Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 171144

Area Forecast Discussion
National Weather Service Green Bay WI
544 AM CST Wed Jan 17 2018

Updated aviation portion for 12Z TAF issuance

.SHORT TERM...Today...Tonight...and Thursday
Issued at 356 AM CST Wed Jan 17 2018

Blowing snow will be the main concern today, as increasing southwest
winds blow around the fresh snow that fell Sunday night through Monday
night. A foot or more of snow fell across the lakeshore counties, so
that`s where the greatest potential for significant blowing and drifting
snow will be.

Decided to issue a winter weather advisory for Door county, which
is typically windy and has as much as two feet of powdery snow on
the ground and adjacent frozen bay. Travel on north south roads such
as highways 42 and 57 cold become difficult this afternoon and early
evening. Elsewhere drifting snow and some blowing snow is expected
in rural areas.

Warm advection should make for near normal high temperatures today,
despite considerable cloud cover. Steady temperatures are expected
tonight with a wind and continued warm advection. A small clipper
system should pass north of Wisconsin Thursday, but limited moisture
should keep it from producing any snow here. Highs will be above

.LONG TERM...Thursday Night Through Tuesday
Issued at 356 AM CST Wed Jan 17 2018

The main forecast concern revolves around the potential of a cyclone
to pass across the region late in the weekend into early next week.
The gfs and canadian models have trended north with the track of the
cyclone over the past 24 hours, while the ecmwf has trended further
south.  Prefer a track more similar to the gfs ensemble mean, which
is a decent compromise between the operational gfs and canadian.

Thursday night through Friday night...As a shortwave trough exits to
the east on Thursday night, should see any lingering clouds over
northern WI depart during the evening or early overnight.
Thereafter, will see periods of broken mid and high clouds overhead
for the rest of Thursday night into Friday night.  Southwest winds
will be gusty on Friday, though they will continue to bring in
warmer air.  Highs on Friday should reach into the mid and upper
30s.  Winds remain breezy on Friday night so temps should not fall

Rest of the forecast....Low pressure will be emerging from the
Rockies on Saturday, but still looks too far away for any impacts on
our weather.  Should see mid and high clouds become overcast through
the day though.  Low level moisture doesn`t arrive until Saturday
night as a warm front lifts into southern WI.  Light precip appears
possible then (wintry mix or freezing drizzle?), but heavier precip
is due to arrive on Sunday as low pressure moves into the mid-
Mississippi Valley. The heavy precip will then continue for Sunday
night into Monday before ending on Monday night.  The track of the
cyclone will play a large role in determining which locations see
heavy snow versus a wintry mix, and expect to see some adjustments
over the coming days.  Even a slight change of the track could make
a huge difference in the forecast weather.

.AVIATION...for 12Z TAF Issuance
Issued at 544 AM CST Wed Jan 17 2018

VFR conditions expected in most areas through midday
Friday. Gusty southwest surface winds should produce blowing and
drifting snow today through this evening, especially near the lake
and bay. The blowing snow could reduce visibility to IFR range at
K2P2, K3D2, and KSUE for awhile this afternoon and evening. A
clipper system may bring some MVFR ceilings to far northern
Wisconsin Thursday afternoon, but little or no snow is expected.

Winter Weather Advisory from 9 AM this morning to 9 PM CST this
evening for WIZ022.


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