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fxus63 kgrb 172051 

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

Forecast discussion for routine afternoon forecast 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 18z taf issuance
issued at 1131 am CST sun Nov 17 2019

Widespread MVFR/IFR cigs exist from north-central WI
to the eastern Dakotas early this afternoon. Scattered snow
showers will locally drop visibilities to IFR as well over central
and north-central WI this afternoon. Otherwise, should see vsbys
and cigs continue to deteriorate as a weak front passes across
other region.

The precipitation should taper off to scattered drizzle or
freezing drizzle in the early evening and then end before
midnight. IFR conditions will continue into the evening hours and
then there will be a slow rise in conditions to MVFR in most
areas overnight.

MVFR ceilings are expected Monday, with possible improvement to
VFR in the afternoon.

Grb watches/warnings/advisories...

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