Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 171115
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
515 AM CST Sun Dec 17 2017

.UPDATE...

Forecast appears to be on track at this hour, with temperatures
holding steady in the low 30s. Widespread low stratus will
continue all day in most locations.

&&

.AVIATION(12Z TAFS)...

Widespread IFR ceilings will remain in place across the region
for the next 24 hours. Patchy light fog will also be possible at
times. KENW and perhaps KMKE may briefly scatter out this
afternoon, but any improvement will be brief, with ceilings
filling back in as the sun begins to set.

IFR is likely tonight, with some guidance indicating LIFR
ceilings.

Winds will be light from the east today, eventually becoming light
and variable, and then light from the west late tonight and
tomorrow.

&&

.PREV DISCUSSION... (Issued 146 AM CST Sun Dec 17 2017)

DISCUSSION...

Early this Morning through Tonight...Forecast Confidence is
High...

Widespread low stratus continues across the region early this
morning. A few areas of fog have also formed, though thus far,
have not seen any observations of particularly low visibility. At
least patchy fog will remain possible through sunrise.

For the most part, the area should remain socked in under low
stratus for most of the day today. A few areas of clearing are
possible this afternoon along the Illinois state line and the
Lake Michigan shore, but overall, that should be exception rather
than rule. Temperatures will gradually warm into the mid to upper
30s across the southern forecast area, but further north, look to
mainly hold steady in the low 30s.

Widespread cloud cover will continue tonight, with lows falling
into the upper 20s to around 30 degrees.

Monday and Tuesday - Confidence...Medium
Quiet and mild stretch continues. Will have to keep an eye on
cloud cover and impact on highs both days though progs suggest a
decreasing trend in LLVL RH for Monday and with an uptick in
southwest flow off the deck any mixing will give the temps a good
boost. Cold front passes to the southeast on Tuesday and winds
shift to the northwest though thermal pattern in the wake of the
front still suggests temps in the mid 30s northwest to low or mid
40s southeast.

Wednesday and Wednesday night - Confidence...Medium
Surface ridge axis will shift off to our east this period with an
850 millibar return flow setting up on Wednesday through Wednesday
night. Best isentropic ascent is setting up across northern or
central WI. So will carry only the small light snow blended pops
in the far northern cwa.

Thursday and Friday - Confidence...Low to Medium
The 00z model runs show that the system is trending warmer for
srn WI. Especially the Euro which brings a pronounced warm surge
into the area that could keep precip liquid longer through
Thursday night with only a changeover to a little light snow for
Friday. Meanwhile the GFS drops the colder air further south into
srn WI quicker on Thursday night with more potential for
accumulating snow than the Euro. The tracks of the surface and 850
features are also not favorable ones for siggy snow in our area,
but with several days to go and potential for still some run to
run variability, this system continues to bear watching.

Friday night and Saturday - Confidence...Medium
Cold air will pour into srn wi in the wake of this system. 925
temps will drop to -11c to -14c with a blustery northwest wind.
With any snowcover that sets up with the Thurs night/Friday system
will likely need to start trending below blended temps.

AVIATION(09Z TAFS)...IFR conditions will continue through the
day today. A brief scattering of the stratus is possible at KMKE
and KENW this afternoon, but confidence in that occurring is low.

Widespread IFR ceilings are expected tonight, though some
guidance is suggesting that cigs could approach LIFR in some
cases.

Winds will be light through the period, with easterly flow today
becoming westerly tonight.

MARINE...Fairly quiet conditions are expected across the nearshore
waters today into Monday, with light easterly winds today becoming
light from the west tonight. 2-3 ft waves today will diminish to
a foot or less tonight.

Southwest winds will increase Monday night into Tuesday, when a
Small Craft Advisory may eventually be needed.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&

$$

Update...Boxell
Today/Tonight and Aviation/Marine...Boxell
Monday THROUGH Saturday...Collar



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