Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 250818

Area Forecast Discussion
National Weather Service Green Bay WI
318 AM CDT Thu Apr 25 2019

Forecast discussion for routine morning forecast issuance

.SHORT TERM...Today...Tonight...and Friday
Issued at 318 AM CDT Thu Apr 25 2019

A weak cold front continues to slowly makes its way through the
western Great Lakes early this morning. The front was currently
located across northwest Wisconsin and will sweep through the
area later this morning and into the early afternoon hours. The
front will bring thickening clouds and isolated showers given the
weak forcing and lift associated with the system this morning.
Showers may become scattered this afternoon across central,
northeast and east-central Wisconsin as a mid level shortwave
tracks through the western Great Lakes area. Some lingering
showers are possible across east-central Wisconsin and the
lakeshore this evening as this shortwave continues to track
through and a secondary cold front sweeps through the region.

Behind this cold front a ridge of high pressure will build in
across the upper Mississippi Valley on Friday, keeping the weather

Highs today will mainly be in the 60s with lows tonight in the
middle 30s to lower 40s. Highs Friday will range from the lower
50s across the north, with highs around 60 across east-central and
northeast Wisconsin.

.LONG TERM...Friday Night Through Wednesday
Issued at 318 AM CDT Thu Apr 25 2019

Forecast concerns generally revolve around the details with a storm
system that is projected to impact the region early this weekend. In
general, models are more tightly clustered with the track and
intensity of the surface low, which is forecast to move across Iowa
and central Illinois on Saturday afternoon and Saturday evening.
Will use a blend of the gfs and ecmwf given their better agreement.
However, the model spread remains quite large with the details for
early next week, so will have to stick with a general model blend
for later periods.

Friday night through Saturday night...An area of low pressure will
be moving across the central Plains on Friday night. Clouds will be
on the increase ahead of the system from late evening into the
overnight from west to east.  But with the surface high stretching
across northeast WI and a very dry airmass ahead of the storm
system, will stick with a dry forecast.  This dry air will play a
role in regards to how far north the precip reaches on Saturday. But
the latest indications suggest precip will start to overwhelm the
dry air over central WI from mid to late morning before spreading
across east-central and possibly northeast WI in the afternoon.  The
strongest forcing via mid-level fgen on the nose of a 45 kt low
level jet is expected to just clip areas from Wood to Manitowoc
counties.  Max wet bulb temps aloft are forecast to be within a
degree or two of freezing within the heaviest precip from late
morning through early evening, so ptype will be strongly influenced
by boundary layer temps.  Given surface temps ranging from the mid
to upper 30s, a rain snow mix looks likely, with some accumulations
(perhaps an inch or two?) possible on grassy surfaces. Accumulations
on roads will be rather difficult given the time of day of the
heaviest precip and the very high sun angle.  The precip will be
exiting in the evening, with dry air reasserting itself through the
night, leading to clearing skies overnight. Highs on Saturday will
be the coolest over the period, and range from the mid 30s to low

Rest of the forecast...High pressure will provide dry and cool
conditions on Sunday.  Then shortwave energy will push an inverted
surface trough towards the area on Monday and Monday night, which
possibly could linger into Tuesday.  Precip chances will remain on
the lower side given the model spread. How far south the front
stalls thereafter will help determine how quickly the threat of
precip returns during the middle to end of next week.

.AVIATION...for 06Z TAF Issuance
Issued at 1039 PM CDT Wed Apr 24 2019

Anticipate mainly just mid and high clouds across northeast WI
tonight as a cold front gradually approaches from the northwest.
Not much precipitation expected tonight into early Thursday;
however, Thursday afternoon light rain may become more widespread
across the southeastern TAF sites with intermittent MVFR
conditions possible. The rain will slowly diminish by Thursday
evening, allowing for improved flying conditions.

Issued at 318 AM CDT Thu Apr 25 2019

Rivers and streams across northeast WI remain at high levels.
This includes high flows in and around area dams as excess water
is being released from earlier rainfall and snowmelt. While light
rain is expected today and this evening, amounts should not
impact current river levels. Please monitor the latest river
forecasts for further information on flooding in your local area.



SHORT TERM.....Kurimski
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