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fxus63 kgrb 180020 

Area forecast discussion
National Weather Service Green Bay WI
620 PM CST sun Nov 17 2019

Updated aviation portion for 00z taf issuance

Short term...tonight and Monday
issued at 251 PM CST sun Nov 17 2019

The latest rap analysis and satellite/radar imagery show an upper
trough moving across the northern Mississippi Valley early this
afternoon. This trough is pushing an occluded front across
Wisconsin, with areas of light precip occurring along the front.
After receiving 1 to 3 inches over parts of north-central WI this
morning, most of the light precip, including snowfall, has been
diminishing across the region. Patchy drizzle and freezing drizzle
have been showing up at times on area radars and surface obs over
northwest/north-central WI as mid-level moisture departs. Because
of previous snowfall and Road temps above freezing, don't think
freezing drizzle will have much impact through the afternoon.
Another area of rain is surging northeast over southern WI, and
should move into east-central WI later this afternoon. Looking
further west, widespread low overcast prevails all the way to the
eastern Dakotas. As the front continues to move east across the
area, forecast concerns revolve around potential for freezing
drizzle/mist followed by cloud cover.

Tonight...the front will slowly move east across north-central WI
in the evening and northeast WI overnight. Steady light rain,
possibly mixed with snow, will depart east-central WI early this
evening. But forecast soundings indicate that the surface to
800mb layer will remain saturated along the front, so think
potential for drizzle and freezing drizzle will persist through
much of the evening. With cooling temperatures and loss of solar
insolation, the freezing drizzle may cause slippery spots may
develop on untreated roadways. Any wet roads may also develop some
black ice as temps fall below freezing. Otherwise, expect a low
overcast cloud deck to persist through the night, with not much of
a fall of temperatures. Lows ranging from the middle 20s to the
low 30s.

Monday...widespread low clouds will continue into the morning. As
the surface ridge axis approaches during the afternoon, may see
some holes in the overcast develop, but not expecting much in the
way of clearing. Will only see a small rise in temps into the
middle to upper 30s.

Long term...Monday night through Sunday
issued at 251 PM CST sun Nov 17 2019

Mostly cloudy skies and generally dry conditions are anticipated
as a ridge of high pressure moves through Monday evening. A warm
front will impact the forecast area late Monday night into
Tuesday morning, but moisture and deep saturation will be limited.
Have raised pops to chance category, and gone with a light mix of
snow and freezing drizzle. Roads may be slippery in spots for the
Tuesday morning commute.

A stronger low pressure system is expected to arrive Wednesday
night into Thursday, and the GFS/European model (ecmwf) have come into better
agreement on a track through southeast Wisconsin. Low-level
thermal profiles and thicknesses would suggest rain across all but
the far northwest part of grb County Warning Area by early Thursday, with the
rain/snow line pushing southeast across all of north central WI
Thursday morning. Could see 1 to 3 inches of accumulation in
our northwest counties before the system pulls out midday
Thursday. Farther southeast, a good slug of moisture, with pwats
exceeding 1 inch, will lead to moderate rainfall late Wednesday
night into Thursday morning, with rainfall totals possibly
reaching a half to three-quarters of an inch. With frost depths
already at 6 inches or more, runoff from the rain could cause
minor flooding issues. Have bumped up pops to likely/categorical
over the entire forecast area.

As the low pressure system exits, there will be potential for a
brief period of light lake effect snow showers over north central
WI Thursday night.

Models have come into better agreement for the weekend, with dry
northwest flow and a storm track remaining north of the forecast
area. Looks like a generally dry weekend, with temperatures near
seasonal normals.

Aviation...for 00z taf issuance
issued at 620 PM CST sun Nov 17 2019

A mix of LIFR/IFR/MVFR ceilings and visibilities were found across the area
during the early evening hours, with the poorest conditions across
central and north central WI, as a weak front crosses the state.
A wintry mix was also pushing across the area. Look for these poor
flying conditions to continue through the evening hours with a mix
of light snow, drizzle and freezing drizzle continuing. However,
as the front exits the area later this evening, ceilings/vsbys are
expected to slowly improve from west to east overnight into
Monday morning, but conditions look to remain MVFR through at
least Monday morning. Ceilings will climb close to or possibly into
low-end VFR range Monday afternoon. Winds will remain on the
light side through the taf period.

Grb watches/warnings/advisories...

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