Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 231702

Area Forecast Discussion
National Weather Service Green Bay WI
1102 AM CST Fri Feb 23 2018

Updated aviation portion for 18Z TAF issuance

.SHORT TERM...Today...Tonight...and Saturday
Issued at 345 AM CST Fri Feb 23 2018

The combination of an strong upper jet at 500mb and
low level warm advection was producing mixed precipitation across
the region at 09z. There was a lull in the activity during the
late evening and early morning hours, and now there will be a few
hours of steadier precipitation before it ends from southwest to
northeast shorty after sunrise. There is potential for a tenth of
an inch or more of ice across parts of central and east central
Wisconsin with a couple inches of additional snow in the north.

West winds will bring mild and somewhat drier air this afternoon,
with temperatures rising above freezing in most places. Partial
clearing is expected tonight, with the coldest temperatures in the
north where there is fresh snow on the ground. Lows will be within
a few degrees of normal in most places. Clouds will increase
Saturday as the next system approaches. Low level dry air will
probably keep any rain or snow away until Saturday night. Highs
Saturday will be close to normal.

.LONG TERM...Saturday Night Through Thursday
Issued at 345 AM CST Fri Feb 23 2018

Flow aloft is forecast to be out of the southwest for the weekend
and much of next week. This will result in warmer than normal
temperatures and occasional storm systems ejecting out of the
southwest trough and approaching the region.

The main concern during this part of the forecast is the system
that will impact the area Saturday night and Sunday morning.

The 00Z versions of the NAM/GFS/ECMWF/Canadian were much more
consistent than they were the previous couple of days. The GFS
still had the strongest surface low but its track was similar to
those of the other models. This system will bring mainly snow to
north central Wisconsin, with more of a rain, wintry mix or
freezing rain event farther to the south and east. It appears that
parts of north central Wisconsin will receive advisory criteria
snow, and possibly even warning criteria, but will wait for the
winter weather advisory that is currently in effect to expire
before issuing any new headlines. Ice accumulations from the
system are forecast to be 0.1 inch or less.

A system is forecast to pass north of the state during the early
part of the upcoming work week, but the next chance for
precipitation should hold off until Tuesday night. Warm advection
to the northeast of a surface low and a weak mid level short wave
passing through the area will bring precipitation chances back to
central and eastern Wisconsin. Rain will gradually change to snow
as the boundary layer cools during the night. There is another
chance for precipitation late Wednesday night and Thursday ahead
of an approaching surface system and mid level trough. This should
start as snow but rain or a mix of rain and snow is expected later
on Thursday as temperatures warm.

Expect high temperatures to be mostly in the 30s to middle 40s
and lows generally in the 20s.

.AVIATION...for 18Z TAF Issuance
Issued at 1102 AM CST Fri Feb 23 2018

MVFR conditions will continue across the area during the afternoon
hours as an area of clearing and drier air works its way in from
the west. Although some model guidance suggests the low clouds
will remain through the overnight hours, the clearing out to the
west suggests otherwise, therefore will go with the more
optimistic forecast with this issuance and bring VFR conditions
to the TAF sites tonight. Some MVFR fog is possible later tonight,
then high clouds will stream in ahead of the next system
approaching from the west Saturday morning.



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