards the region.

ABS

PREV DISCUSSION... /Issued 504 AM CST Wed Jan 11 2017/

TODAY AND TONIGHT...Forecast confidence medium to high.

A shortwave trough currently over the central Great Plains will move
across srn WI this evening while the wave of low pressure tracks
across ne IL. As the wave of low pressure passes to the south and
east, the stationary front over central WI will move south as a cold
front. Cold surface air will undercut warm advection aloft making
for mixed precipitation for much of srn WI. The mixed precipitation
will begin by early afternoon nw of Madison and develop to the east
and south through the afternoon as 850 mb frontogenesis is enhanced
and the shortwave approaches. Issued a Winter Weather Advisory with
the exception of Marquette and Green Lake counties where only snow
and possibly sleet is expected. Farther to the south and east, many
areas will experience all precipitation types including freezing
rain. Ice accumulations will range from a glaze to one tenth of an
inch. Another shortwave trough will then approach early Thu AM with
chances of light snow at that time. High temps today will range from
the middle to upper 20s toward central WI to the middle to upper 30s
far se WI. Lows tonight will range from near 10 above toward central
WI and lower 20s far se WI.

THURSDAY THROUGH SATURDAY...Forecast Confidence...Medium to High

The shortwave will move through Thursday morning, with the snow
winding down by late morning. Looks like around a trace to half an
inch of additional snowfall in the morning...the highest amounts
in the east.

Strong high pressure will move in Thursday night, moving overhead
on Friday. Another wave will be headed this way on Friday though,
with light snow expected to arrive Friday evening per the GFS and
ECMWF. Less confidence in this snowfall, as the NAM and Canadian
hardly have a wave and do not produce precip over southern
Wisconsin.

Should be dry then Saturday behind the wave.

Below normal temps Thursday and Friday will warm back to around
normal by Saturday.

SUNDAY THROUGH TUESDAY...Forecast Confidence...Medium

Models are in good agreement that low pressure will move through
the region early next week. Models do ok with the general track of
the low as well, showing a warm layer aloft could bring a mix with
freezing rain and sleet for a time before precip transitions to
all rain.

The main issue with early next week is model timing. The ECMWF and
GFS are in decent agreement bringing the bulk of the precip Monday
afternoon into Tuesday. The Canadian is much quicker though,
bringing the system through roughly 18 hours earlier. Trended
temps and pops toward ECMWF and GFS for now.

AVIATION/12Z TAFS...Mixed precipitation will develop north and west
of the Milwaukee area during the early to middle afternoon. All rain
is expected in far se WI and near the IL border until sunset when
freezing rain will occur. The mixed precipitation and freezing rain
will occur into the evening hours. Cigs will fall this afternoon to
600 to 1500 feet with vsbys ranging from 1-2 miles toward central WI
where mostly snow is expected while vsbys will range from 2-5 miles
where mixed precipitation is occurring. As this precipitation ends
late tonight another chances of light snow is forecast during Thu
morning for much of srn WI. The cigs will remain low.

MARINE...Modest wly winds early this morning will back sly 10-20
kts into the early afternoon. A cold front will slowly from nw to se
across srn WI and Lake MI. The winds will veer nly 10-20 kts from
late afternoon into the early evening. Waves of 2-4 feet are
expected. No Small Craft Advisory is planned at this time. Winds
will gust into the 20 knot range at times.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER WEATHER ADVISORY from 5 PM this afternoon to midnight CST
     tonight for WIZ066-069>072.

     WINTER WEATHER ADVISORY until 9 PM CST this evening for WIZ056-
     057-062-063-067-068.

     WINTER WEATHER ADVISORY until midnight CST tonight for WIZ051-
     052-058>060-064-065.

LM...None.
&&

$$
TODAY/TONIGHT AND AVIATION/MARINE...Gehring
Thursday THROUGH Tuesday...DDV


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