Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 221538 AAA

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
938 AM CST Wed Feb 22 2017


Stratus continues to diminish across southern Wisconsin this
morning. This is happening early enough in the day to feel good
about temperatures reaching forecast highs this afternoon. Still
think the northern half of the forecast area will be affected by
some mid level clouds as a trough of low pressure approaches.
This could hold temps back a bit, so will have to consider tweaks
to the highs in the north. Otherwise, still looks like a beautiful
day with highs approaching or reaching all time February records.



Stratus will continue to diminish through late morning, with VFR
conditions expected for the afternoon hours. An approaching low
pressure trough will likely bring some high clouds to the north
this afternoon and evening, with maybe a few sprinkles.

A cold front will move through late this evening into tonight.
Looks like a dry frontal passage. Low clouds are likely to move in
behind the front late tonight into Thursday morning, possibly
then hanging around through the day.

There will be a chance for showers tomorrow afternoon, with
widespread showers then expected in the evening and overnight as
a stronger low pressure system approaches. A little thunder is
possible Thursday night.



Areas of fog may continue through the day north of Port Washington
but sswly winds should limit the intensity of the fog. Otherwise,
sswly winds will prevail today into tonight as low pressure moves
from srn MN to across nrn Lake MI. A cold front will then shift the
winds to nly early Thu AM. The winds will then veer nely later Thu
AM and increase to 15 to 25 kts later in the day including high waves.
Thus a Small Craft Advisory may be needed beginning Thu afternoon or
Thu evening. The Advisory would most likely continue into Fri.


.PREV DISCUSSION... /Issued 320 AM CST Wed Feb 22 2017/

TODAY AND TONIGHT...Forecast Confidence Is Medium.

Main issues this period will be fog trends into this morning, and
record high temperatures today.

There is an area of dense fog and low stratus clouds that are slowly
pushing northeastward into far southern Wisconsin. Janesville has
dropped to 1/2 mile visibility with this area. The consensus blend
of short term models suggest that this area of dense fog and low
stratus may continue to push into the southeast half of the forecast
area into the middle morning hours. Based on recent trends, will
expand the Dense Fog Advisory into Green, Rock and Walworth Counties
into the middle morning hours.

In addition, Kenosha continues to drop to 1/4 mile at times during
the overnight hours. Dense fog lingers over the waters of Lake
Michigan, with the moist dew points over the cool waters. This may
affect areas close to the shore into this morning. Will keep the
Dense Fog Advisory going for Milwaukee, Racine and Kenosha Counties
into middle morning hours, mainly for areas near the lakeshore.

The fog and low stratus should mix out by later in the morning. This
should allow for warm air advection with south to southwest winds to
bring record high temperatures to the area once again. Mixing up to
near 925 mb temperatures suggest all-time record highs for the month
of February are likely to be tied or broken today at Milwaukee and

A cold front will push southeast through the area this evening, with
cooler air moving into the area later tonight. Lows should drop into
the upper 30s to around 40, which is still quite mild for this time
of year.

THURSDAY - Confidence...Medium
Models are all latching onto a lead shortwave that gets kicked out
ahead of the primary trough moving out into the central Plains. This
lead wave will combine with some weak waa to bring in some rain
chances during the afternoon. Surface/925 winds progd from the ne so
a cooler day and this is reflected in the 925 thermal pattern with
readings down in the lower single digits celsius. While still above
normal temps in the 40s will have a bite esp with a steady northeast
breeze. Tweaked Superblend guid down a bit to account for the
sustained northeast winds which will keep the eastern areas cooler.

Potent mid level wave will shift ene from the central Plains to the
western Great Lakes. Downstream cyclogenesis will be induced and
result in a fairly strong surface low that is progd to track from IA
to very near the WI/IL border Friday and then off to our east Friday
night. All models show pronounced low level troughing and in some
solutions even a secondary closed circulation in the low levels
which would enhance vertical motion into Friday night as the colder
air sweeps in. Prior to this though, pronounced 850 waa/moist surge
should result in widespread rain and isold TSRA Thursday night.
If surface front can get nudged into srn WI during the day Friday
we could see some sct tsra take shape. The NAM shows potential
for sfc based instab vcnty KENW than the GFS. However latest
model runs suggest better instab likely to be just to our south or
southeast and this lines up with SWODY3 where our far south is in
the Marginal risk. A nudge north would put our far se in a better
zone for stronger storms given the highly dynamical nature of
this system. As colder air wraps in nw-se on Friday night would
expect a changeover in ptypes with some light snow accums esp in
the wrn and nrn CWA. At this time am not including FZRA with this
changeover as the NAM sounding suggests that by the time the
surface temps cool to freezing the dendritic growth zone becomes
saturated. So at this time prefer going with a rain to snow

SATURDAY - Confidence...Medium
Mid level trough axis shifts east though some lingering light
snow/snow showers in a much colder regime that will take temps down
to normal levels or even a bit below. 925 temps will be down to -6c
to -9c with a blustery feel with the nw wind regime.

SUNDAY - Confidence...Low to Medium
Models are all showing a weak mid level wave riding through though
the surface pattern has some model to model variability. The GFS is
the only model that shows qpf while the ECMWF keeps qpf to the north
and the GEM solution is a more southern solution of the GFS. For
now will go with the Superblend pops.

MONDAY - Confidence...Medium
Looks like there is consensus for a dry day with weak ridging
between departed weak system and organizing system in the Plains.

TUESDAY - Confidence...Medium
Another low approaches and this one also looks mainly warm for srn
WI. At this time the GEM is the furthest north with low into cntrl
MN while the GFS and ECMWF suggest more of a track through srn WI.

AVIATION/12Z TAFS/...Main issue will be fog and low stratus trends
into the middle morning hours. Area of dense fog and low stratus
continues to push northeast into the southeast half of the forecast
area this morning. Thus, there may be visibility drops to 1/4
mile and ceilings near airport minimums at times in the southeast
half of the area. This would include Milwaukee, Waukesha and
Kenosha. Madison may see light fog. Fog over the lake may affect
areas close to shore as well into this morning.

After the fog and low stratus dissipate later this morning, expect
mostly sunny skies with increasing south to southwest winds this
afternoon. Winds will weaken and gradually veer to the west and
northwest later tonight, after the passage of a cold front. Should
see some low clouds move southeast into the area later tonight, with
light fog possible.

MARINE...A tightening pressure gradient ahead of an advancing cold
front will bring increasing south to southwest winds this afternoon.
Some gusts to around 20 knots are expected, but gusts to and over
22 knots are not expected at this time. Thus, will not issue a
Small Craft Advisory. Any high waves will be over the open waters
of Lake Michigan.

Strong low pressure moving northeast toward and through the region
Thursday night into Saturday. This will result in a period of gusty
east to southeast winds Thursday night into Friday, then veering to
the west Friday night into Saturday. Frequent gusts of 25 to 30
knots look likely during this time. A few gale force gusts are
possible Thursday night. Increasing waves are expected during this




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