Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 171817 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
1217 PM CST Tue Jan 17 2017

.UPDATE...

The winter weather advisory was allowed to expire at noon. Air
temperatures and pavement temperatures will hover above freezing.
Look for patchy fog through the afternoon and expect some
slippery spots on roads, especially secondary roads. A special
weather statement will handle this for the afternoon.

Light showers will continue off and on through the afternoon due
to a weak shortwave slowly tracking across the region.

&&

.AVIATION/18Z TAFS/...

Low ceilings will persist through the night and gradually improve
Wed morning as clouds scour out. There should be a round of light
showers that track through southern WI late this afternoon into
the early evening. Look for temperatures to drop below freezing
after the rain ends, but wet pavement will be at risk for freezing
once again. Dry weather for the remainder of the TAF period.

&&

.MARINE...

Offshore winds are helping to mix out the fog in the nearshore
waters. The marine dense fog advisory was allowed to expire.

&&

.PREV DISCUSSION... /Issued 343 AM CST Tue Jan 17 2017/

TODAY AND TONIGHT...Forecast Confidence Is Medium.

Strong 500 mb shortwave trough helping drive area of mainly rain
northeastward through the eastern portions of the area. There may
still be some light freezing rain mixed in with the rain across
northern portions of the forecast area, where air and pavement
temperatures are still near freezing. The shortwave trough and the
associated precipitation is expected to move out of the area by
around 12Z to 13Z. Areas of fog will linger as well into this
morning, with dense fog possible in localized areas.

For now, will continue the Winter Weather Advisory as is, until the
precipitation moves out of the area. Some uncertainty with how to
handle the headlines after this point. The south half of the area
expires at 12Z, and the north half at 15Z.

The pavement temperatures are still near freezing across most of the
area, except perhaps the far southeast counties. This should
continue the risk for icing on untreated roads early this morning,
which could affect those on the morning commute. Treated roads
should be fine.

Another 500 mb shortwave trough is expected to slide southeast
through the area this afternoon, exiting this evening. This feature
may bring another shot at some light rain. Temperatures will be in
the mid to upper 30s, with pavement temperatures rising above
freezing, so not expecting any issues with icing this afternoon.

Low clouds should linger today into this evening, before slowly
scattering out across the area later tonight. Lows tonight are
expected to drop into the mid to upper 20s.

WEDNESDAY - Confidence...Medium
Mid level ridging will be dominant with a mild west then southerly
flow setting up which pushes 850 temps well into positive territory
celsius. So expecting temps to get close to 40.

THURSDAY - Confidence...Medium
The mild flow continues with sfc/850 ridging extending back into WI
from the OH Vly. Starting to see a little uptick in moisture from
the south but any precip assoc with this remains to our south. the
models are all showing a large 500 millibar low spinning across the
central Plains with some weak vort lobes extending into WI.
Bufkit soundings show the column remaining dry. the GFS and ECMWF
do show some weak 850 moisture advection though llvl rh panels
keep the better moisture still off to our south.

FRIDAY THROUGH MONDAY - Confidence...Medium
An active 500 millibar flow pattern this period but mild January
temperatures are expected to persist as well. The 500 low in the
central Plains is proggd to get kicked out and become sheared by
upstream system moving into the Rockies. So we should see an uptick
in forcing on Friday though some question on how much as this energy
does weaken. The Euro a little more robust on this than the GFS. The
kicker system then gets kicked into the northern Plains with some
lift from this feature affecting the area with more rain chances.
This last system is then expected to continue through the srn/cntrl
Plains and develop further into the OH Vly for Monday. All the while
the above normal temps will persist with periodic rain chances.

AVIATION/12Z TAFS/...Mainly rain will move northeast of the area
by 12Z to 13Z this morning, with a passing trough of low pressure.
Pavement temperatures may remain near freezing into the morning
hours, which may still result in icy conditions on runways. The
far southeast counties may be warm enough for runway icing to not
be as much of an issue as elsewhere.

Low ceilings and visibilities, below alternate minimums and
approaching airport minimums, are expected to linger today into this
evening. Some dense fog may occur in localized areas this morning.
Winds are expected to remain rather light during this time, backing
north to northwest today into this evening, and west by later
tonight.

MARINE...Dense Fog Advisory was expanded for all of the nearshore
waters of Lake Michigan. Sheboygan airport reported 1/2 mile
visibilities with east northeast winds, so lake likely has similar
values. This advisory lasts until 15Z this morning, and may need
to be extended a bit further, until winds shift to the northwest
this afternoon and mix things up.

&&

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

$$

UPDATE...MRC
TODAY/TONIGHT AND AVIATION/MARINE...Wood
Wednesday THROUGH Monday...Collar



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