Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 121616

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1016 AM CST Thu Jan 12 2017

.AVIATION/18Z TAFS/...Lingering MVFR cigs are moving on out of the
area along with the one last batch of light snow north and east of
the TAF sites. Mid deck lingers for a time with plenty of SKC across
nw WI and MN headed for our area later today/tonight. a Period of
caa and nw winds this evening expected before surface high settles
in for Friday with a lighter wind regime. 700 RH increases Friday
so an increase in mid clouds expected. Low levels to remain dry.



.MARINE...Allowed Small Craft Advisory to expire across southern
zones at 15z as high pressure ridge briefly affects southern Lake
Michigan.  Expect secondary surge of cold air advection tonight
across the near shore waters behind passing cold front.  Colder air
over relatively warmer waters of Lake Michigan will create steep
low level lapse rate which may allow wind gusts to approach 25 knots
tonight, especially over northern marine zones.  A Small Craft
Advisory may need to be reissued tonight.



.PREV DISCUSSION... /Issued 439 AM CST Thu Jan 12 2017/

TODAY AND TONIGHT...Forecast confidence medium.

Sporadic bands of light snow are developing from sw WI to east
central WI with a steadier band of snow over IA. As the shortwave
trough and mid level frontogenesis progresses across srn WI, expect
a steadier band of light snow to affect those areas. A swath of inch
snow is forecast from Lone Rock to the Fond du lac and Sheboygan
areas with little to no snow south of a line from Mequon to Monroe.
Patchy freezing drizzle will still remain a possibility over far se
WI through 9 AM. Cold advection will continue through the day but
afternoon sunshine should be able to boost temps several degrees
from current values. Arctic air does settle over srn WI tonight with
lows below zero north of a line from Lone Rock to Sheboygan and
single digits elsewhere. Although the winds do decrease tonight,
5 to 10 mph winds still yields wind chill temps of 10-19 below
zero mainly north of Madison and Milwaukee for Fri AM.

FRIDAY...Forecast Confidence...Medium to High

Dry weather will likely prevail through the daytime hours Friday
under strong high pressure. High temps are forecast to be 10 or so
degrees below normal.

A weak shortwave may then bring a quick round of light snow to
southern Wisconsin Friday evening into Friday night. There is
somewhat better agreement among models with this wave, so
increased pops a little. Main concern is that these weak and quick
moving waves with relatively small areas of snow are often hard
to pin down where exactly the snow will fall. Won`t take much of a
shift north or south to miss parts of the area. Other than
stronger GFS solution, majority of models suggest just a dusting
to half an inch where it does snow. Could see 1 to 2 inches in
areas per the GFS.

SATURDAY AND SUNDAY...Forecast Confidence...High

High pressure is expected to bring dry weather for Saturday and
Sunday. Temps should be right around normal for mid-January.

SUNDAY NIGHT THROUGH WEDNESDAY...Forecast Confidence...Medium

Increasing confidence that low pressure will move through the
region early next week, bringing widespread precip to the forecast
area. Models continue to agree fairly well with the general track
of the low, showing a warm layer aloft could bring a mix with
freezing rain and sleet for a time before precip transitions to
all rain.

There are still some timing differences among models. A model
blend brings the bulk of precip through later Sunday night through
Monday night. Best chance for mixed precip looks to be at the
onset of precip Sunday night through Monday morning. Mainly rain
would be expected after that, with some chance for a changeover
back to snow late in the system. Current setup suggests little if
any snow accumulation with this transition.

Depending on model timing, the precip should wind down at some
point on Tuesday. Looks dry then Wednesday per the ECMWF and
Canadian, though the GFS brings a low through with some rain and
snow. Went with some low pops, giving a nod to the GFS solution.

Temps should be above normal through the first half of next week.

AVIATION/12Z TAFS/...Cigs will mainly range from 1-3 kft this
morning with steady snow developing mainly north of a line from
Mequon to Monroe. Patchy freezing drizzle will remain possible over
far se WI through about 9 am. Vsbys with the snow will range from 1
to 3SM. For the afternoon, cold and dry air advection will result in
mostly sunny skies followed by an increase in high clouds tonight.

MARINE...High waves will linger for a time this morning especially
south of North Point Lighthouse. Modest nly winds today will back
wly during the afternoon and become nwly tonight. The wind gusts may
reach into the 20 kt range toward Sheboygan.



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