Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
FXUS63 KMKX 212057
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
257 PM CST Sat Jan 21 2017
TONIGHT AND THURSDAY... Forecast confidence is medium.
The main uncertainty for tonight is sky cover. Skies managed to
clear across much of central WI and now southern WI. We should have
mainly clear skies by dark, except for far southern WI where there
will just be breaks in the clouds. The dark is going to do one of
two things. It is going to strengthen the inversion and the
lingering low level moisture that is trapped will be enough for a
low stratus deck again, OR the drier air will win and keep skies
clear with a lack of mixing beneath the inversion.
Winds will diminish overnight. The strong inversion and lingering
low level moisture support yet another night of low clouds and areas
of fog. There could be dense spots again, but probably not
it will take a while for the low clouds and fog to erode away Thu
morning. Mid level clouds will spread in just as the low clouds are
dissipating, so not a lot of sunshine expected, especially toward
the IL border. Warmer air will be working into southern WI ahead of
the approaching system, so highs in the lower 40s are expected.
Sunday Night and Monday...Forecast confidence is medium.
A strong shortwave from the Ohio Valley to the southeast U.S.
moves to the east as a large trough moves into the Western U.S.
A strong surface low will track across Kentucky to the mid
Atlantic states with the northern precipitation shield extending
just to our east.
Tuesday and Wednesday...Forecast confidence is medium.
The western U.S. trough pushes into the Plains Tuesday with an
upper level low across southern Wisconsin Wednesday morning.
The ECMWF has trended north toward the GFS track, but is a slower.
The precipitation from this next system is expected to arrive
Tuesday afternoon on the GFS, with the 12Z ECMWF a little slower.
Precipitation will begin as rain or a rain/snow mix most areas,
with some snow potential in areas mainly north of Madison and
Port Washington. The precipitation will change over to a rain/snow
mix or mainly snow later Tuesday night and persist through
Wednesday. Light snow could continue through Wed night. Boundary
layer temperatures will dictate the precip type.
Models are showing a decent amount of qpf, especially the GFS
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 through Friday...Forecast confidence is medium.
The upper trough lingers across the Upper Midwest.
Cooler cyclonic flow will continue. This will keep clouds in
place and the chance for light snow showers or flurries across
Saturday...Forecast confidence is medium.
The upper trough moves off to the eastern Great Lakes with a
northwest upper flow across southern Wisconsin. We will continue
to be in a rather cold northwest flow in the lower levels.
The low clouds cleared out of central WI all the way down to MSN.
Clouds in southern WI will have some breaks around dark. The
question is whether or not the clouds will fill back in this
There is a better chance of low clouds and fog developing once
again late tonight and taking a while to erode Thu morning. Ceilings
will be below 1000 feet, and likely below 500 feet toward morning.
Rain will spread into southern WI from sw to ne early Thu evening
and persist through the night.
Southwest winds will gradually diminish overnight, become southerly
Thu, and easterly Fri. Conditions are expected to remain below small
craft advisory levels through the remainder of the week.&&
WI...DENSE FOG ADVISORY until noon CST Sunday for WIZ046-047-051-052-
LM...DENSE FOG ADVISORY until midnight CST tonight for LMZ643-644.
TONIGHT/Sunday AND AVIATION/MARINE...Collar
Sunday NIGHT THROUGH Saturday...Hentz