Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 161813 AAC
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
113 PM CDT Sun Jul 16 2017

.UPDATE...

Low clouds are hanging around southern WI longer than expected
today. This is due to low level moisture being trapped beneath
5000 feet with easterly flow. Aloft, winds are from the north to
northwest. The clouds will scatter out as we lose diurnal heating.
Areas near the lakeshore have a better chance of mixing out
earlier today.

Clear skies are in the forecast for tonight. There is a decent
chance of seeing the northern lights between 10 pm and 4 am
tonight. Here is a good source of information:
www.swpc.noaa.gov/products/aurora-3-day-forecast

&&

.AVIATION(18Z TAFS)...

Low clouds are hanging around southern WI longer than expected
today. Look for ceilings to gradually rise through the afternoon.
Clouds will also start to scatter out as we lose daytime heating
late this afternoon. VFR conditions tonight and Monday.

&&

.PREV DISCUSSION... (Issued 1030 AM CDT Sun Jul 16 2017)

UPDATE...

Low clouds will stick around through the morning and then
gradually lift and scatter out this afternoon.

MARINE...

Gusty north to northeast winds will build high waves through the
evening hours. A small craft advisory is in effect. Plan on
lighter winds and waves through much of next week.

PREV DISCUSSION... (Issued 624 AM CDT Sun Jul 16 2017)

UPDATE...

AVIATION(12Z TAFS)...

Winds will shift to the northeast into this morning, and become
gusty by middle to late morning. These gusty northeast winds
should remain into the afternoon.

There is some uncertainty with how widespread any low ceilings
will become into the morning hours. There is already some of this
development in the area, with more moving into the area from the
north and northeast. Thus, will continue to mention ceilings
around 2500 feet in eastern portions of the area this morning,
with values around 1000 feet in the west.

May need to hang onto these low clouds into early this afternoon,
before scattering out later in the day. High pressure passing by
to the north should bring clearing skies and light winds tonight.

Wood

PREV DISCUSSION... (Issued 358 AM CDT Sun Jul 16 2017)

TODAY AND TONIGHT...Forecast Confidence Is Medium.

Cold front has already pushed southward through the lakeshore
areas early this morning, with the rest of the front expected to
slide south through the area by or soon after 12Z this morning.
Strong cold air advection is expected with breezy northeast winds.
This should bring drier air into the area today.

There is some uncertainty with possible low clouds working into
portions of the area from the north and northeast this morning.
Consensus of mesoscale models suggest some of these low clouds
would move into southeast and parts of south central Wisconsin by
12Z this morning, lingering into midday before scattering out.

Already seeing some of this development in northern portions of
the area. May need to hang onto more clouds in the northern
counties this morning to account for these low clouds. Highs
should be around 70 lakeside with onshore winds, to the upper 70s
well inland.

High pressure moving east across Lake Superior tonight should
continue to bring quiet weather and light winds to the area.
Clearing skies with the light winds should lead to cool overnight
lows in the 50s in most spots.

MONDAY THROUGH TUESDAY NIGHT...Forecast Confidence Is Medium.

Models are in good agreement with taking high pressure east of the
region Monday into Tuesday. The influence of the high should bring
another dry period Monday into Monday night, with near normal
temperatures expected. Onshore winds will keep lakeshore areas
cooler than those inland.

It looks to get more unsettled later Tuesday into Tuesday night,
as the models are showing a general trend toward warm air and
moisture advection into the region. This should bring warmer and
more humid conditions into the area. The models are generally
showing a modest low level jet gradually veering into the area by
later Tuesday night.

There is disagreement with the timing and location of surface
fronts. The NAM is the only one bringing a cold front southeast
through the area Tuesday night, with the other models keeping a
warm front either north, over or to the south of the area. They do
show a 500 mb shortwave trough sliding east through the area
Tuesday afternoon and early evening. There is decent elevated CAPE
and modest deep layer shear, mainly later Tuesday into Tuesday
night.

For now, kept the consensus blended PoPs for later Tuesday into
Tuesday night. There is some potential for strong or isolated
severe storms and some heavy rainfall, though details need to be
worked out between the models before having more confidence in
these hazards.

WEDNESDAY THROUGH SATURDAY...Forecast Confidence Is Medium.

500 mb flow generally becomes west northwesterly during this
period. There is a decent shortwave trough that slides through the
area later Wednesday, with other smaller ones at times into the
rest of this period.

Again, as in the earlier time period, there is some disagreement
with the timing and placement of the warm front over the region
Wednesday into Thursday. If the front remains over or just south
of the area, there is the potential for another round of
convection, perhaps in the form of an MCS, later Wednesday into
Wednesday night. The GFS forecast soundings do show decent
elevated CAPE and deep layer shear during this time.

Again, we will have to wait and see if/when the models resolve
the timing and placement issues between them with the surface and
low level features. Certainly another period to watch for
potential strong/severe storms and heavy rainfall. It does look to
remain warm and quite humid during this time.

Another system then potentially may affect the region Friday into
Saturday, with warm air advection developing again ahead of low
pressure. Model differences continue with timing and placement of
these features, but it does look to remain rather active into the
end of the week.

AVIATION(09Z TAFS)...

Cold front will exit the area around 12Z this morning, with winds
shifting to the northeast and becoming gusty by middle to late
morning. These gusty northeast winds should remain into the
afternoon.

There is some uncertainty with how widespread any low ceilings
will become into the morning hours. There is already some of this
development in the area, with more possibly moving into the area
from the north and northeast this morning.

May need to hang onto these low clouds into early this afternoon,
before scattering out later in the day. High pressure passing by
to the north should bring clearing skies and light winds tonight.

MARINE...

Small Craft Advisory remains in effect for middle morning into
this evening across the nearshore waters of Lake Michigan. Gusty
northeast winds are expected to develop this morning, lingering
into this afternoon. This will build waves into the 3 to 5 foot
range this afternoon, lingering into the middle evening hours
before subsiding. Areas south of North Point Lighthouse will see
the higher waves linger into later this evening.

BEACHES...

A Beach Hazards Statement remains in effect for the beaches along
Lake Michigan from Sheboygan County south through Kenosha County.
Northeast winds will become gusty by middle morning, lingering
into the afternoon. This will cause building waves of 3 to 5 feet
to occur at the shore. This will create a high swim risk, in which
rip currents and other dangerous currents are likely to occur.
Stay out of the water today.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement until 10 PM CDT this evening for WIZ052-
     060-066-071-072.

LM...Small Craft Advisory until 1 AM CDT Monday for LMZ645-646.

     Small Craft Advisory until 10 PM CDT this evening for LMZ643-644.

&&

$$

Update...Cronce
Today/Tonight and Aviation/Marine...Wood
Monday THROUGH Saturday...SPM



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