Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 271338 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
738 AM CST Sun Nov 27 2016

.UPDATE...

Dense fog developed over portions of Sheboygan, Ozaukee, and
Washington counties early this morning. It has now expanded into
parts of Milwaukee and Waukesha counties. Reports from law
enforcement, remote sensors, and satellite imagery support areas of
dense fog in Marquette, Green Lake and Fond du Lac counties as well.
A dense fog advisory is in effect for these areas.

Meanwhile, an area of low clouds developed over north central IL
this morning and quickly expanded north into southeast WI. The RAP
has a handle on this in its sfc-1000mb RH. The HRRR also seems to
have a handle on these low clouds. Expect them to pretty much stay
in place until late morning. Then the large area of stratus moving
up from central IL and eastern IA will catch up to it and keep the
southeast part of WI through the whole day. Lowered max temps
accordingly.

&&

.AVIATION/18Z TAFS/...

There is a lot of uncertainty in cloud bases and visibilities for
today.

Low clouds developed over northern IL and expanded into southeast
WI. Bases are around 300 feet. Expect this to persist through mid
morning. Bases may rise to around 800 feet with some daytime mixing.
Another area of low clouds is moving north from central IL and will
catch up to us around midday. Bases with this cloud deck will
likely be in the 800 to 1500 foot range.

Morning dense fog will dissipate by late morning. We may see MVFR
vsbys through the day under the stratus deck.

Winds will start to increase later today. A band of moderate rain
will slide through southern WI this evening. A few rumbles of
thunder are possible. Cloud bases will likely remain low until a
cold front moves through early Tuesday morning.

&&

.PREV DISCUSSION... /Issued 338 AM CST Sun Nov 27 2016/

TODAY AND TONIGHT... Forecast confidence is medium.

Light fog across southern WI will dissipate by mid morning as the
nocturnal inversion decays and southeast surface winds begin to
increase. Expect a period of sunny skies today. An area of stratus
associated with strong moisture transport, currently over MO, will
expand northeast, which should reach southern WI by late afternoon.

It won`t take long for the rain to begin once these clouds arrive.
The forcing is deep and of decent strength, with the left exit
region of the upper jet, nose of a low level jet, 500mb shortwave
trough, and warm air advection. Mesoscale models are consistent in
showing a band of rain to arrive in southwest WI by 8 pm this
evening, reach Madison by 10 pm, and Milwaukee between 11 and
midnight. The band should be out of Madison by midnight or 1 am.
Scattered showers should continue behind the main band of rain
overnight. Forcing seems sufficient, along with steep lapse rates in
the mid levels, to mention thunder with this band of rain. No severe
storms. Rainfall totals for just tonight are expected to be a half
to three quarters of an inch.

The pressure gradient is really going to tighten up over southern WI
as low pressure occludes over the Dakotas this evening. Expect
south wind gusts of 20 to 30 mph overnight.

MONDAY AND MONDAY NIGHT - Forecast Confidence...High.

The surface and upper lows become stationary over the eastern
Dakotas. There may be a break in the precip Monday morning between
shortwaves and as the core of the LLJ weakens and moves east.
Another round of precip is expected Monday afternoon and night. A
branch of the LLJ redevelops and provides another surge of moisture
into the region during this time as a shortwave rotates north across
southeast WI. Precipitation ends Tuesday morning after a surface
cold front passes through overnight.

Temperatures warm with the strong southwest flow so precip type is
easily all rain. South winds will gust 20 to 30 miles per hour
through Monday. Some models show a small amount of elevated
instability in the west but not enough to mention thunder.

TUESDAY THROUGH SUNDAY - Forecast Confidence...Medium.

The lows shifts into Minnesota then slowly meanders east by
Thursday. Drier flow should allow for some sun on Tuesday. Later in
the period cloud cover will return and there are small precip
chances at times due to weak shortwave activity and dominant
cyclonic flow. Temperatures will be slightly cooler as the upper low
hangs around and northwest flow dominates. Lows will be around 30
later in this period so there is a chance for light snow at times.
Little to no accumulation is expected.

AVIATION/12Z TAFS/...

Coming soon.

MARINE...

Southerly winds will increase ahead of approaching low pressure
today. Wind gusts are expected to reach gale force by around
midnight. This looks like a low-end gale event. A gale warning is in
effect from midnight Sun night though most of Monday night. The
strong winds will build high waves, the highest in the northern
marine zones.

Winds will shift to the southwest Tuesday morning and gusts will
approach small craft advisory levels.

MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...GALE WARNING from midnight tonight to 3 AM CST Tuesday for
     LMZ643>646.

$$

TODAY/TONIGHT AND AVIATION/MARINE...MRC

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...DENSE FOG ADVISORY until 9 AM CST this morning for WIZ046-047-
     051-052-059-060-065-066.

LM...GALE WARNING from midnight tonight to 3 AM CST Tuesday for
     LMZ643>646.

&&

$$

UPDATE...MRC
TODAY/TONIGHT AND AVIATION/MARINE...MRC
Monday THROUGH Saturday...Marquardt



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