Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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696
FXUS63 KMKX 211643
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1043 AM CST Sat Jan 21 2017

.UPDATE...Based on analysis of satellite trends, observations,
webcams and calls to counties have extended Dense Fog Advisory for
our north and west through 18z Sunday. With improvement noted in
the southeast counties have decided to cancel early there. This
area will be subject to to more fog formation tonight into Sunday
morning so will reassess potential for new headline this afternoon
there. Otherwise it appears rest of southern WI will see little to
no improvement and for just a small window of time.

PC

&&

.AVIATION/18Z TAFS/...Some breaks have worked into the far
southeast resulting in cigs jumping to MVFR levels. Much of the
rest of the area will likely remain in LIFR or VLIFR conditions
both ceiling and visibility-wise. Even the southeast where
improvement has occurred will be vulnerable to being socked back
in tonight as overall flow pattern remains weak with ample low
level moisture. things should collectively improve Sunday once srn
WI gets in on the gradient of passing low to our south. This
should kick in the north winds helping to dry things out.

PC

&&

.MARINE...Dense fog advisory will remain in effect today. Light
onshore flow and even warmer and more humid air moving northward
across southern Lake Michigan will continue to generate dense fog.
Some improvement is possible once low level winds switch to the
south to southwest much later on. Overall, expect mainly light
winds, shifting from an easterly to southerly direction today and
then to a northerly direction on Sunday. Wind speeds Sunday
afternoon and evening will increase, but remain below small craft
advisory levels.

PC

&&

.PREV DISCUSSION... /Issued 323 AM CST Sat Jan 21 2017/

SHORT TERM...

Today and Tonight...Forecast confidence is high.

Clouds, fog, areas of drizzle and scattered showers will be the
main story through the morning hours. An upper level trough and
associated surface low will track to our west today. This will
eventually send a warm front into the region, resulting in mild
temperatures this afternoon and shunting rain chances to our
north. Low level moisture profiles suggest it will be tough to
lose cloud cover, but we should see improvement in visibility as
southerly winds take hold and cloud bases rise. This improvement
looks to be short lived however as low clouds return tonight with
patchy light fog possible. Well above average temperatures are
expected.

Sunday through Monday...Forecast confidence is medium.

We will continue in this cloudy and active weather pattern until
further notice. Low pressure will track along the Ohio River Valley
and brush southeast WI with rain. The 00Z NAM took the precip
farthest west compared to the GFS and ECMWF...but now the 06Z NAM
backed off.

LONG TERM...
Tuesday through Wednesday...Forecast confidence is medium.

The next system to watch is expected to arrive Tue afternoon as low
pressure tracks across IA and nrn IL. Precip will begin as rain, but
change over to snow or a rain/snow mix later Tue night and persist
through Wed. Light snow showers could continue through Wed night.
Surface temperatures will dictate the precip type, as there is no
warm layer aloft.

Models are showing a decent amount of qpf, between 0.25 and 0.50
inch. Because of the mild temperatures, not expecting much snow
accumulation, but 1 to 2 inches toward central WI is not out of the
question.

Thursday and beyond...Forecast confidence is medium.

Cooler cyclonic flow will continue overhead through Friday and
potentially through the weekend. The GFS is colder than the ECMWF.
This will keep clouds in place and the chance for light snow showers
across southern WI.

AVIATION/12Z TAFS/...
Widespread fog will persist across the region through at least
this morning. A warm front will approach from the south as the day
progresses and result in a wind shift to a more southerly
direction. This should result in improving conditions this
afternoon, though IFR/MVFR visibility and ceilings will linger.
Clouds will linger into tonight, with the potential for ceilings
and visibility to lower once again. A cold front passage Sunday
will result in a wind shift to the north.

MARINE...
Dense fog advisory will remain in effect today. Occasional
drizzle and light rain showers will temporarily help improve
visibilities at times, but light onshore flow and even warmer and
more humid air moving northward across southern Lake Michigan will
continue to generate dense fog. Some improvement is possible once
low level winds switch to the south to southwest later on
Saturday and increase. Overall, expect mainly light winds,
shifting from an easterly to southerly direction today and then to
a northerly direction on Sunday. Wind speeds Sunday afternoon and
evening will increase, but remain below small craft advisory
levels.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...DENSE FOG ADVISORY until noon CST Sunday for WIZ046-047-051-052-
     056>060-062-063-067-068.

LM...DENSE FOG ADVISORY until 6 PM CST this evening for LMZ643>646.

&&

$$
TODAY/TONIGHT AND AVIATION/MARINE...Gagan
Sunday THROUGH Friday...MRC



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