Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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106
FXUS63 KMKX 091754
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1154 AM CST Mon Dec 9 2019

.UPDATE...Hoisted Winter Weather Advisory to account for a quick
hitting band of snow moving through this afternoon. Some slushy
accums can`t be ruled out. Main impact will be 1/4 to 1/2SM vsbys
as band moves through. May see some refreeze overnight as colder
air funnels into the area and surface temps respond to the
subfreezing temps.

PC

&&

.AVIATION(18Z TAFS)...Widespread LIFR conditions with lower
cigs/vsbys in place with broad low across the area. This will
improve somewhat and have been seeing an overall improving trend
in vsbys. However band of moderate to heavy snow showers will
sweep through this afternoon with vsbys going down to 1/4 to 1/2
mile for a short period of time. Some slushy accums possible due
to the snow intensity. Cold advection works in overnight with some
refreeze potential as road surface temps respond to the influx of
colder air.

PC

&&

.PREV DISCUSSION... (Issued 908 AM CST Mon Dec 9 2019)

UPDATE...Still widespread fog out there and some drizzle too.
Re-issued SPS to highlight some of the areas that have vsbys aob
1/2SM. Otherwise forecast on track at the moment.

PC

MARINE...Hoisted a dense fog advisory for mainly the southern
areas where higher dew point air resides. This is also where
webcams are showing fairly poor visibilities.

PC

PREV DISCUSSION... (Issued 613 AM CST Mon Dec 9 2019)

UPDATE...

Forecast remains on track. Areas of fog persist across most of the
area this morning with visibilities dropping below 2 miles at
most locations. Light rain/drizzle continues across our eastern
areas this morning, but did bump PoPs down a bit out west for this
morning. Could see a lull in the rain and drizzle mid-morning as
the center of the surface low moves over wisconsin, but as the
mid-level shortwave trough approaches the region, expect another
round of rain transitioning to a wintry mix late
afternoon/evening. Then a cold front will traverse through
the area and breezy northerly winds will develop by this evening.

AVIATION(12Z TAFS)...

Mostly IFR ceilings and visibilities will continue through most
of the day today across South Wisconsin terminals. This morning`s
light rain/drizzle will persist as well. May see it diminish a bit
by mid-morning, but expect another round of rain transitioning to
a wintry mix late afternoon/evening. Then breezy northerly winds
will develop late this afternoon/evening in the wake of the
passing cold front. Breezy conditions will last through the end of
the period with ceilings improving to MVFR levels.

PREV DISCUSSION... (Issued 352 AM CST Mon Dec 9 2019)

DISCUSSION...

Today and Tonight...Forecast Confidence is Medium...

So far most of the light rain and drizzle has been limited to area
east of the Kettle Moraine early this morning. As a surface low
pushes into Southern Wisconsin this morning, fog has developed and
will persist across portions of southwestern Wisconsin over the
next few hours. The initial round of light rain/drizzle will
likely taper off and go into a lull later this morning. As a mid-
level shortwave trough pushes into the western Great Lakes, can
expect another round of precipitation with mainly rain this
afternoon. As temperatures fall, rain will give way to a wintry
mix late afternoon/evening. Best chances for accumulating snow,
generally less than an inch, will be for areas north of I-94,
while more of a mix of rain/snow will be possible for the southern
areas. As the cold front pushes through and mid-level drying
occurs, some freezing rain may be possible at times. Precipitation
will quickly diminish tonight as cold, dry air pushes into the
area. Additionally, strong gusty winds will develop late this
afternoon/evening behind the cold front as well. Can expect colder
temperatures tonight with lows in the teens and dipping into the
single digits across the Wisconsin river valley.

Tuesday and Wednesday...Forecast confidence is high.

No big changes to this cold forecast, though it doesn`t look quite
as cold on Wednesday. We should see more clouds later
Tuesday/Wednesday morning and this will keep temps a tad warmer
than previously expected for Wed morning lows. Wind chills are now
only running 5 to 10 below north of Milwaukee and Madison and
around zero south. The models are showing a mid level short wave
pushing across the Great Lakes early Wednesday (the source of the
clouds). However, the soundings look very dry other than a shallow
low level layer of moisture. So, won`t mention any flurries or
light snow at this time.

Thursday through Sunday...Forecast confidence is medium.

The pattern continues to transition into a more zonal flow for the
latter half of the week. This allows temps to return to more
normal levels by the end of the week. In addition, a series of
short waves will track through the region. The models suggest one
fast mover on Thursday could produce some light snow, mainly north
of Milwaukee and Madison. There`s another one later Friday into
Friday night that could do the same. Surface cyclogenesis occurs
to our east with a surface low moving northeast along the
Appalachians Friday night into Saturday. The precip shield may
spread as far west as Wisconsin, so we may see some mixed
rain/snow with that given our more mild temps moving in. Sunday is
looking fairly dry right now.

Monday...Forecast confidence is low.

The ECMWF is cranking up a strong surface low over the Ohio Valley
and lifting it northeast next Monday. It has a rather copious
precip axis lifting into southern Wisconsin Monday through
Tuesday...all snow. Meanwhile, the GFS shows a similar low
intensity/track, but it keeps the precip south of Wisconsin.
Typically, a track this far south and east wouldn`t bring us the
precip the ECMWF is producing. Certainly way too far off to get
too concerned/excited for snow, but it is a system that will have
to be watched over the next week.

AVIATION(09Z TAFS)...

Light rain/drizzle continues to push through southern Wisconsin.
A surface low is currently moving across the area and with the
increasing moisture and light winds, fog has developed for
portions of the area as well. Mostly IFR ceilings have developed
at the southern Wisconsin terminals and will likely persist
through the day. Otherwise, expect another round of wintry
precipitation this afternoon/evening ahead of a cold front with
gusty northerly winds developing this evening in its wake.


MARINE...

A surface low continues to push into the area early this morning
and will then move across Lake Michigan through the day today.
Winds will remain lighter and more variable this morning/early
afternoon. However, stronger north to northwest winds will develop
this afternoon behind a cold front and will persist overnight
tonight. Winds will gradually diminish and breezy westerly winds
will linger into Tuesday. A much colder airmass will follow which
will lead to freezing spray at times through mid-week.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory from 3 PM to 5 PM CST this afternoon for
     WIZ051-052-058>060-064>066-069>072.

     Winter Weather Advisory until 3 PM CST this afternoon for WIZ046-
     047-056-057-062-063-067-068.

LM...Dense Fog Advisory until noon CST today for LMZ080-643>646-669-
     671-673-675-777-779-870-872-874-876-878.

     Gale Warning from 6 PM this evening to 2 AM CST Tuesday for
     LMZ080-675-777-779-876-878.

     Small Craft Advisory from 4 PM this afternoon to 6 AM CST
     Tuesday for LMZ643>646.

&&

$$
Today/Tonight and Aviation/Marine...Wagner
Tuesday through Sunday...Davis



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