Area Forecast Discussion
Issued by NWS Green Bay, WI

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786
FXUS63 KGRB 221243
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
643 AM CST Thu Feb 22 2018

Updated aviation portion for 12Z TAF issuance

.SHORT TERM...Today...Tonight...and Friday
Issued at 330 AM CST Thu Feb 22 2018

1040MB surface high centered over the northern Great
Lakes was producing light winds across northeast Wisconsin at 09z.
Where snow was on the ground and skies were clear, it was as cold
as -11F at Land O` Lakes, but where skies were cloudy and there
was little snow it was as warm as 21F at Manitowoc. Mid and high
clouds will increase today as warm advection produces rising
motion in the mid and upper levels. The air is dry near the
surface, so any light snow that can fall from the middle clouds
will likely evaporate before reaching the ground. Highs today will
be 3 to 5 degrees below normal.

Shortwave energy lifting northeast from the central Plains will
provide upper support and enhance the vertical motion from
continued low level warm advection. The models forecast saturation
after 00z this evening, with about two tenths of an inch of water
equivalent to fall as some sort of precipitation tonight and early
Friday. Forecast soundings suggest 2 to 3 inches of snow west of a
Wausau to Iron Mountain line with perhaps some sleet mixed. East
of there there should be more sleet and freezing rain and less
snow, and by the time you get to the lakeshore the boundary layer
could be warm enough for rain.

Will issue winter weather advisories for the entire forecast
area. While this is not going to be a big storm, the precipitation
could produce hazardous travel for the morning commute to work or
school Friday. Temperatures tonight will only fall a few degrees
from todays highs due to cloud cover and increasing winds. The
precipitation should end before midday friday, with mild modified
Pacific air allowing temperatures to rise about 5 degrees above
normal with gusty west winds.

.LONG TERM...Friday Night Through Wednesday
Issued at 330 AM CST Thu Feb 22 2018

Flow aloft is forecast to be from the southwest or zonal
throughout this part of the forecast. This will result in above
normal temperatures and at least one major system impacting the
area.

The 00Z versions of the NAM and GFS were similar in their handling
of the next major system, coming up this weekend, while the ECMWF
and Canadian have a weaker surface low tracking farther to the
south. The warm air wrapped around the system makes the
precipitation type forecast a challenge once again. There is a
chance for rain or snow in central Wisconsin Saturday afternoon,
and a slight chance farther east and north. Precipitation will
spread across the rest of the area Saturday night with snow in the
north, rain in the south, and freezing rain/a wintry mix between
the two. Freezing rain chances spread across more of the area
later in the night but there is only a chance for light snow in
the north Sunday morning. Snowfall totals in the far north look
like they will exceed 6 inches but the southern part of the
forecast area may see little snow. Ice accumulation is possible
west and north of the Fox Valley. Forecast confidence is low to
medium for this system based on differing model solutions.

Warm advection associated with a surface low over the Plains, and
an approaching mid level short wave bring a chance for snow and/or
rain to the southern part of the area. Otherwise, mainly dry
weather can be expected through midweek.
&&

.AVIATION...for 12Z TAF Issuance
Issued at 643 AM CST Thu Feb 22 2018

VFR conditions should prevail through the daylight
hours. Ceilings and visibilities will fall from west to east this
evening as a mixture of snow, sleet and freezing rain move in ahead
of a strong upper level disturbance. Challenging flying conditions
are expected overnight and early Friday due to IFR conditions and
wintry precipitation. A few inches of snow are likely west of a
Wausau to Crivitz line, while a mixture of sleet, freezing rain
and snow are expected further east. Conditions will improve by
Friday afternoon as drier air moves in on gusty west winds.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 9 PM this evening to 9 AM CST
Friday for WIZ005-010>013-018>022-038>040-048>050-073-074.

Winter Weather Advisory from 6 PM this evening to 9 AM CST
Friday for WIZ030-031-035>037-045.
&&

$$

SHORT TERM.....RDM
LONG TERM......MG
AVIATION.......RDM



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